From: Oleg Nesterov <oleg@xxxxxxxxxx> Subject: signal: simplify set_user_sigmask/restore_user_sigmask task->saved_sigmask and ->restore_sigmask are only used in the ret-from- syscall paths. This means that set_user_sigmask() can save ->blocked in ->saved_sigmask and do set_restore_sigmask() to indicate that ->blocked was modified. This way the callers do not need 2 sigset_t's passed to set/restore and restore_user_sigmask() renamed to restore_saved_sigmask_unless() turns into the trivial helper which just calls restore_saved_sigmask(). Link: http://lkml.kernel.org/r/20190606113206.GA9464@xxxxxxxxxx Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Deepa Dinamani <deepa.kernel@xxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx> Cc: Eric Wong <e@xxxxxxxxx> Cc: Jason Baron <jbaron@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> Cc: David Laight <David.Laight@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/aio.c | 20 +++------ fs/eventpoll.c | 12 +---- fs/io_uring.c | 11 +---- fs/select.c | 34 +++++----------- include/linux/compat.h | 3 - include/linux/sched/signal.h | 12 ++++- include/linux/signal.h | 4 - kernel/signal.c | 69 +++++++++------------------------ 8 files changed, 57 insertions(+), 108 deletions(-) --- a/fs/aio.c~signal-simplify-set_user_sigmask-restore_user_sigmask +++ a/fs/aio.c @@ -2094,7 +2094,6 @@ SYSCALL_DEFINE6(io_pgetevents, const struct __aio_sigset __user *, usig) { struct __aio_sigset ksig = { NULL, }; - sigset_t ksigmask, sigsaved; struct timespec64 ts; bool interrupted; int ret; @@ -2105,14 +2104,14 @@ SYSCALL_DEFINE6(io_pgetevents, if (usig && copy_from_user(&ksig, usig, sizeof(ksig))) return -EFAULT; - ret = set_user_sigmask(ksig.sigmask, &ksigmask, &sigsaved, ksig.sigsetsize); + ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize); if (ret) return ret; ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL); interrupted = signal_pending(current); - restore_user_sigmask(ksig.sigmask, &sigsaved, interrupted); + restore_saved_sigmask_unless(interrupted); if (interrupted && !ret) ret = -ERESTARTNOHAND; @@ -2130,7 +2129,6 @@ SYSCALL_DEFINE6(io_pgetevents_time32, const struct __aio_sigset __user *, usig) { struct __aio_sigset ksig = { NULL, }; - sigset_t ksigmask, sigsaved; struct timespec64 ts; bool interrupted; int ret; @@ -2142,14 +2140,14 @@ SYSCALL_DEFINE6(io_pgetevents_time32, return -EFAULT; - ret = set_user_sigmask(ksig.sigmask, &ksigmask, &sigsaved, ksig.sigsetsize); + ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize); if (ret) return ret; ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL); interrupted = signal_pending(current); - restore_user_sigmask(ksig.sigmask, &sigsaved, interrupted); + restore_saved_sigmask_unless(interrupted); if (interrupted && !ret) ret = -ERESTARTNOHAND; @@ -2198,7 +2196,6 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents, const struct __compat_aio_sigset __user *, usig) { struct __compat_aio_sigset ksig = { NULL, }; - sigset_t ksigmask, sigsaved; struct timespec64 t; bool interrupted; int ret; @@ -2209,14 +2206,14 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents, if (usig && copy_from_user(&ksig, usig, sizeof(ksig))) return -EFAULT; - ret = set_compat_user_sigmask(ksig.sigmask, &ksigmask, &sigsaved, ksig.sigsetsize); + ret = set_compat_user_sigmask(ksig.sigmask, ksig.sigsetsize); if (ret) return ret; ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL); interrupted = signal_pending(current); - restore_user_sigmask(ksig.sigmask, &sigsaved, interrupted); + restore_saved_sigmask_unless(interrupted); if (interrupted && !ret) ret = -ERESTARTNOHAND; @@ -2234,7 +2231,6 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents_tim const struct __compat_aio_sigset __user *, usig) { struct __compat_aio_sigset ksig = { NULL, }; - sigset_t ksigmask, sigsaved; struct timespec64 t; bool interrupted; int ret; @@ -2245,14 +2241,14 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents_tim if (usig && copy_from_user(&ksig, usig, sizeof(ksig))) return -EFAULT; - ret = set_compat_user_sigmask(ksig.sigmask, &ksigmask, &sigsaved, ksig.sigsetsize); + ret = set_compat_user_sigmask(ksig.sigmask, ksig.sigsetsize); if (ret) return ret; ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL); interrupted = signal_pending(current); - restore_user_sigmask(ksig.sigmask, &sigsaved, interrupted); + restore_saved_sigmask_unless(interrupted); if (interrupted && !ret) ret = -ERESTARTNOHAND; --- a/fs/eventpoll.c~signal-simplify-set_user_sigmask-restore_user_sigmask +++ a/fs/eventpoll.c @@ -2313,19 +2313,17 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, size_t, sigsetsize) { int error; - sigset_t ksigmask, sigsaved; /* * If the caller wants a certain signal mask to be set during the wait, * we apply it here. */ - error = set_user_sigmask(sigmask, &ksigmask, &sigsaved, sigsetsize); + error = set_user_sigmask(sigmask, sigsetsize); if (error) return error; error = do_epoll_wait(epfd, events, maxevents, timeout); - - restore_user_sigmask(sigmask, &sigsaved, error == -EINTR); + restore_saved_sigmask_unless(error == -EINTR); return error; } @@ -2338,19 +2336,17 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, compat_size_t, sigsetsize) { long err; - sigset_t ksigmask, sigsaved; /* * If the caller wants a certain signal mask to be set during the wait, * we apply it here. */ - err = set_compat_user_sigmask(sigmask, &ksigmask, &sigsaved, sigsetsize); + err = set_compat_user_sigmask(sigmask, sigsetsize); if (err) return err; err = do_epoll_wait(epfd, events, maxevents, timeout); - - restore_user_sigmask(sigmask, &sigsaved, err == -EINTR); + restore_saved_sigmask_unless(err == -EINTR); return err; } --- a/fs/io_uring.c~signal-simplify-set_user_sigmask-restore_user_sigmask +++ a/fs/io_uring.c @@ -2400,7 +2400,6 @@ static int io_cqring_wait(struct io_ring const sigset_t __user *sig, size_t sigsz) { struct io_cq_ring *ring = ctx->cq_ring; - sigset_t ksigmask, sigsaved; int ret; if (io_cqring_events(ring) >= min_events) @@ -2410,21 +2409,17 @@ static int io_cqring_wait(struct io_ring #ifdef CONFIG_COMPAT if (in_compat_syscall()) ret = set_compat_user_sigmask((const compat_sigset_t __user *)sig, - &ksigmask, &sigsaved, sigsz); + sigsz); else #endif - ret = set_user_sigmask(sig, &ksigmask, - &sigsaved, sigsz); + ret = set_user_sigmask(sig, sigsz); if (ret) return ret; } ret = wait_event_interruptible(ctx->wait, io_cqring_events(ring) >= min_events); - - if (sig) - restore_user_sigmask(sig, &sigsaved, ret == -ERESTARTSYS); - + restore_saved_sigmask_unless(ret == -ERESTARTSYS); if (ret == -ERESTARTSYS) ret = -EINTR; --- a/fs/select.c~signal-simplify-set_user_sigmask-restore_user_sigmask +++ a/fs/select.c @@ -730,7 +730,6 @@ static long do_pselect(int n, fd_set __u const sigset_t __user *sigmask, size_t sigsetsize, enum poll_time_type type) { - sigset_t ksigmask, sigsaved; struct timespec64 ts, end_time, *to = NULL; int ret; @@ -753,12 +752,12 @@ static long do_pselect(int n, fd_set __u return -EINVAL; } - ret = set_user_sigmask(sigmask, &ksigmask, &sigsaved, sigsetsize); + ret = set_user_sigmask(sigmask, sigsetsize); if (ret) return ret; ret = core_sys_select(n, inp, outp, exp, to); - restore_user_sigmask(sigmask, &sigsaved, ret == -ERESTARTNOHAND); + restore_saved_sigmask_unless(ret == -ERESTARTNOHAND); ret = poll_select_copy_remaining(&end_time, tsp, type, ret); return ret; @@ -1086,7 +1085,6 @@ SYSCALL_DEFINE5(ppoll, struct pollfd __u struct __kernel_timespec __user *, tsp, const sigset_t __user *, sigmask, size_t, sigsetsize) { - sigset_t ksigmask, sigsaved; struct timespec64 ts, end_time, *to = NULL; int ret; @@ -1099,17 +1097,16 @@ SYSCALL_DEFINE5(ppoll, struct pollfd __u return -EINVAL; } - ret = set_user_sigmask(sigmask, &ksigmask, &sigsaved, sigsetsize); + ret = set_user_sigmask(sigmask, sigsetsize); if (ret) return ret; ret = do_sys_poll(ufds, nfds, to); - restore_user_sigmask(sigmask, &sigsaved, ret == -EINTR); + restore_saved_sigmask_unless(ret == -EINTR); /* We can restart this syscall, usually */ if (ret == -EINTR) ret = -ERESTARTNOHAND; - ret = poll_select_copy_remaining(&end_time, tsp, PT_TIMESPEC, ret); return ret; @@ -1121,7 +1118,6 @@ SYSCALL_DEFINE5(ppoll_time32, struct pol struct old_timespec32 __user *, tsp, const sigset_t __user *, sigmask, size_t, sigsetsize) { - sigset_t ksigmask, sigsaved; struct timespec64 ts, end_time, *to = NULL; int ret; @@ -1134,17 +1130,16 @@ SYSCALL_DEFINE5(ppoll_time32, struct pol return -EINVAL; } - ret = set_user_sigmask(sigmask, &ksigmask, &sigsaved, sigsetsize); + ret = set_user_sigmask(sigmask, sigsetsize); if (ret) return ret; ret = do_sys_poll(ufds, nfds, to); - restore_user_sigmask(sigmask, &sigsaved, ret == -EINTR); + restore_saved_sigmask_unless(ret == -EINTR); /* We can restart this syscall, usually */ if (ret == -EINTR) ret = -ERESTARTNOHAND; - ret = poll_select_copy_remaining(&end_time, tsp, PT_OLD_TIMESPEC, ret); return ret; @@ -1319,7 +1314,6 @@ static long do_compat_pselect(int n, com void __user *tsp, compat_sigset_t __user *sigmask, compat_size_t sigsetsize, enum poll_time_type type) { - sigset_t ksigmask, sigsaved; struct timespec64 ts, end_time, *to = NULL; int ret; @@ -1342,12 +1336,12 @@ static long do_compat_pselect(int n, com return -EINVAL; } - ret = set_compat_user_sigmask(sigmask, &ksigmask, &sigsaved, sigsetsize); + ret = set_compat_user_sigmask(sigmask, sigsetsize); if (ret) return ret; ret = compat_core_sys_select(n, inp, outp, exp, to); - restore_user_sigmask(sigmask, &sigsaved, ret == -ERESTARTNOHAND); + restore_saved_sigmask_unless(ret == -ERESTARTNOHAND); ret = poll_select_copy_remaining(&end_time, tsp, type, ret); return ret; @@ -1402,7 +1396,6 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time32, str unsigned int, nfds, struct old_timespec32 __user *, tsp, const compat_sigset_t __user *, sigmask, compat_size_t, sigsetsize) { - sigset_t ksigmask, sigsaved; struct timespec64 ts, end_time, *to = NULL; int ret; @@ -1415,17 +1408,16 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time32, str return -EINVAL; } - ret = set_compat_user_sigmask(sigmask, &ksigmask, &sigsaved, sigsetsize); + ret = set_compat_user_sigmask(sigmask, sigsetsize); if (ret) return ret; ret = do_sys_poll(ufds, nfds, to); - restore_user_sigmask(sigmask, &sigsaved, ret == -EINTR); + restore_saved_sigmask_unless(ret == -EINTR); /* We can restart this syscall, usually */ if (ret == -EINTR) ret = -ERESTARTNOHAND; - ret = poll_select_copy_remaining(&end_time, tsp, PT_OLD_TIMESPEC, ret); return ret; @@ -1437,7 +1429,6 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time64, str unsigned int, nfds, struct __kernel_timespec __user *, tsp, const compat_sigset_t __user *, sigmask, compat_size_t, sigsetsize) { - sigset_t ksigmask, sigsaved; struct timespec64 ts, end_time, *to = NULL; int ret; @@ -1450,17 +1441,16 @@ COMPAT_SYSCALL_DEFINE5(ppoll_time64, str return -EINVAL; } - ret = set_compat_user_sigmask(sigmask, &ksigmask, &sigsaved, sigsetsize); + ret = set_compat_user_sigmask(sigmask, sigsetsize); if (ret) return ret; ret = do_sys_poll(ufds, nfds, to); - restore_user_sigmask(sigmask, &sigsaved, ret == -EINTR); + restore_saved_sigmask_unless(ret == -EINTR); /* We can restart this syscall, usually */ if (ret == -EINTR) ret = -ERESTARTNOHAND; - ret = poll_select_copy_remaining(&end_time, tsp, PT_TIMESPEC, ret); return ret; --- a/include/linux/compat.h~signal-simplify-set_user_sigmask-restore_user_sigmask +++ a/include/linux/compat.h @@ -138,8 +138,7 @@ typedef struct { compat_sigset_word sig[_COMPAT_NSIG_WORDS]; } compat_sigset_t; -int set_compat_user_sigmask(const compat_sigset_t __user *usigmask, - sigset_t *set, sigset_t *oldset, +int set_compat_user_sigmask(const compat_sigset_t __user *umask, size_t sigsetsize); struct compat_sigaction { --- a/include/linux/sched/signal.h~signal-simplify-set_user_sigmask-restore_user_sigmask +++ a/include/linux/sched/signal.h @@ -420,7 +420,6 @@ void task_join_group_stop(struct task_st static inline void set_restore_sigmask(void) { set_thread_flag(TIF_RESTORE_SIGMASK); - WARN_ON(!test_thread_flag(TIF_SIGPENDING)); } static inline void clear_tsk_restore_sigmask(struct task_struct *task) @@ -451,7 +450,6 @@ static inline bool test_and_clear_restor static inline void set_restore_sigmask(void) { current->restore_sigmask = true; - WARN_ON(!test_thread_flag(TIF_SIGPENDING)); } static inline void clear_tsk_restore_sigmask(struct task_struct *task) { @@ -484,6 +482,16 @@ static inline void restore_saved_sigmask __set_current_blocked(¤t->saved_sigmask); } +extern int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize); + +static inline void restore_saved_sigmask_unless(bool interrupted) +{ + if (interrupted) + WARN_ON(!test_thread_flag(TIF_SIGPENDING)); + else + restore_saved_sigmask(); +} + static inline sigset_t *sigmask_to_save(void) { sigset_t *res = ¤t->blocked; --- a/include/linux/signal.h~signal-simplify-set_user_sigmask-restore_user_sigmask +++ a/include/linux/signal.h @@ -273,10 +273,6 @@ extern int group_send_sig_info(int sig, struct task_struct *p, enum pid_type type); extern int __group_send_sig_info(int, struct kernel_siginfo *, struct task_struct *); extern int sigprocmask(int, sigset_t *, sigset_t *); -extern int set_user_sigmask(const sigset_t __user *usigmask, sigset_t *set, - sigset_t *oldset, size_t sigsetsize); -extern void restore_user_sigmask(const void __user *usigmask, - sigset_t *sigsaved, bool interrupted); extern void set_current_blocked(sigset_t *); extern void __set_current_blocked(const sigset_t *); extern int show_unhandled_signals; --- a/kernel/signal.c~signal-simplify-set_user_sigmask-restore_user_sigmask +++ a/kernel/signal.c @@ -2951,80 +2951,49 @@ EXPORT_SYMBOL(sigprocmask); * * This is useful for syscalls such as ppoll, pselect, io_pgetevents and * epoll_pwait where a new sigmask is passed from userland for the syscalls. + * + * Note that it does set_restore_sigmask() in advance, so it must be always + * paired with restore_saved_sigmask_unless() before return from syscall. */ -int set_user_sigmask(const sigset_t __user *usigmask, sigset_t *set, - sigset_t *oldset, size_t sigsetsize) +int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize) { - if (!usigmask) - return 0; + sigset_t kmask; + if (!umask) + return 0; if (sigsetsize != sizeof(sigset_t)) return -EINVAL; - if (copy_from_user(set, usigmask, sizeof(sigset_t))) + if (copy_from_user(&kmask, umask, sizeof(sigset_t))) return -EFAULT; - *oldset = current->blocked; - set_current_blocked(set); + set_restore_sigmask(); + current->saved_sigmask = current->blocked; + set_current_blocked(&kmask); return 0; } -EXPORT_SYMBOL(set_user_sigmask); #ifdef CONFIG_COMPAT -int set_compat_user_sigmask(const compat_sigset_t __user *usigmask, - sigset_t *set, sigset_t *oldset, +int set_compat_user_sigmask(const compat_sigset_t __user *umask, size_t sigsetsize) { - if (!usigmask) - return 0; + sigset_t kmask; + if (!umask) + return 0; if (sigsetsize != sizeof(compat_sigset_t)) return -EINVAL; - if (get_compat_sigset(set, usigmask)) + if (get_compat_sigset(&kmask, umask)) return -EFAULT; - *oldset = current->blocked; - set_current_blocked(set); + set_restore_sigmask(); + current->saved_sigmask = current->blocked; + set_current_blocked(&kmask); return 0; } -EXPORT_SYMBOL(set_compat_user_sigmask); #endif -/* - * restore_user_sigmask: - * usigmask: sigmask passed in from userland. - * sigsaved: saved sigmask when the syscall started and changed the sigmask to - * usigmask. - * - * This is useful for syscalls such as ppoll, pselect, io_pgetevents and - * epoll_pwait where a new sigmask is passed in from userland for the syscalls. - */ -void restore_user_sigmask(const void __user *usigmask, sigset_t *sigsaved, - bool interrupted) -{ - - if (!usigmask) - return; - /* - * When signals are pending, do not restore them here. - * Restoring sigmask here can lead to delivering signals that the above - * syscalls are intended to block because of the sigmask passed in. - */ - if (interrupted) { - current->saved_sigmask = *sigsaved; - set_restore_sigmask(); - return; - } - - /* - * This is needed because the fast syscall return path does not restore - * saved_sigmask when signals are not pending. - */ - set_current_blocked(sigsaved); -} -EXPORT_SYMBOL(restore_user_sigmask); - /** * sys_rt_sigprocmask - change the list of currently blocked signals * @how: whether to add, remove, or set signals _
