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eCryptfs: Allow 2 scatterlist entries for encrypted filenames
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The buffers allocated while encrypting and decrypting long filenames can
sometimes straddle two pages. In this situation, virt_to_scatterlist()
will return -ENOMEM, causing the operation to fail and the user will get
scary error messages in their logs:

kernel: ecryptfs_write_tag_70_packet: Internal error whilst attempting
to convert filename memory to scatterlist; expected rc = 1; got rc =
[-12]. block_aligned_filename_size = [272]
kernel: ecryptfs_encrypt_filename: Error attempting to generate tag 70
packet; rc = [-12]
kernel: ecryptfs_encrypt_and_encode_filename: Error attempting to
encrypt filename; rc = [-12]
kernel: ecryptfs_lookup: Error attempting to encrypt and encode
filename; rc = [-12]

The solution is to allow up to 2 scatterlist entries to be used.

Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
Cc: <stable@kernel.org>
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Tyler Hicks committed May 27, 2011
1 parent 0785055 commit 8d08dab
Showing 1 changed file with 21 additions and 25 deletions.
46 changes: 21 additions & 25 deletions fs/ecryptfs/keystore.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -599,8 +599,8 @@ struct ecryptfs_write_tag_70_packet_silly_stack {
struct mutex *tfm_mutex;
char *block_aligned_filename;
struct ecryptfs_auth_tok *auth_tok;
struct scatterlist src_sg;
struct scatterlist dst_sg;
struct scatterlist src_sg[2];
struct scatterlist dst_sg[2];
struct blkcipher_desc desc;
char iv[ECRYPTFS_MAX_IV_BYTES];
char hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
Expand Down Expand Up @@ -816,23 +816,21 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
filename_size);
rc = virt_to_scatterlist(s->block_aligned_filename,
s->block_aligned_filename_size, &s->src_sg, 1);
if (rc != 1) {
s->block_aligned_filename_size, s->src_sg, 2);
if (rc < 1) {
printk(KERN_ERR "%s: Internal error whilst attempting to "
"convert filename memory to scatterlist; "
"expected rc = 1; got rc = [%d]. "
"convert filename memory to scatterlist; rc = [%d]. "
"block_aligned_filename_size = [%zd]\n", __func__, rc,
s->block_aligned_filename_size);
goto out_release_free_unlock;
}
rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
&s->dst_sg, 1);
if (rc != 1) {
s->dst_sg, 2);
if (rc < 1) {
printk(KERN_ERR "%s: Internal error whilst attempting to "
"convert encrypted filename memory to scatterlist; "
"expected rc = 1; got rc = [%d]. "
"block_aligned_filename_size = [%zd]\n", __func__, rc,
s->block_aligned_filename_size);
"rc = [%d]. block_aligned_filename_size = [%zd]\n",
__func__, rc, s->block_aligned_filename_size);
goto out_release_free_unlock;
}
/* The characters in the first block effectively do the job
Expand All @@ -855,7 +853,7 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
mount_crypt_stat->global_default_fn_cipher_key_bytes);
goto out_release_free_unlock;
}
rc = crypto_blkcipher_encrypt_iv(&s->desc, &s->dst_sg, &s->src_sg,
rc = crypto_blkcipher_encrypt_iv(&s->desc, s->dst_sg, s->src_sg,
s->block_aligned_filename_size);
if (rc) {
printk(KERN_ERR "%s: Error attempting to encrypt filename; "
Expand Down Expand Up @@ -891,8 +889,8 @@ struct ecryptfs_parse_tag_70_packet_silly_stack {
struct mutex *tfm_mutex;
char *decrypted_filename;
struct ecryptfs_auth_tok *auth_tok;
struct scatterlist src_sg;
struct scatterlist dst_sg;
struct scatterlist src_sg[2];
struct scatterlist dst_sg[2];
struct blkcipher_desc desc;
char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
char iv[ECRYPTFS_MAX_IV_BYTES];
Expand Down Expand Up @@ -1008,13 +1006,12 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
}
mutex_lock(s->tfm_mutex);
rc = virt_to_scatterlist(&data[(*packet_size)],
s->block_aligned_filename_size, &s->src_sg, 1);
if (rc != 1) {
s->block_aligned_filename_size, s->src_sg, 2);
if (rc < 1) {
printk(KERN_ERR "%s: Internal error whilst attempting to "
"convert encrypted filename memory to scatterlist; "
"expected rc = 1; got rc = [%d]. "
"block_aligned_filename_size = [%zd]\n", __func__, rc,
s->block_aligned_filename_size);
"rc = [%d]. block_aligned_filename_size = [%zd]\n",
__func__, rc, s->block_aligned_filename_size);
goto out_unlock;
}
(*packet_size) += s->block_aligned_filename_size;
Expand All @@ -1028,13 +1025,12 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
goto out_unlock;
}
rc = virt_to_scatterlist(s->decrypted_filename,
s->block_aligned_filename_size, &s->dst_sg, 1);
if (rc != 1) {
s->block_aligned_filename_size, s->dst_sg, 2);
if (rc < 1) {
printk(KERN_ERR "%s: Internal error whilst attempting to "
"convert decrypted filename memory to scatterlist; "
"expected rc = 1; got rc = [%d]. "
"block_aligned_filename_size = [%zd]\n", __func__, rc,
s->block_aligned_filename_size);
"rc = [%d]. block_aligned_filename_size = [%zd]\n",
__func__, rc, s->block_aligned_filename_size);
goto out_free_unlock;
}
/* The characters in the first block effectively do the job of
Expand Down Expand Up @@ -1065,7 +1061,7 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
mount_crypt_stat->global_default_fn_cipher_key_bytes);
goto out_free_unlock;
}
rc = crypto_blkcipher_decrypt_iv(&s->desc, &s->dst_sg, &s->src_sg,
rc = crypto_blkcipher_decrypt_iv(&s->desc, s->dst_sg, s->src_sg,
s->block_aligned_filename_size);
if (rc) {
printk(KERN_ERR "%s: Error attempting to decrypt filename; "
Expand Down

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