eCryptfs: Prevent file create race condition
The file creation path prematurely called d_instantiate() and
unlock_new_inode() before the eCryptfs inode info was fully
allocated and initialized and before the eCryptfs metadata was written
to the lower file.
This could result in race conditions in subsequent file and inode
operations leading to unexpected error conditions or a null pointer
dereference while attempting to use the unallocated memory.
https://launchpad.net/bugs/813146
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Cc: stable@kernel.org
diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 58609bd..203a1fd 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -967,7 +967,7 @@
/**
* ecryptfs_new_file_context
- * @ecryptfs_dentry: The eCryptfs dentry
+ * @ecryptfs_inode: The eCryptfs inode
*
* If the crypto context for the file has not yet been established,
* this is where we do that. Establishing a new crypto context
@@ -984,13 +984,13 @@
*
* Returns zero on success; non-zero otherwise
*/
-int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
+int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
{
struct ecryptfs_crypt_stat *crypt_stat =
- &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
+ &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
&ecryptfs_superblock_to_private(
- ecryptfs_dentry->d_sb)->mount_crypt_stat;
+ ecryptfs_inode->i_sb)->mount_crypt_stat;
int cipher_name_len;
int rc = 0;
@@ -1299,12 +1299,12 @@
}
static int
-ecryptfs_write_metadata_to_contents(struct dentry *ecryptfs_dentry,
+ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
char *virt, size_t virt_len)
{
int rc;
- rc = ecryptfs_write_lower(ecryptfs_dentry->d_inode, virt,
+ rc = ecryptfs_write_lower(ecryptfs_inode, virt,
0, virt_len);
if (rc < 0)
printk(KERN_ERR "%s: Error attempting to write header "
@@ -1338,7 +1338,8 @@
/**
* ecryptfs_write_metadata
- * @ecryptfs_dentry: The eCryptfs dentry
+ * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
+ * @ecryptfs_inode: The newly created eCryptfs inode
*
* Write the file headers out. This will likely involve a userspace
* callout, in which the session key is encrypted with one or more
@@ -1348,10 +1349,11 @@
*
* Returns zero on success; non-zero on error
*/
-int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry)
+int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
+ struct inode *ecryptfs_inode)
{
struct ecryptfs_crypt_stat *crypt_stat =
- &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
+ &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
unsigned int order;
char *virt;
size_t virt_len;
@@ -1391,7 +1393,7 @@
rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, virt,
size);
else
- rc = ecryptfs_write_metadata_to_contents(ecryptfs_dentry, virt,
+ rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
virt_len);
if (rc) {
printk(KERN_ERR "%s: Error writing metadata out to lower file; "