From: Paul Moore <paul@paul-moore.com>
To: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org, cj.chengjian@huawei.com,
john.johansen@canonical.com, casey@schaufler-ca.com
Subject: [PATCH] proc: prevent changes to overridden credentials
Date: Fri, 19 Apr 2019 14:55:12 -0400 [thread overview]
Message-ID: <155570011247.27135.12509150054846153288.stgit@chester> (raw)
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>
---
fs/proc/base.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index ddef482f1334..87ba007b86db 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2539,6 +2539,11 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
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)
next reply other threads:[~2019-04-19 18:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-19 18:55 Paul Moore [this message]
2019-04-19 18:59 ` [PATCH] proc: prevent changes to overridden credentials Paul Moore
2019-04-19 20:26 ` James Morris
2019-04-29 13:57 ` Paul Moore
2019-04-19 19:03 ` John Johansen
2019-04-21 17:14 ` Casey Schaufler
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