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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * linux/fs/proc/root.c | |
4 | * | |
5 | * Copyright (C) 1991, 1992 Linus Torvalds | |
6 | * | |
7 | * proc root directory handling functions | |
8 | */ | |
9 | ||
7c0f6ba6 | 10 | #include <linux/uaccess.h> |
1da177e4 LT |
11 | |
12 | #include <linux/errno.h> | |
13 | #include <linux/time.h> | |
14 | #include <linux/proc_fs.h> | |
15 | #include <linux/stat.h> | |
1da177e4 | 16 | #include <linux/init.h> |
914e2637 | 17 | #include <linux/sched.h> |
03441a34 | 18 | #include <linux/sched/stat.h> |
1da177e4 LT |
19 | #include <linux/module.h> |
20 | #include <linux/bitops.h> | |
87a8ebd6 | 21 | #include <linux/user_namespace.h> |
66f592e2 | 22 | #include <linux/fs_context.h> |
f6c7a1f3 | 23 | #include <linux/mount.h> |
07543f5c | 24 | #include <linux/pid_namespace.h> |
66f592e2 | 25 | #include <linux/fs_parser.h> |
5b825c3a | 26 | #include <linux/cred.h> |
60a3c3a5 | 27 | #include <linux/magic.h> |
66f592e2 | 28 | #include <linux/slab.h> |
1da177e4 | 29 | |
fee781e6 AB |
30 | #include "internal.h" |
31 | ||
66f592e2 DH |
32 | struct proc_fs_context { |
33 | struct pid_namespace *pid_ns; | |
34 | unsigned int mask; | |
35 | int hidepid; | |
36 | int gid; | |
97412950 VK |
37 | }; |
38 | ||
66f592e2 DH |
39 | enum proc_param { |
40 | Opt_gid, | |
41 | Opt_hidepid, | |
97412950 VK |
42 | }; |
43 | ||
66f592e2 DH |
44 | static const struct fs_parameter_spec proc_param_specs[] = { |
45 | fsparam_u32("gid", Opt_gid), | |
46 | fsparam_u32("hidepid", Opt_hidepid), | |
47 | {} | |
48 | }; | |
49 | ||
50 | static const struct fs_parameter_description proc_fs_parameters = { | |
51 | .name = "proc", | |
52 | .specs = proc_param_specs, | |
53 | }; | |
54 | ||
55 | static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param) | |
97412950 | 56 | { |
66f592e2 DH |
57 | struct proc_fs_context *ctx = fc->fs_private; |
58 | struct fs_parse_result result; | |
59 | int opt; | |
60 | ||
61 | opt = fs_parse(fc, &proc_fs_parameters, param, &result); | |
62 | if (opt < 0) | |
63 | return opt; | |
64 | ||
65 | switch (opt) { | |
66 | case Opt_gid: | |
67 | ctx->gid = result.uint_32; | |
68 | break; | |
69 | ||
70 | case Opt_hidepid: | |
71 | ctx->hidepid = result.uint_32; | |
72 | if (ctx->hidepid < HIDEPID_OFF || | |
73 | ctx->hidepid > HIDEPID_INVISIBLE) | |
74 | return invalf(fc, "proc: hidepid value must be between 0 and 2.\n"); | |
75 | break; | |
76 | ||
77 | default: | |
78 | return -EINVAL; | |
97412950 VK |
79 | } |
80 | ||
66f592e2 DH |
81 | ctx->mask |= 1 << opt; |
82 | return 0; | |
97412950 VK |
83 | } |
84 | ||
66f592e2 DH |
85 | static void proc_apply_options(struct super_block *s, |
86 | struct fs_context *fc, | |
87 | struct pid_namespace *pid_ns, | |
88 | struct user_namespace *user_ns) | |
97412950 | 89 | { |
66f592e2 DH |
90 | struct proc_fs_context *ctx = fc->fs_private; |
91 | ||
92 | if (ctx->mask & (1 << Opt_gid)) | |
93 | pid_ns->pid_gid = make_kgid(user_ns, ctx->gid); | |
94 | if (ctx->mask & (1 << Opt_hidepid)) | |
95 | pid_ns->hide_pid = ctx->hidepid; | |
97412950 VK |
96 | } |
97 | ||
66f592e2 | 98 | static int proc_fill_super(struct super_block *s, struct fs_context *fc) |
60a3c3a5 | 99 | { |
66f592e2 | 100 | struct pid_namespace *pid_ns = get_pid_ns(s->s_fs_info); |
60a3c3a5 DH |
101 | struct inode *root_inode; |
102 | int ret; | |
103 | ||
66f592e2 | 104 | proc_apply_options(s, fc, pid_ns, current_user_ns()); |
60a3c3a5 DH |
105 | |
106 | /* User space would break if executables or devices appear on proc */ | |
107 | s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV; | |
108 | s->s_flags |= SB_NODIRATIME | SB_NOSUID | SB_NOEXEC; | |
109 | s->s_blocksize = 1024; | |
110 | s->s_blocksize_bits = 10; | |
111 | s->s_magic = PROC_SUPER_MAGIC; | |
112 | s->s_op = &proc_sops; | |
113 | s->s_time_gran = 1; | |
114 | ||
115 | /* | |
116 | * procfs isn't actually a stacking filesystem; however, there is | |
117 | * too much magic going on inside it to permit stacking things on | |
118 | * top of it | |
119 | */ | |
120 | s->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH; | |
121 | ||
122 | /* procfs dentries and inodes don't require IO to create */ | |
123 | s->s_shrink.seeks = 0; | |
124 | ||
125 | pde_get(&proc_root); | |
126 | root_inode = proc_get_inode(s, &proc_root); | |
127 | if (!root_inode) { | |
128 | pr_err("proc_fill_super: get root inode failed\n"); | |
129 | return -ENOMEM; | |
130 | } | |
131 | ||
132 | s->s_root = d_make_root(root_inode); | |
133 | if (!s->s_root) { | |
134 | pr_err("proc_fill_super: allocate dentry failed\n"); | |
135 | return -ENOMEM; | |
136 | } | |
137 | ||
138 | ret = proc_setup_self(s); | |
139 | if (ret) { | |
140 | return ret; | |
141 | } | |
142 | return proc_setup_thread_self(s); | |
143 | } | |
144 | ||
66f592e2 | 145 | static int proc_reconfigure(struct fs_context *fc) |
97412950 | 146 | { |
66f592e2 | 147 | struct super_block *sb = fc->root->d_sb; |
97412950 | 148 | struct pid_namespace *pid = sb->s_fs_info; |
02b9984d TT |
149 | |
150 | sync_filesystem(sb); | |
66f592e2 DH |
151 | |
152 | proc_apply_options(sb, fc, pid, current_user_ns()); | |
153 | return 0; | |
97412950 VK |
154 | } |
155 | ||
66f592e2 | 156 | static int proc_get_tree(struct fs_context *fc) |
1da177e4 | 157 | { |
66f592e2 | 158 | struct proc_fs_context *ctx = fc->fs_private; |
07543f5c | 159 | |
66f592e2 DH |
160 | put_user_ns(fc->user_ns); |
161 | fc->user_ns = get_user_ns(ctx->pid_ns->user_ns); | |
162 | fc->s_fs_info = ctx->pid_ns; | |
163 | return vfs_get_super(fc, vfs_get_keyed_super, proc_fill_super); | |
164 | } | |
07543f5c | 165 | |
66f592e2 DH |
166 | static void proc_fs_context_free(struct fs_context *fc) |
167 | { | |
168 | struct proc_fs_context *ctx = fc->fs_private; | |
169 | ||
170 | if (ctx->pid_ns) | |
171 | put_pid_ns(ctx->pid_ns); | |
172 | kfree(ctx); | |
173 | } | |
174 | ||
175 | static const struct fs_context_operations proc_fs_context_ops = { | |
176 | .free = proc_fs_context_free, | |
177 | .parse_param = proc_parse_param, | |
178 | .get_tree = proc_get_tree, | |
179 | .reconfigure = proc_reconfigure, | |
180 | }; | |
181 | ||
182 | static int proc_init_fs_context(struct fs_context *fc) | |
183 | { | |
184 | struct proc_fs_context *ctx; | |
185 | ||
186 | ctx = kzalloc(sizeof(struct proc_fs_context), GFP_KERNEL); | |
187 | if (!ctx) | |
188 | return -ENOMEM; | |
07543f5c | 189 | |
66f592e2 DH |
190 | ctx->pid_ns = get_pid_ns(task_active_pid_ns(current)); |
191 | fc->fs_private = ctx; | |
192 | fc->ops = &proc_fs_context_ops; | |
193 | return 0; | |
07543f5c PE |
194 | } |
195 | ||
196 | static void proc_kill_sb(struct super_block *sb) | |
197 | { | |
198 | struct pid_namespace *ns; | |
199 | ||
200 | ns = (struct pid_namespace *)sb->s_fs_info; | |
021ada7d AV |
201 | if (ns->proc_self) |
202 | dput(ns->proc_self); | |
0097875b EB |
203 | if (ns->proc_thread_self) |
204 | dput(ns->proc_thread_self); | |
07543f5c PE |
205 | kill_anon_super(sb); |
206 | put_pid_ns(ns); | |
1da177e4 LT |
207 | } |
208 | ||
c2319540 | 209 | static struct file_system_type proc_fs_type = { |
66f592e2 DH |
210 | .name = "proc", |
211 | .init_fs_context = proc_init_fs_context, | |
212 | .parameters = &proc_fs_parameters, | |
213 | .kill_sb = proc_kill_sb, | |
214 | .fs_flags = FS_USERNS_MOUNT, | |
1da177e4 LT |
215 | }; |
216 | ||
1da177e4 LT |
217 | void __init proc_root_init(void) |
218 | { | |
195b8cf0 | 219 | proc_init_kmemcache(); |
1270dd8d | 220 | set_proc_pid_nlink(); |
e656d8a6 | 221 | proc_self_init(); |
0097875b | 222 | proc_thread_self_init(); |
155134fe | 223 | proc_symlink("mounts", NULL, "self/mounts"); |
457c4cbc EB |
224 | |
225 | proc_net_init(); | |
36a5aeb8 | 226 | proc_mkdir("fs", NULL); |
928b4d8c | 227 | proc_mkdir("driver", NULL); |
eb6d38d5 | 228 | proc_create_mount_point("fs/nfsd"); /* somewhere for the nfsd filesystem to be mounted */ |
1da177e4 LT |
229 | #if defined(CONFIG_SUN_OPENPROMFS) || defined(CONFIG_SUN_OPENPROMFS_MODULE) |
230 | /* just give it a mountpoint */ | |
eb6d38d5 | 231 | proc_create_mount_point("openprom"); |
1da177e4 LT |
232 | #endif |
233 | proc_tty_init(); | |
9c37066d | 234 | proc_mkdir("bus", NULL); |
77b14db5 | 235 | proc_sys_init(); |
1539d584 AD |
236 | |
237 | register_filesystem(&proc_fs_type); | |
1da177e4 LT |
238 | } |
239 | ||
a528d35e DH |
240 | static int proc_root_getattr(const struct path *path, struct kstat *stat, |
241 | u32 request_mask, unsigned int query_flags) | |
1da177e4 | 242 | { |
a528d35e | 243 | generic_fillattr(d_inode(path->dentry), stat); |
76b6159b AV |
244 | stat->nlink = proc_root.nlink + nr_processes(); |
245 | return 0; | |
246 | } | |
1da177e4 | 247 | |
00cd8dd3 | 248 | static struct dentry *proc_root_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags) |
76b6159b | 249 | { |
867aaccf | 250 | if (!proc_pid_lookup(dentry, flags)) |
1da177e4 | 251 | return NULL; |
66f592e2 | 252 | |
335eb531 | 253 | return proc_lookup(dir, dentry, flags); |
1da177e4 LT |
254 | } |
255 | ||
f0c3b509 | 256 | static int proc_root_readdir(struct file *file, struct dir_context *ctx) |
1da177e4 | 257 | { |
f0c3b509 | 258 | if (ctx->pos < FIRST_PROCESS_ENTRY) { |
94fc5d9d RG |
259 | int error = proc_readdir(file, ctx); |
260 | if (unlikely(error <= 0)) | |
261 | return error; | |
f0c3b509 | 262 | ctx->pos = FIRST_PROCESS_ENTRY; |
1da177e4 | 263 | } |
1da177e4 | 264 | |
f0c3b509 | 265 | return proc_pid_readdir(file, ctx); |
1da177e4 LT |
266 | } |
267 | ||
268 | /* | |
269 | * The root /proc directory is special, as it has the | |
270 | * <pid> directories. Thus we don't use the generic | |
271 | * directory handling functions for that.. | |
272 | */ | |
00977a59 | 273 | static const struct file_operations proc_root_operations = { |
1da177e4 | 274 | .read = generic_read_dir, |
f50752ea AV |
275 | .iterate_shared = proc_root_readdir, |
276 | .llseek = generic_file_llseek, | |
1da177e4 LT |
277 | }; |
278 | ||
279 | /* | |
280 | * proc root can do almost nothing.. | |
281 | */ | |
c5ef1c42 | 282 | static const struct inode_operations proc_root_inode_operations = { |
1da177e4 | 283 | .lookup = proc_root_lookup, |
76b6159b | 284 | .getattr = proc_root_getattr, |
1da177e4 LT |
285 | }; |
286 | ||
287 | /* | |
288 | * This is the root "inode" in the /proc tree.. | |
289 | */ | |
290 | struct proc_dir_entry proc_root = { | |
291 | .low_ino = PROC_ROOT_INO, | |
292 | .namelen = 5, | |
1da177e4 LT |
293 | .mode = S_IFDIR | S_IRUGO | S_IXUGO, |
294 | .nlink = 2, | |
9cdd83e3 | 295 | .refcnt = REFCOUNT_INIT(1), |
1da177e4 LT |
296 | .proc_iops = &proc_root_inode_operations, |
297 | .proc_fops = &proc_root_operations, | |
298 | .parent = &proc_root, | |
4f113437 | 299 | .subdir = RB_ROOT, |
24074a35 | 300 | .name = "/proc", |
1da177e4 LT |
301 | }; |
302 | ||
6f4e6433 PE |
303 | int pid_ns_prepare_proc(struct pid_namespace *ns) |
304 | { | |
66f592e2 DH |
305 | struct proc_fs_context *ctx; |
306 | struct fs_context *fc; | |
6f4e6433 PE |
307 | struct vfsmount *mnt; |
308 | ||
66f592e2 DH |
309 | fc = fs_context_for_mount(&proc_fs_type, SB_KERNMOUNT); |
310 | if (IS_ERR(fc)) | |
311 | return PTR_ERR(fc); | |
312 | ||
313 | if (fc->user_ns != ns->user_ns) { | |
314 | put_user_ns(fc->user_ns); | |
315 | fc->user_ns = get_user_ns(ns->user_ns); | |
316 | } | |
317 | ||
318 | ctx = fc->fs_private; | |
319 | if (ctx->pid_ns != ns) { | |
320 | put_pid_ns(ctx->pid_ns); | |
321 | get_pid_ns(ns); | |
322 | ctx->pid_ns = ns; | |
323 | } | |
324 | ||
325 | mnt = fc_mount(fc); | |
326 | put_fs_context(fc); | |
6f4e6433 PE |
327 | if (IS_ERR(mnt)) |
328 | return PTR_ERR(mnt); | |
329 | ||
579441a3 | 330 | ns->proc_mnt = mnt; |
6f4e6433 PE |
331 | return 0; |
332 | } | |
333 | ||
334 | void pid_ns_release_proc(struct pid_namespace *ns) | |
335 | { | |
905ad269 | 336 | kern_unmount(ns->proc_mnt); |
6f4e6433 | 337 | } |