From: Steve French <stfrench@microsoft.com>
Date: Fri, 12 Jun 2020 10:36:37 -0500
Subject: [PATCH] cifs: fix chown and chgrp when idsfromsid mount option
 enabled
Git-commit: a6603398278480aafef644d4c40549b5c5064c73
References: bsc#1190317
Patch-mainline: v5.8-rc1

idsfromsid was ignored in chown and chgrp causing it to fail
when upcalls were not configured for lookup.  idsfromsid allows
mapping users when setting user or group ownership using
"special SID" (reserved for this).  Add support for chmod and chgrp
when idsfromsid mount option is enabled.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
 fs/cifs/cifsacl.c | 57 ++++++++++++++++++++++++++++++++++-------------
 1 file changed, 42 insertions(+), 15 deletions(-)

diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index 63aaa363ed14..6025d7fc7bbf 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -1000,7 +1000,7 @@ static int parse_sec_desc(struct cifs_sb_info *cifs_sb,
 /* 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,
-	bool mode_from_sid, int *aclflag)
+	bool mode_from_sid, bool id_from_sid, int *aclflag)
 {
 	int rc = 0;
 	__u32 dacloffset;
@@ -1041,12 +1041,23 @@ static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
 			if (!nowner_sid_ptr)
 				return -ENOMEM;
 			id = from_kuid(&init_user_ns, uid);
-			rc = id_to_sid(id, SIDOWNER, nowner_sid_ptr);
-			if (rc) {
-				cifs_dbg(FYI, "%s: Mapping error %d for owner id %d\n",
-					 __func__, rc, id);
-				kfree(nowner_sid_ptr);
-				return rc;
+			if (id_from_sid) {
+				struct owner_sid *osid = (struct owner_sid *)nowner_sid_ptr;
+				/* Populate the user ownership fields S-1-5-88-1 */
+				osid->Revision = 1;
+				osid->NumAuth = 3;
+				osid->Authority[5] = 5;
+				osid->SubAuthorities[0] = cpu_to_le32(88);
+				osid->SubAuthorities[1] = cpu_to_le32(1);
+				osid->SubAuthorities[2] = cpu_to_le32(id);
+			} else { /* lookup sid with upcall */
+				rc = id_to_sid(id, SIDOWNER, nowner_sid_ptr);
+				if (rc) {
+					cifs_dbg(FYI, "%s: Mapping error %d for owner id %d\n",
+						 __func__, rc, id);
+					kfree(nowner_sid_ptr);
+					return rc;
+				}
 			}
 			cifs_copy_sid(owner_sid_ptr, nowner_sid_ptr);
 			kfree(nowner_sid_ptr);
@@ -1061,12 +1072,23 @@ static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
 			if (!ngroup_sid_ptr)
 				return -ENOMEM;
 			id = from_kgid(&init_user_ns, gid);
-			rc = id_to_sid(id, SIDGROUP, ngroup_sid_ptr);
-			if (rc) {
-				cifs_dbg(FYI, "%s: Mapping error %d for group id %d\n",
-					 __func__, rc, id);
-				kfree(ngroup_sid_ptr);
-				return rc;
+			if (id_from_sid) {
+				struct owner_sid *gsid = (struct owner_sid *)ngroup_sid_ptr;
+				/* Populate the group ownership fields S-1-5-88-2 */
+				gsid->Revision = 1;
+				gsid->NumAuth = 3;
+				gsid->Authority[5] = 5;
+				gsid->SubAuthorities[0] = cpu_to_le32(88);
+				gsid->SubAuthorities[1] = cpu_to_le32(2);
+				gsid->SubAuthorities[2] = cpu_to_le32(id);
+			} else { /* lookup sid with upcall */
+				rc = id_to_sid(id, SIDGROUP, ngroup_sid_ptr);
+				if (rc) {
+					cifs_dbg(FYI, "%s: Mapping error %d for group id %d\n",
+						 __func__, rc, id);
+					kfree(ngroup_sid_ptr);
+					return rc;
+				}
 			}
 			cifs_copy_sid(group_sid_ptr, ngroup_sid_ptr);
 			kfree(ngroup_sid_ptr);
@@ -1269,7 +1291,7 @@ id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64 nmode,
 	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;
+	bool mode_from_sid, id_from_sid;
 
 	if (IS_ERR(tlink))
 		return PTR_ERR(tlink);
@@ -1312,8 +1334,13 @@ id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64 nmode,
 	else
 		mode_from_sid = false;
 
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UID_FROM_ACL)
+		id_from_sid = true;
+	else
+		id_from_sid = false;
+
 	rc = build_sec_desc(pntsd, pnntsd, secdesclen, nmode, uid, gid,
-			    mode_from_sid, &aclflag);
+			    mode_from_sid, id_from_sid, &aclflag);
 
 	cifs_dbg(NOISY, "build_sec_desc rc: %d\n", rc);
 
-- 
2.33.0