diff options
| author | Li Zefan <lizf@cn.fujitsu.com> | 2008-09-02 14:35:52 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-09-02 19:21:38 -0700 |
| commit | 36fd71d293898a59b14e49da1f6e81c1a58f2035 (patch) | |
| tree | e67d5a0f6fc6caa83558f57588d9f69a46e5f4c9 /security/device_cgroup.c | |
| parent | 09a2910e54646f7a334702fbafa7a6129dc072e6 (diff) | |
| download | lwn-36fd71d293898a59b14e49da1f6e81c1a58f2035.tar.gz lwn-36fd71d293898a59b14e49da1f6e81c1a58f2035.zip | |
devcgroup: fix race against rmdir()
During the use of a dev_cgroup, we should guarantee the corresponding
cgroup won't be deleted (i.e. via rmdir). This can be done through
css_get(&dev_cgroup->css), but here we can just get and use the dev_cgroup
under rcu_read_lock.
And also remove checking NULL dev_cgroup, it won't be NULL since a task
always belongs to a cgroup.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security/device_cgroup.c')
| -rw-r--r-- | security/device_cgroup.c | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 7bd296cca041..46f23971f7e4 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -508,12 +508,11 @@ int devcgroup_inode_permission(struct inode *inode, int mask) return 0; if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode)) return 0; - dev_cgroup = css_to_devcgroup(task_subsys_state(current, - devices_subsys_id)); - if (!dev_cgroup) - return 0; rcu_read_lock(); + + dev_cgroup = task_devcgroup(current); + list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) { if (wh->type & DEV_ALL) goto acc_check; @@ -533,6 +532,7 @@ acc_check: rcu_read_unlock(); return 0; } + rcu_read_unlock(); return -EPERM; @@ -543,12 +543,10 @@ int devcgroup_inode_mknod(int mode, dev_t dev) struct dev_cgroup *dev_cgroup; struct dev_whitelist_item *wh; - dev_cgroup = css_to_devcgroup(task_subsys_state(current, - devices_subsys_id)); - if (!dev_cgroup) - return 0; - rcu_read_lock(); + + dev_cgroup = task_devcgroup(current); + list_for_each_entry(wh, &dev_cgroup->whitelist, list) { if (wh->type & DEV_ALL) goto acc_check; @@ -566,6 +564,8 @@ acc_check: rcu_read_unlock(); return 0; } + rcu_read_unlock(); + return -EPERM; } |