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| author | Paul Moore <paul@paul-moore.com> | 2019-04-19 21:55:12 +0300 |
|---|---|---|
| committer | Paul Moore <paul@paul-moore.com> | 2019-04-29 16:51:21 +0300 |
| commit | 35a196bef449b5824033865b963ed9a43fb8c730 (patch) | |
| tree | bed797d4bac8508de8e185e3bd08247a9ed33891 /fs/proc/base.c | |
| parent | c750e6929d3c76d13d1d0ba475989d6dd74785d5 (diff) | |
| download | linux-35a196bef449b5824033865b963ed9a43fb8c730.tar.xz | |
proc: prevent changes to overridden credentials
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>
Diffstat (limited to 'fs/proc/base.c')
| -rw-r--r-- | fs/proc/base.c | 5 |
1 files changed, 5 insertions, 0 deletions
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) |