[PATCH v4 2/5] kernel/pid.c: implement additional checks upon pidfd_create() parameters
From: Matthew Bobrowski <repnop@google.com>
Date: 2021-08-08 05:25:20
Also in:
linux-fsdevel
Subsystem:
the rest · Maintainer:
Linus Torvalds
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 behavior, 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 <redacted> --- kernel/pid.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
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;
--
2.32.0.605.g8dce9f2422-goog
/M