From 81b9d8ac0640b285a3c369cd41a85f6c240d3a60 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 9 Feb 2024 14:06:50 +0100 Subject: pidfd: change pidfd_send_signal() to respect PIDFD_THREAD Turn kill_pid_info() into kill_pid_info_type(), this allows to pass any pid_type to group_send_sig_info(), despite its name it should work fine even if type = PIDTYPE_PID. Change pidfd_send_signal() to use PIDTYPE_PID or PIDTYPE_TGID depending on PIDFD_THREAD. While at it kill another TODO comment in pidfd_show_fdinfo(). As Christian expains fdinfo reports f_flags, userspace can already detect PIDFD_THREAD. Reviewed-by: Tycho Andersen Signed-off-by: Oleg Nesterov Link: https://lore.kernel.org/r/20240209130650.GA8048@redhat.com Signed-off-by: Christian Brauner --- kernel/signal.c | 39 +++++++++++++++++++++++---------------- 1 file changed, 23 insertions(+), 16 deletions(-) (limited to 'kernel/signal.c') diff --git a/kernel/signal.c b/kernel/signal.c index 1450689302d9..8b8169623850 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -47,6 +47,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -1436,7 +1437,8 @@ void lockdep_assert_task_sighand_held(struct task_struct *task) #endif /* - * send signal info to all the members of a group + * send signal info to all the members of a thread group or to the + * individual thread if type == PIDTYPE_PID. */ int group_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p, enum pid_type type) @@ -1478,7 +1480,8 @@ int __kill_pgrp_info(int sig, struct kernel_siginfo *info, struct pid *pgrp) return ret; } -int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid) +static int kill_pid_info_type(int sig, struct kernel_siginfo *info, + struct pid *pid, enum pid_type type) { int error = -ESRCH; struct task_struct *p; @@ -1487,11 +1490,10 @@ int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid) rcu_read_lock(); p = pid_task(pid, PIDTYPE_PID); if (p) - error = group_send_sig_info(sig, info, p, PIDTYPE_TGID); + error = group_send_sig_info(sig, info, p, type); rcu_read_unlock(); if (likely(!p || error != -ESRCH)) return error; - /* * The task was unhashed in between, try again. If it * is dead, pid_task() will return NULL, if we race with @@ -1500,6 +1502,11 @@ int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid) } } +int kill_pid_info(int sig, struct kernel_siginfo *info, struct pid *pid) +{ + return kill_pid_info_type(sig, info, pid, PIDTYPE_TGID); +} + static int kill_proc_info(int sig, struct kernel_siginfo *info, pid_t pid) { int error; @@ -3873,14 +3880,10 @@ static struct pid *pidfd_to_pid(const struct file *file) * @info: signal info * @flags: future flags * - * The syscall currently only signals via PIDTYPE_PID which covers - * kill(, . It does not signal threads or process - * groups. - * In order to extend the syscall to threads and process groups the @flags - * argument should be used. In essence, the @flags argument will determine - * what is signaled and not the file descriptor itself. Put in other words, - * grouping is a property of the flags argument not a property of the file - * descriptor. + * Send the signal to the thread group or to the individual thread depending + * on PIDFD_THREAD. + * In the future extension to @flags may be used to override the default scope + * of @pidfd. * * Return: 0 on success, negative errno on failure */ @@ -3891,6 +3894,7 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, struct fd f; struct pid *pid; kernel_siginfo_t kinfo; + enum pid_type type; /* Enforce flags be set to 0 until we add an extension. */ if (flags) @@ -3911,6 +3915,11 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, if (!access_pidfd_pidns(pid)) goto err; + if (f.file->f_flags & PIDFD_THREAD) + type = PIDTYPE_PID; + else + type = PIDTYPE_TGID; + if (info) { ret = copy_siginfo_from_user_any(&kinfo, info); if (unlikely(ret)) @@ -3926,12 +3935,10 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, (kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL)) goto err; } else { - prepare_kill_siginfo(sig, &kinfo, PIDTYPE_TGID); + prepare_kill_siginfo(sig, &kinfo, type); } - /* TODO: respect PIDFD_THREAD */ - ret = kill_pid_info(sig, &kinfo, pid); - + ret = kill_pid_info_type(sig, &kinfo, pid, type); err: fdput(f); return ret; -- cgit v1.2.3