On 2012-10-02 00:52:23, Willy Tarreau wrote: > 2.6.32-longterm review patch. If anyone has any objections, please let me > know.
Hi - Please drop this patch. It incorrectly calculates f_namelen and I haven't had a chance to fix it yet. When I get a fix ready, I'll forward the corrected patch to stable@v.k.o. Thanks! Tyler > > ------------------ > > From: Tyler Hicks <tyhi...@canonical.com> > > commit 4a26620df451ad46151ad21d711ed43e963c004e upstream. > > 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 <tyhi...@canonical.com> > Reported-by: Kees Cook <keesc...@chromium.org> > Reviewed-by: Kees Cook <keesc...@chromium.org> > Reviewed-by: John Johansen <john.johan...@canonical.com> > Signed-off-by: Colin Ian King <colin.k...@canonical.com> > Acked-by: Stefan Bader <stefan.ba...@canonical.com> > Signed-off-by: Tim Gardner <tim.gard...@canonical.com> > Signed-off-by: Willy Tarreau <w...@1wt.eu> > --- > 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; > } > > /** > -- > 1.7.2.1.45.g54fbc > > >
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