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>

fs/cifs/cifsacl.c

@@ -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;
-
+	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 +
 				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);
-
+		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 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,
+	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 @@ static int set_cifs_acl_by_path(struct cifs_sb_info *cifs_sb, const char *path,
 	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);
 		}
 

fs/cifs/cifsproto.h

@@ -146,11 +146,12 @@ extern int cifs_get_inode_info_unix(struct inode **pinode,
 extern int cifs_acl_to_fattr(struct cifs_sb_info *cifs_sb,
 			      struct cifs_fattr *fattr, struct inode *inode,
 			      const char *path, const __u16 *pfid);
-extern int mode_to_cifs_acl(struct inode *inode, const char *path, __u64);
+extern int id_mode_to_cifs_acl(struct inode *inode, const char *path, __u64,
+					uid_t, gid_t);
 extern struct cifs_ntsd *get_cifs_acl(struct cifs_sb_info *, struct inode *,
 					const char *, u32 *);
 extern int set_cifs_acl(struct cifs_ntsd *, __u32, struct inode *,
-				const char *);
+				const char *, int);
 
 extern void cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
 			       struct cifs_sb_info *cifs_sb);
@@ -420,7 +421,7 @@ extern int CIFSSMBSetEA(const int xid, struct cifs_tcon *tcon,
 extern int CIFSSMBGetCIFSACL(const int xid, struct cifs_tcon *tcon,
 			__u16 fid, struct cifs_ntsd **acl_inf, __u32 *buflen);
 extern int CIFSSMBSetCIFSACL(const int, struct cifs_tcon *, __u16,
-			struct cifs_ntsd *, __u32);
+			struct cifs_ntsd *, __u32, int);
 extern int CIFSSMBGetPosixACL(const int xid, struct cifs_tcon *tcon,
 		const unsigned char *searchName,
 		char *acl_inf, const int buflen, const int acl_type,

fs/cifs/cifssmb.c

@@ -3463,7 +3463,7 @@ CIFSSMBGetCIFSACL(const int xid, struct cifs_tcon *tcon, __u16 fid,
 
 int
 CIFSSMBSetCIFSACL(const int xid, struct cifs_tcon *tcon, __u16 fid,
-			struct cifs_ntsd *pntsd, __u32 acllen)
+			struct cifs_ntsd *pntsd, __u32 acllen, int aclflag)
 {
 	__u16 byte_count, param_count, data_count, param_offset, data_offset;
 	int rc = 0;
@@ -3500,7 +3500,7 @@ CIFSSMBSetCIFSACL(const int xid, struct cifs_tcon *tcon, __u16 fid,
 
 	pSMB->Fid = fid; /* file handle always le */
 	pSMB->Reserved2 = 0;
-	pSMB->AclFlags = cpu_to_le32(CIFS_ACL_DACL);
+	pSMB->AclFlags = cpu_to_le32(aclflag);
 
 	if (pntsd && acllen) {
 		memcpy((char *) &pSMBr->hdr.Protocol + data_offset,

fs/cifs/inode.c

@@ -2096,6 +2096,8 @@ static int
 cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs)
 {
 	int xid;
+	uid_t uid = NO_CHANGE_32;
+	gid_t gid = NO_CHANGE_32;
 	struct inode *inode = direntry->d_inode;
 	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 	struct cifsInodeInfo *cifsInode = CIFS_I(inode);
@@ -2146,13 +2148,25 @@ cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs)
 			goto cifs_setattr_exit;
 	}
 
-	/*
-	 * Without unix extensions we can't send ownership changes to the
-	 * server, so silently ignore them. This is consistent with how
-	 * local DOS/Windows filesystems behave (VFAT, NTFS, etc). With
-	 * CIFSACL support + proper Windows to Unix idmapping, we may be
-	 * able to support this in the future.
-	 */
+	if (attrs->ia_valid & ATTR_UID)
+		uid = attrs->ia_uid;
+
+	if (attrs->ia_valid & ATTR_GID)
+		gid = attrs->ia_gid;
+
+#ifdef CONFIG_CIFS_ACL
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL) {
+		if (uid != NO_CHANGE_32 || gid != NO_CHANGE_32) {
+			rc = id_mode_to_cifs_acl(inode, full_path, NO_CHANGE_64,
+							uid, gid);
+			if (rc) {
+				cFYI(1, "%s: Setting id failed with error: %d",
+					__func__, rc);
+				goto cifs_setattr_exit;
+			}
+		}
+	} else
+#endif /* CONFIG_CIFS_ACL */
 	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID))
 		attrs->ia_valid &= ~(ATTR_UID | ATTR_GID);
 
@@ -2161,15 +2175,12 @@ cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs)
 		attrs->ia_valid &= ~ATTR_MODE;
 
 	if (attrs->ia_valid & ATTR_MODE) {
-		cFYI(1, "Mode changed to 0%o", attrs->ia_mode);
 		mode = attrs->ia_mode;
-	}
-
-	if (attrs->ia_valid & ATTR_MODE) {
 		rc = 0;
 #ifdef CONFIG_CIFS_ACL
 		if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL) {
-			rc = mode_to_cifs_acl(inode, full_path, mode);
+			rc = id_mode_to_cifs_acl(inode, full_path, mode,
+						NO_CHANGE_32, NO_CHANGE_32);
 			if (rc) {
 				cFYI(1, "%s: Setting ACL failed with error: %d",
 					__func__, rc);

fs/cifs/xattr.c

@@ -178,7 +178,7 @@ int cifs_setxattr(struct dentry *direntry, const char *ea_name,
 #ifdef CONFIG_CIFS_ACL
 			memcpy(pacl, ea_value, value_size);
 			rc = set_cifs_acl(pacl, value_size,
-				direntry->d_inode, full_path);
+				direntry->d_inode, full_path, CIFS_ACL_DACL);
 			if (rc == 0) /* force revalidate of the inode */
 				CIFS_I(direntry->d_inode)->time = 0;
 			kfree(pacl);