Refactor the logic to restore the sigmask before the syscall returns into an api. This is useful for versions of syscalls that pass in the sigmask and expect the current->sigmask to be changed during the execution and restored after the execution of the syscall.
With the advent of new y2038 syscalls in the subsequent patches, we add 2 more new versions of the syscalls(for pselect, ppoll and io_pgetevents) in addition to the existing native and compat versions. Adding such an api reduces the logic that would need to be replicated otherwise. Signed-off-by: Deepa Dinamani <[email protected]> --- fs/aio.c | 29 +++++--------------- fs/eventpoll.c | 30 ++------------------- fs/select.c | 60 ++++++------------------------------------ include/linux/signal.h | 2 ++ kernel/signal.c | 33 +++++++++++++++++++++++ 5 files changed, 51 insertions(+), 103 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 67e5b1f6fb0f..b81c216534d6 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -2111,18 +2111,9 @@ SYSCALL_DEFINE6(io_pgetevents, return ret; ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL); - if (signal_pending(current)) { - if (ksig.sigmask) { - current->saved_sigmask = sigsaved; - set_restore_sigmask(); - } - - if (!ret) - ret = -ERESTARTNOHAND; - } else { - if (ksig.sigmask) - sigprocmask(SIG_SETMASK, &sigsaved, NULL); - } + restore_user_sigmask(ksig.sigmask, &sigsaved); + if (signal_pending(current) && !ret) + ret = -ERESTARTNOHAND; return ret; } @@ -2176,17 +2167,9 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents, return ret; ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL); - if (signal_pending(current)) { - if (ksig.sigmask) { - current->saved_sigmask = sigsaved; - set_restore_sigmask(); - } - if (!ret) - ret = -ERESTARTNOHAND; - } else { - if (ksig.sigmask) - sigprocmask(SIG_SETMASK, &sigsaved, NULL); - } + restore_user_sigmask(ksig.sigmask, &sigsaved); + if (signal_pending(current) && !ret) + ret = -ERESTARTNOHAND; return ret; } diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 2d86eeba837b..8a5a1010886b 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -2229,20 +2229,7 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events, error = do_epoll_wait(epfd, events, maxevents, timeout); - /* - * If we changed the signal mask, we need to restore the original one. - * In case we've got a signal while waiting, we do not restore the - * signal mask yet, and we allow do_signal() to deliver the signal on - * the way back to userspace, before the signal mask is restored. - */ - if (sigmask) { - if (error == -EINTR) { - memcpy(¤t->saved_sigmask, &sigsaved, - sizeof(sigsaved)); - set_restore_sigmask(); - } else - set_current_blocked(&sigsaved); - } + restore_user_sigmask(sigmask, &sigsaved); return error; } @@ -2267,20 +2254,7 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd, err = do_epoll_wait(epfd, events, maxevents, timeout); - /* - * If we changed the signal mask, we need to restore the original one. - * In case we've got a signal while waiting, we do not restore the - * signal mask yet, and we allow do_signal() to deliver the signal on - * the way back to userspace, before the signal mask is restored. - */ - if (sigmask) { - if (err == -EINTR) { - memcpy(¤t->saved_sigmask, &sigsaved, - sizeof(sigsaved)); - set_restore_sigmask(); - } else - set_current_blocked(&sigsaved); - } + restore_user_sigmask(sigmask, &sigsaved); return err; } diff --git a/fs/select.c b/fs/select.c index 65c78b4147a2..eb9132520197 100644 --- a/fs/select.c +++ b/fs/select.c @@ -724,19 +724,7 @@ static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp, ret = core_sys_select(n, inp, outp, exp, to); ret = poll_select_copy_remaining(&end_time, tsp, 0, ret); - if (ret == -ERESTARTNOHAND) { - /* - * Don't restore the signal mask yet. Let do_signal() deliver - * the signal on the way back to userspace, before the signal - * mask is restored. - */ - if (sigmask) { - memcpy(¤t->saved_sigmask, &sigsaved, - sizeof(sigsaved)); - set_restore_sigmask(); - } - } else if (sigmask) - sigprocmask(SIG_SETMASK, &sigsaved, NULL); + restore_user_sigmask(sigmask, &sigsaved); return ret; } @@ -1060,21 +1048,11 @@ SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds, ret = do_sys_poll(ufds, nfds, to); + restore_user_sigmask(sigmask, &sigsaved); + /* We can restart this syscall, usually */ - if (ret == -EINTR) { - /* - * Don't restore the signal mask yet. Let do_signal() deliver - * the signal on the way back to userspace, before the signal - * mask is restored. - */ - if (sigmask) { - memcpy(¤t->saved_sigmask, &sigsaved, - sizeof(sigsaved)); - set_restore_sigmask(); - } + if (ret == -EINTR) ret = -ERESTARTNOHAND; - } else if (sigmask) - sigprocmask(SIG_SETMASK, &sigsaved, NULL); ret = poll_select_copy_remaining(&end_time, tsp, 0, ret); @@ -1316,19 +1294,7 @@ static long do_compat_pselect(int n, compat_ulong_t __user *inp, ret = compat_core_sys_select(n, inp, outp, exp, to); ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret); - if (ret == -ERESTARTNOHAND) { - /* - * Don't restore the signal mask yet. Let do_signal() deliver - * the signal on the way back to userspace, before the signal - * mask is restored. - */ - if (sigmask) { - memcpy(¤t->saved_sigmask, &sigsaved, - sizeof(sigsaved)); - set_restore_sigmask(); - } - } else if (sigmask) - sigprocmask(SIG_SETMASK, &sigsaved, NULL); + restore_user_sigmask(sigmask, &sigsaved); return ret; } @@ -1375,21 +1341,11 @@ COMPAT_SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, ret = do_sys_poll(ufds, nfds, to); + restore_user_sigmask(sigmask, &sigsaved); + /* We can restart this syscall, usually */ - if (ret == -EINTR) { - /* - * Don't restore the signal mask yet. Let do_signal() deliver - * the signal on the way back to userspace, before the signal - * mask is restored. - */ - if (sigmask) { - memcpy(¤t->saved_sigmask, &sigsaved, - sizeof(sigsaved)); - set_restore_sigmask(); - } + if (ret == -EINTR) ret = -ERESTARTNOHAND; - } else if (sigmask) - sigprocmask(SIG_SETMASK, &sigsaved, NULL); ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret); diff --git a/include/linux/signal.h b/include/linux/signal.h index 403e63d01bcf..ed8be17afe89 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -265,6 +265,8 @@ extern int __group_send_sig_info(int, struct 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); extern void set_current_blocked(sigset_t *); extern void __set_current_blocked(const sigset_t *); extern int show_unhandled_signals; diff --git a/kernel/signal.c b/kernel/signal.c index 1d72dcddcaaf..457d1abe62a4 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2783,6 +2783,39 @@ int set_compat_user_sigmask(const compat_sigset_t __user *usigmask, 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) +{ + + 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 (signal_pending(current)) { + 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 -- 2.17.1 _______________________________________________ Y2038 mailing list [email protected] https://lists.linaro.org/mailman/listinfo/y2038
