[PATCH v2 7/9] procfs: add permission checks on the file's opener of /proc/*/personality

Djalal Harouni
2013-10-01T20:34:04Z

If current's cred have changed between ->open() and ->read(), then call
proc_allow_access() to check if the original file's opener had enough
permissions to access the /proc/*/personality entry during ->read().

Cc: Kees Cook <keescook@chromium.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
---
fs/proc/base.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index d4b604d..77f5b84 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2647,11 +2647,23 @@ static const struct file_operations proc_projid_map_operations = {
static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
+ struct file *file = m->private;
+ const struct cred *fcred = file->f_cred;
+ int same_cred = proc_same_open_cred(fcred);
int err = lock_trace(task);
- if (!err) {
- seq_printf(m, "%08x\n", task->personality);
- unlock_trace(task);
+ if (err)
+ return err;
+
+ if (!same_cred &&
+ !proc_allow_access(fcred, task, PTRACE_MODE_ATTACH)) {
+ err = -EPERM;
+ goto out;
}
+
+ seq_printf(m, "%08x\n", task->personality);
+
+out:
+ unlock_trace(task);
return err;
}

--
1.7.11.7