path: root/kernel/cred.c
diff options
authorDavid Howells <dhowells@redhat.com>2011-08-22 14:09:00 +0100
committerJames Morris <jmorris@namei.org>2011-08-23 09:57:35 +1000
commit012146d0728f85f7a5c7c36fb84bba33e2760507 (patch)
tree215ad5926013e6a71d1ea750a81596fa20028dcc /kernel/cred.c
parent6d528b082294f0ddabd6368297546a2c0b67d4fe (diff)
CRED: Fix prepare_kernel_cred() to provide a new thread_group_cred struct
Fix prepare_kernel_cred() to provide a new, separate thread_group_cred struct otherwise when using request_key() ____call_usermodehelper() calls umh_keys_init() with the new creds pointing to init_tgcred, which umh_keys_init() then blithely alters. The problem can be demonstrated by: # keyctl request2 user a debug:a @s 249681132 # grep req /proc/keys 079906a5 I--Q-- 1 perm 1f3f0000 0 0 keyring _req.249681132: 1/4 38ef1626 IR---- 1 expd 0b010000 0 0 .request_ key:ee1d4ec pid:4371 ci:1 The keyring _req.XXXX should have gone away, but something (init_tgcred) is pinning it. That key actually requested can then be removed and a new one created: # keyctl unlink 249681132 1 links removed [root@andromeda ~]# grep req /proc/keys 116cecac IR---- 1 expd 0b010000 0 0 .request_ key:eeb4911 pid:4379 ci:1 36d1cbf8 I--Q-- 1 perm 1f3f0000 0 0 keyring _req.250300689: 1/4 which causes the old _req keyring to go away and a new one to take its place. This is a consequence of the changes in: commit 879669961b11e7f40b518784863a259f735a72bf Author: David Howells <dhowells@redhat.com> Date: Fri Jun 17 11:25:59 2011 +0100 KEYS/DNS: Fix ____call_usermodehelper() to not lose the session keyring and: commit 17f60a7da150fdd0cfb9756f86a262daa72c835f Author: Eric Paris <eparis@redhat.com> Date: Fri Apr 1 17:07:50 2011 -0400 capabilites: allow the application of capability limits to usermode helpers After this patch is applied, the _req keyring and the .request_key key are cleaned up. Signed-off-by: David Howells <dhowells@redhat.com> cc: Eric Paris <eparis@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'kernel/cred.c')
1 files changed, 14 insertions, 2 deletions
diff --git a/kernel/cred.c b/kernel/cred.c
index 174fa84eca3..f1e22556bc4 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -646,6 +646,9 @@ void __init cred_init(void)
struct cred *prepare_kernel_cred(struct task_struct *daemon)
+ struct thread_group_cred *tgcred;
const struct cred *old;
struct cred *new;
@@ -653,6 +656,12 @@ struct cred *prepare_kernel_cred(struct task_struct *daemon)
if (!new)
return NULL;
+ tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
+ if (!tgcred) {
+ kmem_cache_free(cred_jar, new);
+ return NULL;
+ }
kdebug("prepare_kernel_cred() alloc %p", new);
if (daemon)
@@ -669,8 +678,11 @@ struct cred *prepare_kernel_cred(struct task_struct *daemon)
- atomic_inc(&init_tgcred.usage);
- new->tgcred = &init_tgcred;
+ atomic_set(&tgcred->usage, 1);
+ spin_lock_init(&tgcred->lock);
+ tgcred->process_keyring = NULL;
+ tgcred->session_keyring = NULL;
+ new->tgcred = tgcred;
new->request_key_auth = NULL;
new->thread_keyring = NULL;