Merge tag 'v7.1-rc3-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6

Pull smb client fixes from Steve French:

 - Fix for two ACL issues (security fix to validate dacloffset better
   and chmod fix)

 - Fix out of bounds reads (in check_wsl_eas and smb2_check_msg for
   symlinks)

 - Two Kerberos fixes including an important one when AES-256 encryption
   chosen

 - Fix open_cached_dir problem when directory leases disabled

* tag 'v7.1-rc3-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  smb: client: validate dacloffset before building DACL pointers
  smb/client: fix out-of-bounds read in smb2_compound_op()
  smb/client: fix out-of-bounds read in symlink_data()
  smb: client: Zero-pad short GSS session keys per MS-SMB2
  smb: client: Use FullSessionKey for AES-256 encryption key derivation
  smb: client: use kzalloc to zero-initialize security descriptor buffer
  cifs: abort open_cached_dir if we don't request leases

7 files changed, 96 insertions, 24 deletions

diff --git a/fs/smb/client/cached_dir.c b/fs/smb/client/cached_dir.c
index 02791ec3c5a1..88d5e9a32f28 100644
--- a/fs/smb/client/cached_dir.c
+++ b/fs/smb/client/cached_dir.c
@@ -286,6 +286,14 @@ replay_again:
 			    &rqst[0], &oplock, &oparms, utf16_path);
 	if (rc)
 		goto oshr_free;
+
+	if (oplock != SMB2_OPLOCK_LEVEL_II) {
+		rc = -EINVAL;
+		cifs_dbg(FYI, "%s: Oplock level %d not suitable for cached directory\n",
+			 __func__, oplock);
+		goto oshr_free;
+	}
+
 	smb2_set_next_command(tcon, &rqst[0]);
 
 	memset(&qi_iov, 0, sizeof(qi_iov));
diff --git a/fs/smb/client/cifsacl.c b/fs/smb/client/cifsacl.c
index ec5d47779304..786dbbc43c5b 100644
--- a/fs/smb/client/cifsacl.c
+++ b/fs/smb/client/cifsacl.c
@@ -1264,6 +1264,17 @@ static int parse_sid(struct smb_sid *psid, char *end_of_acl)
 	return 0;
 }
 
+static bool dacl_offset_valid(unsigned int acl_len, __u32 dacloffset)
+{
+	if (acl_len < sizeof(struct smb_acl))
+		return false;
+
+	if (dacloffset < sizeof(struct smb_ntsd))
+		return false;
+
+	return dacloffset <= acl_len - sizeof(struct smb_acl);
+}
+
 
 /* Convert CIFS ACL to POSIX form */
 static int parse_sec_desc(struct cifs_sb_info *cifs_sb,
@@ -1284,7 +1295,6 @@ static int parse_sec_desc(struct cifs_sb_info *cifs_sb,
 	group_sid_ptr = (struct smb_sid *)((char *)pntsd +
 				le32_to_cpu(pntsd->gsidoffset));
 	dacloffset = le32_to_cpu(pntsd->dacloffset);
-	dacl_ptr = (struct smb_acl *)((char *)pntsd + dacloffset);
 	cifs_dbg(NOISY, "revision %d type 0x%x ooffset 0x%x goffset 0x%x sacloffset 0x%x dacloffset 0x%x\n",
 		 pntsd->revision, pntsd->type, le32_to_cpu(pntsd->osidoffset),
 		 le32_to_cpu(pntsd->gsidoffset),
@@ -1315,11 +1325,18 @@ static int parse_sec_desc(struct cifs_sb_info *cifs_sb,
 		return rc;
 	}
 
-	if (dacloffset)
+	if (dacloffset) {
+		if (!dacl_offset_valid(acl_len, dacloffset)) {
+			cifs_dbg(VFS, "Server returned illegal DACL offset\n");
+			return -EINVAL;
+		}
+
+		dacl_ptr = (struct smb_acl *)((char *)pntsd + dacloffset);
 		parse_dacl(dacl_ptr, end_of_acl, owner_sid_ptr,
 			   group_sid_ptr, fattr, get_mode_from_special_sid);
-	else
+	} else {
 		cifs_dbg(FYI, "no ACL\n"); /* BB grant all or default perms? */
+	}
 
 	return rc;
 }
@@ -1342,6 +1359,11 @@ static int build_sec_desc(struct smb_ntsd *pntsd, struct smb_ntsd *pnntsd,
 
 	dacloffset = le32_to_cpu(pntsd->dacloffset);
 	if (dacloffset) {
+		if (!dacl_offset_valid(secdesclen, dacloffset)) {
+			cifs_dbg(VFS, "Server returned illegal DACL offset\n");
+			return -EINVAL;
+		}
+
 		dacl_ptr = (struct smb_acl *)((char *)pntsd + dacloffset);
 		rc = validate_dacl(dacl_ptr, end_of_acl);
 		if (rc)
@@ -1710,6 +1732,12 @@ id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64 *pnmode,
 		nsecdesclen = sizeof(struct smb_ntsd) + (sizeof(struct smb_sid) * 2);
 		dacloffset = le32_to_cpu(pntsd->dacloffset);
 		if (dacloffset) {
+			if (!dacl_offset_valid(secdesclen, dacloffset)) {
+				cifs_dbg(VFS, "Server returned illegal DACL offset\n");
+				rc = -EINVAL;
+				goto id_mode_to_cifs_acl_exit;
+			}
+
 			dacl_ptr = (struct smb_acl *)((char *)pntsd + dacloffset);
 			rc = validate_dacl(dacl_ptr, (char *)pntsd + secdesclen);
 			if (rc) {
@@ -1732,7 +1760,7 @@ id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64 *pnmode,
 	 * descriptor parameters, and security descriptor itself
 	 */
 	nsecdesclen = max_t(u32, nsecdesclen, DEFAULT_SEC_DESC_LEN);
-	pnntsd = kmalloc(nsecdesclen, GFP_KERNEL);
+	pnntsd = kzalloc(nsecdesclen, GFP_KERNEL);
 	if (!pnntsd) {
 		kfree(pntsd);
 		cifs_put_tlink(tlink);
@@ -1752,6 +1780,7 @@ id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64 *pnmode,
 		rc = ops->set_acl(pnntsd, nsecdesclen, inode, path, aclflag);
 		cifs_dbg(NOISY, "set_cifs_acl rc: %d\n", rc);
 	}
+id_mode_to_cifs_acl_exit:
 	cifs_put_tlink(tlink);
 
 	kfree(pnntsd);
diff --git a/fs/smb/client/ioctl.c b/fs/smb/client/ioctl.c
index 9afab3237e54..17408bb8ab65 100644
--- a/fs/smb/client/ioctl.c
+++ b/fs/smb/client/ioctl.c
@@ -296,7 +296,7 @@ search_end:
 		break;
 	case SMB2_ENCRYPTION_AES256_CCM:
 	case SMB2_ENCRYPTION_AES256_GCM:
-		out.session_key_length = CIFS_SESS_KEY_SIZE;
+		out.session_key_length = ses->auth_key.len;
 		out.server_in_key_length = out.server_out_key_length = SMB3_GCM256_CRYPTKEY_SIZE;
 		break;
 	default:
diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c
index 286912616c73..6c9c229b91f6 100644
--- a/fs/smb/client/smb2inode.c
+++ b/fs/smb/client/smb2inode.c
@@ -111,7 +111,7 @@ static int check_wsl_eas(struct kvec *rsp_iov)
 	u32 outlen, next;
 	u16 vlen;
 	u8 nlen;
-	u8 *end;
+	u8 *ea_end, *iov_end;
 
 	outlen = le32_to_cpu(rsp->OutputBufferLength);
 	if (outlen < SMB2_WSL_MIN_QUERY_EA_RESP_SIZE ||
@@ -120,15 +120,19 @@ static int check_wsl_eas(struct kvec *rsp_iov)
 
 	ea = (void *)((u8 *)rsp_iov->iov_base +
 		      le16_to_cpu(rsp->OutputBufferOffset));
-	end = (u8 *)rsp_iov->iov_base + rsp_iov->iov_len;
+	ea_end = (u8 *)ea + outlen;
+	iov_end = (u8 *)rsp_iov->iov_base + rsp_iov->iov_len;
+	if (ea_end > iov_end)
+		return -EINVAL;
+
 	for (;;) {
-		if ((u8 *)ea > end - sizeof(*ea))
+		if ((u8 *)ea > ea_end - sizeof(*ea))
 			return -EINVAL;
 
 		nlen = ea->ea_name_length;
 		vlen = le16_to_cpu(ea->ea_value_length);
 		if (nlen != SMB2_WSL_XATTR_NAME_LEN ||
-		    (u8 *)ea->ea_data + nlen + 1 + vlen > end)
+		    (u8 *)ea->ea_data + nlen + 1 + vlen > ea_end)
 			return -EINVAL;
 
 		switch (vlen) {
diff --git a/fs/smb/client/smb2misc.c b/fs/smb/client/smb2misc.c
index 973fce3c959c..2a7355ce1a07 100644
--- a/fs/smb/client/smb2misc.c
+++ b/fs/smb/client/smb2misc.c
@@ -241,7 +241,8 @@ smb2_check_message(char *buf, unsigned int pdu_len, unsigned int len,
 	if (len != calc_len) {
 		/* create failed on symlink */
 		if (command == SMB2_CREATE_HE &&
-		    shdr->Status == STATUS_STOPPED_ON_SYMLINK)
+		    shdr->Status == STATUS_STOPPED_ON_SYMLINK &&
+		    len > calc_len)
 			return 0;
 		/* Windows 7 server returns 24 bytes more */
 		if (calc_len + 24 == len && command == SMB2_OPLOCK_BREAK_HE)
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index cb61051f9af3..995fcdd30681 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -1713,17 +1713,30 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
 	is_binding = (ses->ses_status == SES_GOOD);
 	spin_unlock(&ses->ses_lock);
 
+	/*
+	 * Per MS-SMB2 3.2.5.3, Session.SessionKey is the first 16 bytes of the
+	 * GSS cryptographic key, right-padded with zero bytes if shorter.
+	 * Allocate at least SMB2_NTLMV2_SESSKEY_SIZE bytes (zeroed) so the KDF
+	 * input buffer is always valid for HMAC-SHA256 even with deprecated
+	 * Kerberos enctypes that return a short session key.
+	 */
+	if (unlikely(msg->sesskey_len < SMB2_NTLMV2_SESSKEY_SIZE))
+		cifs_dbg(VFS,
+			 "short GSS session key (%u bytes); zero-padding per MS-SMB2 3.2.5.3\n",
+			 msg->sesskey_len);
+
 	kfree_sensitive(ses->auth_key.response);
-	ses->auth_key.response = kmemdup(msg->data,
-					 msg->sesskey_len,
-					 GFP_KERNEL);
+	ses->auth_key.len = max_t(unsigned int, msg->sesskey_len,
+				  SMB2_NTLMV2_SESSKEY_SIZE);
+	ses->auth_key.response = kzalloc(ses->auth_key.len, GFP_KERNEL);
 	if (!ses->auth_key.response) {
 		cifs_dbg(VFS, "%s: can't allocate (%u bytes) memory\n",
-			 __func__, msg->sesskey_len);
+			 __func__, ses->auth_key.len);
+		ses->auth_key.len = 0;
 		rc = -ENOMEM;
 		goto out_put_spnego_key;
 	}
-	ses->auth_key.len = msg->sesskey_len;
+	memcpy(ses->auth_key.response, msg->data, msg->sesskey_len);
 
 	sess_data->iov[1].iov_base = msg->data + msg->sesskey_len;
 	sess_data->iov[1].iov_len = msg->secblob_len;
diff --git a/fs/smb/client/smb2transport.c b/fs/smb/client/smb2transport.c
index 41009039b4cb..e8eeff9e50d6 100644
--- a/fs/smb/client/smb2transport.c
+++ b/fs/smb/client/smb2transport.c
@@ -251,7 +251,8 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 }
 
 static void generate_key(struct cifs_ses *ses, struct kvec label,
-			 struct kvec context, __u8 *key, unsigned int key_size)
+			 struct kvec context, __u8 *key, unsigned int key_size,
+			 unsigned int full_key_size)
 {
 	unsigned char zero = 0x0;
 	__u8 i[4] = {0, 0, 0, 1};
@@ -265,7 +266,7 @@ static void generate_key(struct cifs_ses *ses, struct kvec label,
 	memset(key, 0x0, key_size);
 
 	hmac_sha256_init_usingrawkey(&hmac_ctx, ses->auth_key.response,
-				     SMB2_NTLMV2_SESSKEY_SIZE);
+				     full_key_size);
 	hmac_sha256_update(&hmac_ctx, i, 4);
 	hmac_sha256_update(&hmac_ctx, label.iov_base, label.iov_len);
 	hmac_sha256_update(&hmac_ctx, &zero, 1);
@@ -298,6 +299,7 @@ generate_smb3signingkey(struct cifs_ses *ses,
 			struct TCP_Server_Info *server,
 			const struct derivation_triplet *ptriplet)
 {
+	unsigned int full_key_size = SMB2_NTLMV2_SESSKEY_SIZE;
 	bool is_binding = false;
 	int chan_index = 0;
 
@@ -330,12 +332,24 @@ generate_smb3signingkey(struct cifs_ses *ses,
 	if (is_binding) {
 		generate_key(ses, ptriplet->signing.label,
 			     ptriplet->signing.context,
-			     ses->chans[chan_index].signkey,
-			     SMB3_SIGN_KEY_SIZE);
+			     ses->chans[chan_index].signkey, SMB3_SIGN_KEY_SIZE,
+			     SMB2_NTLMV2_SESSKEY_SIZE);
 	} else {
 		generate_key(ses, ptriplet->signing.label,
-			     ptriplet->signing.context,
-			     ses->smb3signingkey, SMB3_SIGN_KEY_SIZE);
+			     ptriplet->signing.context, ses->smb3signingkey,
+			     SMB3_SIGN_KEY_SIZE, SMB2_NTLMV2_SESSKEY_SIZE);
+
+		/*
+		 * Per MS-SMB2 3.2.5.3.1, signing key always uses Session.SessionKey
+		 * (first 16 bytes). Encryption/decryption keys use
+		 * Session.FullSessionKey when dialect is 3.1.1 and cipher is
+		 * AES-256-CCM or AES-256-GCM, otherwise Session.SessionKey.
+		 */
+
+		if (server->dialect == SMB311_PROT_ID &&
+		    (server->cipher_type == SMB2_ENCRYPTION_AES256_CCM ||
+		     server->cipher_type == SMB2_ENCRYPTION_AES256_GCM))
+			full_key_size = ses->auth_key.len;
 
 		/* safe to access primary channel, since it will never go away */
 		spin_lock(&ses->chan_lock);
@@ -345,10 +359,13 @@ generate_smb3signingkey(struct cifs_ses *ses,
 
 		generate_key(ses, ptriplet->encryption.label,
 			     ptriplet->encryption.context,
-			     ses->smb3encryptionkey, SMB3_ENC_DEC_KEY_SIZE);
+			     ses->smb3encryptionkey, SMB3_ENC_DEC_KEY_SIZE,
+			     full_key_size);
+
 		generate_key(ses, ptriplet->decryption.label,
 			     ptriplet->decryption.context,
-			     ses->smb3decryptionkey, SMB3_ENC_DEC_KEY_SIZE);
+			     ses->smb3decryptionkey, SMB3_ENC_DEC_KEY_SIZE,
+			     full_key_size);
 	}
 
 #ifdef CONFIG_CIFS_DEBUG_DUMP_KEYS
@@ -361,7 +378,7 @@ generate_smb3signingkey(struct cifs_ses *ses,
 			&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);
+		 (int)ses->auth_key.len, ses->auth_key.response);
 	cifs_dbg(VFS, "Signing Key   %*ph\n",
 		 SMB3_SIGN_KEY_SIZE, ses->smb3signingkey);
 	if ((server->cipher_type == SMB2_ENCRYPTION_AES256_CCM) ||