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>

14 files changed, 144 insertions, 118 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 6dafa857bbb9..d3d9b4abb09b 100644
--- a/fs/btrfs/ioctl.c
+++ b/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;
diff --git a/fs/efivarfs/file.c b/fs/efivarfs/file.c
index 8e568428c88b..a3cc10b1bfe1 100644
--- a/fs/efivarfs/file.c
+++ b/fs/efivarfs/file.c
@@ -110,16 +110,22 @@ out_free:
         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
diff --git a/fs/ext2/ioctl.c b/fs/ext2/ioctl.c
index 0367c0039e68..1b853fb0b163 100644
--- a/fs/ext2/ioctl.c
+++ b/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;
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index e486e49b31ed..272b6e44191b 100644
--- a/fs/ext4/ioctl.c
+++ b/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
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index d174b1f8fd08..1cb0c3afd3dc 100644
--- a/fs/gfs2/file.c
+++ b/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)
diff --git a/fs/hfsplus/ioctl.c b/fs/hfsplus/ioctl.c
index 5e6502ef7415..ce15b9496b77 100644
--- a/fs/hfsplus/ioctl.c
+++ b/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)) {
diff --git a/fs/inode.c b/fs/inode.c
index df6542ec3b88..8072a09fd0b9 100644
--- a/fs/inode.c
+++ b/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);
diff --git a/fs/jfs/ioctl.c b/fs/jfs/ioctl.c
index ba34dae8bd9f..10ee0ecca1a8 100644
--- a/fs/jfs/ioctl.c
+++ b/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);
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 9b96d79eea6c..91b9dac6b2cc 100644
--- a/fs/nilfs2/ioctl.c
+++ b/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);
diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
index 994726ada857..d6f7b299eb23 100644
--- a/fs/ocfs2/ioctl.c
+++ b/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)) {
diff --git a/fs/orangefs/file.c b/fs/orangefs/file.c
index a35c17017210..679a3c8e4fb3 100644
--- a/fs/orangefs/file.c
+++ b/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);
         }
diff --git a/fs/reiserfs/ioctl.c b/fs/reiserfs/ioctl.c
index acbbaf7a0bb2..45e1a5d11af3 100644
--- a/fs/reiserfs/ioctl.c
+++ b/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;
diff --git a/fs/ubifs/ioctl.c b/fs/ubifs/ioctl.c
index 4f1a397fda69..034ad14710d1 100644
--- a/fs/ubifs/ioctl.c
+++ b/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);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f7fdfe93e25d..41d5175ffdd7 100644
--- a/include/linux/fs.h
+++ b/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 */