Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index 1d377b7..f842944 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -701,10 +701,9 @@
 }
 #endif
 
-
 static void parse_dacl(struct cifs_acl *pdacl, char *end_of_acl,
 		       struct cifs_sid *pownersid, struct cifs_sid *pgrpsid,
-		       struct cifs_fattr *fattr)
+		       struct cifs_fattr *fattr, bool mode_from_special_sid)
 {
 	int i;
 	int num_aces = 0;
@@ -757,22 +756,34 @@
 #ifdef CONFIG_CIFS_DEBUG2
 			dump_ace(ppace[i], end_of_acl);
 #endif
-			if (compare_sids(&(ppace[i]->sid), pownersid) == 0)
+			if (mode_from_special_sid &&
+			    (compare_sids(&(ppace[i]->sid),
+					  &sid_unix_NFS_mode) == 0)) {
+				/*
+				 * Full permissions are:
+				 * 07777 = S_ISUID | S_ISGID | S_ISVTX |
+				 *         S_IRWXU | S_IRWXG | S_IRWXO
+				 */
+				fattr->cf_mode &= ~07777;
+				fattr->cf_mode |=
+					le32_to_cpu(ppace[i]->sid.sub_auth[2]);
+				break;
+			} else if (compare_sids(&(ppace[i]->sid), pownersid) == 0)
 				access_flags_to_mode(ppace[i]->access_req,
 						     ppace[i]->type,
 						     &fattr->cf_mode,
 						     &user_mask);
-			if (compare_sids(&(ppace[i]->sid), pgrpsid) == 0)
+			else if (compare_sids(&(ppace[i]->sid), pgrpsid) == 0)
 				access_flags_to_mode(ppace[i]->access_req,
 						     ppace[i]->type,
 						     &fattr->cf_mode,
 						     &group_mask);
-			if (compare_sids(&(ppace[i]->sid), &sid_everyone) == 0)
+			else if (compare_sids(&(ppace[i]->sid), &sid_everyone) == 0)
 				access_flags_to_mode(ppace[i]->access_req,
 						     ppace[i]->type,
 						     &fattr->cf_mode,
 						     &other_mask);
-			if (compare_sids(&(ppace[i]->sid), &sid_authusers) == 0)
+			else if (compare_sids(&(ppace[i]->sid), &sid_authusers) == 0)
 				access_flags_to_mode(ppace[i]->access_req,
 						     ppace[i]->type,
 						     &fattr->cf_mode,
@@ -795,22 +806,49 @@
 
 
 static int set_chmod_dacl(struct cifs_acl *pndacl, struct cifs_sid *pownersid,
-			struct cifs_sid *pgrpsid, __u64 nmode)
+			struct cifs_sid *pgrpsid, __u64 nmode, bool modefromsid)
 {
 	u16 size = 0;
+	u32 num_aces = 0;
 	struct cifs_acl *pnndacl;
 
 	pnndacl = (struct cifs_acl *)((char *)pndacl + sizeof(struct cifs_acl));
 
+	if (modefromsid) {
+		struct cifs_ace *pntace =
+			(struct cifs_ace *)((char *)pnndacl + size);
+		int i;
+
+		pntace->type = ACCESS_ALLOWED;
+		pntace->flags = 0x0;
+		pntace->access_req = 0;
+		pntace->sid.num_subauth = 3;
+		pntace->sid.revision = 1;
+		for (i = 0; i < NUM_AUTHS; i++)
+			pntace->sid.authority[i] =
+				sid_unix_NFS_mode.authority[i];
+		pntace->sid.sub_auth[0] = sid_unix_NFS_mode.sub_auth[0];
+		pntace->sid.sub_auth[1] = sid_unix_NFS_mode.sub_auth[1];
+		pntace->sid.sub_auth[2] = cpu_to_le32(nmode & 07777);
+
+		/* size = 1 + 1 + 2 + 4 + 1 + 1 + 6 + (psid->num_subauth*4) */
+		pntace->size = cpu_to_le16(28);
+		size += 28;
+		num_aces++;
+	}
+
 	size += fill_ace_for_sid((struct cifs_ace *) ((char *)pnndacl + size),
 					pownersid, nmode, S_IRWXU);
+	num_aces++;
 	size += fill_ace_for_sid((struct cifs_ace *)((char *)pnndacl + size),
 					pgrpsid, nmode, S_IRWXG);
+	num_aces++;
 	size += fill_ace_for_sid((struct cifs_ace *)((char *)pnndacl + size),
 					 &sid_everyone, nmode, S_IRWXO);
+	num_aces++;
 
+	pndacl->num_aces = cpu_to_le32(num_aces);
 	pndacl->size = cpu_to_le16(size + sizeof(struct cifs_acl));
-	pndacl->num_aces = cpu_to_le32(3);
 
 	return 0;
 }
@@ -851,7 +889,8 @@
 
 /* Convert CIFS ACL to POSIX form */
 static int parse_sec_desc(struct cifs_sb_info *cifs_sb,
-		struct cifs_ntsd *pntsd, int acl_len, struct cifs_fattr *fattr)
+		struct cifs_ntsd *pntsd, int acl_len, struct cifs_fattr *fattr,
+		bool get_mode_from_special_sid)
 {
 	int rc = 0;
 	struct cifs_sid *owner_sid_ptr, *group_sid_ptr;
@@ -900,7 +939,7 @@
 
 	if (dacloffset)
 		parse_dacl(dacl_ptr, end_of_acl, owner_sid_ptr,
-			   group_sid_ptr, fattr);
+			   group_sid_ptr, fattr, get_mode_from_special_sid);
 	else
 		cifs_dbg(FYI, "no ACL\n"); /* BB grant all or default perms? */
 
@@ -909,7 +948,8 @@
 
 /* Convert permission bits from mode to equivalent CIFS ACL */
 static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
-	__u32 secdesclen, __u64 nmode, kuid_t uid, kgid_t gid, int *aclflag)
+	__u32 secdesclen, __u64 nmode, kuid_t uid, kgid_t gid,
+	bool mode_from_sid, int *aclflag)
 {
 	int rc = 0;
 	__u32 dacloffset;
@@ -934,7 +974,7 @@
 		ndacl_ptr->num_aces = 0;
 
 		rc = set_chmod_dacl(ndacl_ptr, owner_sid_ptr, group_sid_ptr,
-					nmode);
+				    nmode, mode_from_sid);
 		sidsoffset = ndacloffset + le16_to_cpu(ndacl_ptr->size);
 		/* copy sec desc control portion & owner and group sids */
 		copy_sec_desc(pntsd, pnntsd, sidsoffset);
@@ -1128,8 +1168,8 @@
 /* Translate the CIFS ACL (similar to NTFS ACL) for a file into mode bits */
 int
 cifs_acl_to_fattr(struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
-		  struct inode *inode, const char *path,
-		  const struct cifs_fid *pfid)
+		  struct inode *inode, bool mode_from_special_sid,
+		  const char *path, const struct cifs_fid *pfid)
 {
 	struct cifs_ntsd *pntsd = NULL;
 	u32 acllen = 0;
@@ -1156,8 +1196,11 @@
 	if (IS_ERR(pntsd)) {
 		rc = PTR_ERR(pntsd);
 		cifs_dbg(VFS, "%s: error %d getting sec desc\n", __func__, rc);
+	} else if (mode_from_special_sid) {
+		rc = parse_sec_desc(cifs_sb, pntsd, acllen, fattr, true);
 	} else {
-		rc = parse_sec_desc(cifs_sb, pntsd, acllen, fattr);
+		/* get approximated mode from ACL */
+		rc = parse_sec_desc(cifs_sb, pntsd, acllen, fattr, false);
 		kfree(pntsd);
 		if (rc)
 			cifs_dbg(VFS, "parse sec desc failed rc = %d\n", rc);
@@ -1181,6 +1224,7 @@
 	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 	struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);
 	struct smb_version_operations *ops;
+	bool mode_from_sid;
 
 	if (IS_ERR(tlink))
 		return PTR_ERR(tlink);
@@ -1218,8 +1262,13 @@
 		return -ENOMEM;
 	}
 
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MODE_FROM_SID)
+		mode_from_sid = true;
+	else
+		mode_from_sid = false;
+
 	rc = build_sec_desc(pntsd, pnntsd, secdesclen, nmode, uid, gid,
-				&aclflag);
+			    mode_from_sid, &aclflag);
 
 	cifs_dbg(NOISY, "build_sec_desc rc: %d\n", rc);