executor/common_linux.h: open target dir inside syz_mount_image()

Refactor syz_mount_image() to support filesystems not requiring a
backing device and filesystem image (e.g. FUSE). To do that, we check for
the presence of the pointer to the array of struct fs_image_segment: if
missingi, there is no need to setup the loop device and we can proceed
directly with the mount() syscall.
Add syz_mount_image$fuse() (specialization for FUSE) inside
sys/linux/fs_fuse.txt.

3 files changed, 33 insertions, 24 deletions

diff --git a/sys/linux/filesystem.txt b/sys/linux/filesystem.txt
index f6f952196..2e5d29753 100644
--- a/sys/linux/filesystem.txt
+++ b/sys/linux/filesystem.txt
@@ -64,31 +64,31 @@ syz_read_part_table(size intptr, nsegs len[segments], segments ptr[in, array[fs_
 
 define SYZ_MOUNT_IMAGE_TIMEOUT	50
 
-syz_mount_image$vfat(fs ptr[in, string["vfat"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[vfat_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$msdos(fs ptr[in, string["msdos"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[msdos_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$bfs(fs ptr[in, string["bfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts const[0]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$xfs(fs ptr[in, string["xfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[xfs_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$minix(fs ptr[in, string["minix"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts const[0]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$reiserfs(fs ptr[in, string["reiserfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[reiserfs_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$hfs(fs ptr[in, string["hfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[hfs_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$hfsplus(fs ptr[in, string["hfsplus"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[hfsplus_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$iso9660(fs ptr[in, string["iso9660"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[iso9660_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$gfs2(fs ptr[in, string["gfs2"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[gfs2_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$jfs(fs ptr[in, string["jfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[jfs_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$btrfs(fs ptr[in, string["btrfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[btrfs_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$ntfs(fs ptr[in, string["ntfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[ntfs_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$ext4(fs ptr[in, string[ext4_types]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[ext4_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$f2fs(fs ptr[in, string["f2fs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[f2fs_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$ocfs2(fs ptr[in, string["ocfs2"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, string]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$nfs(fs ptr[in, string["nfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, string]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$nfs4(fs ptr[in, string["nfs4"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, string]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$cifs(fs ptr[in, string["cifs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, string]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$ceph(fs ptr[in, string["ceph"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, string]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$erofs(fs ptr[in, string["erofs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[erofs_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$exfat(fs ptr[in, string["exfat"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[exfat_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
-syz_mount_image$afs(fs ptr[in, string["afs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[afs_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$vfat(fs ptr[in, string["vfat"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[vfat_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$msdos(fs ptr[in, string["msdos"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[msdos_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$bfs(fs ptr[in, string["bfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts const[0]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$xfs(fs ptr[in, string["xfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[xfs_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$minix(fs ptr[in, string["minix"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts const[0]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$reiserfs(fs ptr[in, string["reiserfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[reiserfs_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$hfs(fs ptr[in, string["hfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[hfs_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$hfsplus(fs ptr[in, string["hfsplus"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[hfsplus_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$iso9660(fs ptr[in, string["iso9660"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[iso9660_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$gfs2(fs ptr[in, string["gfs2"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[gfs2_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$jfs(fs ptr[in, string["jfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[jfs_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$btrfs(fs ptr[in, string["btrfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[btrfs_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$ntfs(fs ptr[in, string["ntfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[ntfs_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$ext4(fs ptr[in, string[ext4_types]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[ext4_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$f2fs(fs ptr[in, string["f2fs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[f2fs_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$ocfs2(fs ptr[in, string["ocfs2"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, string]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$nfs(fs ptr[in, string["nfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, string]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$nfs4(fs ptr[in, string["nfs4"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, string]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$cifs(fs ptr[in, string["cifs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, string]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$ceph(fs ptr[in, string["ceph"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, string]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$erofs(fs ptr[in, string["erofs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[erofs_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$exfat(fs ptr[in, string["exfat"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[exfat_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$afs(fs ptr[in, string["afs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[afs_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
 # Note: tmpfs does not need an image, but we use this in tests.
-syz_mount_image$tmpfs(fs ptr[in, string["tmpfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[tmpfs_options]]) (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
+syz_mount_image$tmpfs(fs ptr[in, string["tmpfs"]], dir ptr[in, filename], size intptr, nsegs len[segments], segments ptr[in, array[fs_image_segment]], flags flags[mount_flags], opts ptr[in, fs_options[tmpfs_options]]) fd_dir (timeout[SYZ_MOUNT_IMAGE_TIMEOUT])
 
 fs_image_segment {
 	data	ptr[in, array[int8]]
diff --git a/sys/linux/fs_fuse.txt b/sys/linux/fs_fuse.txt
index ce75b6d6b..9b1364c3e 100644
--- a/sys/linux/fs_fuse.txt
+++ b/sys/linux/fs_fuse.txt
@@ -41,6 +41,7 @@ write$FUSE_NOTIFY_STORE(fd fd_fuse, arg ptr[in, fuse_notify[FUSE_NOTIFY_STORE, f
 write$FUSE_NOTIFY_RETRIEVE(fd fd_fuse, arg ptr[in, fuse_notify[FUSE_NOTIFY_RETRIEVE, fuse_notify_retrieve_out]], len bytesize[arg])
 write$FUSE_NOTIFY_DELETE(fd fd_fuse, arg ptr[in, fuse_notify[FUSE_NOTIFY_DELETE, fuse_notify_delete_out]], len bytesize[arg])
 
+syz_mount_image$fuse(fs ptr[in, string["fuse"]], dir ptr[in, filename], size const[0], nsegs const[0], segments const[0], flags flags[mount_flags], opts ptr[in, fuse_options]) fd_dir
 syz_fuse_handle_req(fd fd_fuse, buf ptr[in, read_buffer], len bytesize[buf], res ptr[in, syz_fuse_req_out])
 
 type fuse_ino int64[0:6]
diff --git a/sys/linux/test/syz_mount_image_fuse b/sys/linux/test/syz_mount_image_fuse
new file mode 100644
index 000000000..9b2c0db17
--- /dev/null
+++ b/sys/linux/test/syz_mount_image_fuse
@@ -0,0 +1,8 @@
+r0 = openat$fuse(0xffffffffffffff9c, &AUTO='/dev/fuse\x00', 0x2, 0x0)
+r1 = getuid()
+r2 = getgid()
+r3 = syz_mount_image$fuse(&AUTO='fuse\x00', &AUTO='./file0\x00', 0x0, 0x0, 0x0, 0x0, &AUTO={{'fd', 0x3d, r0}, 0x2c, {'rootmode', 0x3d, 0x4000}, 0x2c, {'user_id', 0x3d, r1}, 0x2c, {'group_id', 0x3d, r2}, 0x2c, {[], [], 0x0}})
+# FUSE_INIT
+syz_fuse_handle_req(r0, &AUTO=""/8192, AUTO, &AUTO={&AUTO={AUTO, 0x0, 0x0, {AUTO, AUTO, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, AUTO, AUTO, [0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0]}}, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0})
+# FUSE_OPENDIR
+syz_fuse_handle_req(r0, &AUTO=""/8192, AUTO, &AUTO={0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, &AUTO={AUTO, 0x0, 0x0, {0x0, 0x0, 0x0}}, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0})