4.14-stable review patch. If anyone has any objections, please let me know.
------------------ [ Upstream commit 8da0b4f692c6d90b09c91f271517db746a22ff67 ] Access to timerslack_ns is controlled by a process having CAP_SYS_NICE in its effective capability set, but the current check looks in the root namespace instead of the process' user namespace. Since a process is allowed to do other activities controlled by CAP_SYS_NICE inside a namespace, it should also be able to adjust timerslack_ns. Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Benjamin Gordon <[email protected]> Acked-by: "Eric W. Biederman" <[email protected]> Cc: John Stultz <[email protected]> Cc: "Eric W. Biederman" <[email protected]> Cc: Kees Cook <[email protected]> Cc: "Serge E. Hallyn" <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Arjan van de Ven <[email protected]> Cc: Oren Laadan <[email protected]> Cc: Ruchi Kandoi <[email protected]> Cc: Rom Lemarchand <[email protected]> Cc: Todd Kjos <[email protected]> Cc: Colin Cross <[email protected]> Cc: Nick Kralevich <[email protected]> Cc: Dmitry Shmidt <[email protected]> Cc: Elliott Hughes <[email protected]> Cc: Alexey Dobriyan <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- fs/proc/base.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 9063738ff1f0..e26155a97afa 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2374,10 +2374,13 @@ static ssize_t timerslack_ns_write(struct file *file, const char __user *buf, return -ESRCH; if (p != current) { - if (!capable(CAP_SYS_NICE)) { + rcu_read_lock(); + if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) { + rcu_read_unlock(); count = -EPERM; goto out; } + rcu_read_unlock(); err = security_task_setscheduler(p); if (err) { @@ -2410,11 +2413,14 @@ static int timerslack_ns_show(struct seq_file *m, void *v) return -ESRCH; if (p != current) { - - if (!capable(CAP_SYS_NICE)) { + rcu_read_lock(); + if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) { + rcu_read_unlock(); err = -EPERM; goto out; } + rcu_read_unlock(); + err = security_task_getscheduler(p); if (err) goto out; -- 2.19.1
