From 4a26620df451ad46151ad21d711ed43e963c004e Mon Sep 17 00:00:00 2001 From: Tyler Hicks Date: Sat, 5 Nov 2011 13:45:08 -0400 Subject: eCryptfs: Improve statfs reporting 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 Reported-by: Kees Cook Reviewed-by: Kees Cook Reviewed-by: John Johansen --- 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(-) diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c index 63ab2451064..ea993128155 100644 --- a/fs/ecryptfs/crypto.c +++ b/fs/ecryptfs/crypto.c @@ -1990,6 +1990,17 @@ 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 @@ -2008,13 +2019,7 @@ 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) { @@ -2239,3 +2244,52 @@ 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 a2362df58ae..867b64c5d84 100644 --- a/fs/ecryptfs/ecryptfs_kernel.h +++ b/fs/ecryptfs/ecryptfs_kernel.h @@ -162,6 +162,10 @@ ecryptfs_get_key_payload_data(struct key *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." @@ -701,6 +705,8 @@ 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 8e3b943e330..2333203a120 100644 --- a/fs/ecryptfs/keystore.c +++ b/fs/ecryptfs/keystore.c @@ -679,10 +679,7 @@ 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; @@ -934,10 +931,10 @@ 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 9df7fd6e0c3..cf152823bbf 100644 --- a/fs/ecryptfs/super.c +++ b/fs/ecryptfs/super.c @@ -30,6 +30,8 @@ #include #include #include +#include +#include #include "ecryptfs_kernel.h" struct kmem_cache *ecryptfs_inode_info_cache; @@ -102,10 +104,20 @@ static void ecryptfs_destroy_inode(struct inode *inode) 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; } /** -- cgit v1.2.3 From 545d680938be1e86a6c5250701ce9abaf360c495 Mon Sep 17 00:00:00 2001 From: Tyler Hicks Date: Tue, 7 Feb 2012 17:55:40 -0600 Subject: eCryptfs: Copy up lower inode attrs after setting lower xattr After passing through a ->setxattr() call, eCryptfs needs to copy the inode attributes from the lower inode to the eCryptfs inode, as they may have changed in the lower filesystem's ->setxattr() path. One example is if an extended attribute containing a POSIX Access Control List is being set. The new ACL may cause the lower filesystem to modify the mode of the lower inode and the eCryptfs inode would need to be updated to reflect the new mode. https://launchpad.net/bugs/926292 Signed-off-by: Tyler Hicks Reported-by: Sebastien Bacher Cc: John Johansen Cc: --- fs/ecryptfs/inode.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c index 19892d7d2ed..ab35b113003 100644 --- a/fs/ecryptfs/inode.c +++ b/fs/ecryptfs/inode.c @@ -1085,6 +1085,8 @@ ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value, } rc = vfs_setxattr(lower_dentry, name, value, size, flags); + if (!rc) + fsstack_copy_attr_all(dentry->d_inode, lower_dentry->d_inode); out: return rc; } -- cgit v1.2.3 From 465c9343c5b746ec2325a220fa3e50cc647d2db7 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Fri, 10 Feb 2012 13:39:50 +0800 Subject: ecryptfs: remove the second argument of k[un]map_atomic() Signed-off-by: Cong Wang Signed-off-by: Tyler Hicks --- fs/ecryptfs/mmap.c | 4 ++-- fs/ecryptfs/read_write.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c index 10ec695ccd6..a46b3a8fee1 100644 --- a/fs/ecryptfs/mmap.c +++ b/fs/ecryptfs/mmap.c @@ -150,7 +150,7 @@ ecryptfs_copy_up_encrypted_with_header(struct page *page, /* This is a header extent */ char *page_virt; - page_virt = kmap_atomic(page, KM_USER0); + page_virt = kmap_atomic(page); memset(page_virt, 0, PAGE_CACHE_SIZE); /* TODO: Support more than one header extent */ if (view_extent_num == 0) { @@ -163,7 +163,7 @@ ecryptfs_copy_up_encrypted_with_header(struct page *page, crypt_stat, &written); } - kunmap_atomic(page_virt, KM_USER0); + kunmap_atomic(page_virt); flush_dcache_page(page); if (rc) { printk(KERN_ERR "%s: Error reading xattr " diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c index 5c0106f7577..b2a34a192f4 100644 --- a/fs/ecryptfs/read_write.c +++ b/fs/ecryptfs/read_write.c @@ -156,7 +156,7 @@ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset, ecryptfs_page_idx, rc); goto out; } - ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0); + ecryptfs_page_virt = kmap_atomic(ecryptfs_page); /* * pos: where we're now writing, offset: where the request was @@ -179,7 +179,7 @@ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset, (data + data_offset), num_bytes); data_offset += num_bytes; } - kunmap_atomic(ecryptfs_page_virt, KM_USER0); + kunmap_atomic(ecryptfs_page_virt); flush_dcache_page(ecryptfs_page); SetPageUptodate(ecryptfs_page); unlock_page(ecryptfs_page); -- cgit v1.2.3