Messages in this thread Patch in this message | | | Date | Tue, 30 Oct 2018 12:00:12 -0600 | Subject | [PATCH v2] proc: use ns_capable instead of capable for timerslack_ns | From | Benjamin Gordon <> |
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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.
Signed-off-by: Benjamin Gordon <bmgordon@google.com> Cc: John Stultz <john.stultz@linaro.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Kees Cook <keescook@chromium.org> Cc: "Serge E. Hallyn" <serge@hallyn.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Oren Laadan <orenl@cellrox.com> Cc: Ruchi Kandoi <kandoiruchi@google.com> Cc: Rom Lemarchand <romlem@android.com> Cc: Todd Kjos <tkjos@google.com> Cc: Colin Cross <ccross@android.com> Cc: Nick Kralevich <nnk@google.com> Cc: Dmitry Shmidt <dimitrysh@google.com> Cc: Elliott Hughes <enh@google.com> Cc: Android Kernel Team <kernel-team@android.com> Cc: Andrew Morton <akpm@linux-foundation.org> ---
Changes from v1: - Use the namespace of the target process instead of the file opener. Didn't carry over John Stultz' Acked-by since the changes aren't cosmetic.
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 c78d8da09b52c..bdc093ba81dd3 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2385,10 +2385,13 @@ 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) { @@ -2421,11 +2424,14 @@ 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; -- 2.19.1.568.g152ad8e336-goog
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