vfs: create a generic checking and prep function for FS_IOC_SETFLAGS

Create a generic function to check incoming FS_IOC_SETFLAGS flag values
and later prepare the inode for updates so that we can standardize the
implementations that follow ext4's flag values.

Note that the efivarfs implementation no longer fails a no-op SETFLAGS
without CAP_LINUX_IMMUTABLE since that's the behavior in ext*.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: David Sterba <dsterba@suse.com>
Reviewed-by: Bob Peterson <rpeterso@redhat.com>

fs/btrfs/ioctl.c

@@ -187,7 +187,7 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
 	struct btrfs_inode *binode = BTRFS_I(inode);
 	struct btrfs_root *root = binode->root;
 	struct btrfs_trans_handle *trans;
-	unsigned int fsflags;
+	unsigned int fsflags, old_fsflags;
 	int ret;
 	const char *comp = NULL;
 	u32 binode_flags = binode->flags;
@@ -212,13 +212,10 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
 	inode_lock(inode);
 
 	fsflags = btrfs_mask_fsflags_for_type(inode, fsflags);
-	if ((fsflags ^ btrfs_inode_flags_to_fsflags(binode->flags)) &
-	    (FS_APPEND_FL | FS_IMMUTABLE_FL)) {
-		if (!capable(CAP_LINUX_IMMUTABLE)) {
-			ret = -EPERM;
-			goto out_unlock;
-		}
-	}
+	old_fsflags = btrfs_inode_flags_to_fsflags(binode->flags);
+	ret = vfs_ioc_setflags_prepare(inode, old_fsflags, fsflags);
+	if (ret)
+		goto out_unlock;
 
 	if (fsflags & FS_SYNC_FL)
 		binode_flags |= BTRFS_INODE_SYNC;

fs/efivarfs/file.c

@@ -110,16 +110,22 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 	return size;
 }
 
-static int
-efivarfs_ioc_getxflags(struct file *file, void __user *arg)
+static inline unsigned int efivarfs_getflags(struct inode *inode)
 {
-	struct inode *inode = file->f_mapping->host;
 	unsigned int i_flags;
 	unsigned int flags = 0;
 
 	i_flags = inode->i_flags;
 	if (i_flags & S_IMMUTABLE)
 		flags |= FS_IMMUTABLE_FL;
+	return flags;
+}
+
+static int
+efivarfs_ioc_getxflags(struct file *file, void __user *arg)
+{
+	struct inode *inode = file->f_mapping->host;
+	unsigned int flags = efivarfs_getflags(inode);
 
 	if (copy_to_user(arg, &flags, sizeof(flags)))
 		return -EFAULT;
@@ -132,6 +138,7 @@ efivarfs_ioc_setxflags(struct file *file, void __user *arg)
 	struct inode *inode = file->f_mapping->host;
 	unsigned int flags;
 	unsigned int i_flags = 0;
+	unsigned int oldflags = efivarfs_getflags(inode);
 	int error;
 
 	if (!inode_owner_or_capable(inode))
@@ -143,9 +150,6 @@ efivarfs_ioc_setxflags(struct file *file, void __user *arg)
 	if (flags & ~FS_IMMUTABLE_FL)
 		return -EOPNOTSUPP;
 
-	if (!capable(CAP_LINUX_IMMUTABLE))
-		return -EPERM;
-
 	if (flags & FS_IMMUTABLE_FL)
 		i_flags |= S_IMMUTABLE;
 
@@ -155,12 +159,16 @@ efivarfs_ioc_setxflags(struct file *file, void __user *arg)
 		return error;
 
 	inode_lock(inode);
+
+	error = vfs_ioc_setflags_prepare(inode, oldflags, flags);
+	if (error)
+		goto out;
+
 	inode_set_flags(inode, i_flags, S_IMMUTABLE);
+out:
 	inode_unlock(inode);
-
 	mnt_drop_write_file(file);
-
-	return 0;
+	return error;
 }
 
 static long

fs/ext2/ioctl.c

@@ -60,18 +60,10 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		}
 		oldflags = ei->i_flags;
 
-		/*
-		 * The IMMUTABLE and APPEND_ONLY flags can only be changed by
-		 * the relevant capability.
-		 *
-		 * This test looks nicer. Thanks to Pauline Middelink
-		 */
-		if ((flags ^ oldflags) & (EXT2_APPEND_FL | EXT2_IMMUTABLE_FL)) {
-			if (!capable(CAP_LINUX_IMMUTABLE)) {
-				inode_unlock(inode);
-				ret = -EPERM;
-				goto setflags_out;
-			}
+		ret = vfs_ioc_setflags_prepare(inode, oldflags, flags);
+		if (ret) {
+			inode_unlock(inode);
+			goto setflags_out;
 		}
 
 		flags = flags & EXT2_FL_USER_MODIFIABLE;

fs/ext4/ioctl.c

@@ -289,16 +289,9 @@ static int ext4_ioctl_setflags(struct inode *inode,
 	/* The JOURNAL_DATA flag is modifiable only by root */
 	jflag = flags & EXT4_JOURNAL_DATA_FL;
 
-	/*
-	 * The IMMUTABLE and APPEND_ONLY flags can only be changed by
-	 * the relevant capability.
-	 *
-	 * This test looks nicer. Thanks to Pauline Middelink
-	 */
-	if ((flags ^ oldflags) & (EXT4_APPEND_FL | EXT4_IMMUTABLE_FL)) {
-		if (!capable(CAP_LINUX_IMMUTABLE))
-			goto flags_out;
-	}
+	err = vfs_ioc_setflags_prepare(inode, oldflags, flags);
+	if (err)
+		goto flags_out;
 
 	/*
 	 * The JOURNAL_DATA flag can only be changed by

fs/gfs2/file.c

@@ -136,27 +136,36 @@ static struct {
 	{FS_JOURNAL_DATA_FL, GFS2_DIF_JDATA | GFS2_DIF_INHERIT_JDATA},
 };
 
+static inline u32 gfs2_gfsflags_to_fsflags(struct inode *inode, u32 gfsflags)
+{
+	int i;
+	u32 fsflags = 0;
+
+	if (S_ISDIR(inode->i_mode))
+		gfsflags &= ~GFS2_DIF_JDATA;
+	else
+		gfsflags &= ~GFS2_DIF_INHERIT_JDATA;
+
+	for (i = 0; i < ARRAY_SIZE(fsflag_gfs2flag); i++)
+		if (gfsflags & fsflag_gfs2flag[i].gfsflag)
+			fsflags |= fsflag_gfs2flag[i].fsflag;
+	return fsflags;
+}
+
 static int gfs2_get_flags(struct file *filp, u32 __user *ptr)
 {
 	struct inode *inode = file_inode(filp);
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_holder gh;
-	int i, error;
-	u32 gfsflags, fsflags = 0;
+	int error;
+	u32 fsflags;
 
 	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
 	error = gfs2_glock_nq(&gh);
 	if (error)
 		goto out_uninit;
 
-	gfsflags = ip->i_diskflags;
-	if (S_ISDIR(inode->i_mode))
-		gfsflags &= ~GFS2_DIF_JDATA;
-	else
-		gfsflags &= ~GFS2_DIF_INHERIT_JDATA;
-	for (i = 0; i < ARRAY_SIZE(fsflag_gfs2flag); i++)
-		if (gfsflags & fsflag_gfs2flag[i].gfsflag)
-			fsflags |= fsflag_gfs2flag[i].fsflag;
+	fsflags = gfs2_gfsflags_to_fsflags(inode, ip->i_diskflags);
 
 	if (put_user(fsflags, ptr))
 		error = -EFAULT;
@@ -200,9 +209,11 @@ void gfs2_set_inode_flags(struct inode *inode)
  * @filp: file pointer
  * @reqflags: The flags to set
  * @mask: Indicates which flags are valid
+ * @fsflags: The FS_* inode flags passed in
  *
  */
-static int do_gfs2_set_flags(struct file *filp, u32 reqflags, u32 mask)
+static int do_gfs2_set_flags(struct file *filp, u32 reqflags, u32 mask,
+			     const u32 fsflags)
 {
 	struct inode *inode = file_inode(filp);
 	struct gfs2_inode *ip = GFS2_I(inode);
@@ -210,7 +221,7 @@ static int do_gfs2_set_flags(struct file *filp, u32 reqflags, u32 mask)
 	struct buffer_head *bh;
 	struct gfs2_holder gh;
 	int error;
-	u32 new_flags, flags;
+	u32 new_flags, flags, oldflags;
 
 	error = mnt_want_write_file(filp);
 	if (error)
@@ -220,6 +231,11 @@ static int do_gfs2_set_flags(struct file *filp, u32 reqflags, u32 mask)
 	if (error)
 		goto out_drop_write;
 
+	oldflags = gfs2_gfsflags_to_fsflags(inode, ip->i_diskflags);
+	error = vfs_ioc_setflags_prepare(inode, oldflags, fsflags);
+	if (error)
+		goto out;
+
 	error = -EACCES;
 	if (!inode_owner_or_capable(inode))
 		goto out;
@@ -308,7 +324,7 @@ static int gfs2_set_flags(struct file *filp, u32 __user *ptr)
 		mask &= ~(GFS2_DIF_TOPDIR | GFS2_DIF_INHERIT_JDATA);
 	}
 
-	return do_gfs2_set_flags(filp, gfsflags, mask);
+	return do_gfs2_set_flags(filp, gfsflags, mask, fsflags);
 }
 
 static int gfs2_getlabel(struct file *filp, char __user *label)

fs/hfsplus/ioctl.c

@@ -57,9 +57,8 @@ static int hfsplus_ioctl_bless(struct file *file, int __user *user_flags)
 	return 0;
 }
 
-static int hfsplus_ioctl_getflags(struct file *file, int __user *user_flags)
+static inline unsigned int hfsplus_getflags(struct inode *inode)
 {
-	struct inode *inode = file_inode(file);
 	struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
 	unsigned int flags = 0;
 
@@ -69,6 +68,13 @@ static int hfsplus_ioctl_getflags(struct file *file, int __user *user_flags)
 		flags |= FS_APPEND_FL;
 	if (hip->userflags & HFSPLUS_FLG_NODUMP)
 		flags |= FS_NODUMP_FL;
+	return flags;
+}
+
+static int hfsplus_ioctl_getflags(struct file *file, int __user *user_flags)
+{
+	struct inode *inode = file_inode(file);
+	unsigned int flags = hfsplus_getflags(inode);
 
 	return put_user(flags, user_flags);
 }
@@ -78,6 +84,7 @@ static int hfsplus_ioctl_setflags(struct file *file, int __user *user_flags)
 	struct inode *inode = file_inode(file);
 	struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
 	unsigned int flags, new_fl = 0;
+	unsigned int oldflags = hfsplus_getflags(inode);
 	int err = 0;
 
 	err = mnt_want_write_file(file);
@@ -96,13 +103,9 @@ static int hfsplus_ioctl_setflags(struct file *file, int __user *user_flags)
 
 	inode_lock(inode);
 
-	if ((flags & (FS_IMMUTABLE_FL|FS_APPEND_FL)) ||
-	    inode->i_flags & (S_IMMUTABLE|S_APPEND)) {
-		if (!capable(CAP_LINUX_IMMUTABLE)) {
-			err = -EPERM;
-			goto out_unlock_inode;
-		}
-	}
+	err = vfs_ioc_setflags_prepare(inode, oldflags, flags);
+	if (err)
+		goto out_unlock_inode;
 
 	/* don't silently ignore unsupported ext2 flags */
 	if (flags & ~(FS_IMMUTABLE_FL|FS_APPEND_FL|FS_NODUMP_FL)) {

fs/inode.c

@@ -2170,3 +2170,27 @@ struct timespec64 current_time(struct inode *inode)
 	return timespec64_trunc(now, inode->i_sb->s_time_gran);
 }
 EXPORT_SYMBOL(current_time);
+
+/*
+ * Generic function to check FS_IOC_SETFLAGS values and reject any invalid
+ * configurations.
+ *
+ * Note: the caller should be holding i_mutex, or else be sure that they have
+ * exclusive access to the inode structure.
+ */
+int vfs_ioc_setflags_prepare(struct inode *inode, unsigned int oldflags,
+			     unsigned int flags)
+{
+	/*
+	 * The IMMUTABLE and APPEND_ONLY flags can only be changed by
+	 * the relevant capability.
+	 *
+	 * This test looks nicer. Thanks to Pauline Middelink
+	 */
+	if ((flags ^ oldflags) & (FS_APPEND_FL | FS_IMMUTABLE_FL) &&
+	    !capable(CAP_LINUX_IMMUTABLE))
+		return -EPERM;
+
+	return 0;
+}
+EXPORT_SYMBOL(vfs_ioc_setflags_prepare);

fs/jfs/ioctl.c

@@ -98,24 +98,16 @@ long jfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		/* Lock against other parallel changes of flags */
 		inode_lock(inode);
 
-		oldflags = jfs_inode->mode2;
-
-		/*
-		 * The IMMUTABLE and APPEND_ONLY flags can only be changed by
-		 * the relevant capability.
-		 */
-		if ((oldflags & JFS_IMMUTABLE_FL) ||
-			((flags ^ oldflags) &
-			(JFS_APPEND_FL | JFS_IMMUTABLE_FL))) {
-			if (!capable(CAP_LINUX_IMMUTABLE)) {
-				inode_unlock(inode);
-				err = -EPERM;
-				goto setflags_out;
-			}
+		oldflags = jfs_map_ext2(jfs_inode->mode2 & JFS_FL_USER_VISIBLE,
+					0);
+		err = vfs_ioc_setflags_prepare(inode, oldflags, flags);
+		if (err) {
+			inode_unlock(inode);
+			goto setflags_out;
 		}
 
 		flags = flags & JFS_FL_USER_MODIFIABLE;
-		flags |= oldflags & ~JFS_FL_USER_MODIFIABLE;
+		flags |= jfs_inode->mode2 & ~JFS_FL_USER_MODIFIABLE;
 		jfs_inode->mode2 = flags;
 
 		jfs_set_inode_flags(inode);

fs/nilfs2/ioctl.c

@@ -148,13 +148,8 @@ static int nilfs_ioctl_setflags(struct inode *inode, struct file *filp,
 
 	oldflags = NILFS_I(inode)->i_flags;
 
-	/*
-	 * The IMMUTABLE and APPEND_ONLY flags can only be changed by the
-	 * relevant capability.
-	 */
-	ret = -EPERM;
-	if (((flags ^ oldflags) & (FS_APPEND_FL | FS_IMMUTABLE_FL)) &&
-	    !capable(CAP_LINUX_IMMUTABLE))
+	ret = vfs_ioc_setflags_prepare(inode, oldflags, flags);
+	if (ret)
 		goto out;
 
 	ret = nilfs_transaction_begin(inode->i_sb, &ti, 0);

fs/ocfs2/ioctl.c

@@ -106,16 +106,9 @@ static int ocfs2_set_inode_attr(struct inode *inode, unsigned flags,
 	flags = flags & mask;
 	flags |= oldflags & ~mask;
 
-	/*
-	 * The IMMUTABLE and APPEND_ONLY flags can only be changed by
-	 * the relevant capability.
-	 */
-	status = -EPERM;
-	if ((oldflags & OCFS2_IMMUTABLE_FL) || ((flags ^ oldflags) &
-		(OCFS2_APPEND_FL | OCFS2_IMMUTABLE_FL))) {
-		if (!capable(CAP_LINUX_IMMUTABLE))
-			goto bail_unlock;
-	}
+	status = vfs_ioc_setflags_prepare(inode, oldflags, flags);
+	if (status)
+		goto bail_unlock;
 
 	handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
 	if (IS_ERR(handle)) {

fs/orangefs/file.c

@@ -357,11 +357,28 @@ static ssize_t orangefs_file_write_iter(struct kiocb *iocb,
 	return ret;
 }
 
+static int orangefs_getflags(struct inode *inode, unsigned long *uval)
+{
+	__u64 val = 0;
+	int ret;
+
+	ret = orangefs_inode_getxattr(inode,
+				      "user.pvfs2.meta_hint",
+				      &val, sizeof(val));
+	if (ret < 0 && ret != -ENODATA)
+		return ret;
+	else if (ret == -ENODATA)
+		val = 0;
+	*uval = val;
+	return 0;
+}
+
 /*
  * Perform a miscellaneous operation on a file.
  */
 static long orangefs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
+	struct inode *inode = file_inode(file);
 	int ret = -ENOTTY;
 	__u64 val = 0;
 	unsigned long uval;
@@ -375,20 +392,16 @@ static long orangefs_ioctl(struct file *file, unsigned int cmd, unsigned long ar
 	 * and append flags
 	 */
 	if (cmd == FS_IOC_GETFLAGS) {
-		val = 0;
-		ret = orangefs_inode_getxattr(file_inode(file),
-					      "user.pvfs2.meta_hint",
-					      &val, sizeof(val));
-		if (ret < 0 && ret != -ENODATA)
+		ret = orangefs_getflags(inode, &uval);
+		if (ret)
 			return ret;
-		else if (ret == -ENODATA)
-			val = 0;
-		uval = val;
 		gossip_debug(GOSSIP_FILE_DEBUG,
 			     "orangefs_ioctl: FS_IOC_GETFLAGS: %llu\n",
 			     (unsigned long long)uval);
 		return put_user(uval, (int __user *)arg);
 	} else if (cmd == FS_IOC_SETFLAGS) {
+		unsigned long old_uval;
+
 		ret = 0;
 		if (get_user(uval, (int __user *)arg))
 			return -EFAULT;
@@ -404,11 +417,17 @@ static long orangefs_ioctl(struct file *file, unsigned int cmd, unsigned long ar
 			gossip_err("orangefs_ioctl: the FS_IOC_SETFLAGS only supports setting one of FS_IMMUTABLE_FL|FS_APPEND_FL|FS_NOATIME_FL\n");
 			return -EINVAL;
 		}
+		ret = orangefs_getflags(inode, &old_uval);
+		if (ret)
+			return ret;
+		ret = vfs_ioc_setflags_prepare(inode, old_uval, uval);
+		if (ret)
+			return ret;
 		val = uval;
 		gossip_debug(GOSSIP_FILE_DEBUG,
 			     "orangefs_ioctl: FS_IOC_SETFLAGS: %llu\n",
 			     (unsigned long long)val);
-		ret = orangefs_inode_setxattr(file_inode(file),
+		ret = orangefs_inode_setxattr(inode,
 					      "user.pvfs2.meta_hint",
 					      &val, sizeof(val), 0);
 	}

fs/reiserfs/ioctl.c

@@ -74,13 +74,11 @@ long reiserfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 				err = -EPERM;
 				goto setflags_out;
 			}
-			if (((flags ^ REISERFS_I(inode)->
-			      i_attrs) & (REISERFS_IMMUTABLE_FL |
-					  REISERFS_APPEND_FL))
-			    && !capable(CAP_LINUX_IMMUTABLE)) {
-				err = -EPERM;
+			err = vfs_ioc_setflags_prepare(inode,
+						     REISERFS_I(inode)->i_attrs,
+						     flags);
+			if (err)
 				goto setflags_out;
-			}
 			if ((flags & REISERFS_NOTAIL_FL) &&
 			    S_ISREG(inode->i_mode)) {
 				int result;

fs/ubifs/ioctl.c

@@ -107,18 +107,11 @@ static int setflags(struct inode *inode, int flags)
 	if (err)
 		return err;
 
-	/*
-	 * The IMMUTABLE and APPEND_ONLY flags can only be changed by
-	 * the relevant capability.
-	 */
 	mutex_lock(&ui->ui_mutex);
 	oldflags = ubifs2ioctl(ui->flags);
-	if ((flags ^ oldflags) & (FS_APPEND_FL | FS_IMMUTABLE_FL)) {
-		if (!capable(CAP_LINUX_IMMUTABLE)) {
-			err = -EPERM;
-			goto out_unlock;
-		}
-	}
+	err = vfs_ioc_setflags_prepare(inode, oldflags, flags);
+	if (err)
+		goto out_unlock;
 
 	ui->flags = ioctl2ubifs(flags);
 	ubifs_set_inode_flags(inode);

include/linux/fs.h

@@ -3546,4 +3546,7 @@ static inline struct sock *io_uring_get_socket(struct file *file)
 }
 #endif
 
+int vfs_ioc_setflags_prepare(struct inode *inode, unsigned int oldflags,
+			     unsigned int flags);
+
 #endif /* _LINUX_FS_H */