eCryptfs: Handle failed metadata read in lookup

When failing to read the lower file's crypto metadata during a lookup,
eCryptfs must continue on without throwing an error. For example, there
may be a plaintext file in the lower mount point that the user wants to
delete through the eCryptfs mount.

If an error is encountered while reading the metadata in lookup(), the
eCryptfs inode's size could be incorrect. We must be sure to reread the
plaintext inode size from the metadata when performing an open() or
setattr(). The metadata is already being read in those paths, so this
adds minimal performance overhead.

This patch introduces a flag which will track whether or not the
plaintext inode size has been read so that an incorrect i_size can be
fixed in the open() or setattr() paths.

https://bugs.launchpad.net/bugs/509180

Cc: <stable@kernel.org>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 380bee1094c3..e70282775e2c 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -269,6 +269,7 @@ struct ecryptfs_crypt_stat {
 #define ECRYPTFS_ENCFN_USE_MOUNT_FNEK 0x00000800
 #define ECRYPTFS_ENCFN_USE_FEK        0x00001000
 #define ECRYPTFS_UNLINK_SIGS          0x00002000
+#define ECRYPTFS_I_SIZE_INITIALIZED   0x00004000
         u32 flags;
         unsigned int file_version;
         size_t iv_bytes;
@@ -628,6 +629,7 @@ struct ecryptfs_open_req {
 int ecryptfs_interpose(struct dentry *hidden_dentry,
                        struct dentry *this_dentry, struct super_block *sb,
                        u32 flags);
+void ecryptfs_i_size_init(const char *page_virt, struct inode *inode);
 int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
                                         struct dentry *lower_dentry,
                                         struct inode *ecryptfs_dir_inode);