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authorDavid Howells <dhowells@redhat.com>2009-05-08 13:55:27 +0100
committerJames Morris <jmorris@namei.org>2009-05-11 08:15:39 +1000
commit107db7c7dd137aeb7361b8c2606ac936c0be58ff (patch)
tree7e8e024bbed52ac111a0b2ac878da1a95752c28b /fs/proc
parent5e751e992f3fb08ba35e1ca8095ec8fbf9eda523 (diff)
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>
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/base.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index fb45615943c..23342e188a6 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: