From: Benjamin Gordon <bmgordon@xxxxxxxxxx> Subject: fs/proc/base.c: use ns_capable instead of capable for timerslack_ns 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-bmgordon@xxxxxxxxxx Signed-off-by: Benjamin Gordon <bmgordon@xxxxxxxxxx> Acked-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: John Stultz <john.stultz@xxxxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: "Serge E. Hallyn" <serge@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx> Cc: Oren Laadan <orenl@xxxxxxxxxxx> Cc: Ruchi Kandoi <kandoiruchi@xxxxxxxxxx> Cc: Rom Lemarchand <romlem@xxxxxxxxxxx> Cc: Todd Kjos <tkjos@xxxxxxxxxx> Cc: Colin Cross <ccross@xxxxxxxxxxx> Cc: Nick Kralevich <nnk@xxxxxxxxxx> Cc: Dmitry Shmidt <dimitrysh@xxxxxxxxxx> Cc: Elliott Hughes <enh@xxxxxxxxxx> Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/base.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) --- a/fs/proc/base.c~proc-use-ns_capable-instead-of-capable-for-timerslack_ns +++ a/fs/proc/base.c @@ -2356,10 +2356,13 @@ static ssize_t timerslack_ns_write(struc 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 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; _
