diff mbox series

[v3,2/5] kernel/pid.c: implement additional checks upon pidfd_create() parameters

Message ID ce0d38ce25490d9e144b5e76573f62eb1d3cf8b3.1626845288.git.repnop@google.com (mailing list archive)
State New, archived
Headers show
Series Add pidfd support to the fanotify API | expand

Commit Message

Matthew Bobrowski July 21, 2021, 6:17 a.m. UTC 
By adding the pidfd_create() declaration to linux/pid.h, we
effectively expose this function to the rest of the kernel. In order
to avoid any unintended behaviour, or set false expectations upon this
function, ensure that constraints are forced upon each of the passed
parameters. This includes the checking of whether the passed struct
pid is a thread-group leader as pidfd creation is currently limited to
such pid types.

Signed-off-by: Matthew Bobrowski <repnop@google.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
---
 kernel/pid.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/kernel/pid.c b/kernel/pid.c
index d3cd95b8b080..efe87db44683 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -559,6 +559,12 @@  int pidfd_create(struct pid *pid, unsigned int flags)
 {
 	int fd;
 
+	if (!pid || !pid_has_task(pid, PIDTYPE_TGID))
+		return -EINVAL;
+
+	if (flags & ~(O_NONBLOCK | O_RDWR | O_CLOEXEC))
+		return -EINVAL;
+
 	fd = anon_inode_getfd("[pidfd]", &pidfd_fops, get_pid(pid),
 			      flags | O_RDWR | O_CLOEXEC);
 	if (fd < 0)
@@ -598,10 +604,7 @@  SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags)
 	if (!p)
 		return -ESRCH;
 
-	if (pid_has_task(p, PIDTYPE_TGID))
-		fd = pidfd_create(p, flags);
-	else
-		fd = -EINVAL;
+	fd = pidfd_create(p, flags);
 
 	put_pid(p);
 	return fd;