[CIFS] SMB3 Signing enablement
SMB3 uses a much faster method of signing (which is also better in other ways),
AES-CMAC. With the kernel now supporting AES-CMAC since last release, we
are overdue to allow SMB3 signing (today only CIFS and SMB2 and SMB2.1,
but not SMB3 and SMB3.1 can sign) - and we need this also for checking
secure negotation and also per-share encryption (two other new SMB3 features
which we need to implement).
This patch needs some work in a few areas - for example we need to
move signing for SMB2/SMB3 from per-socket to per-user (we may be able to
use the "nosharesock" mount option in the interim for the multiuser case),
and Shirish found a bug in the earlier authentication overhaul
(setting signing flags properly) - but those can be done in followon
patches.
Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Steve French <smfrench@gmail.com>
diff --git a/fs/cifs/Kconfig b/fs/cifs/Kconfig
index 2906ee2..603f18a 100644
--- a/fs/cifs/Kconfig
+++ b/fs/cifs/Kconfig
@@ -10,6 +10,7 @@
select CRYPTO_ECB
select CRYPTO_DES
select CRYPTO_SHA256
+ select CRYPTO_CMAC
help
This is the client VFS module for the Common Internet File System
(CIFS) protocol which is the successor to the Server Message Block
diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
index 3308759..3d8bf94 100644
--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -705,6 +705,9 @@
void
cifs_crypto_shash_release(struct TCP_Server_Info *server)
{
+ if (server->secmech.cmacaes)
+ crypto_free_shash(server->secmech.cmacaes);
+
if (server->secmech.hmacsha256)
crypto_free_shash(server->secmech.hmacsha256);
@@ -714,6 +717,8 @@
if (server->secmech.hmacmd5)
crypto_free_shash(server->secmech.hmacmd5);
+ kfree(server->secmech.sdesccmacaes);
+
kfree(server->secmech.sdeschmacsha256);
kfree(server->secmech.sdeschmacmd5);
@@ -747,6 +752,13 @@
goto crypto_allocate_hmacsha256_fail;
}
+ server->secmech.cmacaes = crypto_alloc_shash("cmac(aes)", 0, 0);
+ if (IS_ERR(server->secmech.cmacaes)) {
+ cifs_dbg(VFS, "could not allocate crypto cmac-aes");
+ rc = PTR_ERR(server->secmech.cmacaes);
+ goto crypto_allocate_cmacaes_fail;
+ }
+
size = sizeof(struct shash_desc) +
crypto_shash_descsize(server->secmech.hmacmd5);
server->secmech.sdeschmacmd5 = kmalloc(size, GFP_KERNEL);
@@ -777,8 +789,22 @@
server->secmech.sdeschmacsha256->shash.tfm = server->secmech.hmacsha256;
server->secmech.sdeschmacsha256->shash.flags = 0x0;
+ size = sizeof(struct shash_desc) +
+ crypto_shash_descsize(server->secmech.cmacaes);
+ server->secmech.sdesccmacaes = kmalloc(size, GFP_KERNEL);
+ if (!server->secmech.sdesccmacaes) {
+ cifs_dbg(VFS, "%s: Can't alloc cmacaes\n", __func__);
+ rc = -ENOMEM;
+ goto crypto_allocate_cmacaes_sdesc_fail;
+ }
+ server->secmech.sdesccmacaes->shash.tfm = server->secmech.cmacaes;
+ server->secmech.sdesccmacaes->shash.flags = 0x0;
+
return 0;
+crypto_allocate_cmacaes_sdesc_fail:
+ kfree(server->secmech.sdeschmacsha256);
+
crypto_allocate_hmacsha256_sdesc_fail:
kfree(server->secmech.sdescmd5);
@@ -786,6 +812,9 @@
kfree(server->secmech.sdeschmacmd5);
crypto_allocate_hmacmd5_sdesc_fail:
+ crypto_free_shash(server->secmech.cmacaes);
+
+crypto_allocate_cmacaes_fail:
crypto_free_shash(server->secmech.hmacsha256);
crypto_allocate_hmacsha256_fail:
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 9a1e37a..2d0f524 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -125,9 +125,11 @@
struct crypto_shash *hmacmd5; /* hmac-md5 hash function */
struct crypto_shash *md5; /* md5 hash function */
struct crypto_shash *hmacsha256; /* hmac-sha256 hash function */
+ struct crypto_shash *cmacaes; /* block-cipher based MAC function */
struct sdesc *sdeschmacmd5; /* ctxt to generate ntlmv2 hash, CR1 */
struct sdesc *sdescmd5; /* ctxt to generate cifs/smb signature */
struct sdesc *sdeschmacsha256; /* ctxt to generate smb2 signature */
+ struct sdesc *sdesccmacaes; /* ctxt to generate smb3 signature */
};
/* per smb session structure/fields */
@@ -538,6 +540,7 @@
int timeAdj; /* Adjust for difference in server time zone in sec */
__u64 CurrentMid; /* multiplex id - rotating counter */
char cryptkey[CIFS_CRYPTO_KEY_SIZE]; /* used by ntlm, ntlmv2 etc */
+ char smb3signingkey[SMB3_SIGN_KEY_SIZE]; /* for signing smb3 packets */
/* 16th byte of RFC1001 workstation name is always null */
char workstation_RFC1001_name[RFC1001_NAME_LEN_WITH_NULL];
__u32 sequence_number; /* for signing, protected by srv_mutex */
diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h
index 7e8523c..11ca24a 100644
--- a/fs/cifs/cifspdu.h
+++ b/fs/cifs/cifspdu.h
@@ -142,6 +142,11 @@
*/
#define CIFS_SESS_KEY_SIZE (16)
+/*
+ * Size of the smb3 signing key
+ */
+#define SMB3_SIGN_KEY_SIZE (16)
+
#define CIFS_CLIENT_CHALLENGE_SIZE (8)
#define CIFS_SERVER_CHALLENGE_SIZE (8)
#define CIFS_HMAC_MD5_HASH_SIZE (16)
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index a82b3c0..ff669e7c 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -436,6 +436,7 @@
extern int cifs_crypto_shash_allocate(struct TCP_Server_Info *);
extern void cifs_crypto_shash_release(struct TCP_Server_Info *);
extern int calc_seckey(struct cifs_ses *);
+extern int generate_smb3signingkey(struct TCP_Server_Info *);
#ifdef CONFIG_CIFS_WEAK_PW_HASH
extern int calc_lanman_hash(const char *password, const char *cryptkey,
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 53a1780..354ea77 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3841,6 +3841,7 @@
server->sequence_number = 0x2;
server->session_estab = true;
ses->auth_key.response = NULL;
+ generate_smb3signingkey(server);
}
mutex_unlock(&server->srv_mutex);
diff --git a/fs/cifs/smb2glob.h b/fs/cifs/smb2glob.h
index 7c0e214..c383508 100644
--- a/fs/cifs/smb2glob.h
+++ b/fs/cifs/smb2glob.h
@@ -54,5 +54,7 @@
#define SMB2_SIGNATURE_SIZE (16)
#define SMB2_NTLMV2_SESSKEY_SIZE (16)
#define SMB2_HMACSHA256_SIZE (32)
+#define SMB2_CMACAES_SIZE (16)
+#define SMB3_SIGNKEY_SIZE (16)
#endif /* _SMB2_GLOB_H */
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index c802ecf..87563ee 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -117,10 +117,154 @@
}
int
+generate_smb3signingkey(struct TCP_Server_Info *server)
+{
+ unsigned char zero = 0x0;
+ __u8 i[4] = {0, 0, 0, 1};
+ __u8 L[4] = {0, 0, 0, 128};
+ int rc = 0;
+ unsigned char prfhash[SMB2_HMACSHA256_SIZE];
+ unsigned char *hashptr = prfhash;
+
+ memset(prfhash, 0x0, SMB2_HMACSHA256_SIZE);
+ memset(server->smb3signingkey, 0x0, SMB3_SIGNKEY_SIZE);
+
+ rc = crypto_shash_setkey(server->secmech.hmacsha256,
+ server->session_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
+ if (rc) {
+ cifs_dbg(VFS, "%s: Could not set with session key\n", __func__);
+ goto smb3signkey_ret;
+ }
+
+ rc = crypto_shash_init(&server->secmech.sdeschmacsha256->shash);
+ if (rc) {
+ cifs_dbg(VFS, "%s: Could not init sign hmac\n", __func__);
+ goto smb3signkey_ret;
+ }
+
+ rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+ i, 4);
+ if (rc) {
+ cifs_dbg(VFS, "%s: Could not update with n\n", __func__);
+ goto smb3signkey_ret;
+ }
+
+ rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+ "SMB2AESCMAC", 12);
+ if (rc) {
+ cifs_dbg(VFS, "%s: Could not update with label\n", __func__);
+ goto smb3signkey_ret;
+ }
+
+ rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+ &zero, 1);
+ if (rc) {
+ cifs_dbg(VFS, "%s: Could not update with zero\n", __func__);
+ goto smb3signkey_ret;
+ }
+
+ rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+ "SmbSign", 8);
+ if (rc) {
+ cifs_dbg(VFS, "%s: Could not update with context\n", __func__);
+ goto smb3signkey_ret;
+ }
+
+ rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+ L, 4);
+ if (rc) {
+ cifs_dbg(VFS, "%s: Could not update with L\n", __func__);
+ goto smb3signkey_ret;
+ }
+
+ rc = crypto_shash_final(&server->secmech.sdeschmacsha256->shash,
+ hashptr);
+ if (rc) {
+ cifs_dbg(VFS, "%s: Could not generate sha256 hash\n", __func__);
+ goto smb3signkey_ret;
+ }
+
+ memcpy(server->smb3signingkey, hashptr, SMB3_SIGNKEY_SIZE);
+
+smb3signkey_ret:
+ return rc;
+}
+
+int
smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
{
- cifs_dbg(FYI, "smb3 signatures not supported yet\n");
- return -EOPNOTSUPP;
+ int i, rc;
+ unsigned char smb3_signature[SMB2_CMACAES_SIZE];
+ unsigned char *sigptr = smb3_signature;
+ struct kvec *iov = rqst->rq_iov;
+ int n_vec = rqst->rq_nvec;
+ struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
+
+ memset(smb3_signature, 0x0, SMB2_CMACAES_SIZE);
+ memset(smb2_pdu->Signature, 0x0, SMB2_SIGNATURE_SIZE);
+
+ rc = crypto_shash_setkey(server->secmech.cmacaes,
+ server->smb3signingkey, SMB2_CMACAES_SIZE);
+ if (rc) {
+ cifs_dbg(VFS, "%s: Could not set key for cmac aes\n", __func__);
+ return rc;
+ }
+
+ rc = crypto_shash_init(&server->secmech.sdesccmacaes->shash);
+ if (rc) {
+ cifs_dbg(VFS, "%s: Could not init cmac aes\n", __func__);
+ return rc;
+ }
+
+ for (i = 0; i < n_vec; i++) {
+ if (iov[i].iov_len == 0)
+ continue;
+ if (iov[i].iov_base == NULL) {
+ cifs_dbg(VFS, "null iovec entry");
+ return -EIO;
+ }
+ /*
+ * The first entry includes a length field (which does not get
+ * signed that occupies the first 4 bytes before the header).
+ */
+ if (i == 0) {
+ if (iov[0].iov_len <= 8) /* cmd field at offset 9 */
+ break; /* nothing to sign or corrupt header */
+ rc =
+ crypto_shash_update(
+ &server->secmech.sdesccmacaes->shash,
+ iov[i].iov_base + 4, iov[i].iov_len - 4);
+ } else {
+ rc =
+ crypto_shash_update(
+ &server->secmech.sdesccmacaes->shash,
+ iov[i].iov_base, iov[i].iov_len);
+ }
+ if (rc) {
+ cifs_dbg(VFS, "%s: Couldn't update cmac aes with payload\n",
+ __func__);
+ return rc;
+ }
+ }
+
+ /* now hash over the rq_pages array */
+ for (i = 0; i < rqst->rq_npages; i++) {
+ struct kvec p_iov;
+
+ cifs_rqst_page_to_kvec(rqst, i, &p_iov);
+ crypto_shash_update(&server->secmech.sdesccmacaes->shash,
+ p_iov.iov_base, p_iov.iov_len);
+ kunmap(rqst->rq_pages[i]);
+ }
+
+ rc = crypto_shash_final(&server->secmech.sdesccmacaes->shash,
+ sigptr);
+ if (rc)
+ cifs_dbg(VFS, "%s: Could not generate cmac aes\n", __func__);
+
+ memcpy(smb2_pdu->Signature, sigptr, SMB2_SIGNATURE_SIZE);
+
+ return rc;
}
/* must be called with server->srv_mutex held */