This is a note to let you know that I've just added the patch titled
eCryptfs: Improve statfs reporting
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ecryptfs-improve-statfs-reporting.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 4a26620df451ad46151ad21d711ed43e963c004e Mon Sep 17 00:00:00 2001
From: Tyler Hicks <[email protected]>
Date: Sat, 5 Nov 2011 13:45:08 -0400
Subject: eCryptfs: Improve statfs reporting
From: Tyler Hicks <[email protected]>
commit 4a26620df451ad46151ad21d711ed43e963c004e upstream.
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]>
Cc: Herton Ronaldo Krzesinski <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/ecryptfs/crypto.c | 68 +++++++++++++++++++++++++++++++++++++-----
fs/ecryptfs/ecryptfs_kernel.h | 6 +++
fs/ecryptfs/keystore.c | 9 +----
fs/ecryptfs/super.c | 14 ++++++++
4 files changed, 83 insertions(+), 14 deletions(-)
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1987,6 +1987,17 @@ 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
@@ -2005,13 +2016,7 @@ ecryptfs_decode_from_filename(unsigned c
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) {
@@ -2236,3 +2241,52 @@ 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;
+}
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -227,6 +227,10 @@ ecryptfs_get_key_payload_data(struct key
#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."
@@ -765,6 +769,8 @@ ecryptfs_parse_tag_70_packet(char **file
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);
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -678,10 +678,7 @@ ecryptfs_write_tag_70_packet(char *dest,
* 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;
@@ -933,10 +930,10 @@ ecryptfs_parse_tag_70_packet(char **file
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;
}
--- a/fs/ecryptfs/super.c
+++ b/fs/ecryptfs/super.c
@@ -30,6 +30,8 @@
#include <linux/seq_file.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;
@@ -103,10 +105,20 @@ static void ecryptfs_destroy_inode(struc
static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
+ int rc;
if (!lower_dentry->d_sb->s_op->statfs)
return -ENOSYS;
- return lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
+
+ 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;
}
/**
Patches currently in stable-queue which might be from [email protected] are
queue-3.0/ecryptfs-improve-statfs-reporting.patch
queue-3.0/ecryptfs-copy-up-attributes-of-the-lower-target-inode-after-rename.patch
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