Commit | Line | Data |
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20c8ccb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
86039bd3 AA |
2 | /* |
3 | * fs/userfaultfd.c | |
4 | * | |
5 | * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org> | |
6 | * Copyright (C) 2008-2009 Red Hat, Inc. | |
7 | * Copyright (C) 2015 Red Hat, Inc. | |
8 | * | |
86039bd3 AA |
9 | * Some part derived from fs/eventfd.c (anon inode setup) and |
10 | * mm/ksm.c (mm hashing). | |
11 | */ | |
12 | ||
9cd75c3c | 13 | #include <linux/list.h> |
86039bd3 | 14 | #include <linux/hashtable.h> |
174cd4b1 | 15 | #include <linux/sched/signal.h> |
6e84f315 | 16 | #include <linux/sched/mm.h> |
86039bd3 | 17 | #include <linux/mm.h> |
17fca131 | 18 | #include <linux/mm_inline.h> |
6dfeaff9 | 19 | #include <linux/mmu_notifier.h> |
86039bd3 AA |
20 | #include <linux/poll.h> |
21 | #include <linux/slab.h> | |
22 | #include <linux/seq_file.h> | |
23 | #include <linux/file.h> | |
24 | #include <linux/bug.h> | |
25 | #include <linux/anon_inodes.h> | |
26 | #include <linux/syscalls.h> | |
27 | #include <linux/userfaultfd_k.h> | |
28 | #include <linux/mempolicy.h> | |
29 | #include <linux/ioctl.h> | |
30 | #include <linux/security.h> | |
cab350af | 31 | #include <linux/hugetlb.h> |
5c041f5d | 32 | #include <linux/swapops.h> |
2d5de004 | 33 | #include <linux/miscdevice.h> |
40f45fe8 | 34 | #include <linux/uio.h> |
86039bd3 | 35 | |
2d337b71 Z |
36 | static int sysctl_unprivileged_userfaultfd __read_mostly; |
37 | ||
38 | #ifdef CONFIG_SYSCTL | |
39 | static struct ctl_table vm_userfaultfd_table[] = { | |
40 | { | |
41 | .procname = "unprivileged_userfaultfd", | |
42 | .data = &sysctl_unprivileged_userfaultfd, | |
43 | .maxlen = sizeof(sysctl_unprivileged_userfaultfd), | |
44 | .mode = 0644, | |
45 | .proc_handler = proc_dointvec_minmax, | |
46 | .extra1 = SYSCTL_ZERO, | |
47 | .extra2 = SYSCTL_ONE, | |
48 | }, | |
2d337b71 Z |
49 | }; |
50 | #endif | |
cefdca0a | 51 | |
68279f9c | 52 | static struct kmem_cache *userfaultfd_ctx_cachep __ro_after_init; |
3004ec9c | 53 | |
893e26e6 PE |
54 | struct userfaultfd_fork_ctx { |
55 | struct userfaultfd_ctx *orig; | |
56 | struct userfaultfd_ctx *new; | |
57 | struct list_head list; | |
58 | }; | |
59 | ||
897ab3e0 MR |
60 | struct userfaultfd_unmap_ctx { |
61 | struct userfaultfd_ctx *ctx; | |
62 | unsigned long start; | |
63 | unsigned long end; | |
64 | struct list_head list; | |
65 | }; | |
66 | ||
86039bd3 | 67 | struct userfaultfd_wait_queue { |
a9b85f94 | 68 | struct uffd_msg msg; |
ac6424b9 | 69 | wait_queue_entry_t wq; |
86039bd3 | 70 | struct userfaultfd_ctx *ctx; |
15a77c6f | 71 | bool waken; |
86039bd3 AA |
72 | }; |
73 | ||
74 | struct userfaultfd_wake_range { | |
75 | unsigned long start; | |
76 | unsigned long len; | |
77 | }; | |
78 | ||
22e5fe2a NA |
79 | /* internal indication that UFFD_API ioctl was successfully executed */ |
80 | #define UFFD_FEATURE_INITIALIZED (1u << 31) | |
81 | ||
82 | static bool userfaultfd_is_initialized(struct userfaultfd_ctx *ctx) | |
83 | { | |
84 | return ctx->features & UFFD_FEATURE_INITIALIZED; | |
85 | } | |
86 | ||
d61ea1cb PX |
87 | static bool userfaultfd_wp_async_ctx(struct userfaultfd_ctx *ctx) |
88 | { | |
89 | return ctx && (ctx->features & UFFD_FEATURE_WP_ASYNC); | |
90 | } | |
91 | ||
2bad466c PX |
92 | /* |
93 | * Whether WP_UNPOPULATED is enabled on the uffd context. It is only | |
94 | * meaningful when userfaultfd_wp()==true on the vma and when it's | |
95 | * anonymous. | |
96 | */ | |
97 | bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma) | |
98 | { | |
99 | struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx; | |
100 | ||
101 | if (!ctx) | |
102 | return false; | |
103 | ||
104 | return ctx->features & UFFD_FEATURE_WP_UNPOPULATED; | |
105 | } | |
106 | ||
ac6424b9 | 107 | static int userfaultfd_wake_function(wait_queue_entry_t *wq, unsigned mode, |
86039bd3 AA |
108 | int wake_flags, void *key) |
109 | { | |
110 | struct userfaultfd_wake_range *range = key; | |
111 | int ret; | |
112 | struct userfaultfd_wait_queue *uwq; | |
113 | unsigned long start, len; | |
114 | ||
115 | uwq = container_of(wq, struct userfaultfd_wait_queue, wq); | |
116 | ret = 0; | |
86039bd3 AA |
117 | /* len == 0 means wake all */ |
118 | start = range->start; | |
119 | len = range->len; | |
a9b85f94 AA |
120 | if (len && (start > uwq->msg.arg.pagefault.address || |
121 | start + len <= uwq->msg.arg.pagefault.address)) | |
86039bd3 | 122 | goto out; |
15a77c6f AA |
123 | WRITE_ONCE(uwq->waken, true); |
124 | /* | |
a9668cd6 PZ |
125 | * The Program-Order guarantees provided by the scheduler |
126 | * ensure uwq->waken is visible before the task is woken. | |
15a77c6f | 127 | */ |
86039bd3 | 128 | ret = wake_up_state(wq->private, mode); |
a9668cd6 | 129 | if (ret) { |
86039bd3 AA |
130 | /* |
131 | * Wake only once, autoremove behavior. | |
132 | * | |
a9668cd6 PZ |
133 | * After the effect of list_del_init is visible to the other |
134 | * CPUs, the waitqueue may disappear from under us, see the | |
135 | * !list_empty_careful() in handle_userfault(). | |
136 | * | |
137 | * try_to_wake_up() has an implicit smp_mb(), and the | |
138 | * wq->private is read before calling the extern function | |
139 | * "wake_up_state" (which in turns calls try_to_wake_up). | |
86039bd3 | 140 | */ |
2055da97 | 141 | list_del_init(&wq->entry); |
a9668cd6 | 142 | } |
86039bd3 AA |
143 | out: |
144 | return ret; | |
145 | } | |
146 | ||
147 | /** | |
148 | * userfaultfd_ctx_get - Acquires a reference to the internal userfaultfd | |
149 | * context. | |
150 | * @ctx: [in] Pointer to the userfaultfd context. | |
86039bd3 AA |
151 | */ |
152 | static void userfaultfd_ctx_get(struct userfaultfd_ctx *ctx) | |
153 | { | |
ca880420 | 154 | refcount_inc(&ctx->refcount); |
86039bd3 AA |
155 | } |
156 | ||
157 | /** | |
158 | * userfaultfd_ctx_put - Releases a reference to the internal userfaultfd | |
159 | * context. | |
160 | * @ctx: [in] Pointer to userfaultfd context. | |
161 | * | |
162 | * The userfaultfd context reference must have been previously acquired either | |
163 | * with userfaultfd_ctx_get() or userfaultfd_ctx_fdget(). | |
164 | */ | |
165 | static void userfaultfd_ctx_put(struct userfaultfd_ctx *ctx) | |
166 | { | |
ca880420 | 167 | if (refcount_dec_and_test(&ctx->refcount)) { |
86039bd3 AA |
168 | VM_BUG_ON(spin_is_locked(&ctx->fault_pending_wqh.lock)); |
169 | VM_BUG_ON(waitqueue_active(&ctx->fault_pending_wqh)); | |
170 | VM_BUG_ON(spin_is_locked(&ctx->fault_wqh.lock)); | |
171 | VM_BUG_ON(waitqueue_active(&ctx->fault_wqh)); | |
9cd75c3c PE |
172 | VM_BUG_ON(spin_is_locked(&ctx->event_wqh.lock)); |
173 | VM_BUG_ON(waitqueue_active(&ctx->event_wqh)); | |
86039bd3 AA |
174 | VM_BUG_ON(spin_is_locked(&ctx->fd_wqh.lock)); |
175 | VM_BUG_ON(waitqueue_active(&ctx->fd_wqh)); | |
d2005e3f | 176 | mmdrop(ctx->mm); |
3004ec9c | 177 | kmem_cache_free(userfaultfd_ctx_cachep, ctx); |
86039bd3 AA |
178 | } |
179 | } | |
180 | ||
a9b85f94 | 181 | static inline void msg_init(struct uffd_msg *msg) |
86039bd3 | 182 | { |
a9b85f94 AA |
183 | BUILD_BUG_ON(sizeof(struct uffd_msg) != 32); |
184 | /* | |
185 | * Must use memset to zero out the paddings or kernel data is | |
186 | * leaked to userland. | |
187 | */ | |
188 | memset(msg, 0, sizeof(struct uffd_msg)); | |
189 | } | |
190 | ||
191 | static inline struct uffd_msg userfault_msg(unsigned long address, | |
d172b1a3 | 192 | unsigned long real_address, |
a9b85f94 | 193 | unsigned int flags, |
9d4ac934 AP |
194 | unsigned long reason, |
195 | unsigned int features) | |
a9b85f94 AA |
196 | { |
197 | struct uffd_msg msg; | |
d172b1a3 | 198 | |
a9b85f94 AA |
199 | msg_init(&msg); |
200 | msg.event = UFFD_EVENT_PAGEFAULT; | |
824ddc60 | 201 | |
d172b1a3 NA |
202 | msg.arg.pagefault.address = (features & UFFD_FEATURE_EXACT_ADDRESS) ? |
203 | real_address : address; | |
204 | ||
7677f7fd AR |
205 | /* |
206 | * These flags indicate why the userfault occurred: | |
207 | * - UFFD_PAGEFAULT_FLAG_WP indicates a write protect fault. | |
208 | * - UFFD_PAGEFAULT_FLAG_MINOR indicates a minor fault. | |
209 | * - Neither of these flags being set indicates a MISSING fault. | |
210 | * | |
211 | * Separately, UFFD_PAGEFAULT_FLAG_WRITE indicates it was a write | |
212 | * fault. Otherwise, it was a read fault. | |
213 | */ | |
86039bd3 | 214 | if (flags & FAULT_FLAG_WRITE) |
a9b85f94 | 215 | msg.arg.pagefault.flags |= UFFD_PAGEFAULT_FLAG_WRITE; |
86039bd3 | 216 | if (reason & VM_UFFD_WP) |
a9b85f94 | 217 | msg.arg.pagefault.flags |= UFFD_PAGEFAULT_FLAG_WP; |
7677f7fd AR |
218 | if (reason & VM_UFFD_MINOR) |
219 | msg.arg.pagefault.flags |= UFFD_PAGEFAULT_FLAG_MINOR; | |
9d4ac934 | 220 | if (features & UFFD_FEATURE_THREAD_ID) |
a36985d3 | 221 | msg.arg.pagefault.feat.ptid = task_pid_vnr(current); |
a9b85f94 | 222 | return msg; |
86039bd3 AA |
223 | } |
224 | ||
369cd212 MK |
225 | #ifdef CONFIG_HUGETLB_PAGE |
226 | /* | |
227 | * Same functionality as userfaultfd_must_wait below with modifications for | |
228 | * hugepmd ranges. | |
229 | */ | |
230 | static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, | |
29a22b9e SB |
231 | struct vm_fault *vmf, |
232 | unsigned long reason) | |
369cd212 | 233 | { |
29a22b9e | 234 | struct vm_area_struct *vma = vmf->vma; |
1e2c0436 | 235 | pte_t *ptep, pte; |
369cd212 MK |
236 | bool ret = true; |
237 | ||
29a22b9e | 238 | assert_fault_locked(vmf); |
1e2c0436 | 239 | |
29a22b9e | 240 | ptep = hugetlb_walk(vma, vmf->address, vma_mmu_pagesize(vma)); |
1e2c0436 | 241 | if (!ptep) |
369cd212 MK |
242 | goto out; |
243 | ||
244 | ret = false; | |
e6c0c032 | 245 | pte = huge_ptep_get(vma->vm_mm, vmf->address, ptep); |
369cd212 MK |
246 | |
247 | /* | |
248 | * Lockless access: we're in a wait_event so it's ok if it | |
5c041f5d PX |
249 | * changes under us. PTE markers should be handled the same as none |
250 | * ptes here. | |
369cd212 | 251 | */ |
5c041f5d | 252 | if (huge_pte_none_mostly(pte)) |
369cd212 | 253 | ret = true; |
1e2c0436 | 254 | if (!huge_pte_write(pte) && (reason & VM_UFFD_WP)) |
369cd212 MK |
255 | ret = true; |
256 | out: | |
257 | return ret; | |
258 | } | |
259 | #else | |
260 | static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, | |
29a22b9e SB |
261 | struct vm_fault *vmf, |
262 | unsigned long reason) | |
369cd212 MK |
263 | { |
264 | return false; /* should never get here */ | |
265 | } | |
266 | #endif /* CONFIG_HUGETLB_PAGE */ | |
267 | ||
8d2afd96 AA |
268 | /* |
269 | * Verify the pagetables are still not ok after having reigstered into | |
270 | * the fault_pending_wqh to avoid userland having to UFFDIO_WAKE any | |
40f45fe8 | 271 | * userfault that has already been resolved, if userfaultfd_read_iter and |
8d2afd96 AA |
272 | * UFFDIO_COPY|ZEROPAGE are being run simultaneously on two different |
273 | * threads. | |
274 | */ | |
275 | static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx, | |
29a22b9e | 276 | struct vm_fault *vmf, |
8d2afd96 AA |
277 | unsigned long reason) |
278 | { | |
279 | struct mm_struct *mm = ctx->mm; | |
29a22b9e | 280 | unsigned long address = vmf->address; |
8d2afd96 | 281 | pgd_t *pgd; |
c2febafc | 282 | p4d_t *p4d; |
8d2afd96 AA |
283 | pud_t *pud; |
284 | pmd_t *pmd, _pmd; | |
285 | pte_t *pte; | |
c33c7948 | 286 | pte_t ptent; |
8d2afd96 AA |
287 | bool ret = true; |
288 | ||
29a22b9e | 289 | assert_fault_locked(vmf); |
8d2afd96 AA |
290 | |
291 | pgd = pgd_offset(mm, address); | |
292 | if (!pgd_present(*pgd)) | |
293 | goto out; | |
c2febafc KS |
294 | p4d = p4d_offset(pgd, address); |
295 | if (!p4d_present(*p4d)) | |
296 | goto out; | |
297 | pud = pud_offset(p4d, address); | |
8d2afd96 AA |
298 | if (!pud_present(*pud)) |
299 | goto out; | |
300 | pmd = pmd_offset(pud, address); | |
2b683a4f | 301 | again: |
26e1a0c3 | 302 | _pmd = pmdp_get_lockless(pmd); |
a365ac09 | 303 | if (pmd_none(_pmd)) |
8d2afd96 AA |
304 | goto out; |
305 | ||
306 | ret = false; | |
2b683a4f | 307 | if (!pmd_present(_pmd) || pmd_devmap(_pmd)) |
a365ac09 HY |
308 | goto out; |
309 | ||
63b2d417 AA |
310 | if (pmd_trans_huge(_pmd)) { |
311 | if (!pmd_write(_pmd) && (reason & VM_UFFD_WP)) | |
312 | ret = true; | |
8d2afd96 | 313 | goto out; |
63b2d417 | 314 | } |
8d2afd96 | 315 | |
8d2afd96 | 316 | pte = pte_offset_map(pmd, address); |
2b683a4f HD |
317 | if (!pte) { |
318 | ret = true; | |
319 | goto again; | |
320 | } | |
8d2afd96 AA |
321 | /* |
322 | * Lockless access: we're in a wait_event so it's ok if it | |
5c041f5d PX |
323 | * changes under us. PTE markers should be handled the same as none |
324 | * ptes here. | |
8d2afd96 | 325 | */ |
c33c7948 RR |
326 | ptent = ptep_get(pte); |
327 | if (pte_none_mostly(ptent)) | |
8d2afd96 | 328 | ret = true; |
c33c7948 | 329 | if (!pte_write(ptent) && (reason & VM_UFFD_WP)) |
63b2d417 | 330 | ret = true; |
8d2afd96 AA |
331 | pte_unmap(pte); |
332 | ||
333 | out: | |
334 | return ret; | |
335 | } | |
336 | ||
2f064a59 | 337 | static inline unsigned int userfaultfd_get_blocking_state(unsigned int flags) |
3e69ad08 PX |
338 | { |
339 | if (flags & FAULT_FLAG_INTERRUPTIBLE) | |
340 | return TASK_INTERRUPTIBLE; | |
341 | ||
342 | if (flags & FAULT_FLAG_KILLABLE) | |
343 | return TASK_KILLABLE; | |
344 | ||
345 | return TASK_UNINTERRUPTIBLE; | |
346 | } | |
347 | ||
86039bd3 AA |
348 | /* |
349 | * The locking rules involved in returning VM_FAULT_RETRY depending on | |
350 | * FAULT_FLAG_ALLOW_RETRY, FAULT_FLAG_RETRY_NOWAIT and | |
351 | * FAULT_FLAG_KILLABLE are not straightforward. The "Caution" | |
352 | * recommendation in __lock_page_or_retry is not an understatement. | |
353 | * | |
c1e8d7c6 | 354 | * If FAULT_FLAG_ALLOW_RETRY is set, the mmap_lock must be released |
86039bd3 AA |
355 | * before returning VM_FAULT_RETRY only if FAULT_FLAG_RETRY_NOWAIT is |
356 | * not set. | |
357 | * | |
358 | * If FAULT_FLAG_ALLOW_RETRY is set but FAULT_FLAG_KILLABLE is not | |
359 | * set, VM_FAULT_RETRY can still be returned if and only if there are | |
c1e8d7c6 | 360 | * fatal_signal_pending()s, and the mmap_lock must be released before |
86039bd3 AA |
361 | * returning it. |
362 | */ | |
2b740303 | 363 | vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason) |
86039bd3 | 364 | { |
b8da2e46 PX |
365 | struct vm_area_struct *vma = vmf->vma; |
366 | struct mm_struct *mm = vma->vm_mm; | |
86039bd3 AA |
367 | struct userfaultfd_ctx *ctx; |
368 | struct userfaultfd_wait_queue uwq; | |
2b740303 | 369 | vm_fault_t ret = VM_FAULT_SIGBUS; |
3e69ad08 | 370 | bool must_wait; |
2f064a59 | 371 | unsigned int blocking_state; |
86039bd3 | 372 | |
64c2b203 | 373 | /* |
94ccd21e DH |
374 | * We don't do userfault handling for the final child pid update |
375 | * and when coredumping (faults triggered by get_dump_page()). | |
64c2b203 AA |
376 | */ |
377 | if (current->flags & (PF_EXITING|PF_DUMPCORE)) | |
378 | goto out; | |
379 | ||
29a22b9e | 380 | assert_fault_locked(vmf); |
64c2b203 | 381 | |
b8da2e46 | 382 | ctx = vma->vm_userfaultfd_ctx.ctx; |
86039bd3 | 383 | if (!ctx) |
ba85c702 | 384 | goto out; |
86039bd3 AA |
385 | |
386 | BUG_ON(ctx->mm != mm); | |
387 | ||
7677f7fd AR |
388 | /* Any unrecognized flag is a bug. */ |
389 | VM_BUG_ON(reason & ~__VM_UFFD_FLAGS); | |
390 | /* 0 or > 1 flags set is a bug; we expect exactly 1. */ | |
391 | VM_BUG_ON(!reason || (reason & (reason - 1))); | |
86039bd3 | 392 | |
2d6d6f5a PS |
393 | if (ctx->features & UFFD_FEATURE_SIGBUS) |
394 | goto out; | |
2d5de004 | 395 | if (!(vmf->flags & FAULT_FLAG_USER) && (ctx->flags & UFFD_USER_MODE_ONLY)) |
37cd0575 | 396 | goto out; |
2d6d6f5a | 397 | |
86039bd3 AA |
398 | /* |
399 | * If it's already released don't get it. This avoids to loop | |
400 | * in __get_user_pages if userfaultfd_release waits on the | |
c1e8d7c6 | 401 | * caller of handle_userfault to release the mmap_lock. |
86039bd3 | 402 | */ |
6aa7de05 | 403 | if (unlikely(READ_ONCE(ctx->released))) { |
656710a6 AA |
404 | /* |
405 | * Don't return VM_FAULT_SIGBUS in this case, so a non | |
406 | * cooperative manager can close the uffd after the | |
407 | * last UFFDIO_COPY, without risking to trigger an | |
408 | * involuntary SIGBUS if the process was starting the | |
409 | * userfaultfd while the userfaultfd was still armed | |
410 | * (but after the last UFFDIO_COPY). If the uffd | |
411 | * wasn't already closed when the userfault reached | |
412 | * this point, that would normally be solved by | |
413 | * userfaultfd_must_wait returning 'false'. | |
414 | * | |
415 | * If we were to return VM_FAULT_SIGBUS here, the non | |
416 | * cooperative manager would be instead forced to | |
417 | * always call UFFDIO_UNREGISTER before it can safely | |
418 | * close the uffd. | |
419 | */ | |
420 | ret = VM_FAULT_NOPAGE; | |
ba85c702 | 421 | goto out; |
656710a6 | 422 | } |
86039bd3 AA |
423 | |
424 | /* | |
425 | * Check that we can return VM_FAULT_RETRY. | |
426 | * | |
427 | * NOTE: it should become possible to return VM_FAULT_RETRY | |
428 | * even if FAULT_FLAG_TRIED is set without leading to gup() | |
429 | * -EBUSY failures, if the userfaultfd is to be extended for | |
430 | * VM_UFFD_WP tracking and we intend to arm the userfault | |
431 | * without first stopping userland access to the memory. For | |
432 | * VM_UFFD_MISSING userfaults this is enough for now. | |
433 | */ | |
82b0f8c3 | 434 | if (unlikely(!(vmf->flags & FAULT_FLAG_ALLOW_RETRY))) { |
86039bd3 AA |
435 | /* |
436 | * Validate the invariant that nowait must allow retry | |
437 | * to be sure not to return SIGBUS erroneously on | |
438 | * nowait invocations. | |
439 | */ | |
82b0f8c3 | 440 | BUG_ON(vmf->flags & FAULT_FLAG_RETRY_NOWAIT); |
86039bd3 AA |
441 | #ifdef CONFIG_DEBUG_VM |
442 | if (printk_ratelimit()) { | |
443 | printk(KERN_WARNING | |
82b0f8c3 JK |
444 | "FAULT_FLAG_ALLOW_RETRY missing %x\n", |
445 | vmf->flags); | |
86039bd3 AA |
446 | dump_stack(); |
447 | } | |
448 | #endif | |
ba85c702 | 449 | goto out; |
86039bd3 AA |
450 | } |
451 | ||
452 | /* | |
453 | * Handle nowait, not much to do other than tell it to retry | |
454 | * and wait. | |
455 | */ | |
ba85c702 | 456 | ret = VM_FAULT_RETRY; |
82b0f8c3 | 457 | if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT) |
ba85c702 | 458 | goto out; |
86039bd3 | 459 | |
c1e8d7c6 | 460 | /* take the reference before dropping the mmap_lock */ |
86039bd3 AA |
461 | userfaultfd_ctx_get(ctx); |
462 | ||
86039bd3 AA |
463 | init_waitqueue_func_entry(&uwq.wq, userfaultfd_wake_function); |
464 | uwq.wq.private = current; | |
d172b1a3 NA |
465 | uwq.msg = userfault_msg(vmf->address, vmf->real_address, vmf->flags, |
466 | reason, ctx->features); | |
86039bd3 | 467 | uwq.ctx = ctx; |
15a77c6f | 468 | uwq.waken = false; |
86039bd3 | 469 | |
3e69ad08 | 470 | blocking_state = userfaultfd_get_blocking_state(vmf->flags); |
dfa37dc3 | 471 | |
b8da2e46 PX |
472 | /* |
473 | * Take the vma lock now, in order to safely call | |
474 | * userfaultfd_huge_must_wait() later. Since acquiring the | |
475 | * (sleepable) vma lock can modify the current task state, that | |
476 | * must be before explicitly calling set_current_state(). | |
477 | */ | |
478 | if (is_vm_hugetlb_page(vma)) | |
479 | hugetlb_vma_lock_read(vma); | |
480 | ||
cbcfa130 | 481 | spin_lock_irq(&ctx->fault_pending_wqh.lock); |
86039bd3 AA |
482 | /* |
483 | * After the __add_wait_queue the uwq is visible to userland | |
484 | * through poll/read(). | |
485 | */ | |
15b726ef AA |
486 | __add_wait_queue(&ctx->fault_pending_wqh, &uwq.wq); |
487 | /* | |
488 | * The smp_mb() after __set_current_state prevents the reads | |
489 | * following the spin_unlock to happen before the list_add in | |
490 | * __add_wait_queue. | |
491 | */ | |
15a77c6f | 492 | set_current_state(blocking_state); |
cbcfa130 | 493 | spin_unlock_irq(&ctx->fault_pending_wqh.lock); |
86039bd3 | 494 | |
b8da2e46 | 495 | if (!is_vm_hugetlb_page(vma)) |
29a22b9e | 496 | must_wait = userfaultfd_must_wait(ctx, vmf, reason); |
369cd212 | 497 | else |
29a22b9e | 498 | must_wait = userfaultfd_huge_must_wait(ctx, vmf, reason); |
b8da2e46 PX |
499 | if (is_vm_hugetlb_page(vma)) |
500 | hugetlb_vma_unlock_read(vma); | |
29a22b9e | 501 | release_fault_lock(vmf); |
8d2afd96 | 502 | |
f9bf3522 | 503 | if (likely(must_wait && !READ_ONCE(ctx->released))) { |
a9a08845 | 504 | wake_up_poll(&ctx->fd_wqh, EPOLLIN); |
86039bd3 | 505 | schedule(); |
ba85c702 | 506 | } |
86039bd3 | 507 | |
ba85c702 | 508 | __set_current_state(TASK_RUNNING); |
15b726ef AA |
509 | |
510 | /* | |
511 | * Here we race with the list_del; list_add in | |
512 | * userfaultfd_ctx_read(), however because we don't ever run | |
513 | * list_del_init() to refile across the two lists, the prev | |
514 | * and next pointers will never point to self. list_add also | |
515 | * would never let any of the two pointers to point to | |
516 | * self. So list_empty_careful won't risk to see both pointers | |
517 | * pointing to self at any time during the list refile. The | |
518 | * only case where list_del_init() is called is the full | |
519 | * removal in the wake function and there we don't re-list_add | |
520 | * and it's fine not to block on the spinlock. The uwq on this | |
521 | * kernel stack can be released after the list_del_init. | |
522 | */ | |
2055da97 | 523 | if (!list_empty_careful(&uwq.wq.entry)) { |
cbcfa130 | 524 | spin_lock_irq(&ctx->fault_pending_wqh.lock); |
15b726ef AA |
525 | /* |
526 | * No need of list_del_init(), the uwq on the stack | |
527 | * will be freed shortly anyway. | |
528 | */ | |
2055da97 | 529 | list_del(&uwq.wq.entry); |
cbcfa130 | 530 | spin_unlock_irq(&ctx->fault_pending_wqh.lock); |
86039bd3 | 531 | } |
86039bd3 AA |
532 | |
533 | /* | |
534 | * ctx may go away after this if the userfault pseudo fd is | |
535 | * already released. | |
536 | */ | |
537 | userfaultfd_ctx_put(ctx); | |
538 | ||
ba85c702 AA |
539 | out: |
540 | return ret; | |
86039bd3 AA |
541 | } |
542 | ||
8c9e7bb7 AA |
543 | static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx, |
544 | struct userfaultfd_wait_queue *ewq) | |
9cd75c3c | 545 | { |
0cbb4b4f AA |
546 | struct userfaultfd_ctx *release_new_ctx; |
547 | ||
9a69a829 AA |
548 | if (WARN_ON_ONCE(current->flags & PF_EXITING)) |
549 | goto out; | |
9cd75c3c PE |
550 | |
551 | ewq->ctx = ctx; | |
552 | init_waitqueue_entry(&ewq->wq, current); | |
0cbb4b4f | 553 | release_new_ctx = NULL; |
9cd75c3c | 554 | |
cbcfa130 | 555 | spin_lock_irq(&ctx->event_wqh.lock); |
9cd75c3c PE |
556 | /* |
557 | * After the __add_wait_queue the uwq is visible to userland | |
558 | * through poll/read(). | |
559 | */ | |
560 | __add_wait_queue(&ctx->event_wqh, &ewq->wq); | |
561 | for (;;) { | |
562 | set_current_state(TASK_KILLABLE); | |
563 | if (ewq->msg.event == 0) | |
564 | break; | |
6aa7de05 | 565 | if (READ_ONCE(ctx->released) || |
9cd75c3c | 566 | fatal_signal_pending(current)) { |
384632e6 AA |
567 | /* |
568 | * &ewq->wq may be queued in fork_event, but | |
569 | * __remove_wait_queue ignores the head | |
570 | * parameter. It would be a problem if it | |
571 | * didn't. | |
572 | */ | |
9cd75c3c | 573 | __remove_wait_queue(&ctx->event_wqh, &ewq->wq); |
7eb76d45 MR |
574 | if (ewq->msg.event == UFFD_EVENT_FORK) { |
575 | struct userfaultfd_ctx *new; | |
576 | ||
577 | new = (struct userfaultfd_ctx *) | |
578 | (unsigned long) | |
579 | ewq->msg.arg.reserved.reserved1; | |
0cbb4b4f | 580 | release_new_ctx = new; |
7eb76d45 | 581 | } |
9cd75c3c PE |
582 | break; |
583 | } | |
584 | ||
cbcfa130 | 585 | spin_unlock_irq(&ctx->event_wqh.lock); |
9cd75c3c | 586 | |
a9a08845 | 587 | wake_up_poll(&ctx->fd_wqh, EPOLLIN); |
9cd75c3c PE |
588 | schedule(); |
589 | ||
cbcfa130 | 590 | spin_lock_irq(&ctx->event_wqh.lock); |
9cd75c3c PE |
591 | } |
592 | __set_current_state(TASK_RUNNING); | |
cbcfa130 | 593 | spin_unlock_irq(&ctx->event_wqh.lock); |
9cd75c3c | 594 | |
0cbb4b4f | 595 | if (release_new_ctx) { |
a17c7d8f | 596 | userfaultfd_release_new(release_new_ctx); |
0cbb4b4f AA |
597 | userfaultfd_ctx_put(release_new_ctx); |
598 | } | |
599 | ||
9cd75c3c PE |
600 | /* |
601 | * ctx may go away after this if the userfault pseudo fd is | |
602 | * already released. | |
603 | */ | |
9a69a829 | 604 | out: |
a759a909 NA |
605 | atomic_dec(&ctx->mmap_changing); |
606 | VM_BUG_ON(atomic_read(&ctx->mmap_changing) < 0); | |
9cd75c3c | 607 | userfaultfd_ctx_put(ctx); |
9cd75c3c PE |
608 | } |
609 | ||
610 | static void userfaultfd_event_complete(struct userfaultfd_ctx *ctx, | |
611 | struct userfaultfd_wait_queue *ewq) | |
612 | { | |
613 | ewq->msg.event = 0; | |
614 | wake_up_locked(&ctx->event_wqh); | |
615 | __remove_wait_queue(&ctx->event_wqh, &ewq->wq); | |
616 | } | |
617 | ||
893e26e6 PE |
618 | int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs) |
619 | { | |
620 | struct userfaultfd_ctx *ctx = NULL, *octx; | |
621 | struct userfaultfd_fork_ctx *fctx; | |
622 | ||
623 | octx = vma->vm_userfaultfd_ctx.ctx; | |
afd58439 Z |
624 | if (!octx) |
625 | return 0; | |
626 | ||
627 | if (!(octx->features & UFFD_FEATURE_EVENT_FORK)) { | |
a17c7d8f | 628 | userfaultfd_reset_ctx(vma); |
893e26e6 PE |
629 | return 0; |
630 | } | |
631 | ||
632 | list_for_each_entry(fctx, fcs, list) | |
633 | if (fctx->orig == octx) { | |
634 | ctx = fctx->new; | |
635 | break; | |
636 | } | |
637 | ||
638 | if (!ctx) { | |
639 | fctx = kmalloc(sizeof(*fctx), GFP_KERNEL); | |
640 | if (!fctx) | |
641 | return -ENOMEM; | |
642 | ||
643 | ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL); | |
644 | if (!ctx) { | |
645 | kfree(fctx); | |
646 | return -ENOMEM; | |
647 | } | |
648 | ||
ca880420 | 649 | refcount_set(&ctx->refcount, 1); |
893e26e6 | 650 | ctx->flags = octx->flags; |
893e26e6 PE |
651 | ctx->features = octx->features; |
652 | ctx->released = false; | |
5e4c24a5 | 653 | init_rwsem(&ctx->map_changing_lock); |
a759a909 | 654 | atomic_set(&ctx->mmap_changing, 0); |
893e26e6 | 655 | ctx->mm = vma->vm_mm; |
00bb31fa | 656 | mmgrab(ctx->mm); |
893e26e6 PE |
657 | |
658 | userfaultfd_ctx_get(octx); | |
5e4c24a5 | 659 | down_write(&octx->map_changing_lock); |
a759a909 | 660 | atomic_inc(&octx->mmap_changing); |
5e4c24a5 | 661 | up_write(&octx->map_changing_lock); |
893e26e6 PE |
662 | fctx->orig = octx; |
663 | fctx->new = ctx; | |
664 | list_add_tail(&fctx->list, fcs); | |
665 | } | |
666 | ||
667 | vma->vm_userfaultfd_ctx.ctx = ctx; | |
668 | return 0; | |
669 | } | |
670 | ||
8c9e7bb7 | 671 | static void dup_fctx(struct userfaultfd_fork_ctx *fctx) |
893e26e6 PE |
672 | { |
673 | struct userfaultfd_ctx *ctx = fctx->orig; | |
674 | struct userfaultfd_wait_queue ewq; | |
675 | ||
676 | msg_init(&ewq.msg); | |
677 | ||
678 | ewq.msg.event = UFFD_EVENT_FORK; | |
679 | ewq.msg.arg.reserved.reserved1 = (unsigned long)fctx->new; | |
680 | ||
8c9e7bb7 | 681 | userfaultfd_event_wait_completion(ctx, &ewq); |
893e26e6 PE |
682 | } |
683 | ||
684 | void dup_userfaultfd_complete(struct list_head *fcs) | |
685 | { | |
893e26e6 PE |
686 | struct userfaultfd_fork_ctx *fctx, *n; |
687 | ||
688 | list_for_each_entry_safe(fctx, n, fcs, list) { | |
8c9e7bb7 | 689 | dup_fctx(fctx); |
893e26e6 PE |
690 | list_del(&fctx->list); |
691 | kfree(fctx); | |
692 | } | |
693 | } | |
694 | ||
72f87654 PE |
695 | void mremap_userfaultfd_prep(struct vm_area_struct *vma, |
696 | struct vm_userfaultfd_ctx *vm_ctx) | |
697 | { | |
698 | struct userfaultfd_ctx *ctx; | |
699 | ||
700 | ctx = vma->vm_userfaultfd_ctx.ctx; | |
3cfd22be PX |
701 | |
702 | if (!ctx) | |
703 | return; | |
704 | ||
705 | if (ctx->features & UFFD_FEATURE_EVENT_REMAP) { | |
72f87654 PE |
706 | vm_ctx->ctx = ctx; |
707 | userfaultfd_ctx_get(ctx); | |
5e4c24a5 | 708 | down_write(&ctx->map_changing_lock); |
a759a909 | 709 | atomic_inc(&ctx->mmap_changing); |
5e4c24a5 | 710 | up_write(&ctx->map_changing_lock); |
3cfd22be PX |
711 | } else { |
712 | /* Drop uffd context if remap feature not enabled */ | |
a17c7d8f | 713 | userfaultfd_reset_ctx(vma); |
72f87654 PE |
714 | } |
715 | } | |
716 | ||
90794bf1 | 717 | void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *vm_ctx, |
72f87654 PE |
718 | unsigned long from, unsigned long to, |
719 | unsigned long len) | |
720 | { | |
90794bf1 | 721 | struct userfaultfd_ctx *ctx = vm_ctx->ctx; |
72f87654 PE |
722 | struct userfaultfd_wait_queue ewq; |
723 | ||
724 | if (!ctx) | |
725 | return; | |
726 | ||
727 | if (to & ~PAGE_MASK) { | |
728 | userfaultfd_ctx_put(ctx); | |
729 | return; | |
730 | } | |
731 | ||
732 | msg_init(&ewq.msg); | |
733 | ||
734 | ewq.msg.event = UFFD_EVENT_REMAP; | |
735 | ewq.msg.arg.remap.from = from; | |
736 | ewq.msg.arg.remap.to = to; | |
737 | ewq.msg.arg.remap.len = len; | |
738 | ||
739 | userfaultfd_event_wait_completion(ctx, &ewq); | |
740 | } | |
741 | ||
70ccb92f | 742 | bool userfaultfd_remove(struct vm_area_struct *vma, |
d811914d | 743 | unsigned long start, unsigned long end) |
05ce7724 PE |
744 | { |
745 | struct mm_struct *mm = vma->vm_mm; | |
746 | struct userfaultfd_ctx *ctx; | |
747 | struct userfaultfd_wait_queue ewq; | |
748 | ||
749 | ctx = vma->vm_userfaultfd_ctx.ctx; | |
d811914d | 750 | if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_REMOVE)) |
70ccb92f | 751 | return true; |
05ce7724 PE |
752 | |
753 | userfaultfd_ctx_get(ctx); | |
5e4c24a5 | 754 | down_write(&ctx->map_changing_lock); |
a759a909 | 755 | atomic_inc(&ctx->mmap_changing); |
5e4c24a5 | 756 | up_write(&ctx->map_changing_lock); |
d8ed45c5 | 757 | mmap_read_unlock(mm); |
05ce7724 | 758 | |
05ce7724 PE |
759 | msg_init(&ewq.msg); |
760 | ||
d811914d MR |
761 | ewq.msg.event = UFFD_EVENT_REMOVE; |
762 | ewq.msg.arg.remove.start = start; | |
763 | ewq.msg.arg.remove.end = end; | |
05ce7724 PE |
764 | |
765 | userfaultfd_event_wait_completion(ctx, &ewq); | |
766 | ||
70ccb92f | 767 | return false; |
05ce7724 PE |
768 | } |
769 | ||
897ab3e0 MR |
770 | static bool has_unmap_ctx(struct userfaultfd_ctx *ctx, struct list_head *unmaps, |
771 | unsigned long start, unsigned long end) | |
772 | { | |
773 | struct userfaultfd_unmap_ctx *unmap_ctx; | |
774 | ||
775 | list_for_each_entry(unmap_ctx, unmaps, list) | |
776 | if (unmap_ctx->ctx == ctx && unmap_ctx->start == start && | |
777 | unmap_ctx->end == end) | |
778 | return true; | |
779 | ||
780 | return false; | |
781 | } | |
782 | ||
65ac1320 | 783 | int userfaultfd_unmap_prep(struct vm_area_struct *vma, unsigned long start, |
69dbe6da | 784 | unsigned long end, struct list_head *unmaps) |
897ab3e0 | 785 | { |
65ac1320 LH |
786 | struct userfaultfd_unmap_ctx *unmap_ctx; |
787 | struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx; | |
897ab3e0 | 788 | |
65ac1320 LH |
789 | if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_UNMAP) || |
790 | has_unmap_ctx(ctx, unmaps, start, end)) | |
791 | return 0; | |
897ab3e0 | 792 | |
65ac1320 LH |
793 | unmap_ctx = kzalloc(sizeof(*unmap_ctx), GFP_KERNEL); |
794 | if (!unmap_ctx) | |
795 | return -ENOMEM; | |
897ab3e0 | 796 | |
65ac1320 | 797 | userfaultfd_ctx_get(ctx); |
5e4c24a5 | 798 | down_write(&ctx->map_changing_lock); |
65ac1320 | 799 | atomic_inc(&ctx->mmap_changing); |
5e4c24a5 | 800 | up_write(&ctx->map_changing_lock); |
65ac1320 LH |
801 | unmap_ctx->ctx = ctx; |
802 | unmap_ctx->start = start; | |
803 | unmap_ctx->end = end; | |
804 | list_add_tail(&unmap_ctx->list, unmaps); | |
897ab3e0 MR |
805 | |
806 | return 0; | |
807 | } | |
808 | ||
809 | void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf) | |
810 | { | |
811 | struct userfaultfd_unmap_ctx *ctx, *n; | |
812 | struct userfaultfd_wait_queue ewq; | |
813 | ||
814 | list_for_each_entry_safe(ctx, n, uf, list) { | |
815 | msg_init(&ewq.msg); | |
816 | ||
817 | ewq.msg.event = UFFD_EVENT_UNMAP; | |
818 | ewq.msg.arg.remove.start = ctx->start; | |
819 | ewq.msg.arg.remove.end = ctx->end; | |
820 | ||
821 | userfaultfd_event_wait_completion(ctx->ctx, &ewq); | |
822 | ||
823 | list_del(&ctx->list); | |
824 | kfree(ctx); | |
825 | } | |
826 | } | |
827 | ||
86039bd3 AA |
828 | static int userfaultfd_release(struct inode *inode, struct file *file) |
829 | { | |
830 | struct userfaultfd_ctx *ctx = file->private_data; | |
831 | struct mm_struct *mm = ctx->mm; | |
86039bd3 AA |
832 | /* len == 0 means wake all */ |
833 | struct userfaultfd_wake_range range = { .len = 0, }; | |
86039bd3 | 834 | |
6aa7de05 | 835 | WRITE_ONCE(ctx->released, true); |
86039bd3 | 836 | |
a17c7d8f | 837 | userfaultfd_release_all(mm, ctx); |
94d7d923 | 838 | |
86039bd3 | 839 | /* |
15b726ef | 840 | * After no new page faults can wait on this fault_*wqh, flush |
86039bd3 | 841 | * the last page faults that may have been already waiting on |
15b726ef | 842 | * the fault_*wqh. |
86039bd3 | 843 | */ |
cbcfa130 | 844 | spin_lock_irq(&ctx->fault_pending_wqh.lock); |
ac5be6b4 | 845 | __wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, &range); |
c430d1e8 | 846 | __wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, &range); |
cbcfa130 | 847 | spin_unlock_irq(&ctx->fault_pending_wqh.lock); |
86039bd3 | 848 | |
5a18b64e MR |
849 | /* Flush pending events that may still wait on event_wqh */ |
850 | wake_up_all(&ctx->event_wqh); | |
851 | ||
a9a08845 | 852 | wake_up_poll(&ctx->fd_wqh, EPOLLHUP); |
86039bd3 AA |
853 | userfaultfd_ctx_put(ctx); |
854 | return 0; | |
855 | } | |
856 | ||
15b726ef | 857 | /* fault_pending_wqh.lock must be hold by the caller */ |
6dcc27fd PE |
858 | static inline struct userfaultfd_wait_queue *find_userfault_in( |
859 | wait_queue_head_t *wqh) | |
86039bd3 | 860 | { |
ac6424b9 | 861 | wait_queue_entry_t *wq; |
15b726ef | 862 | struct userfaultfd_wait_queue *uwq; |
86039bd3 | 863 | |
456a7378 | 864 | lockdep_assert_held(&wqh->lock); |
86039bd3 | 865 | |
15b726ef | 866 | uwq = NULL; |
6dcc27fd | 867 | if (!waitqueue_active(wqh)) |
15b726ef AA |
868 | goto out; |
869 | /* walk in reverse to provide FIFO behavior to read userfaults */ | |
2055da97 | 870 | wq = list_last_entry(&wqh->head, typeof(*wq), entry); |
15b726ef AA |
871 | uwq = container_of(wq, struct userfaultfd_wait_queue, wq); |
872 | out: | |
873 | return uwq; | |
86039bd3 | 874 | } |
6dcc27fd PE |
875 | |
876 | static inline struct userfaultfd_wait_queue *find_userfault( | |
877 | struct userfaultfd_ctx *ctx) | |
878 | { | |
879 | return find_userfault_in(&ctx->fault_pending_wqh); | |
880 | } | |
86039bd3 | 881 | |
9cd75c3c PE |
882 | static inline struct userfaultfd_wait_queue *find_userfault_evt( |
883 | struct userfaultfd_ctx *ctx) | |
884 | { | |
885 | return find_userfault_in(&ctx->event_wqh); | |
886 | } | |
887 | ||
076ccb76 | 888 | static __poll_t userfaultfd_poll(struct file *file, poll_table *wait) |
86039bd3 AA |
889 | { |
890 | struct userfaultfd_ctx *ctx = file->private_data; | |
076ccb76 | 891 | __poll_t ret; |
86039bd3 AA |
892 | |
893 | poll_wait(file, &ctx->fd_wqh, wait); | |
894 | ||
22e5fe2a | 895 | if (!userfaultfd_is_initialized(ctx)) |
a9a08845 | 896 | return EPOLLERR; |
9cd75c3c | 897 | |
22e5fe2a NA |
898 | /* |
899 | * poll() never guarantees that read won't block. | |
900 | * userfaults can be waken before they're read(). | |
901 | */ | |
902 | if (unlikely(!(file->f_flags & O_NONBLOCK))) | |
a9a08845 | 903 | return EPOLLERR; |
22e5fe2a NA |
904 | /* |
905 | * lockless access to see if there are pending faults | |
906 | * __pollwait last action is the add_wait_queue but | |
907 | * the spin_unlock would allow the waitqueue_active to | |
908 | * pass above the actual list_add inside | |
909 | * add_wait_queue critical section. So use a full | |
910 | * memory barrier to serialize the list_add write of | |
911 | * add_wait_queue() with the waitqueue_active read | |
912 | * below. | |
913 | */ | |
914 | ret = 0; | |
915 | smp_mb(); | |
916 | if (waitqueue_active(&ctx->fault_pending_wqh)) | |
917 | ret = EPOLLIN; | |
918 | else if (waitqueue_active(&ctx->event_wqh)) | |
919 | ret = EPOLLIN; | |
920 | ||
921 | return ret; | |
86039bd3 AA |
922 | } |
923 | ||
893e26e6 PE |
924 | static const struct file_operations userfaultfd_fops; |
925 | ||
b537900f DC |
926 | static int resolve_userfault_fork(struct userfaultfd_ctx *new, |
927 | struct inode *inode, | |
893e26e6 PE |
928 | struct uffd_msg *msg) |
929 | { | |
930 | int fd; | |
893e26e6 | 931 | |
4f0b9194 | 932 | fd = anon_inode_create_getfd("[userfaultfd]", &userfaultfd_fops, new, |
abec3d01 | 933 | O_RDONLY | (new->flags & UFFD_SHARED_FCNTL_FLAGS), inode); |
893e26e6 PE |
934 | if (fd < 0) |
935 | return fd; | |
936 | ||
893e26e6 PE |
937 | msg->arg.reserved.reserved1 = 0; |
938 | msg->arg.fork.ufd = fd; | |
893e26e6 PE |
939 | return 0; |
940 | } | |
941 | ||
86039bd3 | 942 | static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait, |
b537900f | 943 | struct uffd_msg *msg, struct inode *inode) |
86039bd3 AA |
944 | { |
945 | ssize_t ret; | |
946 | DECLARE_WAITQUEUE(wait, current); | |
15b726ef | 947 | struct userfaultfd_wait_queue *uwq; |
893e26e6 PE |
948 | /* |
949 | * Handling fork event requires sleeping operations, so | |
950 | * we drop the event_wqh lock, then do these ops, then | |
951 | * lock it back and wake up the waiter. While the lock is | |
952 | * dropped the ewq may go away so we keep track of it | |
953 | * carefully. | |
954 | */ | |
955 | LIST_HEAD(fork_event); | |
956 | struct userfaultfd_ctx *fork_nctx = NULL; | |
86039bd3 | 957 | |
15b726ef | 958 | /* always take the fd_wqh lock before the fault_pending_wqh lock */ |
ae62c16e | 959 | spin_lock_irq(&ctx->fd_wqh.lock); |
86039bd3 AA |
960 | __add_wait_queue(&ctx->fd_wqh, &wait); |
961 | for (;;) { | |
962 | set_current_state(TASK_INTERRUPTIBLE); | |
15b726ef AA |
963 | spin_lock(&ctx->fault_pending_wqh.lock); |
964 | uwq = find_userfault(ctx); | |
965 | if (uwq) { | |
2c5b7e1b AA |
966 | /* |
967 | * Use a seqcount to repeat the lockless check | |
968 | * in wake_userfault() to avoid missing | |
969 | * wakeups because during the refile both | |
970 | * waitqueue could become empty if this is the | |
971 | * only userfault. | |
972 | */ | |
973 | write_seqcount_begin(&ctx->refile_seq); | |
974 | ||
86039bd3 | 975 | /* |
15b726ef AA |
976 | * The fault_pending_wqh.lock prevents the uwq |
977 | * to disappear from under us. | |
978 | * | |
979 | * Refile this userfault from | |
980 | * fault_pending_wqh to fault_wqh, it's not | |
981 | * pending anymore after we read it. | |
982 | * | |
983 | * Use list_del() by hand (as | |
984 | * userfaultfd_wake_function also uses | |
985 | * list_del_init() by hand) to be sure nobody | |
986 | * changes __remove_wait_queue() to use | |
987 | * list_del_init() in turn breaking the | |
988 | * !list_empty_careful() check in | |
2055da97 | 989 | * handle_userfault(). The uwq->wq.head list |
15b726ef AA |
990 | * must never be empty at any time during the |
991 | * refile, or the waitqueue could disappear | |
992 | * from under us. The "wait_queue_head_t" | |
993 | * parameter of __remove_wait_queue() is unused | |
994 | * anyway. | |
86039bd3 | 995 | */ |
2055da97 | 996 | list_del(&uwq->wq.entry); |
c430d1e8 | 997 | add_wait_queue(&ctx->fault_wqh, &uwq->wq); |
15b726ef | 998 | |
2c5b7e1b AA |
999 | write_seqcount_end(&ctx->refile_seq); |
1000 | ||
a9b85f94 AA |
1001 | /* careful to always initialize msg if ret == 0 */ |
1002 | *msg = uwq->msg; | |
15b726ef | 1003 | spin_unlock(&ctx->fault_pending_wqh.lock); |
86039bd3 AA |
1004 | ret = 0; |
1005 | break; | |
1006 | } | |
15b726ef | 1007 | spin_unlock(&ctx->fault_pending_wqh.lock); |
9cd75c3c PE |
1008 | |
1009 | spin_lock(&ctx->event_wqh.lock); | |
1010 | uwq = find_userfault_evt(ctx); | |
1011 | if (uwq) { | |
1012 | *msg = uwq->msg; | |
1013 | ||
893e26e6 PE |
1014 | if (uwq->msg.event == UFFD_EVENT_FORK) { |
1015 | fork_nctx = (struct userfaultfd_ctx *) | |
1016 | (unsigned long) | |
1017 | uwq->msg.arg.reserved.reserved1; | |
2055da97 | 1018 | list_move(&uwq->wq.entry, &fork_event); |
384632e6 AA |
1019 | /* |
1020 | * fork_nctx can be freed as soon as | |
1021 | * we drop the lock, unless we take a | |
1022 | * reference on it. | |
1023 | */ | |
1024 | userfaultfd_ctx_get(fork_nctx); | |
893e26e6 PE |
1025 | spin_unlock(&ctx->event_wqh.lock); |
1026 | ret = 0; | |
1027 | break; | |
1028 | } | |
1029 | ||
9cd75c3c PE |
1030 | userfaultfd_event_complete(ctx, uwq); |
1031 | spin_unlock(&ctx->event_wqh.lock); | |
1032 | ret = 0; | |
1033 | break; | |
1034 | } | |
1035 | spin_unlock(&ctx->event_wqh.lock); | |
1036 | ||
86039bd3 AA |
1037 | if (signal_pending(current)) { |
1038 | ret = -ERESTARTSYS; | |
1039 | break; | |
1040 | } | |
1041 | if (no_wait) { | |
1042 | ret = -EAGAIN; | |
1043 | break; | |
1044 | } | |
ae62c16e | 1045 | spin_unlock_irq(&ctx->fd_wqh.lock); |
86039bd3 | 1046 | schedule(); |
ae62c16e | 1047 | spin_lock_irq(&ctx->fd_wqh.lock); |
86039bd3 AA |
1048 | } |
1049 | __remove_wait_queue(&ctx->fd_wqh, &wait); | |
1050 | __set_current_state(TASK_RUNNING); | |
ae62c16e | 1051 | spin_unlock_irq(&ctx->fd_wqh.lock); |
86039bd3 | 1052 | |
893e26e6 | 1053 | if (!ret && msg->event == UFFD_EVENT_FORK) { |
b537900f | 1054 | ret = resolve_userfault_fork(fork_nctx, inode, msg); |
cbcfa130 | 1055 | spin_lock_irq(&ctx->event_wqh.lock); |
384632e6 AA |
1056 | if (!list_empty(&fork_event)) { |
1057 | /* | |
1058 | * The fork thread didn't abort, so we can | |
1059 | * drop the temporary refcount. | |
1060 | */ | |
1061 | userfaultfd_ctx_put(fork_nctx); | |
1062 | ||
1063 | uwq = list_first_entry(&fork_event, | |
1064 | typeof(*uwq), | |
1065 | wq.entry); | |
1066 | /* | |
1067 | * If fork_event list wasn't empty and in turn | |
1068 | * the event wasn't already released by fork | |
1069 | * (the event is allocated on fork kernel | |
1070 | * stack), put the event back to its place in | |
1071 | * the event_wq. fork_event head will be freed | |
1072 | * as soon as we return so the event cannot | |
1073 | * stay queued there no matter the current | |
1074 | * "ret" value. | |
1075 | */ | |
1076 | list_del(&uwq->wq.entry); | |
1077 | __add_wait_queue(&ctx->event_wqh, &uwq->wq); | |
893e26e6 | 1078 | |
384632e6 AA |
1079 | /* |
1080 | * Leave the event in the waitqueue and report | |
1081 | * error to userland if we failed to resolve | |
1082 | * the userfault fork. | |
1083 | */ | |
1084 | if (likely(!ret)) | |
893e26e6 | 1085 | userfaultfd_event_complete(ctx, uwq); |
384632e6 AA |
1086 | } else { |
1087 | /* | |
1088 | * Here the fork thread aborted and the | |
1089 | * refcount from the fork thread on fork_nctx | |
1090 | * has already been released. We still hold | |
1091 | * the reference we took before releasing the | |
1092 | * lock above. If resolve_userfault_fork | |
1093 | * failed we've to drop it because the | |
1094 | * fork_nctx has to be freed in such case. If | |
1095 | * it succeeded we'll hold it because the new | |
1096 | * uffd references it. | |
1097 | */ | |
1098 | if (ret) | |
1099 | userfaultfd_ctx_put(fork_nctx); | |
893e26e6 | 1100 | } |
cbcfa130 | 1101 | spin_unlock_irq(&ctx->event_wqh.lock); |
893e26e6 PE |
1102 | } |
1103 | ||
86039bd3 AA |
1104 | return ret; |
1105 | } | |
1106 | ||
40f45fe8 | 1107 | static ssize_t userfaultfd_read_iter(struct kiocb *iocb, struct iov_iter *to) |
86039bd3 | 1108 | { |
40f45fe8 | 1109 | struct file *file = iocb->ki_filp; |
86039bd3 AA |
1110 | struct userfaultfd_ctx *ctx = file->private_data; |
1111 | ssize_t _ret, ret = 0; | |
a9b85f94 | 1112 | struct uffd_msg msg; |
b537900f | 1113 | struct inode *inode = file_inode(file); |
40f45fe8 | 1114 | bool no_wait; |
86039bd3 | 1115 | |
22e5fe2a | 1116 | if (!userfaultfd_is_initialized(ctx)) |
86039bd3 | 1117 | return -EINVAL; |
86039bd3 | 1118 | |
40f45fe8 | 1119 | no_wait = file->f_flags & O_NONBLOCK || iocb->ki_flags & IOCB_NOWAIT; |
86039bd3 | 1120 | for (;;) { |
40f45fe8 | 1121 | if (iov_iter_count(to) < sizeof(msg)) |
86039bd3 | 1122 | return ret ? ret : -EINVAL; |
b537900f | 1123 | _ret = userfaultfd_ctx_read(ctx, no_wait, &msg, inode); |
86039bd3 AA |
1124 | if (_ret < 0) |
1125 | return ret ? ret : _ret; | |
40f45fe8 JA |
1126 | _ret = !copy_to_iter_full(&msg, sizeof(msg), to); |
1127 | if (_ret) | |
86039bd3 | 1128 | return ret ? ret : -EFAULT; |
a9b85f94 | 1129 | ret += sizeof(msg); |
86039bd3 AA |
1130 | /* |
1131 | * Allow to read more than one fault at time but only | |
1132 | * block if waiting for the very first one. | |
1133 | */ | |
40f45fe8 | 1134 | no_wait = true; |
86039bd3 AA |
1135 | } |
1136 | } | |
1137 | ||
1138 | static void __wake_userfault(struct userfaultfd_ctx *ctx, | |
1139 | struct userfaultfd_wake_range *range) | |
1140 | { | |
cbcfa130 | 1141 | spin_lock_irq(&ctx->fault_pending_wqh.lock); |
86039bd3 | 1142 | /* wake all in the range and autoremove */ |
15b726ef | 1143 | if (waitqueue_active(&ctx->fault_pending_wqh)) |
ac5be6b4 | 1144 | __wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, |
15b726ef AA |
1145 | range); |
1146 | if (waitqueue_active(&ctx->fault_wqh)) | |
c430d1e8 | 1147 | __wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, range); |
cbcfa130 | 1148 | spin_unlock_irq(&ctx->fault_pending_wqh.lock); |
86039bd3 AA |
1149 | } |
1150 | ||
1151 | static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx, | |
1152 | struct userfaultfd_wake_range *range) | |
1153 | { | |
2c5b7e1b AA |
1154 | unsigned seq; |
1155 | bool need_wakeup; | |
1156 | ||
86039bd3 AA |
1157 | /* |
1158 | * To be sure waitqueue_active() is not reordered by the CPU | |
1159 | * before the pagetable update, use an explicit SMP memory | |
3e4e28c5 | 1160 | * barrier here. PT lock release or mmap_read_unlock(mm) still |
86039bd3 AA |
1161 | * have release semantics that can allow the |
1162 | * waitqueue_active() to be reordered before the pte update. | |
1163 | */ | |
1164 | smp_mb(); | |
1165 | ||
1166 | /* | |
1167 | * Use waitqueue_active because it's very frequent to | |
1168 | * change the address space atomically even if there are no | |
1169 | * userfaults yet. So we take the spinlock only when we're | |
1170 | * sure we've userfaults to wake. | |
1171 | */ | |
2c5b7e1b AA |
1172 | do { |
1173 | seq = read_seqcount_begin(&ctx->refile_seq); | |
1174 | need_wakeup = waitqueue_active(&ctx->fault_pending_wqh) || | |
1175 | waitqueue_active(&ctx->fault_wqh); | |
1176 | cond_resched(); | |
1177 | } while (read_seqcount_retry(&ctx->refile_seq, seq)); | |
1178 | if (need_wakeup) | |
86039bd3 AA |
1179 | __wake_userfault(ctx, range); |
1180 | } | |
1181 | ||
2ef5d724 AR |
1182 | static __always_inline int validate_unaligned_range( |
1183 | struct mm_struct *mm, __u64 start, __u64 len) | |
86039bd3 AA |
1184 | { |
1185 | __u64 task_size = mm->task_size; | |
1186 | ||
86039bd3 AA |
1187 | if (len & ~PAGE_MASK) |
1188 | return -EINVAL; | |
1189 | if (!len) | |
1190 | return -EINVAL; | |
e71e2ace | 1191 | if (start < mmap_min_addr) |
86039bd3 | 1192 | return -EINVAL; |
e71e2ace | 1193 | if (start >= task_size) |
86039bd3 | 1194 | return -EINVAL; |
e71e2ace | 1195 | if (len > task_size - start) |
86039bd3 | 1196 | return -EINVAL; |
2ef5d724 AR |
1197 | if (start + len <= start) |
1198 | return -EINVAL; | |
86039bd3 AA |
1199 | return 0; |
1200 | } | |
1201 | ||
2ef5d724 AR |
1202 | static __always_inline int validate_range(struct mm_struct *mm, |
1203 | __u64 start, __u64 len) | |
1204 | { | |
1205 | if (start & ~PAGE_MASK) | |
1206 | return -EINVAL; | |
1207 | ||
1208 | return validate_unaligned_range(mm, start, len); | |
1209 | } | |
1210 | ||
86039bd3 AA |
1211 | static int userfaultfd_register(struct userfaultfd_ctx *ctx, |
1212 | unsigned long arg) | |
1213 | { | |
1214 | struct mm_struct *mm = ctx->mm; | |
a17c7d8f | 1215 | struct vm_area_struct *vma, *cur; |
86039bd3 AA |
1216 | int ret; |
1217 | struct uffdio_register uffdio_register; | |
1218 | struct uffdio_register __user *user_uffdio_register; | |
a17c7d8f | 1219 | unsigned long vm_flags; |
86039bd3 | 1220 | bool found; |
ce53e8e6 | 1221 | bool basic_ioctls; |
a17c7d8f | 1222 | unsigned long start, end; |
11a9b902 | 1223 | struct vma_iterator vmi; |
d61ea1cb | 1224 | bool wp_async = userfaultfd_wp_async_ctx(ctx); |
86039bd3 AA |
1225 | |
1226 | user_uffdio_register = (struct uffdio_register __user *) arg; | |
1227 | ||
1228 | ret = -EFAULT; | |
1229 | if (copy_from_user(&uffdio_register, user_uffdio_register, | |
1230 | sizeof(uffdio_register)-sizeof(__u64))) | |
1231 | goto out; | |
1232 | ||
1233 | ret = -EINVAL; | |
1234 | if (!uffdio_register.mode) | |
1235 | goto out; | |
7677f7fd | 1236 | if (uffdio_register.mode & ~UFFD_API_REGISTER_MODES) |
86039bd3 AA |
1237 | goto out; |
1238 | vm_flags = 0; | |
1239 | if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MISSING) | |
1240 | vm_flags |= VM_UFFD_MISSING; | |
00b151f2 PX |
1241 | if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP) { |
1242 | #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP | |
1243 | goto out; | |
1244 | #endif | |
86039bd3 | 1245 | vm_flags |= VM_UFFD_WP; |
00b151f2 | 1246 | } |
7677f7fd AR |
1247 | if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MINOR) { |
1248 | #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR | |
1249 | goto out; | |
1250 | #endif | |
1251 | vm_flags |= VM_UFFD_MINOR; | |
1252 | } | |
86039bd3 | 1253 | |
e71e2ace | 1254 | ret = validate_range(mm, uffdio_register.range.start, |
86039bd3 AA |
1255 | uffdio_register.range.len); |
1256 | if (ret) | |
1257 | goto out; | |
1258 | ||
1259 | start = uffdio_register.range.start; | |
1260 | end = start + uffdio_register.range.len; | |
1261 | ||
d2005e3f ON |
1262 | ret = -ENOMEM; |
1263 | if (!mmget_not_zero(mm)) | |
1264 | goto out; | |
1265 | ||
11a9b902 | 1266 | ret = -EINVAL; |
d8ed45c5 | 1267 | mmap_write_lock(mm); |
11a9b902 LH |
1268 | vma_iter_init(&vmi, mm, start); |
1269 | vma = vma_find(&vmi, end); | |
86039bd3 AA |
1270 | if (!vma) |
1271 | goto out_unlock; | |
1272 | ||
cab350af MK |
1273 | /* |
1274 | * If the first vma contains huge pages, make sure start address | |
1275 | * is aligned to huge page size. | |
1276 | */ | |
1277 | if (is_vm_hugetlb_page(vma)) { | |
1278 | unsigned long vma_hpagesize = vma_kernel_pagesize(vma); | |
1279 | ||
1280 | if (start & (vma_hpagesize - 1)) | |
1281 | goto out_unlock; | |
1282 | } | |
1283 | ||
86039bd3 AA |
1284 | /* |
1285 | * Search for not compatible vmas. | |
86039bd3 AA |
1286 | */ |
1287 | found = false; | |
ce53e8e6 | 1288 | basic_ioctls = false; |
11a9b902 LH |
1289 | cur = vma; |
1290 | do { | |
86039bd3 AA |
1291 | cond_resched(); |
1292 | ||
1293 | BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^ | |
7677f7fd | 1294 | !!(cur->vm_flags & __VM_UFFD_FLAGS)); |
86039bd3 AA |
1295 | |
1296 | /* check not compatible vmas */ | |
1297 | ret = -EINVAL; | |
d61ea1cb | 1298 | if (!vma_can_userfault(cur, vm_flags, wp_async)) |
86039bd3 | 1299 | goto out_unlock; |
29ec9066 AA |
1300 | |
1301 | /* | |
1302 | * UFFDIO_COPY will fill file holes even without | |
1303 | * PROT_WRITE. This check enforces that if this is a | |
1304 | * MAP_SHARED, the process has write permission to the backing | |
1305 | * file. If VM_MAYWRITE is set it also enforces that on a | |
1306 | * MAP_SHARED vma: there is no F_WRITE_SEAL and no further | |
1307 | * F_WRITE_SEAL can be taken until the vma is destroyed. | |
1308 | */ | |
1309 | ret = -EPERM; | |
1310 | if (unlikely(!(cur->vm_flags & VM_MAYWRITE))) | |
1311 | goto out_unlock; | |
1312 | ||
cab350af MK |
1313 | /* |
1314 | * If this vma contains ending address, and huge pages | |
1315 | * check alignment. | |
1316 | */ | |
1317 | if (is_vm_hugetlb_page(cur) && end <= cur->vm_end && | |
1318 | end > cur->vm_start) { | |
1319 | unsigned long vma_hpagesize = vma_kernel_pagesize(cur); | |
1320 | ||
1321 | ret = -EINVAL; | |
1322 | ||
1323 | if (end & (vma_hpagesize - 1)) | |
1324 | goto out_unlock; | |
1325 | } | |
63b2d417 AA |
1326 | if ((vm_flags & VM_UFFD_WP) && !(cur->vm_flags & VM_MAYWRITE)) |
1327 | goto out_unlock; | |
86039bd3 AA |
1328 | |
1329 | /* | |
1330 | * Check that this vma isn't already owned by a | |
1331 | * different userfaultfd. We can't allow more than one | |
1332 | * userfaultfd to own a single vma simultaneously or we | |
1333 | * wouldn't know which one to deliver the userfaults to. | |
1334 | */ | |
1335 | ret = -EBUSY; | |
1336 | if (cur->vm_userfaultfd_ctx.ctx && | |
1337 | cur->vm_userfaultfd_ctx.ctx != ctx) | |
1338 | goto out_unlock; | |
1339 | ||
cab350af MK |
1340 | /* |
1341 | * Note vmas containing huge pages | |
1342 | */ | |
ce53e8e6 MR |
1343 | if (is_vm_hugetlb_page(cur)) |
1344 | basic_ioctls = true; | |
cab350af | 1345 | |
86039bd3 | 1346 | found = true; |
11a9b902 | 1347 | } for_each_vma_range(vmi, cur, end); |
86039bd3 AA |
1348 | BUG_ON(!found); |
1349 | ||
a17c7d8f LS |
1350 | ret = userfaultfd_register_range(ctx, vma, vm_flags, start, end, |
1351 | wp_async); | |
11a9b902 | 1352 | |
86039bd3 | 1353 | out_unlock: |
d8ed45c5 | 1354 | mmap_write_unlock(mm); |
d2005e3f | 1355 | mmput(mm); |
86039bd3 | 1356 | if (!ret) { |
14819305 PX |
1357 | __u64 ioctls_out; |
1358 | ||
1359 | ioctls_out = basic_ioctls ? UFFD_API_RANGE_IOCTLS_BASIC : | |
1360 | UFFD_API_RANGE_IOCTLS; | |
1361 | ||
1362 | /* | |
1363 | * Declare the WP ioctl only if the WP mode is | |
1364 | * specified and all checks passed with the range | |
1365 | */ | |
1366 | if (!(uffdio_register.mode & UFFDIO_REGISTER_MODE_WP)) | |
1367 | ioctls_out &= ~((__u64)1 << _UFFDIO_WRITEPROTECT); | |
1368 | ||
f6191471 AR |
1369 | /* CONTINUE ioctl is only supported for MINOR ranges. */ |
1370 | if (!(uffdio_register.mode & UFFDIO_REGISTER_MODE_MINOR)) | |
1371 | ioctls_out &= ~((__u64)1 << _UFFDIO_CONTINUE); | |
1372 | ||
86039bd3 AA |
1373 | /* |
1374 | * Now that we scanned all vmas we can already tell | |
1375 | * userland which ioctls methods are guaranteed to | |
1376 | * succeed on this range. | |
1377 | */ | |
14819305 | 1378 | if (put_user(ioctls_out, &user_uffdio_register->ioctls)) |
86039bd3 AA |
1379 | ret = -EFAULT; |
1380 | } | |
1381 | out: | |
1382 | return ret; | |
1383 | } | |
1384 | ||
1385 | static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, | |
1386 | unsigned long arg) | |
1387 | { | |
1388 | struct mm_struct *mm = ctx->mm; | |
1389 | struct vm_area_struct *vma, *prev, *cur; | |
1390 | int ret; | |
1391 | struct uffdio_range uffdio_unregister; | |
86039bd3 AA |
1392 | bool found; |
1393 | unsigned long start, end, vma_end; | |
1394 | const void __user *buf = (void __user *)arg; | |
11a9b902 | 1395 | struct vma_iterator vmi; |
d61ea1cb | 1396 | bool wp_async = userfaultfd_wp_async_ctx(ctx); |
86039bd3 AA |
1397 | |
1398 | ret = -EFAULT; | |
1399 | if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister))) | |
1400 | goto out; | |
1401 | ||
e71e2ace | 1402 | ret = validate_range(mm, uffdio_unregister.start, |
86039bd3 AA |
1403 | uffdio_unregister.len); |
1404 | if (ret) | |
1405 | goto out; | |
1406 | ||
1407 | start = uffdio_unregister.start; | |
1408 | end = start + uffdio_unregister.len; | |
1409 | ||
d2005e3f ON |
1410 | ret = -ENOMEM; |
1411 | if (!mmget_not_zero(mm)) | |
1412 | goto out; | |
1413 | ||
d8ed45c5 | 1414 | mmap_write_lock(mm); |
86039bd3 | 1415 | ret = -EINVAL; |
11a9b902 LH |
1416 | vma_iter_init(&vmi, mm, start); |
1417 | vma = vma_find(&vmi, end); | |
1418 | if (!vma) | |
86039bd3 AA |
1419 | goto out_unlock; |
1420 | ||
cab350af MK |
1421 | /* |
1422 | * If the first vma contains huge pages, make sure start address | |
1423 | * is aligned to huge page size. | |
1424 | */ | |
1425 | if (is_vm_hugetlb_page(vma)) { | |
1426 | unsigned long vma_hpagesize = vma_kernel_pagesize(vma); | |
1427 | ||
1428 | if (start & (vma_hpagesize - 1)) | |
1429 | goto out_unlock; | |
1430 | } | |
1431 | ||
86039bd3 AA |
1432 | /* |
1433 | * Search for not compatible vmas. | |
86039bd3 AA |
1434 | */ |
1435 | found = false; | |
11a9b902 LH |
1436 | cur = vma; |
1437 | do { | |
86039bd3 AA |
1438 | cond_resched(); |
1439 | ||
1440 | BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^ | |
7677f7fd | 1441 | !!(cur->vm_flags & __VM_UFFD_FLAGS)); |
86039bd3 AA |
1442 | |
1443 | /* | |
1444 | * Check not compatible vmas, not strictly required | |
1445 | * here as not compatible vmas cannot have an | |
1446 | * userfaultfd_ctx registered on them, but this | |
1447 | * provides for more strict behavior to notice | |
1448 | * unregistration errors. | |
1449 | */ | |
d61ea1cb | 1450 | if (!vma_can_userfault(cur, cur->vm_flags, wp_async)) |
86039bd3 AA |
1451 | goto out_unlock; |
1452 | ||
1453 | found = true; | |
11a9b902 | 1454 | } for_each_vma_range(vmi, cur, end); |
86039bd3 AA |
1455 | BUG_ON(!found); |
1456 | ||
11a9b902 LH |
1457 | vma_iter_set(&vmi, start); |
1458 | prev = vma_prev(&vmi); | |
270aa010 PX |
1459 | if (vma->vm_start < start) |
1460 | prev = vma; | |
1461 | ||
86039bd3 | 1462 | ret = 0; |
11a9b902 | 1463 | for_each_vma_range(vmi, vma, end) { |
86039bd3 AA |
1464 | cond_resched(); |
1465 | ||
d61ea1cb | 1466 | BUG_ON(!vma_can_userfault(vma, vma->vm_flags, wp_async)); |
86039bd3 AA |
1467 | |
1468 | /* | |
1469 | * Nothing to do: this vma is already registered into this | |
1470 | * userfaultfd and with the right tracking mode too. | |
1471 | */ | |
1472 | if (!vma->vm_userfaultfd_ctx.ctx) | |
1473 | goto skip; | |
1474 | ||
01e881f5 AA |
1475 | WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); |
1476 | ||
86039bd3 AA |
1477 | if (vma->vm_start > start) |
1478 | start = vma->vm_start; | |
1479 | vma_end = min(end, vma->vm_end); | |
1480 | ||
09fa5296 AA |
1481 | if (userfaultfd_missing(vma)) { |
1482 | /* | |
1483 | * Wake any concurrent pending userfault while | |
1484 | * we unregister, so they will not hang | |
1485 | * permanently and it avoids userland to call | |
1486 | * UFFDIO_WAKE explicitly. | |
1487 | */ | |
1488 | struct userfaultfd_wake_range range; | |
1489 | range.start = start; | |
1490 | range.len = vma_end - start; | |
1491 | wake_userfault(vma->vm_userfaultfd_ctx.ctx, &range); | |
1492 | } | |
1493 | ||
a17c7d8f LS |
1494 | vma = userfaultfd_clear_vma(&vmi, prev, vma, |
1495 | start, vma_end); | |
94d7d923 LS |
1496 | if (IS_ERR(vma)) { |
1497 | ret = PTR_ERR(vma); | |
1498 | break; | |
86039bd3 | 1499 | } |
94d7d923 | 1500 | |
86039bd3 AA |
1501 | skip: |
1502 | prev = vma; | |
1503 | start = vma->vm_end; | |
11a9b902 LH |
1504 | } |
1505 | ||
86039bd3 | 1506 | out_unlock: |
d8ed45c5 | 1507 | mmap_write_unlock(mm); |
d2005e3f | 1508 | mmput(mm); |
86039bd3 AA |
1509 | out: |
1510 | return ret; | |
1511 | } | |
1512 | ||
1513 | /* | |
ba85c702 AA |
1514 | * userfaultfd_wake may be used in combination with the |
1515 | * UFFDIO_*_MODE_DONTWAKE to wakeup userfaults in batches. | |
86039bd3 AA |
1516 | */ |
1517 | static int userfaultfd_wake(struct userfaultfd_ctx *ctx, | |
1518 | unsigned long arg) | |
1519 | { | |
1520 | int ret; | |
1521 | struct uffdio_range uffdio_wake; | |
1522 | struct userfaultfd_wake_range range; | |
1523 | const void __user *buf = (void __user *)arg; | |
1524 | ||
1525 | ret = -EFAULT; | |
1526 | if (copy_from_user(&uffdio_wake, buf, sizeof(uffdio_wake))) | |
1527 | goto out; | |
1528 | ||
e71e2ace | 1529 | ret = validate_range(ctx->mm, uffdio_wake.start, uffdio_wake.len); |
86039bd3 AA |
1530 | if (ret) |
1531 | goto out; | |
1532 | ||
1533 | range.start = uffdio_wake.start; | |
1534 | range.len = uffdio_wake.len; | |
1535 | ||
1536 | /* | |
1537 | * len == 0 means wake all and we don't want to wake all here, | |
1538 | * so check it again to be sure. | |
1539 | */ | |
1540 | VM_BUG_ON(!range.len); | |
1541 | ||
1542 | wake_userfault(ctx, &range); | |
1543 | ret = 0; | |
1544 | ||
1545 | out: | |
1546 | return ret; | |
1547 | } | |
1548 | ||
ad465cae AA |
1549 | static int userfaultfd_copy(struct userfaultfd_ctx *ctx, |
1550 | unsigned long arg) | |
1551 | { | |
1552 | __s64 ret; | |
1553 | struct uffdio_copy uffdio_copy; | |
1554 | struct uffdio_copy __user *user_uffdio_copy; | |
1555 | struct userfaultfd_wake_range range; | |
d9712937 | 1556 | uffd_flags_t flags = 0; |
ad465cae AA |
1557 | |
1558 | user_uffdio_copy = (struct uffdio_copy __user *) arg; | |
1559 | ||
df2cc96e | 1560 | ret = -EAGAIN; |
a759a909 | 1561 | if (atomic_read(&ctx->mmap_changing)) |
df2cc96e MR |
1562 | goto out; |
1563 | ||
ad465cae AA |
1564 | ret = -EFAULT; |
1565 | if (copy_from_user(&uffdio_copy, user_uffdio_copy, | |
1566 | /* don't copy "copy" last field */ | |
1567 | sizeof(uffdio_copy)-sizeof(__s64))) | |
1568 | goto out; | |
1569 | ||
2ef5d724 AR |
1570 | ret = validate_unaligned_range(ctx->mm, uffdio_copy.src, |
1571 | uffdio_copy.len); | |
1572 | if (ret) | |
1573 | goto out; | |
e71e2ace | 1574 | ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len); |
ad465cae AA |
1575 | if (ret) |
1576 | goto out; | |
2ef5d724 | 1577 | |
ad465cae | 1578 | ret = -EINVAL; |
72981e0e | 1579 | if (uffdio_copy.mode & ~(UFFDIO_COPY_MODE_DONTWAKE|UFFDIO_COPY_MODE_WP)) |
ad465cae | 1580 | goto out; |
d9712937 AR |
1581 | if (uffdio_copy.mode & UFFDIO_COPY_MODE_WP) |
1582 | flags |= MFILL_ATOMIC_WP; | |
d2005e3f | 1583 | if (mmget_not_zero(ctx->mm)) { |
5e4c24a5 LG |
1584 | ret = mfill_atomic_copy(ctx, uffdio_copy.dst, uffdio_copy.src, |
1585 | uffdio_copy.len, flags); | |
d2005e3f | 1586 | mmput(ctx->mm); |
96333187 | 1587 | } else { |
e86b298b | 1588 | return -ESRCH; |
d2005e3f | 1589 | } |
ad465cae AA |
1590 | if (unlikely(put_user(ret, &user_uffdio_copy->copy))) |
1591 | return -EFAULT; | |
1592 | if (ret < 0) | |
1593 | goto out; | |
1594 | BUG_ON(!ret); | |
1595 | /* len == 0 would wake all */ | |
1596 | range.len = ret; | |
1597 | if (!(uffdio_copy.mode & UFFDIO_COPY_MODE_DONTWAKE)) { | |
1598 | range.start = uffdio_copy.dst; | |
1599 | wake_userfault(ctx, &range); | |
1600 | } | |
1601 | ret = range.len == uffdio_copy.len ? 0 : -EAGAIN; | |
1602 | out: | |
1603 | return ret; | |
1604 | } | |
1605 | ||
1606 | static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx, | |
1607 | unsigned long arg) | |
1608 | { | |
1609 | __s64 ret; | |
1610 | struct uffdio_zeropage uffdio_zeropage; | |
1611 | struct uffdio_zeropage __user *user_uffdio_zeropage; | |
1612 | struct userfaultfd_wake_range range; | |
1613 | ||
1614 | user_uffdio_zeropage = (struct uffdio_zeropage __user *) arg; | |
1615 | ||
df2cc96e | 1616 | ret = -EAGAIN; |
a759a909 | 1617 | if (atomic_read(&ctx->mmap_changing)) |
df2cc96e MR |
1618 | goto out; |
1619 | ||
ad465cae AA |
1620 | ret = -EFAULT; |
1621 | if (copy_from_user(&uffdio_zeropage, user_uffdio_zeropage, | |
1622 | /* don't copy "zeropage" last field */ | |
1623 | sizeof(uffdio_zeropage)-sizeof(__s64))) | |
1624 | goto out; | |
1625 | ||
e71e2ace | 1626 | ret = validate_range(ctx->mm, uffdio_zeropage.range.start, |
ad465cae AA |
1627 | uffdio_zeropage.range.len); |
1628 | if (ret) | |
1629 | goto out; | |
1630 | ret = -EINVAL; | |
1631 | if (uffdio_zeropage.mode & ~UFFDIO_ZEROPAGE_MODE_DONTWAKE) | |
1632 | goto out; | |
1633 | ||
d2005e3f | 1634 | if (mmget_not_zero(ctx->mm)) { |
5e4c24a5 LG |
1635 | ret = mfill_atomic_zeropage(ctx, uffdio_zeropage.range.start, |
1636 | uffdio_zeropage.range.len); | |
d2005e3f | 1637 | mmput(ctx->mm); |
9d95aa4b | 1638 | } else { |
e86b298b | 1639 | return -ESRCH; |
d2005e3f | 1640 | } |
ad465cae AA |
1641 | if (unlikely(put_user(ret, &user_uffdio_zeropage->zeropage))) |
1642 | return -EFAULT; | |
1643 | if (ret < 0) | |
1644 | goto out; | |
1645 | /* len == 0 would wake all */ | |
1646 | BUG_ON(!ret); | |
1647 | range.len = ret; | |
1648 | if (!(uffdio_zeropage.mode & UFFDIO_ZEROPAGE_MODE_DONTWAKE)) { | |
1649 | range.start = uffdio_zeropage.range.start; | |
1650 | wake_userfault(ctx, &range); | |
1651 | } | |
1652 | ret = range.len == uffdio_zeropage.range.len ? 0 : -EAGAIN; | |
1653 | out: | |
1654 | return ret; | |
1655 | } | |
1656 | ||
63b2d417 AA |
1657 | static int userfaultfd_writeprotect(struct userfaultfd_ctx *ctx, |
1658 | unsigned long arg) | |
1659 | { | |
1660 | int ret; | |
1661 | struct uffdio_writeprotect uffdio_wp; | |
1662 | struct uffdio_writeprotect __user *user_uffdio_wp; | |
1663 | struct userfaultfd_wake_range range; | |
23080e27 | 1664 | bool mode_wp, mode_dontwake; |
63b2d417 | 1665 | |
a759a909 | 1666 | if (atomic_read(&ctx->mmap_changing)) |
63b2d417 AA |
1667 | return -EAGAIN; |
1668 | ||
1669 | user_uffdio_wp = (struct uffdio_writeprotect __user *) arg; | |
1670 | ||
1671 | if (copy_from_user(&uffdio_wp, user_uffdio_wp, | |
1672 | sizeof(struct uffdio_writeprotect))) | |
1673 | return -EFAULT; | |
1674 | ||
e71e2ace | 1675 | ret = validate_range(ctx->mm, uffdio_wp.range.start, |
63b2d417 AA |
1676 | uffdio_wp.range.len); |
1677 | if (ret) | |
1678 | return ret; | |
1679 | ||
1680 | if (uffdio_wp.mode & ~(UFFDIO_WRITEPROTECT_MODE_DONTWAKE | | |
1681 | UFFDIO_WRITEPROTECT_MODE_WP)) | |
1682 | return -EINVAL; | |
23080e27 PX |
1683 | |
1684 | mode_wp = uffdio_wp.mode & UFFDIO_WRITEPROTECT_MODE_WP; | |
1685 | mode_dontwake = uffdio_wp.mode & UFFDIO_WRITEPROTECT_MODE_DONTWAKE; | |
1686 | ||
1687 | if (mode_wp && mode_dontwake) | |
63b2d417 AA |
1688 | return -EINVAL; |
1689 | ||
cb185d5f | 1690 | if (mmget_not_zero(ctx->mm)) { |
5e4c24a5 LG |
1691 | ret = mwriteprotect_range(ctx, uffdio_wp.range.start, |
1692 | uffdio_wp.range.len, mode_wp); | |
cb185d5f NA |
1693 | mmput(ctx->mm); |
1694 | } else { | |
1695 | return -ESRCH; | |
1696 | } | |
1697 | ||
63b2d417 AA |
1698 | if (ret) |
1699 | return ret; | |
1700 | ||
23080e27 | 1701 | if (!mode_wp && !mode_dontwake) { |
63b2d417 AA |
1702 | range.start = uffdio_wp.range.start; |
1703 | range.len = uffdio_wp.range.len; | |
1704 | wake_userfault(ctx, &range); | |
1705 | } | |
1706 | return ret; | |
1707 | } | |
1708 | ||
f6191471 AR |
1709 | static int userfaultfd_continue(struct userfaultfd_ctx *ctx, unsigned long arg) |
1710 | { | |
1711 | __s64 ret; | |
1712 | struct uffdio_continue uffdio_continue; | |
1713 | struct uffdio_continue __user *user_uffdio_continue; | |
1714 | struct userfaultfd_wake_range range; | |
02891844 | 1715 | uffd_flags_t flags = 0; |
f6191471 AR |
1716 | |
1717 | user_uffdio_continue = (struct uffdio_continue __user *)arg; | |
1718 | ||
1719 | ret = -EAGAIN; | |
a759a909 | 1720 | if (atomic_read(&ctx->mmap_changing)) |
f6191471 AR |
1721 | goto out; |
1722 | ||
1723 | ret = -EFAULT; | |
1724 | if (copy_from_user(&uffdio_continue, user_uffdio_continue, | |
1725 | /* don't copy the output fields */ | |
1726 | sizeof(uffdio_continue) - (sizeof(__s64)))) | |
1727 | goto out; | |
1728 | ||
e71e2ace | 1729 | ret = validate_range(ctx->mm, uffdio_continue.range.start, |
f6191471 AR |
1730 | uffdio_continue.range.len); |
1731 | if (ret) | |
1732 | goto out; | |
1733 | ||
1734 | ret = -EINVAL; | |
02891844 AR |
1735 | if (uffdio_continue.mode & ~(UFFDIO_CONTINUE_MODE_DONTWAKE | |
1736 | UFFDIO_CONTINUE_MODE_WP)) | |
f6191471 | 1737 | goto out; |
02891844 AR |
1738 | if (uffdio_continue.mode & UFFDIO_CONTINUE_MODE_WP) |
1739 | flags |= MFILL_ATOMIC_WP; | |
f6191471 AR |
1740 | |
1741 | if (mmget_not_zero(ctx->mm)) { | |
5e4c24a5 LG |
1742 | ret = mfill_atomic_continue(ctx, uffdio_continue.range.start, |
1743 | uffdio_continue.range.len, flags); | |
f6191471 AR |
1744 | mmput(ctx->mm); |
1745 | } else { | |
1746 | return -ESRCH; | |
1747 | } | |
1748 | ||
1749 | if (unlikely(put_user(ret, &user_uffdio_continue->mapped))) | |
1750 | return -EFAULT; | |
1751 | if (ret < 0) | |
1752 | goto out; | |
1753 | ||
1754 | /* len == 0 would wake all */ | |
1755 | BUG_ON(!ret); | |
1756 | range.len = ret; | |
1757 | if (!(uffdio_continue.mode & UFFDIO_CONTINUE_MODE_DONTWAKE)) { | |
1758 | range.start = uffdio_continue.range.start; | |
1759 | wake_userfault(ctx, &range); | |
1760 | } | |
1761 | ret = range.len == uffdio_continue.range.len ? 0 : -EAGAIN; | |
1762 | ||
1763 | out: | |
1764 | return ret; | |
1765 | } | |
1766 | ||
fc71884a AR |
1767 | static inline int userfaultfd_poison(struct userfaultfd_ctx *ctx, unsigned long arg) |
1768 | { | |
1769 | __s64 ret; | |
1770 | struct uffdio_poison uffdio_poison; | |
1771 | struct uffdio_poison __user *user_uffdio_poison; | |
1772 | struct userfaultfd_wake_range range; | |
1773 | ||
1774 | user_uffdio_poison = (struct uffdio_poison __user *)arg; | |
1775 | ||
1776 | ret = -EAGAIN; | |
1777 | if (atomic_read(&ctx->mmap_changing)) | |
1778 | goto out; | |
1779 | ||
1780 | ret = -EFAULT; | |
1781 | if (copy_from_user(&uffdio_poison, user_uffdio_poison, | |
1782 | /* don't copy the output fields */ | |
1783 | sizeof(uffdio_poison) - (sizeof(__s64)))) | |
1784 | goto out; | |
1785 | ||
1786 | ret = validate_range(ctx->mm, uffdio_poison.range.start, | |
1787 | uffdio_poison.range.len); | |
1788 | if (ret) | |
1789 | goto out; | |
1790 | ||
1791 | ret = -EINVAL; | |
1792 | if (uffdio_poison.mode & ~UFFDIO_POISON_MODE_DONTWAKE) | |
1793 | goto out; | |
1794 | ||
1795 | if (mmget_not_zero(ctx->mm)) { | |
5e4c24a5 LG |
1796 | ret = mfill_atomic_poison(ctx, uffdio_poison.range.start, |
1797 | uffdio_poison.range.len, 0); | |
fc71884a AR |
1798 | mmput(ctx->mm); |
1799 | } else { | |
1800 | return -ESRCH; | |
1801 | } | |
1802 | ||
1803 | if (unlikely(put_user(ret, &user_uffdio_poison->updated))) | |
1804 | return -EFAULT; | |
1805 | if (ret < 0) | |
1806 | goto out; | |
1807 | ||
1808 | /* len == 0 would wake all */ | |
1809 | BUG_ON(!ret); | |
1810 | range.len = ret; | |
1811 | if (!(uffdio_poison.mode & UFFDIO_POISON_MODE_DONTWAKE)) { | |
1812 | range.start = uffdio_poison.range.start; | |
1813 | wake_userfault(ctx, &range); | |
1814 | } | |
1815 | ret = range.len == uffdio_poison.range.len ? 0 : -EAGAIN; | |
1816 | ||
1817 | out: | |
1818 | return ret; | |
1819 | } | |
1820 | ||
d61ea1cb PX |
1821 | bool userfaultfd_wp_async(struct vm_area_struct *vma) |
1822 | { | |
1823 | return userfaultfd_wp_async_ctx(vma->vm_userfaultfd_ctx.ctx); | |
1824 | } | |
1825 | ||
9cd75c3c PE |
1826 | static inline unsigned int uffd_ctx_features(__u64 user_features) |
1827 | { | |
1828 | /* | |
22e5fe2a NA |
1829 | * For the current set of features the bits just coincide. Set |
1830 | * UFFD_FEATURE_INITIALIZED to mark the features as enabled. | |
9cd75c3c | 1831 | */ |
22e5fe2a | 1832 | return (unsigned int)user_features | UFFD_FEATURE_INITIALIZED; |
9cd75c3c PE |
1833 | } |
1834 | ||
adef4406 AA |
1835 | static int userfaultfd_move(struct userfaultfd_ctx *ctx, |
1836 | unsigned long arg) | |
1837 | { | |
1838 | __s64 ret; | |
1839 | struct uffdio_move uffdio_move; | |
1840 | struct uffdio_move __user *user_uffdio_move; | |
1841 | struct userfaultfd_wake_range range; | |
1842 | struct mm_struct *mm = ctx->mm; | |
1843 | ||
1844 | user_uffdio_move = (struct uffdio_move __user *) arg; | |
1845 | ||
1846 | if (atomic_read(&ctx->mmap_changing)) | |
1847 | return -EAGAIN; | |
1848 | ||
1849 | if (copy_from_user(&uffdio_move, user_uffdio_move, | |
1850 | /* don't copy "move" last field */ | |
1851 | sizeof(uffdio_move)-sizeof(__s64))) | |
1852 | return -EFAULT; | |
1853 | ||
1854 | /* Do not allow cross-mm moves. */ | |
1855 | if (mm != current->mm) | |
1856 | return -EINVAL; | |
1857 | ||
1858 | ret = validate_range(mm, uffdio_move.dst, uffdio_move.len); | |
1859 | if (ret) | |
1860 | return ret; | |
1861 | ||
1862 | ret = validate_range(mm, uffdio_move.src, uffdio_move.len); | |
1863 | if (ret) | |
1864 | return ret; | |
1865 | ||
1866 | if (uffdio_move.mode & ~(UFFDIO_MOVE_MODE_ALLOW_SRC_HOLES| | |
1867 | UFFDIO_MOVE_MODE_DONTWAKE)) | |
1868 | return -EINVAL; | |
1869 | ||
1870 | if (mmget_not_zero(mm)) { | |
867a43a3 LG |
1871 | ret = move_pages(ctx, uffdio_move.dst, uffdio_move.src, |
1872 | uffdio_move.len, uffdio_move.mode); | |
adef4406 AA |
1873 | mmput(mm); |
1874 | } else { | |
1875 | return -ESRCH; | |
1876 | } | |
1877 | ||
1878 | if (unlikely(put_user(ret, &user_uffdio_move->move))) | |
1879 | return -EFAULT; | |
1880 | if (ret < 0) | |
1881 | goto out; | |
1882 | ||
1883 | /* len == 0 would wake all */ | |
1884 | VM_WARN_ON(!ret); | |
1885 | range.len = ret; | |
1886 | if (!(uffdio_move.mode & UFFDIO_MOVE_MODE_DONTWAKE)) { | |
1887 | range.start = uffdio_move.dst; | |
1888 | wake_userfault(ctx, &range); | |
1889 | } | |
1890 | ret = range.len == uffdio_move.len ? 0 : -EAGAIN; | |
1891 | ||
1892 | out: | |
1893 | return ret; | |
1894 | } | |
1895 | ||
86039bd3 AA |
1896 | /* |
1897 | * userland asks for a certain API version and we return which bits | |
1898 | * and ioctl commands are implemented in this kernel for such API | |
1899 | * version or -EINVAL if unknown. | |
1900 | */ | |
1901 | static int userfaultfd_api(struct userfaultfd_ctx *ctx, | |
1902 | unsigned long arg) | |
1903 | { | |
1904 | struct uffdio_api uffdio_api; | |
1905 | void __user *buf = (void __user *)arg; | |
22e5fe2a | 1906 | unsigned int ctx_features; |
86039bd3 | 1907 | int ret; |
65603144 | 1908 | __u64 features; |
86039bd3 | 1909 | |
86039bd3 | 1910 | ret = -EFAULT; |
a9b85f94 | 1911 | if (copy_from_user(&uffdio_api, buf, sizeof(uffdio_api))) |
86039bd3 | 1912 | goto out; |
2ff559f3 PX |
1913 | features = uffdio_api.features; |
1914 | ret = -EINVAL; | |
1723f04c | 1915 | if (uffdio_api.api != UFFD_API) |
2ff559f3 | 1916 | goto err_out; |
3c1c24d9 MR |
1917 | ret = -EPERM; |
1918 | if ((features & UFFD_FEATURE_EVENT_FORK) && !capable(CAP_SYS_PTRACE)) | |
1919 | goto err_out; | |
d61ea1cb PX |
1920 | |
1921 | /* WP_ASYNC relies on WP_UNPOPULATED, choose it unconditionally */ | |
1922 | if (features & UFFD_FEATURE_WP_ASYNC) | |
1923 | features |= UFFD_FEATURE_WP_UNPOPULATED; | |
1924 | ||
65603144 AA |
1925 | /* report all available features and ioctls to userland */ |
1926 | uffdio_api.features = UFFD_API_FEATURES; | |
7677f7fd | 1927 | #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR |
964ab004 AR |
1928 | uffdio_api.features &= |
1929 | ~(UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM); | |
00b151f2 PX |
1930 | #endif |
1931 | #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP | |
1932 | uffdio_api.features &= ~UFFD_FEATURE_PAGEFAULT_FLAG_WP; | |
b1f9e876 PX |
1933 | #endif |
1934 | #ifndef CONFIG_PTE_MARKER_UFFD_WP | |
1935 | uffdio_api.features &= ~UFFD_FEATURE_WP_HUGETLBFS_SHMEM; | |
2bad466c | 1936 | uffdio_api.features &= ~UFFD_FEATURE_WP_UNPOPULATED; |
d61ea1cb | 1937 | uffdio_api.features &= ~UFFD_FEATURE_WP_ASYNC; |
7677f7fd | 1938 | #endif |
1723f04c AM |
1939 | |
1940 | ret = -EINVAL; | |
1941 | if (features & ~uffdio_api.features) | |
1942 | goto err_out; | |
1943 | ||
86039bd3 AA |
1944 | uffdio_api.ioctls = UFFD_API_IOCTLS; |
1945 | ret = -EFAULT; | |
1946 | if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api))) | |
1947 | goto out; | |
22e5fe2a | 1948 | |
65603144 | 1949 | /* only enable the requested features for this uffd context */ |
22e5fe2a NA |
1950 | ctx_features = uffd_ctx_features(features); |
1951 | ret = -EINVAL; | |
1952 | if (cmpxchg(&ctx->features, 0, ctx_features) != 0) | |
1953 | goto err_out; | |
1954 | ||
86039bd3 AA |
1955 | ret = 0; |
1956 | out: | |
1957 | return ret; | |
3c1c24d9 MR |
1958 | err_out: |
1959 | memset(&uffdio_api, 0, sizeof(uffdio_api)); | |
1960 | if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api))) | |
1961 | ret = -EFAULT; | |
1962 | goto out; | |
86039bd3 AA |
1963 | } |
1964 | ||
1965 | static long userfaultfd_ioctl(struct file *file, unsigned cmd, | |
1966 | unsigned long arg) | |
1967 | { | |
1968 | int ret = -EINVAL; | |
1969 | struct userfaultfd_ctx *ctx = file->private_data; | |
1970 | ||
22e5fe2a | 1971 | if (cmd != UFFDIO_API && !userfaultfd_is_initialized(ctx)) |
e6485a47 AA |
1972 | return -EINVAL; |
1973 | ||
86039bd3 AA |
1974 | switch(cmd) { |
1975 | case UFFDIO_API: | |
1976 | ret = userfaultfd_api(ctx, arg); | |
1977 | break; | |
1978 | case UFFDIO_REGISTER: | |
1979 | ret = userfaultfd_register(ctx, arg); | |
1980 | break; | |
1981 | case UFFDIO_UNREGISTER: | |
1982 | ret = userfaultfd_unregister(ctx, arg); | |
1983 | break; | |
1984 | case UFFDIO_WAKE: | |
1985 | ret = userfaultfd_wake(ctx, arg); | |
1986 | break; | |
ad465cae AA |
1987 | case UFFDIO_COPY: |
1988 | ret = userfaultfd_copy(ctx, arg); | |
1989 | break; | |
1990 | case UFFDIO_ZEROPAGE: | |
1991 | ret = userfaultfd_zeropage(ctx, arg); | |
1992 | break; | |
adef4406 AA |
1993 | case UFFDIO_MOVE: |
1994 | ret = userfaultfd_move(ctx, arg); | |
1995 | break; | |
63b2d417 AA |
1996 | case UFFDIO_WRITEPROTECT: |
1997 | ret = userfaultfd_writeprotect(ctx, arg); | |
1998 | break; | |
f6191471 AR |
1999 | case UFFDIO_CONTINUE: |
2000 | ret = userfaultfd_continue(ctx, arg); | |
2001 | break; | |
fc71884a AR |
2002 | case UFFDIO_POISON: |
2003 | ret = userfaultfd_poison(ctx, arg); | |
2004 | break; | |
86039bd3 AA |
2005 | } |
2006 | return ret; | |
2007 | } | |
2008 | ||
2009 | #ifdef CONFIG_PROC_FS | |
2010 | static void userfaultfd_show_fdinfo(struct seq_file *m, struct file *f) | |
2011 | { | |
2012 | struct userfaultfd_ctx *ctx = f->private_data; | |
ac6424b9 | 2013 | wait_queue_entry_t *wq; |
86039bd3 AA |
2014 | unsigned long pending = 0, total = 0; |
2015 | ||
cbcfa130 | 2016 | spin_lock_irq(&ctx->fault_pending_wqh.lock); |
2055da97 | 2017 | list_for_each_entry(wq, &ctx->fault_pending_wqh.head, entry) { |
15b726ef AA |
2018 | pending++; |
2019 | total++; | |
2020 | } | |
2055da97 | 2021 | list_for_each_entry(wq, &ctx->fault_wqh.head, entry) { |
86039bd3 AA |
2022 | total++; |
2023 | } | |
cbcfa130 | 2024 | spin_unlock_irq(&ctx->fault_pending_wqh.lock); |
86039bd3 AA |
2025 | |
2026 | /* | |
2027 | * If more protocols will be added, there will be all shown | |
2028 | * separated by a space. Like this: | |
2029 | * protocols: aa:... bb:... | |
2030 | */ | |
2031 | seq_printf(m, "pending:\t%lu\ntotal:\t%lu\nAPI:\t%Lx:%x:%Lx\n", | |
045098e9 | 2032 | pending, total, UFFD_API, ctx->features, |
86039bd3 AA |
2033 | UFFD_API_IOCTLS|UFFD_API_RANGE_IOCTLS); |
2034 | } | |
2035 | #endif | |
2036 | ||
2037 | static const struct file_operations userfaultfd_fops = { | |
2038 | #ifdef CONFIG_PROC_FS | |
2039 | .show_fdinfo = userfaultfd_show_fdinfo, | |
2040 | #endif | |
2041 | .release = userfaultfd_release, | |
2042 | .poll = userfaultfd_poll, | |
40f45fe8 | 2043 | .read_iter = userfaultfd_read_iter, |
86039bd3 | 2044 | .unlocked_ioctl = userfaultfd_ioctl, |
1832f2d8 | 2045 | .compat_ioctl = compat_ptr_ioctl, |
86039bd3 AA |
2046 | .llseek = noop_llseek, |
2047 | }; | |
2048 | ||
3004ec9c AA |
2049 | static void init_once_userfaultfd_ctx(void *mem) |
2050 | { | |
2051 | struct userfaultfd_ctx *ctx = (struct userfaultfd_ctx *) mem; | |
2052 | ||
2053 | init_waitqueue_head(&ctx->fault_pending_wqh); | |
2054 | init_waitqueue_head(&ctx->fault_wqh); | |
9cd75c3c | 2055 | init_waitqueue_head(&ctx->event_wqh); |
3004ec9c | 2056 | init_waitqueue_head(&ctx->fd_wqh); |
2ca97ac8 | 2057 | seqcount_spinlock_init(&ctx->refile_seq, &ctx->fault_pending_wqh.lock); |
3004ec9c AA |
2058 | } |
2059 | ||
2d5de004 | 2060 | static int new_userfaultfd(int flags) |
86039bd3 | 2061 | { |
86039bd3 | 2062 | struct userfaultfd_ctx *ctx; |
40f45fe8 | 2063 | struct file *file; |
284cd241 | 2064 | int fd; |
86039bd3 AA |
2065 | |
2066 | BUG_ON(!current->mm); | |
2067 | ||
2068 | /* Check the UFFD_* constants for consistency. */ | |
37cd0575 | 2069 | BUILD_BUG_ON(UFFD_USER_MODE_ONLY & UFFD_SHARED_FCNTL_FLAGS); |
86039bd3 AA |
2070 | BUILD_BUG_ON(UFFD_CLOEXEC != O_CLOEXEC); |
2071 | BUILD_BUG_ON(UFFD_NONBLOCK != O_NONBLOCK); | |
2072 | ||
37cd0575 | 2073 | if (flags & ~(UFFD_SHARED_FCNTL_FLAGS | UFFD_USER_MODE_ONLY)) |
284cd241 | 2074 | return -EINVAL; |
86039bd3 | 2075 | |
3004ec9c | 2076 | ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL); |
86039bd3 | 2077 | if (!ctx) |
284cd241 | 2078 | return -ENOMEM; |
86039bd3 | 2079 | |
ca880420 | 2080 | refcount_set(&ctx->refcount, 1); |
86039bd3 | 2081 | ctx->flags = flags; |
9cd75c3c | 2082 | ctx->features = 0; |
86039bd3 | 2083 | ctx->released = false; |
5e4c24a5 | 2084 | init_rwsem(&ctx->map_changing_lock); |
a759a909 | 2085 | atomic_set(&ctx->mmap_changing, 0); |
86039bd3 | 2086 | ctx->mm = current->mm; |
40f45fe8 JA |
2087 | |
2088 | fd = get_unused_fd_flags(flags & UFFD_SHARED_FCNTL_FLAGS); | |
2089 | if (fd < 0) | |
2090 | goto err_out; | |
86039bd3 | 2091 | |
4f0b9194 | 2092 | /* Create a new inode so that the LSM can block the creation. */ |
40f45fe8 | 2093 | file = anon_inode_create_getfile("[userfaultfd]", &userfaultfd_fops, ctx, |
abec3d01 | 2094 | O_RDONLY | (flags & UFFD_SHARED_FCNTL_FLAGS), NULL); |
40f45fe8 JA |
2095 | if (IS_ERR(file)) { |
2096 | put_unused_fd(fd); | |
2097 | fd = PTR_ERR(file); | |
2098 | goto err_out; | |
c03e946f | 2099 | } |
40f45fe8 JA |
2100 | /* prevent the mm struct to be freed */ |
2101 | mmgrab(ctx->mm); | |
2102 | file->f_mode |= FMODE_NOWAIT; | |
2103 | fd_install(fd, file); | |
2104 | return fd; | |
2105 | err_out: | |
2106 | kmem_cache_free(userfaultfd_ctx_cachep, ctx); | |
86039bd3 | 2107 | return fd; |
86039bd3 | 2108 | } |
3004ec9c | 2109 | |
2d5de004 AR |
2110 | static inline bool userfaultfd_syscall_allowed(int flags) |
2111 | { | |
2112 | /* Userspace-only page faults are always allowed */ | |
2113 | if (flags & UFFD_USER_MODE_ONLY) | |
2114 | return true; | |
2115 | ||
2116 | /* | |
2117 | * The user is requesting a userfaultfd which can handle kernel faults. | |
2118 | * Privileged users are always allowed to do this. | |
2119 | */ | |
2120 | if (capable(CAP_SYS_PTRACE)) | |
2121 | return true; | |
2122 | ||
2123 | /* Otherwise, access to kernel fault handling is sysctl controlled. */ | |
2124 | return sysctl_unprivileged_userfaultfd; | |
2125 | } | |
2126 | ||
2127 | SYSCALL_DEFINE1(userfaultfd, int, flags) | |
2128 | { | |
2129 | if (!userfaultfd_syscall_allowed(flags)) | |
2130 | return -EPERM; | |
2131 | ||
2132 | return new_userfaultfd(flags); | |
2133 | } | |
2134 | ||
2135 | static long userfaultfd_dev_ioctl(struct file *file, unsigned int cmd, unsigned long flags) | |
2136 | { | |
2137 | if (cmd != USERFAULTFD_IOC_NEW) | |
2138 | return -EINVAL; | |
2139 | ||
2140 | return new_userfaultfd(flags); | |
2141 | } | |
2142 | ||
2143 | static const struct file_operations userfaultfd_dev_fops = { | |
2144 | .unlocked_ioctl = userfaultfd_dev_ioctl, | |
2145 | .compat_ioctl = userfaultfd_dev_ioctl, | |
2146 | .owner = THIS_MODULE, | |
2147 | .llseek = noop_llseek, | |
2148 | }; | |
2149 | ||
2150 | static struct miscdevice userfaultfd_misc = { | |
2151 | .minor = MISC_DYNAMIC_MINOR, | |
2152 | .name = "userfaultfd", | |
2153 | .fops = &userfaultfd_dev_fops | |
2154 | }; | |
2155 | ||
3004ec9c AA |
2156 | static int __init userfaultfd_init(void) |
2157 | { | |
2d5de004 AR |
2158 | int ret; |
2159 | ||
2160 | ret = misc_register(&userfaultfd_misc); | |
2161 | if (ret) | |
2162 | return ret; | |
2163 | ||
3004ec9c AA |
2164 | userfaultfd_ctx_cachep = kmem_cache_create("userfaultfd_ctx_cache", |
2165 | sizeof(struct userfaultfd_ctx), | |
2166 | 0, | |
2167 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, | |
2168 | init_once_userfaultfd_ctx); | |
2d337b71 Z |
2169 | #ifdef CONFIG_SYSCTL |
2170 | register_sysctl_init("vm", vm_userfaultfd_table); | |
2171 | #endif | |
3004ec9c AA |
2172 | return 0; |
2173 | } | |
2174 | __initcall(userfaultfd_init); |