Hi, please consider including the following commit into 2.6.32.y, 3.0.y, 3.2.y:
commit 4a26620df451ad46151ad21d711ed43e963c004e Author: Tyler Hicks <[email protected]> Date: Sat Nov 5 13:45:08 2011 -0400 eCryptfs: Improve statfs reporting It fixes bug https://bugs.launchpad.net/ecryptfs/+bug/885744, but didn't had an Cc stable on it. I noted while running ecryptfs tests on stables that the test for the bug was failing. The fix cherry-picks cleanly on 3.0 and 3.2. For 2.6.32, an backport is needed, the attached backport from Ubuntu 2.6.32 should work. If 2.6.34 or 2.6.35 are still maintained, feel free to include it too, I can provide backported versions if needed. -- []'s Herton
>From c4b1ebcd90bcefabc855aaa12504b1d45772c618 Mon Sep 17 00:00:00 2001 From: Tyler Hicks <[email protected]> Date: Wed, 14 Mar 2012 12:57:45 +0000 Subject: [PATCH] eCryptfs: Improve statfs reporting BugLink: http://bugs.launchpad.net/bugs/885744 statfs() calls on eCryptfs files returned the wrong filesystem type and, when using filename encryption, the wrong maximum filename length. If mount-wide filename encryption is enabled, the cipher block size and the lower filesystem's max filename length will determine the max eCryptfs filename length. Pre-tested, known good lengths are used when the lower filesystem's namelen is 255 and a cipher with 8 or 16 byte block sizes is used. In other, less common cases, we fall back to a safe rounded-down estimate when determining the eCryptfs namelen. https://launchpad.net/bugs/885744 Signed-off-by: Tyler Hicks <[email protected]> Reported-by: Kees Cook <[email protected]> Reviewed-by: Kees Cook <[email protected]> Reviewed-by: John Johansen <[email protected]> (upstream backport of commit 4a26620df451ad46151ad21d711ed43e963c004e) Signed-off-by: Colin Ian King <[email protected]> Acked-by: Stefan Bader <[email protected]> Signed-off-by: Tim Gardner <[email protected]> --- fs/ecryptfs/crypto.c | 68 ++++++++++++++++++++++++++++++++++++----- fs/ecryptfs/ecryptfs_kernel.h | 11 +++++++ fs/ecryptfs/keystore.c | 9 ++---- fs/ecryptfs/super.c | 18 ++++++++++- 4 files changed, 92 insertions(+), 14 deletions(-) diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c index 7e164bb..7786bf6 100644 --- a/fs/ecryptfs/crypto.c +++ b/fs/ecryptfs/crypto.c @@ -2039,6 +2039,17 @@ out: return; } +static size_t ecryptfs_max_decoded_size(size_t encoded_size) +{ + /* Not exact; conservatively long. Every block of 4 + * encoded characters decodes into a block of 3 + * decoded characters. This segment of code provides + * the caller with the maximum amount of allocated + * space that @dst will need to point to in a + * subsequent call. */ + return ((encoded_size + 1) * 3) / 4; +} + /** * ecryptfs_decode_from_filename * @dst: If NULL, this function only sets @dst_size and returns. If @@ -2057,13 +2068,7 @@ ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size, size_t dst_byte_offset = 0; if (dst == NULL) { - /* Not exact; conservatively long. Every block of 4 - * encoded characters decodes into a block of 3 - * decoded characters. This segment of code provides - * the caller with the maximum amount of allocated - * space that @dst will need to point to in a - * subsequent call. */ - (*dst_size) = (((src_size + 1) * 3) / 4); + (*dst_size) = ecryptfs_max_decoded_size(src_size); goto out; } while (src_byte_offset < src_size) { @@ -2289,3 +2294,52 @@ out_free: out: return rc; } + +#define ENC_NAME_MAX_BLOCKLEN_8_OR_16 143 + +int ecryptfs_set_f_namelen(long *namelen, long lower_namelen, + struct ecryptfs_mount_crypt_stat *mount_crypt_stat) +{ + struct blkcipher_desc desc; + struct mutex *tfm_mutex; + size_t cipher_blocksize; + int rc; + + if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) { + (*namelen) = lower_namelen; + return 0; + } + + rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex, + mount_crypt_stat->global_default_fn_cipher_name); + if (unlikely(rc)) { + (*namelen) = 0; + return rc; + } + + mutex_lock(tfm_mutex); + cipher_blocksize = crypto_blkcipher_blocksize(desc.tfm); + mutex_unlock(tfm_mutex); + + /* Return an exact amount for the common cases */ + if (lower_namelen == NAME_MAX + && (cipher_blocksize == 8 || cipher_blocksize == 16)) { + (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16; + return 0; + } + + /* Return a safe estimate for the uncommon cases */ + (*namelen) = lower_namelen; + (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE; + /* Since this is the max decoded size, subtract 1 "decoded block" len */ + (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3; + (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE; + (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES; + /* Worst case is that the filename is padded nearly a full block size */ + (*namelen) -= cipher_blocksize - 1; + + if ((*namelen) < 0) + (*namelen) = 0; + + return 0; +} diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h index 9685315..4181136 100644 --- a/fs/ecryptfs/ecryptfs_kernel.h +++ b/fs/ecryptfs/ecryptfs_kernel.h @@ -219,12 +219,21 @@ ecryptfs_get_key_payload_data(struct key *key) * dentry name */ #define ECRYPTFS_TAG_73_PACKET_TYPE 0x49 /* FEK-encrypted filename as * metadata */ +#define ECRYPTFS_MIN_PKT_LEN_SIZE 1 /* Min size to specify packet length */ +#define ECRYPTFS_MAX_PKT_LEN_SIZE 2 /* Pass at least this many bytes to + * ecryptfs_parse_packet_length() and + * ecryptfs_write_packet_length() + */ /* Constraint: ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES >= * ECRYPTFS_MAX_IV_BYTES */ #define ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES 16 #define ECRYPTFS_NON_NULL 0x42 /* A reasonable substitute for NULL */ #define MD5_DIGEST_SIZE 16 #define ECRYPTFS_TAG_70_DIGEST_SIZE MD5_DIGEST_SIZE +#define ECRYPTFS_TAG_70_MIN_METADATA_SIZE (1 + ECRYPTFS_MIN_PKT_LEN_SIZE \ + + ECRYPTFS_SIG_SIZE + 1 + 1) +#define ECRYPTFS_TAG_70_MAX_METADATA_SIZE (1 + ECRYPTFS_MAX_PKT_LEN_SIZE \ + + ECRYPTFS_SIG_SIZE + 1 + 1) #define ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX "ECRYPTFS_FEK_ENCRYPTED." #define ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE 23 #define ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX "ECRYPTFS_FNEK_ENCRYPTED." @@ -762,6 +771,8 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size, size_t *packet_size, struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *data, size_t max_packet_size); +int ecryptfs_set_f_namelen(long *namelen, long lower_namelen, + struct ecryptfs_mount_crypt_stat *mount_crypt_stat); int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat, loff_t offset); diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c index 8f1a525..4f1feeb 100644 --- a/fs/ecryptfs/keystore.c +++ b/fs/ecryptfs/keystore.c @@ -548,10 +548,7 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes, * Octets N3-N4: Block-aligned encrypted filename * - Consists of a minimum number of random characters, a \0 * separator, and then the filename */ - s->max_packet_size = (1 /* Tag 70 identifier */ - + 3 /* Max Tag 70 packet size */ - + ECRYPTFS_SIG_SIZE /* FNEK sig */ - + 1 /* Cipher identifier */ + s->max_packet_size = (ECRYPTFS_TAG_70_MAX_METADATA_SIZE + s->block_aligned_filename_size); if (dest == NULL) { (*packet_size) = s->max_packet_size; @@ -806,10 +803,10 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size, goto out; } s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP; - if (max_packet_size < (1 + 1 + ECRYPTFS_SIG_SIZE + 1 + 1)) { + if (max_packet_size < ECRYPTFS_TAG_70_MIN_METADATA_SIZE) { printk(KERN_WARNING "%s: max_packet_size is [%zd]; it must be " "at least [%d]\n", __func__, max_packet_size, - (1 + 1 + ECRYPTFS_SIG_SIZE + 1 + 1)); + ECRYPTFS_TAG_70_MIN_METADATA_SIZE); rc = -EINVAL; goto out; } diff --git a/fs/ecryptfs/super.c b/fs/ecryptfs/super.c index 1a037f7..557469a 100644 --- a/fs/ecryptfs/super.c +++ b/fs/ecryptfs/super.c @@ -30,6 +30,8 @@ #include <linux/smp_lock.h> #include <linux/file.h> #include <linux/crypto.h> +#include <linux/statfs.h> +#include <linux/magic.h> #include "ecryptfs_kernel.h" struct kmem_cache *ecryptfs_inode_info_cache; @@ -137,7 +139,21 @@ static void ecryptfs_put_super(struct super_block *sb) */ static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf) { - return vfs_statfs(ecryptfs_dentry_to_lower(dentry), buf); + struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); + int rc; + + if (!lower_dentry->d_sb->s_op->statfs) + return -ENOSYS; + + rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf); + if (rc) + return rc; + + buf->f_type = ECRYPTFS_SUPER_MAGIC; + rc = ecryptfs_set_f_namelen(&buf->f_namelen, buf->f_namelen, + &ecryptfs_superblock_to_private(dentry->d_sb)->mount_crypt_stat); + + return rc; } /** -- 1.7.9.5
