[PATCH 12/15] ksmbd: Use AES-CMAC library for SMB3 signature calculation
From: Eric Biggers
Date: Wed Feb 18 2026 - 16:42:49 EST
Now that AES-CMAC has a library API, convert ksmbd_sign_smb3_pdu() to
use it instead of a "cmac(aes)" crypto_shash.
The result is simpler and faster code. With the library there's no need
to dynamically allocate memory, no need to handle errors, and the
AES-CMAC code is accessed directly without inefficient indirect calls
and other unnecessary API overhead.
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
fs/smb/server/Kconfig | 2 +-
fs/smb/server/auth.c | 51 +++++++++------------------------
fs/smb/server/auth.h | 4 +--
fs/smb/server/crypto_ctx.c | 58 --------------------------------------
fs/smb/server/crypto_ctx.h | 12 --------
fs/smb/server/server.c | 1 -
fs/smb/server/smb2pdu.c | 8 ++----
7 files changed, 19 insertions(+), 117 deletions(-)
diff --git a/fs/smb/server/Kconfig b/fs/smb/server/Kconfig
index 12594879cb64..eae3728cff54 100644
--- a/fs/smb/server/Kconfig
+++ b/fs/smb/server/Kconfig
@@ -6,17 +6,17 @@ config SMB_SERVER
select NLS
select NLS_UTF8
select NLS_UCS2_UTILS
select CRYPTO
select CRYPTO_ECB
+ select CRYPTO_LIB_AES_CBC_MACS
select CRYPTO_LIB_ARC4
select CRYPTO_LIB_DES
select CRYPTO_LIB_MD5
select CRYPTO_LIB_SHA256
select CRYPTO_LIB_SHA512
select CRYPTO_LIB_UTILS
- select CRYPTO_CMAC
select CRYPTO_AEAD2
select CRYPTO_CCM
select CRYPTO_GCM
select ASN1
select OID_REGISTRY
diff --git a/fs/smb/server/auth.c b/fs/smb/server/auth.c
index a69e8694605a..05234e5bd16e 100644
--- a/fs/smb/server/auth.c
+++ b/fs/smb/server/auth.c
@@ -9,12 +9,12 @@
#include <linux/uaccess.h>
#include <linux/backing-dev.h>
#include <linux/writeback.h>
#include <linux/uio.h>
#include <linux/xattr.h>
-#include <crypto/hash.h>
#include <crypto/aead.h>
+#include <crypto/aes-cbc-macs.h>
#include <crypto/md5.h>
#include <crypto/sha2.h>
#include <crypto/utils.h>
#include <linux/random.h>
#include <linux/scatterlist.h>
@@ -488,50 +488,25 @@ void ksmbd_sign_smb2_pdu(struct ksmbd_conn *conn, char *key, struct kvec *iov,
* @iov: buffer iov array
* @n_vec: number of iovecs
* @sig: signature value generated for client request packet
*
*/
-int ksmbd_sign_smb3_pdu(struct ksmbd_conn *conn, char *key, struct kvec *iov,
- int n_vec, char *sig)
+void ksmbd_sign_smb3_pdu(struct ksmbd_conn *conn, char *key, struct kvec *iov,
+ int n_vec, char *sig)
{
- struct ksmbd_crypto_ctx *ctx;
- int rc, i;
-
- ctx = ksmbd_crypto_ctx_find_cmacaes();
- if (!ctx) {
- ksmbd_debug(AUTH, "could not crypto alloc cmac\n");
- return -ENOMEM;
- }
-
- rc = crypto_shash_setkey(CRYPTO_CMACAES_TFM(ctx),
- key,
- SMB2_CMACAES_SIZE);
- if (rc)
- goto out;
-
- rc = crypto_shash_init(CRYPTO_CMACAES(ctx));
- if (rc) {
- ksmbd_debug(AUTH, "cmaces init error %d\n", rc);
- goto out;
- }
+ struct aes_cmac_key cmac_key;
+ struct aes_cmac_ctx cmac_ctx;
+ int i;
- for (i = 0; i < n_vec; i++) {
- rc = crypto_shash_update(CRYPTO_CMACAES(ctx),
- iov[i].iov_base,
- iov[i].iov_len);
- if (rc) {
- ksmbd_debug(AUTH, "cmaces update error %d\n", rc);
- goto out;
- }
- }
+ /* This cannot fail, since we always pass a valid key length. */
+ static_assert(SMB2_CMACAES_SIZE == AES_KEYSIZE_128);
+ aes_cmac_preparekey(&cmac_key, key, SMB2_CMACAES_SIZE);
- rc = crypto_shash_final(CRYPTO_CMACAES(ctx), sig);
- if (rc)
- ksmbd_debug(AUTH, "cmaces generation error %d\n", rc);
-out:
- ksmbd_release_crypto_ctx(ctx);
- return rc;
+ aes_cmac_init(&cmac_ctx, &cmac_key);
+ for (i = 0; i < n_vec; i++)
+ aes_cmac_update(&cmac_ctx, iov[i].iov_base, iov[i].iov_len);
+ aes_cmac_final(&cmac_ctx, sig);
}
struct derivation {
struct kvec label;
struct kvec context;
diff --git a/fs/smb/server/auth.h b/fs/smb/server/auth.h
index 6d351d61b0e5..5767aabc63c9 100644
--- a/fs/smb/server/auth.h
+++ b/fs/smb/server/auth.h
@@ -52,12 +52,12 @@ ksmbd_build_ntlmssp_challenge_blob(struct challenge_message *chgblob,
struct ksmbd_conn *conn);
int ksmbd_krb5_authenticate(struct ksmbd_session *sess, char *in_blob,
int in_len, char *out_blob, int *out_len);
void ksmbd_sign_smb2_pdu(struct ksmbd_conn *conn, char *key, struct kvec *iov,
int n_vec, char *sig);
-int ksmbd_sign_smb3_pdu(struct ksmbd_conn *conn, char *key, struct kvec *iov,
- int n_vec, char *sig);
+void ksmbd_sign_smb3_pdu(struct ksmbd_conn *conn, char *key, struct kvec *iov,
+ int n_vec, char *sig);
int ksmbd_gen_smb30_signingkey(struct ksmbd_session *sess,
struct ksmbd_conn *conn);
int ksmbd_gen_smb311_signingkey(struct ksmbd_session *sess,
struct ksmbd_conn *conn);
void ksmbd_gen_smb30_encryptionkey(struct ksmbd_conn *conn,
diff --git a/fs/smb/server/crypto_ctx.c b/fs/smb/server/crypto_ctx.c
index fe29d186baf6..1cb0ea2042b5 100644
--- a/fs/smb/server/crypto_ctx.c
+++ b/fs/smb/server/crypto_ctx.c
@@ -26,18 +26,10 @@ static inline void free_aead(struct crypto_aead *aead)
{
if (aead)
crypto_free_aead(aead);
}
-static void free_shash(struct shash_desc *shash)
-{
- if (shash) {
- crypto_free_shash(shash->tfm);
- kfree(shash);
- }
-}
-
static struct crypto_aead *alloc_aead(int id)
{
struct crypto_aead *tfm = NULL;
switch (id) {
@@ -58,41 +50,14 @@ static struct crypto_aead *alloc_aead(int id)
}
return tfm;
}
-static struct shash_desc *alloc_shash_desc(int id)
-{
- struct crypto_shash *tfm = NULL;
- struct shash_desc *shash;
-
- switch (id) {
- case CRYPTO_SHASH_CMACAES:
- tfm = crypto_alloc_shash("cmac(aes)", 0, 0);
- break;
- default:
- return NULL;
- }
-
- if (IS_ERR(tfm))
- return NULL;
-
- shash = kzalloc(sizeof(*shash) + crypto_shash_descsize(tfm),
- KSMBD_DEFAULT_GFP);
- if (!shash)
- crypto_free_shash(tfm);
- else
- shash->tfm = tfm;
- return shash;
-}
-
static void ctx_free(struct ksmbd_crypto_ctx *ctx)
{
int i;
- for (i = 0; i < CRYPTO_SHASH_MAX; i++)
- free_shash(ctx->desc[i]);
for (i = 0; i < CRYPTO_AEAD_MAX; i++)
free_aead(ctx->ccmaes[i]);
kfree(ctx);
}
@@ -151,33 +116,10 @@ void ksmbd_release_crypto_ctx(struct ksmbd_crypto_ctx *ctx)
ctx_list.avail_ctx--;
spin_unlock(&ctx_list.ctx_lock);
ctx_free(ctx);
}
-static struct ksmbd_crypto_ctx *____crypto_shash_ctx_find(int id)
-{
- struct ksmbd_crypto_ctx *ctx;
-
- if (id >= CRYPTO_SHASH_MAX)
- return NULL;
-
- ctx = ksmbd_find_crypto_ctx();
- if (ctx->desc[id])
- return ctx;
-
- ctx->desc[id] = alloc_shash_desc(id);
- if (ctx->desc[id])
- return ctx;
- ksmbd_release_crypto_ctx(ctx);
- return NULL;
-}
-
-struct ksmbd_crypto_ctx *ksmbd_crypto_ctx_find_cmacaes(void)
-{
- return ____crypto_shash_ctx_find(CRYPTO_SHASH_CMACAES);
-}
-
static struct ksmbd_crypto_ctx *____crypto_aead_ctx_find(int id)
{
struct ksmbd_crypto_ctx *ctx;
if (id >= CRYPTO_AEAD_MAX)
diff --git a/fs/smb/server/crypto_ctx.h b/fs/smb/server/crypto_ctx.h
index b9476ed520ae..02d2893665a4 100644
--- a/fs/smb/server/crypto_ctx.h
+++ b/fs/smb/server/crypto_ctx.h
@@ -4,18 +4,12 @@
*/
#ifndef __CRYPTO_CTX_H__
#define __CRYPTO_CTX_H__
-#include <crypto/hash.h>
#include <crypto/aead.h>
-enum {
- CRYPTO_SHASH_CMACAES = 0,
- CRYPTO_SHASH_MAX,
-};
-
enum {
CRYPTO_AEAD_AES_GCM = 16,
CRYPTO_AEAD_AES_CCM,
CRYPTO_AEAD_MAX,
};
@@ -26,23 +20,17 @@ enum {
};
struct ksmbd_crypto_ctx {
struct list_head list;
- struct shash_desc *desc[CRYPTO_SHASH_MAX];
struct crypto_aead *ccmaes[CRYPTO_AEAD_MAX];
};
-#define CRYPTO_CMACAES(c) ((c)->desc[CRYPTO_SHASH_CMACAES])
-
-#define CRYPTO_CMACAES_TFM(c) ((c)->desc[CRYPTO_SHASH_CMACAES]->tfm)
-
#define CRYPTO_GCM(c) ((c)->ccmaes[CRYPTO_AEAD_AES_GCM])
#define CRYPTO_CCM(c) ((c)->ccmaes[CRYPTO_AEAD_AES_CCM])
void ksmbd_release_crypto_ctx(struct ksmbd_crypto_ctx *ctx);
-struct ksmbd_crypto_ctx *ksmbd_crypto_ctx_find_cmacaes(void);
struct ksmbd_crypto_ctx *ksmbd_crypto_ctx_find_gcm(void);
struct ksmbd_crypto_ctx *ksmbd_crypto_ctx_find_ccm(void);
void ksmbd_crypto_destroy(void);
int ksmbd_crypto_create(void);
diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c
index c2c074346da1..cc15d9d8468f 100644
--- a/fs/smb/server/server.c
+++ b/fs/smb/server/server.c
@@ -631,11 +631,10 @@ MODULE_AUTHOR("Namjae Jeon <linkinjeon@xxxxxxxxxx>");
MODULE_DESCRIPTION("Linux kernel CIFS/SMB SERVER");
MODULE_LICENSE("GPL");
MODULE_SOFTDEP("pre: ecb");
MODULE_SOFTDEP("pre: nls");
MODULE_SOFTDEP("pre: aes");
-MODULE_SOFTDEP("pre: cmac");
MODULE_SOFTDEP("pre: aead2");
MODULE_SOFTDEP("pre: ccm");
MODULE_SOFTDEP("pre: gcm");
module_init(ksmbd_server_init)
module_exit(ksmbd_server_exit)
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 7a88cf3bd29e..02bfe15edcab 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -8964,12 +8964,11 @@ int smb3_check_sign_req(struct ksmbd_work *work)
memcpy(signature_req, hdr->Signature, SMB2_SIGNATURE_SIZE);
memset(hdr->Signature, 0, SMB2_SIGNATURE_SIZE);
iov[0].iov_base = (char *)&hdr->ProtocolId;
iov[0].iov_len = len;
- if (ksmbd_sign_smb3_pdu(conn, signing_key, iov, 1, signature))
- return 0;
+ ksmbd_sign_smb3_pdu(conn, signing_key, iov, 1, signature);
if (crypto_memneq(signature, signature_req, SMB2_SIGNATURE_SIZE)) {
pr_err("bad smb2 signature\n");
return 0;
}
@@ -9016,13 +9015,12 @@ void smb3_set_sign_rsp(struct ksmbd_work *work)
n_vec++;
} else {
iov = &work->iov[work->iov_idx];
}
- if (!ksmbd_sign_smb3_pdu(conn, signing_key, iov, n_vec,
- signature))
- memcpy(hdr->Signature, signature, SMB2_SIGNATURE_SIZE);
+ ksmbd_sign_smb3_pdu(conn, signing_key, iov, n_vec, signature);
+ memcpy(hdr->Signature, signature, SMB2_SIGNATURE_SIZE);
}
/**
* smb3_preauth_hash_rsp() - handler for computing preauth hash on response
* @work: smb work containing response buffer
--
2.53.0