Let pidfd_send_signal() use pidfds retrieved via CLONE_PIDFD. With this patch pidfd_send_signal() becomes independent of procfs. This fullfils the request made when we merged the pidfd_send_signal() patchset. The pidfd_send_signal() syscall is now always available allowing for it to be used by users without procfs mounted or even users without procfs support compiled into the kernel. Signed-off-by: Christian Brauner <christian@xxxxxxxxxx> Signed-off-by: Jann Horn <jann@xxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: David Howells <dhowells@xxxxxxxxxx> Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@xxxxxxxxx> Cc: Andy Lutomirsky <luto@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Aleksa Sarai <cyphar@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> --- /* changelog */ v1: patch unchanged --- kernel/signal.c | 14 ++++++++++---- kernel/sys_ni.c | 3 --- 2 files changed, 10 insertions(+), 7 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index f98448cf2def..cd83cc376767 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -3513,7 +3513,6 @@ SYSCALL_DEFINE2(kill, pid_t, pid, int, sig) return kill_something_info(sig, &info, pid); } -#ifdef CONFIG_PROC_FS /* * Verify that the signaler and signalee either are in the same pid namespace * or that the signaler's pid namespace is an ancestor of the signalee's pid @@ -3550,6 +3549,14 @@ static int copy_siginfo_from_user_any(kernel_siginfo_t *kinfo, siginfo_t *info) return copy_siginfo_from_user(kinfo, info); } +static struct pid *pidfd_to_pid(const struct file *file) +{ + if (file->f_op == &pidfd_fops) + return file->private_data; + + return tgid_pidfd_to_pid(file); +} + /** * sys_pidfd_send_signal - send a signal to a process through a task file * descriptor @@ -3581,12 +3588,12 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, if (flags) return -EINVAL; - f = fdget_raw(pidfd); + f = fdget(pidfd); if (!f.file) return -EBADF; /* Is this a pidfd? */ - pid = tgid_pidfd_to_pid(f.file); + pid = pidfd_to_pid(f.file); if (IS_ERR(pid)) { ret = PTR_ERR(pid); goto err; @@ -3620,7 +3627,6 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, fdput(f); return ret; } -#endif /* CONFIG_PROC_FS */ static int do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info) diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index d21f4befaea4..4d9ae5ea6caf 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -167,9 +167,6 @@ COND_SYSCALL(syslog); /* kernel/sched/core.c */ -/* kernel/signal.c */ -COND_SYSCALL(pidfd_send_signal); - /* kernel/sys.c */ COND_SYSCALL(setregid); COND_SYSCALL(setgid); -- 2.21.0