[FOCAL][PATCH 7/7] cifs: Adjust key sizes and key generation routines for AES256 encryption
Tim Gardner
tim.gardner at canonical.com
Sun May 2 21:00:33 UTC 2021
From: Shyam Prasad N <sprasad at microsoft.com>
BugLink: https://bugs.launchpad.net/bugs/1921916
For AES256 encryption (GCM and CCM), we need to adjust the size of a few
fields to 32 bytes instead of 16 to accommodate the larger keys.
Also, the L value supplied to the key generator needs to be changed from
to 256 when these algorithms are used.
Keeping the ioctl struct for dumping keys of the same size for now.
Will send out a different patch for that one.
Signed-off-by: Shyam Prasad N <sprasad at microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber at redhat.com>
CC: <stable at vger.kernel.org> # v5.10+
Signed-off-by: Steve French <stfrench at microsoft.com>
(backported from commit 45a4546c6167a2da348a31ca439d8a8ff773b6ea)
[rtg - minor context differences]
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
fs/cifs/cifsglob.h | 4 ++--
fs/cifs/cifspdu.h | 5 +++++
fs/cifs/smb2glob.h | 1 +
fs/cifs/smb2ops.c | 9 +++++----
fs/cifs/smb2transport.c | 37 ++++++++++++++++++++++++++++---------
5 files changed, 41 insertions(+), 15 deletions(-)
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 73a4633daf2a..c80f266da025 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -989,8 +989,8 @@ struct cifs_ses {
bool domainAuto:1;
__u16 session_flags;
__u8 smb3signingkey[SMB3_SIGN_KEY_SIZE];
- __u8 smb3encryptionkey[SMB3_SIGN_KEY_SIZE];
- __u8 smb3decryptionkey[SMB3_SIGN_KEY_SIZE];
+ __u8 smb3encryptionkey[SMB3_ENC_DEC_KEY_SIZE];
+ __u8 smb3decryptionkey[SMB3_ENC_DEC_KEY_SIZE];
__u8 preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
/*
diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h
index 79d842e7240c..db47f1ac8be9 100644
--- a/fs/cifs/cifspdu.h
+++ b/fs/cifs/cifspdu.h
@@ -147,6 +147,11 @@
*/
#define SMB3_SIGN_KEY_SIZE (16)
+/*
+ * Size of the smb3 encryption/decryption keys
+ */
+#define SMB3_ENC_DEC_KEY_SIZE (32)
+
#define CIFS_CLIENT_CHALLENGE_SIZE (8)
#define CIFS_SERVER_CHALLENGE_SIZE (8)
#define CIFS_HMAC_MD5_HASH_SIZE (16)
diff --git a/fs/cifs/smb2glob.h b/fs/cifs/smb2glob.h
index 995852ba3315..78e6a63065ae 100644
--- a/fs/cifs/smb2glob.h
+++ b/fs/cifs/smb2glob.h
@@ -57,6 +57,7 @@
#define SMB2_HMACSHA256_SIZE (32)
#define SMB2_CMACAES_SIZE (16)
#define SMB3_SIGNKEY_SIZE (16)
+#define SMB3_GCM128_CRYPTKEY_SIZE (16)
#define SMB3_GCM256_CRYPTKEY_SIZE (32)
/* Maximum buffer size value we can send with 1 credit */
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index de21365a751d..42ccc2ee66b3 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -3727,7 +3727,7 @@ smb2_get_enc_key(struct TCP_Server_Info *server, __u64 ses_id, int enc, u8 *key)
continue;
ses_enc_key = enc ? ses->smb3encryptionkey :
ses->smb3decryptionkey;
- memcpy(key, ses_enc_key, SMB3_SIGN_KEY_SIZE);
+ memcpy(key, ses_enc_key, SMB3_ENC_DEC_KEY_SIZE);
spin_unlock(&cifs_tcp_ses_lock);
return 0;
}
@@ -3752,7 +3752,7 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst,
int rc = 0;
struct scatterlist *sg;
u8 sign[SMB2_SIGNATURE_SIZE] = {};
- u8 key[SMB3_SIGN_KEY_SIZE];
+ u8 key[SMB3_ENC_DEC_KEY_SIZE];
struct aead_request *req;
char *iv;
unsigned int iv_len;
@@ -3776,10 +3776,11 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst,
tfm = enc ? server->secmech.ccmaesencrypt :
server->secmech.ccmaesdecrypt;
- if (server->cipher_type == SMB2_ENCRYPTION_AES256_GCM)
+ if ((server->cipher_type == SMB2_ENCRYPTION_AES256_CCM) ||
+ (server->cipher_type == SMB2_ENCRYPTION_AES256_GCM))
rc = crypto_aead_setkey(tfm, key, SMB3_GCM256_CRYPTKEY_SIZE);
else
- rc = crypto_aead_setkey(tfm, key, SMB3_SIGN_KEY_SIZE);
+ rc = crypto_aead_setkey(tfm, key, SMB3_GCM128_CRYPTKEY_SIZE);
if (rc) {
cifs_server_dbg(VFS, "%s: Failed to set aead key %d\n", __func__, rc);
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index ff9cf860e85d..d83dc4e4d324 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -235,7 +235,8 @@ static int generate_key(struct cifs_ses *ses, struct kvec label,
{
unsigned char zero = 0x0;
__u8 i[4] = {0, 0, 0, 1};
- __u8 L[4] = {0, 0, 0, 128};
+ __u8 L128[4] = {0, 0, 0, 128};
+ __u8 L256[4] = {0, 0, 1, 0};
int rc = 0;
unsigned char prfhash[SMB2_HMACSHA256_SIZE];
unsigned char *hashptr = prfhash;
@@ -291,8 +292,14 @@ static int generate_key(struct cifs_ses *ses, struct kvec label,
goto smb3signkey_ret;
}
- rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
- L, 4);
+ if ((server->cipher_type == SMB2_ENCRYPTION_AES256_CCM) ||
+ (server->cipher_type == SMB2_ENCRYPTION_AES256_GCM)) {
+ rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+ L256, 4);
+ } else {
+ rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+ L128, 4);
+ }
if (rc) {
cifs_server_dbg(VFS, "%s: Could not update with L\n", __func__);
goto smb3signkey_ret;
@@ -327,6 +334,9 @@ generate_smb3signingkey(struct cifs_ses *ses,
const struct derivation_triplet *ptriplet)
{
int rc;
+#ifdef CONFIG_CIFS_DEBUG_DUMP_KEYS
+ struct TCP_Server_Info *server = ses->server;
+#endif
rc = generate_key(ses, ptriplet->signing.label,
ptriplet->signing.context, ses->smb3signingkey,
@@ -336,13 +346,13 @@ generate_smb3signingkey(struct cifs_ses *ses,
rc = generate_key(ses, ptriplet->encryption.label,
ptriplet->encryption.context, ses->smb3encryptionkey,
- SMB3_SIGN_KEY_SIZE);
+ SMB3_ENC_DEC_KEY_SIZE);
if (rc)
return rc;
rc = generate_key(ses, ptriplet->decryption.label,
ptriplet->decryption.context,
- ses->smb3decryptionkey, SMB3_SIGN_KEY_SIZE);
+ ses->smb3decryptionkey, SMB3_ENC_DEC_KEY_SIZE);
if (rc)
return rc;
@@ -355,14 +365,23 @@ generate_smb3signingkey(struct cifs_ses *ses,
*/
cifs_dbg(VFS, "Session Id %*ph\n", (int)sizeof(ses->Suid),
&ses->Suid);
+ cifs_dbg(VFS, "Cipher type %d\n", server->cipher_type);
cifs_dbg(VFS, "Session Key %*ph\n",
SMB2_NTLMV2_SESSKEY_SIZE, ses->auth_key.response);
cifs_dbg(VFS, "Signing Key %*ph\n",
SMB3_SIGN_KEY_SIZE, ses->smb3signingkey);
- cifs_dbg(VFS, "ServerIn Key %*ph\n",
- SMB3_SIGN_KEY_SIZE, ses->smb3encryptionkey);
- cifs_dbg(VFS, "ServerOut Key %*ph\n",
- SMB3_SIGN_KEY_SIZE, ses->smb3decryptionkey);
+ if ((server->cipher_type == SMB2_ENCRYPTION_AES256_CCM) ||
+ (server->cipher_type == SMB2_ENCRYPTION_AES256_GCM)) {
+ cifs_dbg(VFS, "ServerIn Key %*ph\n",
+ SMB3_GCM256_CRYPTKEY_SIZE, ses->smb3encryptionkey);
+ cifs_dbg(VFS, "ServerOut Key %*ph\n",
+ SMB3_GCM256_CRYPTKEY_SIZE, ses->smb3decryptionkey);
+ } else {
+ cifs_dbg(VFS, "ServerIn Key %*ph\n",
+ SMB3_GCM128_CRYPTKEY_SIZE, ses->smb3encryptionkey);
+ cifs_dbg(VFS, "ServerOut Key %*ph\n",
+ SMB3_GCM128_CRYPTKEY_SIZE, ses->smb3decryptionkey);
+ }
#endif
return rc;
}
--
2.17.1
More information about the kernel-team
mailing list