Commit | Line | Data |
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fba2afaa DL |
1 | /* |
2 | * fs/signalfd.c | |
3 | * | |
4 | * Copyright (C) 2003 Linus Torvalds | |
5 | * | |
6 | * Mon Mar 5, 2007: Davide Libenzi <davidel@xmailserver.org> | |
7 | * Changed ->read() to return a siginfo strcture instead of signal number. | |
8 | * Fixed locking in ->poll(). | |
9 | * Added sighand-detach notification. | |
10 | * Added fd re-use in sys_signalfd() syscall. | |
11 | * Now using anonymous inode source. | |
12 | * Thanks to Oleg Nesterov for useful code review and suggestions. | |
13 | * More comments and suggestions from Arnd Bergmann. | |
b8fceee1 | 14 | * Sat May 19, 2007: Davi E. M. Arnaut <davi@haxent.com.br> |
b3762bfc | 15 | * Retrieve multiple signals with one read() call |
b8fceee1 DL |
16 | * Sun Jul 15, 2007: Davide Libenzi <davidel@xmailserver.org> |
17 | * Attach to the sighand only during read() and poll(). | |
fba2afaa DL |
18 | */ |
19 | ||
20 | #include <linux/file.h> | |
21 | #include <linux/poll.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/fs.h> | |
24 | #include <linux/sched.h> | |
5a0e3ad6 | 25 | #include <linux/slab.h> |
fba2afaa DL |
26 | #include <linux/kernel.h> |
27 | #include <linux/signal.h> | |
28 | #include <linux/list.h> | |
29 | #include <linux/anon_inodes.h> | |
30 | #include <linux/signalfd.h> | |
7ec37dfd | 31 | #include <linux/syscalls.h> |
fba2afaa | 32 | |
d80e731e ON |
33 | void signalfd_cleanup(struct sighand_struct *sighand) |
34 | { | |
35 | wait_queue_head_t *wqh = &sighand->signalfd_wqh; | |
36 | ||
37 | if (likely(!waitqueue_active(wqh))) | |
38 | return; | |
39 | ||
40 | /* wait_queue_t->func(POLLFREE) should do remove_wait_queue() */ | |
41 | wake_up_poll(wqh, POLLHUP | POLLFREE); | |
42 | } | |
43 | ||
fba2afaa | 44 | struct signalfd_ctx { |
fba2afaa | 45 | sigset_t sigmask; |
fba2afaa DL |
46 | }; |
47 | ||
fba2afaa DL |
48 | static int signalfd_release(struct inode *inode, struct file *file) |
49 | { | |
b8fceee1 | 50 | kfree(file->private_data); |
fba2afaa DL |
51 | return 0; |
52 | } | |
53 | ||
54 | static unsigned int signalfd_poll(struct file *file, poll_table *wait) | |
55 | { | |
56 | struct signalfd_ctx *ctx = file->private_data; | |
57 | unsigned int events = 0; | |
fba2afaa | 58 | |
b8fceee1 | 59 | poll_wait(file, ¤t->sighand->signalfd_wqh, wait); |
fba2afaa | 60 | |
b8fceee1 DL |
61 | spin_lock_irq(¤t->sighand->siglock); |
62 | if (next_signal(¤t->pending, &ctx->sigmask) || | |
63 | next_signal(¤t->signal->shared_pending, | |
64 | &ctx->sigmask)) | |
fba2afaa | 65 | events |= POLLIN; |
b8fceee1 | 66 | spin_unlock_irq(¤t->sighand->siglock); |
fba2afaa DL |
67 | |
68 | return events; | |
69 | } | |
70 | ||
71 | /* | |
72 | * Copied from copy_siginfo_to_user() in kernel/signal.c | |
73 | */ | |
74 | static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo, | |
75 | siginfo_t const *kinfo) | |
76 | { | |
77 | long err; | |
78 | ||
79 | BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128); | |
80 | ||
81 | /* | |
14e4a0f2 | 82 | * Unused members should be zero ... |
fba2afaa DL |
83 | */ |
84 | err = __clear_user(uinfo, sizeof(*uinfo)); | |
85 | ||
86 | /* | |
87 | * If you change siginfo_t structure, please be sure | |
88 | * this code is fixed accordingly. | |
89 | */ | |
96358de6 DL |
90 | err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo); |
91 | err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno); | |
92 | err |= __put_user((short) kinfo->si_code, &uinfo->ssi_code); | |
fba2afaa DL |
93 | switch (kinfo->si_code & __SI_MASK) { |
94 | case __SI_KILL: | |
96358de6 DL |
95 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
96 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); | |
fba2afaa DL |
97 | break; |
98 | case __SI_TIMER: | |
96358de6 DL |
99 | err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid); |
100 | err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun); | |
101 | err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr); | |
a2a20c41 | 102 | err |= __put_user(kinfo->si_int, &uinfo->ssi_int); |
fba2afaa DL |
103 | break; |
104 | case __SI_POLL: | |
96358de6 DL |
105 | err |= __put_user(kinfo->si_band, &uinfo->ssi_band); |
106 | err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd); | |
fba2afaa DL |
107 | break; |
108 | case __SI_FAULT: | |
96358de6 | 109 | err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr); |
fba2afaa | 110 | #ifdef __ARCH_SI_TRAPNO |
96358de6 | 111 | err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno); |
b8aeec34 HS |
112 | #endif |
113 | #ifdef BUS_MCEERR_AO | |
114 | /* | |
115 | * Other callers might not initialize the si_lsb field, | |
116 | * so check explicitly for the right codes here. | |
117 | */ | |
118 | if (kinfo->si_code == BUS_MCEERR_AR || | |
119 | kinfo->si_code == BUS_MCEERR_AO) | |
120 | err |= __put_user((short) kinfo->si_addr_lsb, | |
121 | &uinfo->ssi_addr_lsb); | |
fba2afaa DL |
122 | #endif |
123 | break; | |
124 | case __SI_CHLD: | |
96358de6 DL |
125 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
126 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); | |
127 | err |= __put_user(kinfo->si_status, &uinfo->ssi_status); | |
128 | err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime); | |
129 | err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime); | |
fba2afaa DL |
130 | break; |
131 | case __SI_RT: /* This is not generated by the kernel as of now. */ | |
132 | case __SI_MESGQ: /* But this is */ | |
96358de6 DL |
133 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
134 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); | |
135 | err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr); | |
a2a20c41 | 136 | err |= __put_user(kinfo->si_int, &uinfo->ssi_int); |
fba2afaa | 137 | break; |
0859ab59 DL |
138 | default: |
139 | /* | |
140 | * This case catches also the signals queued by sigqueue(). | |
141 | */ | |
96358de6 DL |
142 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
143 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); | |
0859ab59 DL |
144 | err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr); |
145 | err |= __put_user(kinfo->si_int, &uinfo->ssi_int); | |
fba2afaa DL |
146 | break; |
147 | } | |
148 | ||
149 | return err ? -EFAULT: sizeof(*uinfo); | |
150 | } | |
151 | ||
b3762bfc DA |
152 | static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info, |
153 | int nonblock) | |
154 | { | |
155 | ssize_t ret; | |
b3762bfc DA |
156 | DECLARE_WAITQUEUE(wait, current); |
157 | ||
b8fceee1 DL |
158 | spin_lock_irq(¤t->sighand->siglock); |
159 | ret = dequeue_signal(current, &ctx->sigmask, info); | |
b3762bfc DA |
160 | switch (ret) { |
161 | case 0: | |
162 | if (!nonblock) | |
163 | break; | |
164 | ret = -EAGAIN; | |
165 | default: | |
b8fceee1 | 166 | spin_unlock_irq(¤t->sighand->siglock); |
b3762bfc DA |
167 | return ret; |
168 | } | |
169 | ||
b8fceee1 | 170 | add_wait_queue(¤t->sighand->signalfd_wqh, &wait); |
b3762bfc DA |
171 | for (;;) { |
172 | set_current_state(TASK_INTERRUPTIBLE); | |
b8fceee1 | 173 | ret = dequeue_signal(current, &ctx->sigmask, info); |
b3762bfc DA |
174 | if (ret != 0) |
175 | break; | |
176 | if (signal_pending(current)) { | |
177 | ret = -ERESTARTSYS; | |
178 | break; | |
179 | } | |
b8fceee1 | 180 | spin_unlock_irq(¤t->sighand->siglock); |
b3762bfc | 181 | schedule(); |
b8fceee1 | 182 | spin_lock_irq(¤t->sighand->siglock); |
b3762bfc | 183 | } |
b8fceee1 | 184 | spin_unlock_irq(¤t->sighand->siglock); |
b3762bfc | 185 | |
b8fceee1 | 186 | remove_wait_queue(¤t->sighand->signalfd_wqh, &wait); |
b3762bfc DA |
187 | __set_current_state(TASK_RUNNING); |
188 | ||
189 | return ret; | |
190 | } | |
191 | ||
fba2afaa | 192 | /* |
b8fceee1 DL |
193 | * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative |
194 | * error code. The "count" parameter must be at least the size of a | |
195 | * "struct signalfd_siginfo". | |
fba2afaa DL |
196 | */ |
197 | static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count, | |
198 | loff_t *ppos) | |
199 | { | |
200 | struct signalfd_ctx *ctx = file->private_data; | |
b3762bfc DA |
201 | struct signalfd_siginfo __user *siginfo; |
202 | int nonblock = file->f_flags & O_NONBLOCK; | |
203 | ssize_t ret, total = 0; | |
fba2afaa | 204 | siginfo_t info; |
fba2afaa | 205 | |
b3762bfc DA |
206 | count /= sizeof(struct signalfd_siginfo); |
207 | if (!count) | |
fba2afaa | 208 | return -EINVAL; |
fba2afaa | 209 | |
b3762bfc | 210 | siginfo = (struct signalfd_siginfo __user *) buf; |
b3762bfc DA |
211 | do { |
212 | ret = signalfd_dequeue(ctx, &info, nonblock); | |
213 | if (unlikely(ret <= 0)) | |
214 | break; | |
215 | ret = signalfd_copyinfo(siginfo, &info); | |
216 | if (ret < 0) | |
217 | break; | |
218 | siginfo++; | |
219 | total += ret; | |
220 | nonblock = 1; | |
221 | } while (--count); | |
222 | ||
b8fceee1 | 223 | return total ? total: ret; |
fba2afaa DL |
224 | } |
225 | ||
226 | static const struct file_operations signalfd_fops = { | |
227 | .release = signalfd_release, | |
228 | .poll = signalfd_poll, | |
229 | .read = signalfd_read, | |
6038f373 | 230 | .llseek = noop_llseek, |
fba2afaa DL |
231 | }; |
232 | ||
836f92ad HC |
233 | SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask, |
234 | size_t, sizemask, int, flags) | |
fba2afaa | 235 | { |
fba2afaa DL |
236 | sigset_t sigmask; |
237 | struct signalfd_ctx *ctx; | |
fba2afaa | 238 | |
e38b36f3 UD |
239 | /* Check the SFD_* constants for consistency. */ |
240 | BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC); | |
241 | BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK); | |
242 | ||
5fb5e049 | 243 | if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK)) |
9deb27ba UD |
244 | return -EINVAL; |
245 | ||
fba2afaa DL |
246 | if (sizemask != sizeof(sigset_t) || |
247 | copy_from_user(&sigmask, user_mask, sizeof(sigmask))) | |
f50cadaa | 248 | return -EINVAL; |
fba2afaa DL |
249 | sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP)); |
250 | signotset(&sigmask); | |
251 | ||
252 | if (ufd == -1) { | |
253 | ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); | |
254 | if (!ctx) | |
255 | return -ENOMEM; | |
256 | ||
fba2afaa | 257 | ctx->sigmask = sigmask; |
fba2afaa DL |
258 | |
259 | /* | |
260 | * When we call this, the initialization must be complete, since | |
261 | * anon_inode_getfd() will install the fd. | |
262 | */ | |
7d9dbca3 | 263 | ufd = anon_inode_getfd("[signalfd]", &signalfd_fops, ctx, |
628ff7c1 | 264 | O_RDWR | (flags & (O_CLOEXEC | O_NONBLOCK))); |
2030a42c AV |
265 | if (ufd < 0) |
266 | kfree(ctx); | |
fba2afaa | 267 | } else { |
2030a42c | 268 | struct file *file = fget(ufd); |
fba2afaa DL |
269 | if (!file) |
270 | return -EBADF; | |
271 | ctx = file->private_data; | |
272 | if (file->f_op != &signalfd_fops) { | |
273 | fput(file); | |
274 | return -EINVAL; | |
275 | } | |
b8fceee1 DL |
276 | spin_lock_irq(¤t->sighand->siglock); |
277 | ctx->sigmask = sigmask; | |
278 | spin_unlock_irq(¤t->sighand->siglock); | |
279 | ||
280 | wake_up(¤t->sighand->signalfd_wqh); | |
fba2afaa DL |
281 | fput(file); |
282 | } | |
283 | ||
284 | return ufd; | |
fba2afaa | 285 | } |
9deb27ba | 286 | |
836f92ad HC |
287 | SYSCALL_DEFINE3(signalfd, int, ufd, sigset_t __user *, user_mask, |
288 | size_t, sizemask) | |
9deb27ba UD |
289 | { |
290 | return sys_signalfd4(ufd, user_mask, sizemask, 0); | |
291 | } |