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-rw-r--r--security/security.c64
1 files changed, 62 insertions, 2 deletions
diff --git a/security/security.c b/security/security.c
index f32d7d2075c6..4989fb65e662 100644
--- a/security/security.c
+++ b/security/security.c
@@ -41,6 +41,7 @@ struct security_hook_heads security_hook_heads __lsm_ro_after_init;
static ATOMIC_NOTIFIER_HEAD(lsm_notifier_chain);
static struct kmem_cache *lsm_file_cache;
+static struct kmem_cache *lsm_inode_cache;
char *lsm_names;
static struct lsm_blob_sizes blob_sizes __lsm_ro_after_init;
@@ -161,6 +162,13 @@ static void __init lsm_set_blob_sizes(struct lsm_blob_sizes *needed)
lsm_set_blob_size(&needed->lbs_cred, &blob_sizes.lbs_cred);
lsm_set_blob_size(&needed->lbs_file, &blob_sizes.lbs_file);
+ /*
+ * The inode blob gets an rcu_head in addition to
+ * what the modules might need.
+ */
+ if (needed->lbs_inode && blob_sizes.lbs_inode == 0)
+ blob_sizes.lbs_inode = sizeof(struct rcu_head);
+ lsm_set_blob_size(&needed->lbs_inode, &blob_sizes.lbs_inode);
}
/* Prepare LSM for initialization. */
@@ -283,6 +291,7 @@ static void __init ordered_lsm_init(void)
init_debug("cred blob size = %d\n", blob_sizes.lbs_cred);
init_debug("file blob size = %d\n", blob_sizes.lbs_file);
+ init_debug("inode blob size = %d\n", blob_sizes.lbs_inode);
/*
* Create any kmem_caches needed for blobs
@@ -291,6 +300,10 @@ static void __init ordered_lsm_init(void)
lsm_file_cache = kmem_cache_create("lsm_file_cache",
blob_sizes.lbs_file, 0,
SLAB_PANIC, NULL);
+ if (blob_sizes.lbs_inode)
+ lsm_inode_cache = kmem_cache_create("lsm_inode_cache",
+ blob_sizes.lbs_inode, 0,
+ SLAB_PANIC, NULL);
for (lsm = ordered_lsms; *lsm; lsm++)
initialize_lsm(*lsm);
@@ -481,6 +494,27 @@ static int lsm_file_alloc(struct file *file)
return 0;
}
+/**
+ * lsm_inode_alloc - allocate a composite inode blob
+ * @inode: the inode that needs a blob
+ *
+ * Allocate the inode blob for all the modules
+ *
+ * Returns 0, or -ENOMEM if memory can't be allocated.
+ */
+int lsm_inode_alloc(struct inode *inode)
+{
+ if (!lsm_inode_cache) {
+ inode->i_security = NULL;
+ return 0;
+ }
+
+ inode->i_security = kmem_cache_zalloc(lsm_inode_cache, GFP_NOFS);
+ if (inode->i_security == NULL)
+ return -ENOMEM;
+ return 0;
+}
+
/*
* Hook list operation macros.
*
@@ -740,14 +774,40 @@ EXPORT_SYMBOL(security_add_mnt_opt);
int security_inode_alloc(struct inode *inode)
{
- inode->i_security = NULL;
- return call_int_hook(inode_alloc_security, 0, inode);
+ int rc = lsm_inode_alloc(inode);
+
+ if (unlikely(rc))
+ return rc;
+ rc = call_int_hook(inode_alloc_security, 0, inode);
+ if (unlikely(rc))
+ security_inode_free(inode);
+ return rc;
+}
+
+static void inode_free_by_rcu(struct rcu_head *head)
+{
+ /*
+ * The rcu head is at the start of the inode blob
+ */
+ kmem_cache_free(lsm_inode_cache, head);
}
void security_inode_free(struct inode *inode)
{
integrity_inode_free(inode);
call_void_hook(inode_free_security, inode);
+ /*
+ * The inode may still be referenced in a path walk and
+ * a call to security_inode_permission() can be made
+ * after inode_free_security() is called. Ideally, the VFS
+ * wouldn't do this, but fixing that is a much harder
+ * job. For now, simply free the i_security via RCU, and
+ * leave the current inode->i_security pointer intact.
+ * The inode will be freed after the RCU grace period too.
+ */
+ if (inode->i_security)
+ call_rcu((struct rcu_head *)inode->i_security,
+ inode_free_by_rcu);
}
int security_dentry_init_security(struct dentry *dentry, int mode,