[CIFS] Allow to set extended attribute cifs_acl (try #2)

Allow setting cifs_acl on the server.
Pass on to the server the ACL blob generated by an application.
cifs is just a pass-through, it does not monitor or inspect the contents
of the blob, server decides whether to enforce/apply the ACL blob composed
by an application.
If setting of ACL is succeessful, mark the inode for revalidation.

Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifsacl.c

@@ -688,7 +688,7 @@ out:
 }
 
 /* Set an ACL on the server */
-static int set_cifs_acl(struct cifs_ntsd *pnntsd, __u32 acllen,
+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);

fs/cifs/cifsproto.h

@@ -143,6 +143,8 @@ extern int cifs_acl_to_fattr(struct cifs_sb_info *cifs_sb,
 extern int mode_to_cifs_acl(struct inode *inode, const char *path, __u64);
 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 *);
 
 extern int cifs_mount(struct super_block *, struct cifs_sb_info *, char *,
 			const char *);

fs/cifs/xattr.c

@@ -112,6 +112,7 @@ int cifs_setxattr(struct dentry *direntry, const char *ea_name,
 	struct cifsTconInfo *pTcon;
 	struct super_block *sb;
 	char *full_path;
+	struct cifs_ntsd *pacl;
 
 	if (direntry == NULL)
 		return -EIO;
@@ -166,6 +167,25 @@ int cifs_setxattr(struct dentry *direntry, const char *ea_name,
 		rc = CIFSSMBSetEA(xid, pTcon, full_path, ea_name, ea_value,
 			(__u16)value_size, cifs_sb->local_nls,
 			cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);
+	} else if (strncmp(ea_name, CIFS_XATTR_CIFS_ACL,
+			strlen(CIFS_XATTR_CIFS_ACL)) == 0) {
+		pacl = kmalloc(value_size, GFP_KERNEL);
+		if (!pacl) {
+			cFYI(1, "%s: Can't allocate memory for ACL",
+					__func__);
+			rc = -ENOMEM;
+		} else {
+#ifdef CONFIG_CIFS_ACL
+			memcpy(pacl, ea_value, value_size);
+			rc = set_cifs_acl(pacl, value_size,
+				direntry->d_inode, full_path);
+			if (rc == 0) /* force revalidate of the inode */
+				CIFS_I(direntry->d_inode)->time = 0;
+			kfree(pacl);
+#else
+			cFYI(1, "Set CIFS ACL not supported yet");
+#endif /* CONFIG_CIFS_ACL */
+		}
 	} else {
 		int temp;
 		temp = strncmp(ea_name, POSIX_ACL_XATTR_ACCESS,