[PATCH 2/12] Support for larger maximum key size

From: Mike Halcrow
Date: Tue Jun 20 2006 - 17:22:06 EST

Support for larger maximum key size. Necessary for future patches that
will enable cipher selection and keysize specification. Increments the
version number because ECRYPTFS_MAX_KEY_BYTES changes, which changes a
struct that is accessed in both userspace and kernel space.

Note that with this patch, users must upgrade their userspace utility
package to one prefixed ``ecryptfs-util-git-2.6.17-rc6-mm2++'' or
higher (see the eCryptfs SourceForge page for userspace utilities).

Signed-off-by: Michael Halcrow <mhalcrow@xxxxxxxxxx>

---

fs/ecryptfs/ecryptfs_kernel.h | 4 ++--
fs/ecryptfs/keystore.c | 34 ++++++++++++++++++----------------
2 files changed, 20 insertions(+), 18 deletions(-)

d13ab4035bb6c56bfb7d82523069324523e99f62
diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 8e35dbd..1fd6039 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -32,7 +32,7 @@ #include <linux/scatterlist.h>

/* Version verification for shared data structures w/ userspace */
#define ECRYPTFS_VERSION_MAJOR 0x00
-#define ECRYPTFS_VERSION_MINOR 0x01
+#define ECRYPTFS_VERSION_MINOR 0x02
#define ECRYPTFS_SUPPORTED_FILE_VERSION 0x01

#define ECRYPTFS_MAX_PASSWORD_LENGTH 64
@@ -45,7 +45,7 @@ #define ECRYPTFS_SALT_SIZE_HEX (ECRYPTFS
#define ECRYPTFS_SIG_SIZE 8
#define ECRYPTFS_SIG_SIZE_HEX (ECRYPTFS_SIG_SIZE*2)
#define ECRYPTFS_PASSWORD_SIG_SIZE ECRYPTFS_SIG_SIZE_HEX
-#define ECRYPTFS_MAX_KEY_BYTES 16
+#define ECRYPTFS_MAX_KEY_BYTES 64
#define ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES 512
#define ECRYPTFS_DEFAULT_IV_BYTES 16
#define ECRYPTFS_FILE_VERSION 0x01
diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index c250888..a83914c 100644
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -486,8 +486,17 @@ static int decrypt_session_key(struct ec
rc = -ENOMEM;
goto out;
}
+ if (password_s_ptr->session_key_encryption_key_bytes
+ < crypto_tfm_alg_min_keysize(tfm)) {
+ printk(KERN_WARNING "Session key encryption key is [%d] bytes; "
+ "minimum keysize for selected cipher is [%d] bytes.\n",
+ password_s_ptr->session_key_encryption_key_bytes,
+ crypto_tfm_alg_min_keysize(tfm));
+ rc = -EINVAL;
+ goto out;
+ }
crypto_cipher_setkey(tfm, password_s_ptr->session_key_encryption_key,
- password_s_ptr->session_key_encryption_key_bytes);
+ (crypt_stat->key_size_bits / 8));
/* TODO: virt_to_scatterlist */
encrypted_session_key = (char *)__get_free_page(GFP_KERNEL);
if (!encrypted_session_key) {
@@ -806,24 +815,18 @@ write_tag_3_packet(char *dest, int max,
ECRYPTFS_SIG_SIZE);
(*key_rec).enc_key_size_bits = crypt_stat->key_size_bits;
encrypted_session_key_valid = 0;
- if (auth_tok->session_key.encrypted_key_size == 0)
- auth_tok->session_key.encrypted_key_size =
- ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES;
- for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
+ for (i = 0; i < (crypt_stat->key_size_bits / 8); i++)
encrypted_session_key_valid |=
auth_tok->session_key.encrypted_key[i];
- if (auth_tok->session_key.encrypted_key_size == 0) {
- ecryptfs_printk(KERN_WARNING, "auth_tok->session_key."
- "encrypted_key_size == 0");
- auth_tok->session_key.encrypted_key_size =
- ECRYPTFS_DEFAULT_KEY_BYTES;
- }
if (encrypted_session_key_valid) {
memcpy((*key_rec).enc_key,
auth_tok->session_key.encrypted_key,
auth_tok->session_key.encrypted_key_size);
goto encrypted_session_key_set;
}
+ if (auth_tok->session_key.encrypted_key_size == 0)
+ auth_tok->session_key.encrypted_key_size =
+ (crypt_stat->key_size_bits / 8);
if (ECRYPTFS_CHECK_FLAG(auth_tok->token.password.flags,
ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET)) {
ecryptfs_printk(KERN_DEBUG, "Using previously generated "
@@ -832,8 +835,7 @@ write_tag_3_packet(char *dest, int max,
session_key_encryption_key_bytes);
memcpy(session_key_encryption_key,
auth_tok->token.password.session_key_encryption_key,
- auth_tok->token.password.
- session_key_encryption_key_bytes);
+ (crypt_stat->key_size_bits / 8));
ecryptfs_printk(KERN_DEBUG,
"Cached session key " "encryption key: \n");
if (ecryptfs_verbosity > 0)
@@ -870,7 +872,7 @@ write_tag_3_packet(char *dest, int max,
goto out;
}
rc = crypto_cipher_setkey(tfm, session_key_encryption_key,
- ECRYPTFS_DEFAULT_KEY_BYTES);
+ (crypt_stat->key_size_bits / 8));
if (rc < 0) {
ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
"context\n");
@@ -880,7 +882,7 @@ write_tag_3_packet(char *dest, int max,
ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n",
crypt_stat->key_size_bits / 8);
crypto_cipher_encrypt(tfm, dest_sg, src_sg,
- crypt_stat->key_size_bits / 8);
+ (crypt_stat->key_size_bits / 8));
ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
if (ecryptfs_verbosity > 0)
ecryptfs_dump_hex((*key_rec).enc_key,
@@ -889,7 +891,7 @@ encrypted_session_key_set:
/* Now we have a valid key_rec. Append it to the
* key_rec set. */
key_rec_size = (sizeof(struct ecryptfs_key_record)
- - ECRYPTFS_MAX_KEY_BYTES
+ - ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES
+ ((*key_rec).enc_key_size_bits / 8) );
/* TODO: Include a packet size limit as a parameter to this
* function once we have multi-packet headers (for versions
--
1.3.3

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