Revert "smb: client: make SHA-512 TFM ephemeral"

The original patch causes a crash with signed mounts when using
the SMB2.1 dialect

RIP: 0010:smb2_calc_signature+0x10e/0x460 [cifs]
Code: 46 30 00 00 00 00 49 c7 46 38 00 00 00 00 0f 85 3e 01 00 00 48 8b 83 a8 02 00 00 48 89 85 68 ff ff ff 49 8b b4 24 58 01 00 00 <48> 8b 38 ba 10 00 00 00 e8 55 0f 0c e0 41 89 c7 85 c0 0f 85 44 01
RSP: 0018:ffffb349422fb5c8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff98028765b800 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff980200f2b100 RDI: 0000000000000000
RBP: ffffb349422fb680 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff980235e37800
R13: ffffb349422fb900 R14: ffff98027c160700 R15: ffff98028765b820
FS: 000074139b98f780(0000) GS:ffff98097b980000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000011cb78006 CR4: 00000000003726f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
? show_regs+0x6c/0x80
? __die+0x24/0x80
? page_fault_oops+0x175/0x5c0
? hrtimer_try_to_cancel.part.0+0x55/0xf0
? do_user_addr_fault+0x4b2/0x870
? exc_page_fault+0x85/0x1c0
? asm_exc_page_fault+0x27/0x30
? smb2_calc_signature+0x10e/0x460 [cifs]
? smb2_calc_signature+0xa7/0x460 [cifs]
? kmem_cache_alloc_noprof+0x101/0x300
smb2_sign_rqst+0xa2/0xe0 [cifs]
smb2_setup_request+0x12d/0x240 [cifs]
compound_send_recv+0x304/0x1220 [cifs]
cifs_send_recv+0x22/0x40 [cifs]
SMB2_tcon+0x2d9/0x8c0 [cifs]
cifs_get_smb_ses+0x910/0xef0 [cifs]
? cifs_get_smb_ses+0x910/0xef0 [cifs]
cifs_mount_get_session+0x6a/0x250 [cifs]

Reported-by: Paulo Alcantara (Red Hat) <[e-mail]>
Suggested-by: Paulo Alcantara (Red Hat) <[e-mail]>
Signed-off-by: Steve French <[e-mail]>

This reverts commit 220d83b52c7d16ec3c168b82f4e6ce59c645f7ab.

fs/smb/client/cifsencrypt.c

···
 	cifs_free_hash(&server->secmech.aes_cmac);
 	cifs_free_hash(&server->secmech.hmacsha256);
 	cifs_free_hash(&server->secmech.md5);
+	cifs_free_hash(&server->secmech.sha512);
 
 	if (!SERVER_IS_CHAN(server)) {
 		if (server->secmech.enc) {

fs/smb/client/cifsglob.h

···
 struct cifs_secmech {
 	struct shash_desc *md5; /* md5 hash function, for CIFS/SMB1 signatures */
 	struct shash_desc *hmacsha256; /* hmac-sha256 hash function, for SMB2 signatures */
+	struct shash_desc *sha512; /* sha512 hash function, for SMB3.1.1 preauth hash */
 	struct shash_desc *aes_cmac; /* block-cipher based MAC function, for SMB3 signatures */
 
 	struct crypto_aead *enc; /* smb3 encryption AEAD TFM (AES-CCM and AES-GCM) */

fs/smb/client/sess.c

···
 	 * to sign packets before we generate the channel signing key
 	 * (we sign with the session key)
 	 */
-	rc = smb3_crypto_shash_allocate(chan->server);
+	rc = smb311_crypto_shash_allocate(chan->server);
 	if (rc) {
 		cifs_dbg(VFS, "%s: crypto alloc failed\n", __func__);
 		mutex_unlock(&ses->session_mutex);

fs/smb/client/smb2misc.c

···
 		|| (hdr->Status !=
 		    cpu_to_le32(NT_STATUS_MORE_PROCESSING_REQUIRED))))
 		return 0;
-ok:
-	rc = cifs_alloc_hash("sha512", &sha512);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not allocate SHA512 shash, rc=%d\n", __func__, rc);
-		return rc;
-	}
 
+ok:
+	rc = smb311_crypto_shash_allocate(server);
+	if (rc)
+		return rc;
+
+	sha512 = server->secmech.sha512;
 	rc = crypto_shash_init(sha512);
 	if (rc) {
-		cifs_dbg(VFS, "%s: Could not init SHA512 shash, rc=%d\n", __func__, rc);
-		goto err_free;
+		cifs_dbg(VFS, "%s: Could not init sha512 shash\n", __func__);
+		return rc;
 	}
 
 	rc = crypto_shash_update(sha512, ses->preauth_sha_hash,
 				 SMB2_PREAUTH_HASH_SIZE);
 	if (rc) {
-		cifs_dbg(VFS, "%s: Could not update SHA512 shash, rc=%d\n", __func__, rc);
-		goto err_free;
+		cifs_dbg(VFS, "%s: Could not update sha512 shash\n", __func__);
+		return rc;
 	}
 
 	for (i = 0; i < nvec; i++) {
 		rc = crypto_shash_update(sha512, iov[i].iov_base, iov[i].iov_len);
 		if (rc) {
-			cifs_dbg(VFS, "%s: Could not update SHA512 shash, rc=%d\n", __func__, rc);
-			goto err_free;
+			cifs_dbg(VFS, "%s: Could not update sha512 shash\n",
+				 __func__);
+			return rc;
 		}
 	}
 
 	rc = crypto_shash_final(sha512, ses->preauth_sha_hash);
 	if (rc) {
-		cifs_dbg(VFS, "%s: Could not finalize SHA12 shash, rc=%d\n", __func__, rc);
-		goto err_free;
+		cifs_dbg(VFS, "%s: Could not finalize sha512 shash\n",
+			 __func__);
+		return rc;
 	}
-err_free:
-	cifs_free_hash(&sha512);
 
 	return 0;
 }

fs/smb/client/smb2proto.h

···
 extern void smb2_copy_fs_info_to_kstatfs(
 	 struct smb2_fs_full_size_info *pfs_inf,
 	 struct kstatfs *kst);
-extern int smb3_crypto_shash_allocate(struct TCP_Server_Info *server);
+extern int smb311_crypto_shash_allocate(struct TCP_Server_Info *server);
 extern int smb311_update_preauth_hash(struct cifs_ses *ses,
 				      struct TCP_Server_Info *server,
 				      struct kvec *iov, int nvec);

fs/smb/client/smb2transport.c

···
 #include "../common/smb2status.h"
 #include "smb2glob.h"
 
-int smb3_crypto_shash_allocate(struct TCP_Server_Info *server)
+static int
+smb3_crypto_shash_allocate(struct TCP_Server_Info *server)
 {
 	struct cifs_secmech *p = &server->secmech;
 	int rc;
···
 	cifs_free_hash(&p->hmacsha256);
 	return rc;
 }
+
+int
+smb311_crypto_shash_allocate(struct TCP_Server_Info *server)
+{
+	struct cifs_secmech *p = &server->secmech;
+	int rc = 0;
+
+	rc = cifs_alloc_hash("hmac(sha256)", &p->hmacsha256);
+	if (rc)
+		return rc;
+
+	rc = cifs_alloc_hash("cmac(aes)", &p->aes_cmac);
+	if (rc)
+		goto err;
+
+	rc = cifs_alloc_hash("sha512", &p->sha512);
+	if (rc)
+		goto err;
+
+	return 0;
+
+err:
+	cifs_free_hash(&p->aes_cmac);
+	cifs_free_hash(&p->hmacsha256);
+	return rc;
+}
+
 
 static
 int smb2_get_sign_key(__u64 ses_id, struct TCP_Server_Info *server, u8 *key)