fuse2fs: refactor sysadmin predicate

Refactor the code that decides if an access is being made by the
superuser into a helper, which we'll use to fix more permissions
problems in the next patch.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/174553065355.1161102.13914905314262828953.stgit@frogsfrogsfrogs
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 8664745276afc820f5f9e6359c2b986fed9ad83f..dd7559bb2af2b3dd1f517af78276f21462eec7b4 100644 (file)
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -484,6 +484,13 @@ static int fs_writeable(ext2_filsys fs)
        return (fs->flags & EXT2_FLAG_RW) && (fs->super->s_error_count == 0);
 }
 
+static inline int is_superuser(struct fuse2fs *ff, struct fuse_context *ctxt)
+{
+       if (ff->fakeroot)
+               return 1;
+       return ctxt->uid == 0;
+}
+
 static int check_inum_access(ext2_filsys fs, ext2_ino_t ino, mode_t mask)
 {
        struct fuse_context *ctxt = fuse_get_context();
@@ -517,7 +524,7 @@ static int check_inum_access(ext2_filsys fs, ext2_ino_t ino, mode_t mask)
                return -EACCES;
 
        /* Figure out what root's allowed to do */
-       if (ff->fakeroot || ctxt->uid == 0) {
+       if (is_superuser(ff, ctxt)) {
                /* Non-file access always ok */
                if (!LINUX_S_ISREG(inode.i_mode))
                        return 0;
@@ -1801,7 +1808,7 @@ static int op_chmod(const char *path, mode_t mode
                goto out;
        }
 
-       if (!ff->fakeroot && ctxt->uid != 0 && ctxt->uid != inode_uid(inode)) {
+       if (!is_superuser(ff, ctxt) && ctxt->uid != inode_uid(inode)) {
                ret = -EPERM;
                goto out;
        }
@@ -1811,7 +1818,7 @@ static int op_chmod(const char *path, mode_t mode
         * of the user's groups, but FUSE only tells us about the primary
         * group.
         */
-       if (!ff->fakeroot && ctxt->uid != 0 && ctxt->gid != inode_gid(inode))
+       if (!is_superuser(ff, ctxt) && ctxt->gid != inode_gid(inode))
                mode &= ~S_ISGID;
 
        inode.i_mode &= ~0xFFF;
@@ -1868,7 +1875,7 @@ static int op_chown(const char *path, uid_t owner, gid_t group
        /* FUSE seems to feed us ~0 to mean "don't change" */
        if (owner != (uid_t) ~0) {
                /* Only root gets to change UID. */
-               if (!ff->fakeroot && ctxt->uid != 0 &&
+               if (!is_superuser(ff, ctxt) &&
                    !(inode_uid(inode) == ctxt->uid && owner == ctxt->uid)) {
                        ret = -EPERM;
                        goto out;
@@ -1879,7 +1886,7 @@ static int op_chown(const char *path, uid_t owner, gid_t group
 
        if (group != (gid_t) ~0) {
                /* Only root or the owner get to change GID. */
-               if (!ff->fakeroot && ctxt->uid != 0 &&
+               if (!is_superuser(ff, ctxt) &&
                    inode_uid(inode) != ctxt->uid) {
                        ret = -EPERM;
                        goto out;
@@ -3044,7 +3051,7 @@ static int ioctl_setflags(struct fuse2fs *ff, struct fuse2fs_file_handle *fh,
        if (err)
                return translate_error(fs, fh->ino, err);
 
-       if (!ff->fakeroot && ctxt->uid != 0 && inode_uid(inode) != ctxt->uid)
+       if (!is_superuser(ff, ctxt) && inode_uid(inode) != ctxt->uid)
                return -EPERM;
 
        ret = set_iflags(&inode, flags);
@@ -3100,7 +3107,7 @@ static int ioctl_setversion(struct fuse2fs *ff, struct fuse2fs_file_handle *fh,
        if (err)
                return translate_error(fs, fh->ino, err);
 
-       if (!ff->fakeroot && ctxt->uid != 0 && inode_uid(inode) != ctxt->uid)
+       if (!is_superuser(ff, ctxt) && inode_uid(inode) != ctxt->uid)
                return -EPERM;
 
        inode.i_generation = generation;
@@ -3206,7 +3213,7 @@ static int ioctl_fssetxattr(struct fuse2fs *ff, struct fuse2fs_file_handle *fh,
        if (err)
                return translate_error(fs, fh->ino, err);
 
-       if (!ff->fakeroot && ctxt->uid != 0 && inode_uid(inode) != ctxt->uid)
+       if (!is_superuser(ff, ctxt) && inode_uid(inode) != ctxt->uid)
                return -EPERM;
 
        ret = set_iflags(&inode, flags);