diff options
| author | Christian Brauner <brauner@kernel.org> | 2024-07-31 12:01:12 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-08-12 22:03:26 +0200 |
| commit | 3b5bbe798b2451820e74243b738268f51901e7d0 (patch) | |
| tree | 41c7dc949f52c5b19074dd1e732cd4167e0cc6e6 | |
| parent | netfs: clean up after renaming FSCACHE_DEBUG config (diff) | |
| download | linux-3b5bbe798b2451820e74243b738268f51901e7d0.tar.xz linux-3b5bbe798b2451820e74243b738268f51901e7d0.zip | |
pidfd: prevent creation of pidfds for kthreads
It's currently possible to create pidfds for kthreads but it is unclear
what that is supposed to mean. Until we have use-cases for it and we
figured out what behavior we want block the creation of pidfds for
kthreads.
Link: https://lore.kernel.org/r/20240731-gleis-mehreinnahmen-6bbadd128383@brauner
Fixes: 32fcb426ec00 ("pid: add pidfd_open()")
Cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
| -rw-r--r-- | kernel/fork.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index cc760491f201..18bdc87209d0 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2053,11 +2053,24 @@ static int __pidfd_prepare(struct pid *pid, unsigned int flags, struct file **re */ int pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret) { - bool thread = flags & PIDFD_THREAD; - - if (!pid || !pid_has_task(pid, thread ? PIDTYPE_PID : PIDTYPE_TGID)) + if (!pid) return -EINVAL; + scoped_guard(rcu) { + struct task_struct *tsk; + + if (flags & PIDFD_THREAD) + tsk = pid_task(pid, PIDTYPE_PID); + else + tsk = pid_task(pid, PIDTYPE_TGID); + if (!tsk) + return -EINVAL; + + /* Don't create pidfds for kernel threads for now. */ + if (tsk->flags & PF_KTHREAD) + return -EINVAL; + } + return __pidfd_prepare(pid, flags, ret); } @@ -2403,6 +2416,12 @@ __latent_entropy struct task_struct *copy_process( if (clone_flags & CLONE_PIDFD) { int flags = (clone_flags & CLONE_THREAD) ? PIDFD_THREAD : 0; + /* Don't create pidfds for kernel threads for now. */ + if (args->kthread) { + retval = -EINVAL; + goto bad_fork_free_pid; + } + /* Note that no task has been attached to @pid yet. */ retval = __pidfd_prepare(pid, flags, &pidfile); if (retval < 0) |