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BACKPORT: signal: support CLONE_PIDFD with pidfd_send_signal

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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@brauner.io>
Co-developed-by: Jann Horn <jannh@google.com>
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: David Howells <dhowells@redhat.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>

(cherry picked from commit 2151ad1b067275730de1b38c7257478cae47d29e)

Conflicts:
        kernel/sys_ni.c

(1. Replaced COND_SYSCALL with cond_syscall.)

Bug: 135608568
Test: test program using syscall(__NR_sys_pidfd_open,..) and poll()
Change-Id: I621fe6547397e0e68c560d7da60ef7715deb290c
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Christian Brauner 2019-04-17 22:50:25 +02:00 • committed by Suren Baghdasaryan
parent 0e020c19bb
commit b3ae59851f
2 changed files with 9 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

12
kernel/signal.c
View file

@ -2946,7 +2946,6 @@ 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
@ -2968,6 +2967,14 @@ static bool access_pidfd_pidns(struct pid *pid)
return true;
}
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);
}
static int copy_siginfo_from_user_any(siginfo_t *kinfo, siginfo_t __user *info)
{
#ifdef CONFIG_COMPAT
@ -3019,7 +3026,7 @@ 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;
@ -3053,7 +3060,6 @@ err:
fdput(f);
return ret;
}
#endif /* CONFIG_PROC_FS */
static int
do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)

1
kernel/sys_ni.c
View file

@ -152,7 +152,6 @@ cond_syscall(sys_io_cancel);
cond_syscall(sys_io_getevents);
cond_syscall(sys_sysfs);
cond_syscall(sys_syslog);
cond_syscall(sys_pidfd_send_signal);
cond_syscall(sys_process_vm_readv);
cond_syscall(sys_process_vm_writev);
cond_syscall(compat_sys_process_vm_readv);