4.20-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/20181030180012.232896-1-bmgor...@google.com Signed-off-by: Benjamin Gordon <bmgor...@google.com> Acked-by: "Eric W. Biederman" <ebied...@xmission.com> Cc: John Stultz <john.stu...@linaro.org> Cc: "Eric W. Biederman" <ebied...@xmission.com> Cc: Kees Cook <keesc...@chromium.org> Cc: "Serge E. Hallyn" <se...@hallyn.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Arjan van de Ven <ar...@linux.intel.com> Cc: Oren Laadan <or...@cellrox.com> Cc: Ruchi Kandoi <kandoiru...@google.com> Cc: Rom Lemarchand <rom...@android.com> Cc: Todd Kjos <tk...@google.com> Cc: Colin Cross <ccr...@android.com> Cc: Nick Kralevich <n...@google.com> Cc: Dmitry Shmidt <dimitr...@google.com> Cc: Elliott Hughes <e...@google.com> Cc: Alexey Dobriyan <adobri...@gmail.com> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Sasha Levin <sas...@kernel.org> --- 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 ce3465479447..98525af0953e 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2356,10 +2356,13 @@ 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) { @@ -2392,11 +2395,14 @@ 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
