| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.1 036/122] proc: prevent changes to overridden credentials | Date | Thu, 23 May 2019 21:05:58 +0200 |
| |
From: Paul Moore <paul@paul-moore.com>
commit 35a196bef449b5824033865b963ed9a43fb8c730 upstream.
Prevent userspace from changing the the /proc/PID/attr values if the task's credentials are currently overriden. This not only makes sense conceptually, it also prevents some really bizarre error cases caused when trying to commit credentials to a task with overridden credentials.
Cc: <stable@vger.kernel.org> Reported-by: "chengjian (D)" <cj.chengjian@huawei.com> Signed-off-by: Paul Moore <paul@paul-moore.com> Acked-by: John Johansen <john.johansen@canonical.com> Acked-by: James Morris <james.morris@microsoft.com> Acked-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/proc/base.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2540,6 +2540,11 @@ static ssize_t proc_pid_attr_write(struc rcu_read_unlock(); return -EACCES; } + /* Prevent changes to overridden credentials. */ + if (current_cred() != current_real_cred()) { + rcu_read_unlock(); + return -EBUSY; + } rcu_read_unlock(); if (count > PAGE_SIZE)
|