diff options
| author | David Howells <dhowells@redhat.com> | 2009-05-08 13:55:27 +0100 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2009-05-11 08:15:39 +1000 |
| commit | 107db7c7dd137aeb7361b8c2606ac936c0be58ff (patch) | |
| tree | 7e8e024bbed52ac111a0b2ac878da1a95752c28b | |
| parent | 5e751e992f3fb08ba35e1ca8095ec8fbf9eda523 (diff) | |
| download | lwn-107db7c7dd137aeb7361b8c2606ac936c0be58ff.tar.gz lwn-107db7c7dd137aeb7361b8c2606ac936c0be58ff.zip | |
CRED: Guard the setprocattr security hook against ptrace
Guard the setprocattr security hook against ptrace by taking the target task's
cred_guard_mutex around it. The problem is that setprocattr() may otherwise
note the lack of a debugger, and then perform an action on that basis whilst
letting a debugger attach between the two points. Holding cred_guard_mutex
across the test and the action prevents ptrace_attach() from doing that.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
| -rw-r--r-- | fs/proc/base.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index fb45615943c2..23342e188a66 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2128,9 +2128,15 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf, if (copy_from_user(page, buf, count)) goto out_free; + /* Guard against adverse ptrace interaction */ + length = mutex_lock_interruptible(&task->cred_guard_mutex); + if (length < 0) + goto out_free; + length = security_setprocattr(task, (char*)file->f_path.dentry->d_name.name, (void*)page, count); + mutex_unlock(&task->cred_guard_mutex); out_free: free_page((unsigned long) page); out: |