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authorLi Zefan <lizf@cn.fujitsu.com>2008-09-02 14:35:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-09-02 19:21:38 -0700
commit36fd71d293898a59b14e49da1f6e81c1a58f2035 (patch)
treee67d5a0f6fc6caa83558f57588d9f69a46e5f4c9 /security
parent09a2910e54646f7a334702fbafa7a6129dc072e6 (diff)
downloadlinux-linaro-stable-36fd71d293898a59b14e49da1f6e81c1a58f2035.tar.gz
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')
-rw-r--r--security/device_cgroup.c18
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;
}