linux/security/selinux
Ondrej Mosnacek 08abe46b2c selinux: fall back to SECURITY_FS_USE_GENFS if no xattr support
When a superblock is assigned the SECURITY_FS_USE_XATTR behavior by the
policy yet it lacks xattr support, try to fall back to genfs rather than
rejecting the mount. If a genfscon rule is found for the filesystem,
then change the behavior to SECURITY_FS_USE_GENFS, otherwise reject the
mount as before. A similar fallback is already done in security_fs_use()
if no behavior specification is found for the given filesystem.

This is needed e.g. for virtiofs, which may or may not support xattrs
depending on the backing host filesystem.

Example:
    # seinfo --genfs | grep ' ramfs'
       genfscon ramfs /  system_u:object_r:ramfs_t:s0
    # echo '(fsuse xattr ramfs (system_u object_r fs_t ((s0) (s0))))' >ramfs_xattr.cil
    # semodule -i ramfs_xattr.cil
    # mount -t ramfs none /mnt

Before:
    mount: /mnt: mount(2) system call failed: Operation not supported.

After:
    (mount succeeds)
    # ls -Zd /mnt
    system_u:object_r:ramfs_t:s0 /mnt

See also:
https://lore.kernel.org/selinux/20210105142148.GA3200@redhat.com/T/
https://github.com/fedora-selinux/selinux-policy/pull/478

Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-01-13 08:55:11 -05:00
..
include selinux: make selinuxfs_mount static 2021-01-12 10:02:26 -05:00
ss selinux: mark some global variables __ro_after_init 2021-01-12 10:08:55 -05:00
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
avc.c selinux: mark some global variables __ro_after_init 2021-01-12 10:08:55 -05:00
hooks.c selinux: fall back to SECURITY_FS_USE_GENFS if no xattr support 2021-01-13 08:55:11 -05:00
ibpkey.c selinux: remove unused global variables 2021-01-12 09:49:01 -05:00
Kconfig Documentation,selinux: deprecate setting checkreqprot to 1 2020-02-10 10:49:01 -05:00
Makefile selinux: hash context structure directly 2020-04-17 16:04:34 -04:00
netif.c selinux: remove unused global variables 2021-01-12 09:49:01 -05:00
netlabel.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13 2019-05-21 11:28:45 +02:00
netlink.c selinux: mark some global variables __ro_after_init 2021-01-12 10:08:55 -05:00
netnode.c selinux: remove unused global variables 2021-01-12 09:49:01 -05:00
netport.c selinux: remove unused global variables 2021-01-12 09:49:01 -05:00
nlmsgtab.c net: bridge: vlan: add rtm definitions and dump support 2020-01-15 13:48:17 +01:00
selinuxfs.c selinux: mark some global variables __ro_after_init 2021-01-12 10:08:55 -05:00
status.c selinux: move status variables out of selinux_ss 2020-02-10 10:49:01 -05:00
xfrm.c selinux: mark selinux_xfrm_refcount as __read_mostly 2021-01-12 10:12:58 -05:00