cifs: Call id to SID mapping functions to change owner/group (try #4 repost)

Now build security descriptor to change either owner or group at the
server.  Initially security descriptor was built to change only
(D)ACL, that functionality has been extended.

When either an Owner or a Group of a file object at the server is changed,
rest of security descriptor remains same (DACL etc.).

To set security descriptor, it is necessary to open that file
with permission bits of either WRITE_DAC if DACL is being modified or
WRITE_OWNER (Take Ownership) if Owner or Group is being changed.

It is the server that decides whether a set security descriptor with
either owner or group change succeeds or not.

Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 83 insertions, 52 deletions

diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index 992f1fb299d1..72ddf23ef6f7 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -904,7 +904,7 @@ static void parse_dacl(struct cifs_acl *pdacl, char *end_of_acl,
 	acl_size = sizeof(struct cifs_acl);
 
 	num_aces = le32_to_cpu(pdacl->num_aces);
-	if (num_aces  > 0) {
+	if (num_aces > 0) {
 		umode_t user_mask = S_IRWXU;
 		umode_t group_mask = S_IRWXG;
 		umode_t other_mask = S_IRWXU | S_IRWXG | S_IRWXO;
@@ -1066,52 +1066,82 @@ static int parse_sec_desc(struct cifs_sb_info *cifs_sb,
 	else
 		cFYI(1, "no ACL"); /* BB grant all or default perms? */
 
-/*	cifscred->uid = owner_sid_ptr->rid;
-	cifscred->gid = group_sid_ptr->rid;
-	memcpy((void *)(&(cifscred->osid)), (void *)owner_sid_ptr,
-			sizeof(struct cifs_sid));
-	memcpy((void *)(&(cifscred->gsid)), (void *)group_sid_ptr,
-			sizeof(struct cifs_sid)); */
-
 	return rc;
 }
 
-
 /* Convert permission bits from mode to equivalent CIFS ACL */
 static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
-				struct inode *inode, __u64 nmode)
+	__u32 secdesclen, __u64 nmode, uid_t uid, gid_t gid, int *aclflag)
 {
 	int rc = 0;
 	__u32 dacloffset;
 	__u32 ndacloffset;
 	__u32 sidsoffset;
 	struct cifs_sid *owner_sid_ptr, *group_sid_ptr;
+	struct cifs_sid *nowner_sid_ptr, *ngroup_sid_ptr;
 	struct cifs_acl *dacl_ptr = NULL;  /* no need for SACL ptr */
 	struct cifs_acl *ndacl_ptr = NULL; /* no need for SACL ptr */
 
-	if ((inode == NULL) || (pntsd == NULL) || (pnntsd == NULL))
-		return -EIO;
-
-	owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
+	if (nmode != NO_CHANGE_64) { /* chmod */
+		owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
 				le32_to_cpu(pntsd->osidoffset));
-	group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
+		group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
 				le32_to_cpu(pntsd->gsidoffset));
-
-	dacloffset = le32_to_cpu(pntsd->dacloffset);
-	dacl_ptr = (struct cifs_acl *)((char *)pntsd + dacloffset);
-
-	ndacloffset = sizeof(struct cifs_ntsd);
-	ndacl_ptr = (struct cifs_acl *)((char *)pnntsd + ndacloffset);
-	ndacl_ptr->revision = dacl_ptr->revision;
-	ndacl_ptr->size = 0;
-	ndacl_ptr->num_aces = 0;
-
-	rc = set_chmod_dacl(ndacl_ptr, owner_sid_ptr, group_sid_ptr, nmode);
-
-	sidsoffset = ndacloffset + le16_to_cpu(ndacl_ptr->size);
-
-	/* copy security descriptor control portion and owner and group sid */
-	copy_sec_desc(pntsd, pnntsd, sidsoffset);
+		dacloffset = le32_to_cpu(pntsd->dacloffset);
+		dacl_ptr = (struct cifs_acl *)((char *)pntsd + dacloffset);
+		ndacloffset = sizeof(struct cifs_ntsd);
+		ndacl_ptr = (struct cifs_acl *)((char *)pnntsd + ndacloffset);
+		ndacl_ptr->revision = dacl_ptr->revision;
+		ndacl_ptr->size = 0;
+		ndacl_ptr->num_aces = 0;
+
+		rc = set_chmod_dacl(ndacl_ptr, owner_sid_ptr, group_sid_ptr,
+					nmode);
+		sidsoffset = ndacloffset + le16_to_cpu(ndacl_ptr->size);
+		/* copy sec desc control portion & owner and group sids */
+		copy_sec_desc(pntsd, pnntsd, sidsoffset);
+		*aclflag = CIFS_ACL_DACL;
+	} else {
+		memcpy(pnntsd, pntsd, secdesclen);
+		if (uid != NO_CHANGE_32) { /* chown */
+			owner_sid_ptr = (struct cifs_sid *)((char *)pnntsd +
+					le32_to_cpu(pnntsd->osidoffset));
+			nowner_sid_ptr = kmalloc(sizeof(struct cifs_sid),
+								GFP_KERNEL);
+			if (!nowner_sid_ptr)
+				return -ENOMEM;
+			rc = id_to_sid(uid, SIDOWNER, nowner_sid_ptr);
+			if (rc) {
+				cFYI(1, "%s: Mapping error %d for owner id %d",
+						__func__, rc, uid);
+				kfree(nowner_sid_ptr);
+				return rc;
+			}
+			memcpy(owner_sid_ptr, nowner_sid_ptr,
+					sizeof(struct cifs_sid));
+			kfree(nowner_sid_ptr);
+			*aclflag = CIFS_ACL_OWNER;
+		}
+		if (gid != NO_CHANGE_32) { /* chgrp */
+			group_sid_ptr = (struct cifs_sid *)((char *)pnntsd +
+					le32_to_cpu(pnntsd->gsidoffset));
+			ngroup_sid_ptr = kmalloc(sizeof(struct cifs_sid),
+								GFP_KERNEL);
+			if (!ngroup_sid_ptr)
+				return -ENOMEM;
+			rc = id_to_sid(gid, SIDGROUP, ngroup_sid_ptr);
+			if (rc) {
+				cFYI(1, "%s: Mapping error %d for group id %d",
+						__func__, rc, gid);
+				kfree(ngroup_sid_ptr);
+				return rc;
+			}
+			memcpy(group_sid_ptr, ngroup_sid_ptr,
+					sizeof(struct cifs_sid));
+			kfree(ngroup_sid_ptr);
+			*aclflag = CIFS_ACL_GROUP;
+		}
+	}
 
 	return rc;
 }
@@ -1192,13 +1222,15 @@ struct cifs_ntsd *get_cifs_acl(struct cifs_sb_info *cifs_sb,
 	return pntsd;
 }
 
-static int set_cifs_acl_by_path(struct cifs_sb_info *cifs_sb, const char *path,
-		struct cifs_ntsd *pnntsd, u32 acllen)
+ /* Set an ACL on the server */
+int set_cifs_acl(struct cifs_ntsd *pnntsd, __u32 acllen,
+			struct inode *inode, const char *path, int aclflag)
 {
 	int oplock = 0;
-	int xid, rc, create_options = 0;
+	int xid, rc, access_flags, create_options = 0;
 	__u16 fid;
 	struct cifs_tcon *tcon;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 	struct tcon_link *tlink = cifs_sb_tlink(cifs_sb);
 
 	if (IS_ERR(tlink))
@@ -1210,15 +1242,20 @@ static int set_cifs_acl_by_path(struct cifs_sb_info *cifs_sb, const char *path,
 	if (backup_cred(cifs_sb))
 		create_options |= CREATE_OPEN_BACKUP_INTENT;
 
-	rc = CIFSSMBOpen(xid, tcon, path, FILE_OPEN, WRITE_DAC, create_options,
-			 &fid, &oplock, NULL, cifs_sb->local_nls,
-			 cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
+	if (aclflag == CIFS_ACL_OWNER || aclflag == CIFS_ACL_GROUP)
+		access_flags = WRITE_OWNER;
+	else
+		access_flags = WRITE_DAC;
+
+	rc = CIFSSMBOpen(xid, tcon, path, FILE_OPEN, access_flags,
+			create_options, &fid, &oplock, NULL, cifs_sb->local_nls,
+			cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
 	if (rc) {
 		cERROR(1, "Unable to open file to set ACL");
 		goto out;
 	}
 
-	rc = CIFSSMBSetCIFSACL(xid, tcon, fid, pnntsd, acllen);
+	rc = CIFSSMBSetCIFSACL(xid, tcon, fid, pnntsd, acllen, aclflag);
 	cFYI(DBG2, "SetCIFSACL rc = %d", rc);
 
 	CIFSSMBClose(xid, tcon, fid);
@@ -1228,17 +1265,6 @@ out:
 	return rc;
 }
 
-/* Set an ACL on the server */
-int set_cifs_acl(struct cifs_ntsd *pnntsd, __u32 acllen,
-				struct inode *inode, const char *path)
-{
-	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
-
-	cFYI(DBG2, "set ACL for %s from mode 0x%x", path, inode->i_mode);
-
-	return set_cifs_acl_by_path(cifs_sb, path, pnntsd, acllen);
-}
-
 /* Translate the CIFS ACL (simlar to NTFS ACL) for a file into mode bits */
 int
 cifs_acl_to_fattr(struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
@@ -1270,9 +1296,12 @@ cifs_acl_to_fattr(struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
 }
 
 /* Convert mode bits to an ACL so we can update the ACL on the server */
-int mode_to_cifs_acl(struct inode *inode, const char *path, __u64 nmode)
+int
+id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64 nmode,
+			uid_t uid, gid_t gid)
 {
 	int rc = 0;
+	int aclflag = CIFS_ACL_DACL; /* default flag to set */
 	__u32 secdesclen = 0;
 	struct cifs_ntsd *pntsd = NULL; /* acl obtained from server */
 	struct cifs_ntsd *pnntsd = NULL; /* modified acl to be sent to server */
@@ -1302,13 +1331,15 @@ int mode_to_cifs_acl(struct inode *inode, const char *path, __u64 nmode)
 			return -ENOMEM;
 		}
 
-		rc = build_sec_desc(pntsd, pnntsd, inode, nmode);
+		rc = build_sec_desc(pntsd, pnntsd, secdesclen, nmode, uid, gid,
+					&aclflag);
 
 		cFYI(DBG2, "build_sec_desc rc: %d", rc);
 
 		if (!rc) {
 			/* Set the security descriptor */
-			rc = set_cifs_acl(pnntsd, secdesclen, inode, path);
+			rc = set_cifs_acl(pnntsd, secdesclen, inode,
+						path, aclflag);
 			cFYI(DBG2, "set_cifs_acl rc: %d", rc);
 		}