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> | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/signal.h> | |
27 | #include <linux/list.h> | |
28 | #include <linux/anon_inodes.h> | |
29 | #include <linux/signalfd.h> | |
7ec37dfd | 30 | #include <linux/syscalls.h> |
fba2afaa DL |
31 | |
32 | struct signalfd_ctx { | |
fba2afaa | 33 | sigset_t sigmask; |
fba2afaa DL |
34 | }; |
35 | ||
fba2afaa DL |
36 | static int signalfd_release(struct inode *inode, struct file *file) |
37 | { | |
b8fceee1 | 38 | kfree(file->private_data); |
fba2afaa DL |
39 | return 0; |
40 | } | |
41 | ||
42 | static unsigned int signalfd_poll(struct file *file, poll_table *wait) | |
43 | { | |
44 | struct signalfd_ctx *ctx = file->private_data; | |
45 | unsigned int events = 0; | |
fba2afaa | 46 | |
b8fceee1 | 47 | poll_wait(file, ¤t->sighand->signalfd_wqh, wait); |
fba2afaa | 48 | |
b8fceee1 DL |
49 | spin_lock_irq(¤t->sighand->siglock); |
50 | if (next_signal(¤t->pending, &ctx->sigmask) || | |
51 | next_signal(¤t->signal->shared_pending, | |
52 | &ctx->sigmask)) | |
fba2afaa | 53 | events |= POLLIN; |
b8fceee1 | 54 | spin_unlock_irq(¤t->sighand->siglock); |
fba2afaa DL |
55 | |
56 | return events; | |
57 | } | |
58 | ||
59 | /* | |
60 | * Copied from copy_siginfo_to_user() in kernel/signal.c | |
61 | */ | |
62 | static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo, | |
63 | siginfo_t const *kinfo) | |
64 | { | |
65 | long err; | |
66 | ||
67 | BUILD_BUG_ON(sizeof(struct signalfd_siginfo) != 128); | |
68 | ||
69 | /* | |
14e4a0f2 | 70 | * Unused members should be zero ... |
fba2afaa DL |
71 | */ |
72 | err = __clear_user(uinfo, sizeof(*uinfo)); | |
73 | ||
74 | /* | |
75 | * If you change siginfo_t structure, please be sure | |
76 | * this code is fixed accordingly. | |
77 | */ | |
96358de6 DL |
78 | err |= __put_user(kinfo->si_signo, &uinfo->ssi_signo); |
79 | err |= __put_user(kinfo->si_errno, &uinfo->ssi_errno); | |
80 | err |= __put_user((short) kinfo->si_code, &uinfo->ssi_code); | |
fba2afaa DL |
81 | switch (kinfo->si_code & __SI_MASK) { |
82 | case __SI_KILL: | |
96358de6 DL |
83 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
84 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); | |
fba2afaa DL |
85 | break; |
86 | case __SI_TIMER: | |
96358de6 DL |
87 | err |= __put_user(kinfo->si_tid, &uinfo->ssi_tid); |
88 | err |= __put_user(kinfo->si_overrun, &uinfo->ssi_overrun); | |
89 | err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr); | |
fba2afaa DL |
90 | break; |
91 | case __SI_POLL: | |
96358de6 DL |
92 | err |= __put_user(kinfo->si_band, &uinfo->ssi_band); |
93 | err |= __put_user(kinfo->si_fd, &uinfo->ssi_fd); | |
fba2afaa DL |
94 | break; |
95 | case __SI_FAULT: | |
96358de6 | 96 | err |= __put_user((long) kinfo->si_addr, &uinfo->ssi_addr); |
fba2afaa | 97 | #ifdef __ARCH_SI_TRAPNO |
96358de6 | 98 | err |= __put_user(kinfo->si_trapno, &uinfo->ssi_trapno); |
fba2afaa DL |
99 | #endif |
100 | break; | |
101 | case __SI_CHLD: | |
96358de6 DL |
102 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
103 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); | |
104 | err |= __put_user(kinfo->si_status, &uinfo->ssi_status); | |
105 | err |= __put_user(kinfo->si_utime, &uinfo->ssi_utime); | |
106 | err |= __put_user(kinfo->si_stime, &uinfo->ssi_stime); | |
fba2afaa DL |
107 | break; |
108 | case __SI_RT: /* This is not generated by the kernel as of now. */ | |
109 | case __SI_MESGQ: /* But this is */ | |
96358de6 DL |
110 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
111 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); | |
112 | err |= __put_user((long) kinfo->si_ptr, &uinfo->ssi_ptr); | |
fba2afaa DL |
113 | break; |
114 | default: /* this is just in case for now ... */ | |
96358de6 DL |
115 | err |= __put_user(kinfo->si_pid, &uinfo->ssi_pid); |
116 | err |= __put_user(kinfo->si_uid, &uinfo->ssi_uid); | |
fba2afaa DL |
117 | break; |
118 | } | |
119 | ||
120 | return err ? -EFAULT: sizeof(*uinfo); | |
121 | } | |
122 | ||
b3762bfc DA |
123 | static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, siginfo_t *info, |
124 | int nonblock) | |
125 | { | |
126 | ssize_t ret; | |
b3762bfc DA |
127 | DECLARE_WAITQUEUE(wait, current); |
128 | ||
b8fceee1 DL |
129 | spin_lock_irq(¤t->sighand->siglock); |
130 | ret = dequeue_signal(current, &ctx->sigmask, info); | |
b3762bfc DA |
131 | switch (ret) { |
132 | case 0: | |
133 | if (!nonblock) | |
134 | break; | |
135 | ret = -EAGAIN; | |
136 | default: | |
b8fceee1 | 137 | spin_unlock_irq(¤t->sighand->siglock); |
b3762bfc DA |
138 | return ret; |
139 | } | |
140 | ||
b8fceee1 | 141 | add_wait_queue(¤t->sighand->signalfd_wqh, &wait); |
b3762bfc DA |
142 | for (;;) { |
143 | set_current_state(TASK_INTERRUPTIBLE); | |
b8fceee1 | 144 | ret = dequeue_signal(current, &ctx->sigmask, info); |
b3762bfc DA |
145 | if (ret != 0) |
146 | break; | |
147 | if (signal_pending(current)) { | |
148 | ret = -ERESTARTSYS; | |
149 | break; | |
150 | } | |
b8fceee1 | 151 | spin_unlock_irq(¤t->sighand->siglock); |
b3762bfc | 152 | schedule(); |
b8fceee1 | 153 | spin_lock_irq(¤t->sighand->siglock); |
b3762bfc | 154 | } |
b8fceee1 | 155 | spin_unlock_irq(¤t->sighand->siglock); |
b3762bfc | 156 | |
b8fceee1 | 157 | remove_wait_queue(¤t->sighand->signalfd_wqh, &wait); |
b3762bfc DA |
158 | __set_current_state(TASK_RUNNING); |
159 | ||
160 | return ret; | |
161 | } | |
162 | ||
fba2afaa | 163 | /* |
b8fceee1 DL |
164 | * Returns a multiple of the size of a "struct signalfd_siginfo", or a negative |
165 | * error code. The "count" parameter must be at least the size of a | |
166 | * "struct signalfd_siginfo". | |
fba2afaa DL |
167 | */ |
168 | static ssize_t signalfd_read(struct file *file, char __user *buf, size_t count, | |
169 | loff_t *ppos) | |
170 | { | |
171 | struct signalfd_ctx *ctx = file->private_data; | |
b3762bfc DA |
172 | struct signalfd_siginfo __user *siginfo; |
173 | int nonblock = file->f_flags & O_NONBLOCK; | |
174 | ssize_t ret, total = 0; | |
fba2afaa | 175 | siginfo_t info; |
fba2afaa | 176 | |
b3762bfc DA |
177 | count /= sizeof(struct signalfd_siginfo); |
178 | if (!count) | |
fba2afaa | 179 | return -EINVAL; |
fba2afaa | 180 | |
b3762bfc | 181 | siginfo = (struct signalfd_siginfo __user *) buf; |
b3762bfc DA |
182 | do { |
183 | ret = signalfd_dequeue(ctx, &info, nonblock); | |
184 | if (unlikely(ret <= 0)) | |
185 | break; | |
186 | ret = signalfd_copyinfo(siginfo, &info); | |
187 | if (ret < 0) | |
188 | break; | |
189 | siginfo++; | |
190 | total += ret; | |
191 | nonblock = 1; | |
192 | } while (--count); | |
193 | ||
b8fceee1 | 194 | return total ? total: ret; |
fba2afaa DL |
195 | } |
196 | ||
197 | static const struct file_operations signalfd_fops = { | |
198 | .release = signalfd_release, | |
199 | .poll = signalfd_poll, | |
200 | .read = signalfd_read, | |
201 | }; | |
202 | ||
fba2afaa DL |
203 | asmlinkage long sys_signalfd(int ufd, sigset_t __user *user_mask, size_t sizemask) |
204 | { | |
205 | int error; | |
206 | sigset_t sigmask; | |
207 | struct signalfd_ctx *ctx; | |
fba2afaa DL |
208 | struct file *file; |
209 | struct inode *inode; | |
fba2afaa DL |
210 | |
211 | if (sizemask != sizeof(sigset_t) || | |
212 | copy_from_user(&sigmask, user_mask, sizeof(sigmask))) | |
f50cadaa | 213 | return -EINVAL; |
fba2afaa DL |
214 | sigdelsetmask(&sigmask, sigmask(SIGKILL) | sigmask(SIGSTOP)); |
215 | signotset(&sigmask); | |
216 | ||
217 | if (ufd == -1) { | |
218 | ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); | |
219 | if (!ctx) | |
220 | return -ENOMEM; | |
221 | ||
fba2afaa | 222 | ctx->sigmask = sigmask; |
fba2afaa DL |
223 | |
224 | /* | |
225 | * When we call this, the initialization must be complete, since | |
226 | * anon_inode_getfd() will install the fd. | |
227 | */ | |
228 | error = anon_inode_getfd(&ufd, &inode, &file, "[signalfd]", | |
229 | &signalfd_fops, ctx); | |
230 | if (error) | |
231 | goto err_fdalloc; | |
232 | } else { | |
233 | file = fget(ufd); | |
234 | if (!file) | |
235 | return -EBADF; | |
236 | ctx = file->private_data; | |
237 | if (file->f_op != &signalfd_fops) { | |
238 | fput(file); | |
239 | return -EINVAL; | |
240 | } | |
b8fceee1 DL |
241 | spin_lock_irq(¤t->sighand->siglock); |
242 | ctx->sigmask = sigmask; | |
243 | spin_unlock_irq(¤t->sighand->siglock); | |
244 | ||
245 | wake_up(¤t->sighand->signalfd_wqh); | |
fba2afaa DL |
246 | fput(file); |
247 | } | |
248 | ||
249 | return ufd; | |
250 | ||
251 | err_fdalloc: | |
b8fceee1 | 252 | kfree(ctx); |
fba2afaa DL |
253 | return error; |
254 | } | |
255 |