Let pidfd_send_signal() use pidfds retrieved via pidctl(). 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 <[email protected]> Reviewed-by: David Howells <[email protected]> Acked-by: Serge Hallyn <[email protected]> Cc: Arnd Bergmann <[email protected]> Cc: "Eric W. Biederman" <[email protected]> Cc: Kees Cook <[email protected]> Cc: Alexey Dobriyan <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Jann Horn <[email protected] Cc: "Michael Kerrisk (man-pages)" <[email protected]> Cc: Konstantin Khlebnikov <[email protected]> Cc: Jonathan Kowalski <[email protected]> Cc: "Dmitry V. Levin" <[email protected]> Cc: Andy Lutomirsky <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Nagarathnam Muthusamy <[email protected]> Cc: Aleksa Sarai <[email protected]> Cc: Al Viro <[email protected]> --- kernel/signal.c | 20 +++++++++----------- kernel/sys_ni.c | 3 --- 2 files changed, 9 insertions(+), 14 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index b7953934aa99..d77183be1677 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 @@ -3521,16 +3520,13 @@ SYSCALL_DEFINE2(kill, pid_t, pid, int, sig) */ static bool access_pidfd_pidns(struct pid *pid) { + int ret; struct pid_namespace *active = task_active_pid_ns(current); struct pid_namespace *p = ns_of_pid(pid); - for (;;) { - if (!p) - return false; - if (p == active) - break; - p = p->parent; - } + ret = pidnscmp(active, p); + if (ret < 0) + return false; return true; } @@ -3581,12 +3577,15 @@ 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); + if (f.file->f_op == &pidfd_fops) + pid = f.file->private_data; + else + pid = tgid_pidfd_to_pid(f.file); if (IS_ERR(pid)) { ret = PTR_ERR(pid); goto err; @@ -3625,7 +3624,6 @@ 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
