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authorMichael Weiß <michael.weiss@aisec.fraunhofer.de>2022-10-24 21:15:52 +0200
committerChristian Brauner (Microsoft) <brauner@kernel.org>2022-11-07 10:24:22 +0100
commit42da66ac7bcb19181385e851094ceedfe7c81984 (patch)
tree8aa20b43ac0678d30061832706ff8c74b469c02f /fs/squashfs
parent9abf2313adc1ca1b6180c508c25f22f9395cc780 (diff)
squashfs: enable idmapped mounts
For squashfs all needed functionality for idmapped mounts is already implemented by the generic handlers in the VFS. Thus, it is sufficient to just enable the corresponding FS_ALLOW_IDMAP flag to support idmapped mounts. We use this for unprivileged (user namespaced) containers based on squashfs images as rootfs in GyroidOS. A simple test using the mount-idmapped tool executed as user with uid=1000 looks as follows: $ mkdir test $ echo "test" > test/test_file $ mksquashfs test/ fs.img $ sudo mkdir /mnt/test $ sudo mkdir /mnt/mapped $ sudo mount fs.img -o loop /mnt/test/ $ sudo ./mount-idmapped --map-mount b:1000:2000:1 /mnt/test/ /mnt/mapped/ $ mount | tail -n2 fs.img on /mnt/test type squashfs (ro,relatime,errors=continue) fs.img on /mnt/mapped type squashfs (ro,relatime,idmapped,errors=continue) $ ls -lan /mnt/test/ total 5 drwxr-xr-x 2 1000 1000 32 Okt 24 13:36 . drwxr-xr-x 6 0 0 4096 Okt 24 13:38 .. -rw-r--r-- 1 1000 1000 5 Okt 24 13:36 test_file $ ls -lan /mnt/mapped/ total 5 drwxr-xr-x 2 2000 2000 32 Okt 24 13:36 . drwxr-xr-x 6 0 0 4096 Okt 24 13:38 .. -rw-r--r-- 1 2000 2000 5 Okt 24 13:36 test_file Signed-off-by: Michael Weiß <michael.weiss@aisec.fraunhofer.de> Reviewed-by: Christian Brauner <brauner@kernel.org> Reviewed-by: Phillip Lougher <phillip@squashfs.org.uk> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Diffstat (limited to 'fs/squashfs')
-rw-r--r--fs/squashfs/super.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index 32565dafa7f3..2636cb354435 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -568,7 +568,7 @@ static struct file_system_type squashfs_fs_type = {
.init_fs_context = squashfs_init_fs_context,
.parameters = squashfs_fs_parameters,
.kill_sb = kill_block_super,
- .fs_flags = FS_REQUIRES_DEV
+ .fs_flags = FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
};
MODULE_ALIAS_FS("squashfs");