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>
Co-developed-by: Jann Horn <jann@xxxxxxxxx>
Signed-off-by: Jann Horn <jann@xxxxxxxxx>
Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
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: Aleksa Sarai <cyphar@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
/* changelog */
v1: patch unchanged
v2:
- Oleg Nesterov <oleg@xxxxxxxxxx>:
- split s/fdget_raw()/fdget()/ into separate patch as it has nothing to
do with supporting CLONE_PIDFD
v3:
- Christian Brauner <christian@xxxxxxxxxx>:
- Linus has applied the s/fdget_raw()/fdget()/ patch right away so the
patch is gone from the series
---
kernel/signal.c | 12 +++++++++---
kernel/sys_ni.c | 3 ---
2 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/kernel/signal.c b/kernel/signal.c
index f98448cf2def..1581140f2d99 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
@@ -3586,7 +3593,7 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig,
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
