[PATCH] Smack: Restore the smackfsdef mount option and add missing prefixes

From: David Howells
Date: Tue May 28 2019 - 16:51:07 EST


From: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>

The 5.1 mount system rework changed the smackfsdef mount option
to smackfsdefault. This fixes the regression by making smackfsdef
treated the same way as smackfsdefault.

Also fix the smack_param_specs[] to have "smack" prefixes on all the names.
This isn't visible to a user unless they either:

(a) Try to mount a filesystem that's converted to the internal mount API
and that implements the ->parse_monolithic() context operation - and
only then if they call security_fs_context_parse_param() rather than
security_sb_eat_lsm_opts().

There are no examples of this upstream yet, but nfs will probably want
to do this for nfs2 or nfs3.

(b) Use fsconfig() to configure the filesystem - in which case
security_fs_context_parse_param() will be called.

This issue is that smack_sb_eat_lsm_opts() checks for the "smack" prefix on
the options, but smack_fs_context_parse_param() does not.

Fixes: c3300aaf95fb ("smack: get rid of match_token()")
Fixes: 2febd254adc4 ("smack: Implement filesystem context security hooks")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Jose Bollo <jose.bollo@xxxxxxx>
Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

security/smack/smack_lsm.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 0de725f88bed..d99450b4f511 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -68,6 +68,7 @@ static struct {
int len;
int opt;
} smk_mount_opts[] = {
+ {"smackfsdef", sizeof("smackfsdef") - 1, Opt_fsdefault},
A(fsdefault), A(fsfloor), A(fshat), A(fsroot), A(fstransmute)
};
#undef A
@@ -682,11 +683,12 @@ static int smack_fs_context_dup(struct fs_context *fc,
}

static const struct fs_parameter_spec smack_param_specs[] = {
- fsparam_string("fsdefault", Opt_fsdefault),
- fsparam_string("fsfloor", Opt_fsfloor),
- fsparam_string("fshat", Opt_fshat),
- fsparam_string("fsroot", Opt_fsroot),
- fsparam_string("fstransmute", Opt_fstransmute),
+ fsparam_string("smackfsdef", Opt_fsdefault),
+ fsparam_string("smackfsdefault", Opt_fsdefault),
+ fsparam_string("smackfsfloor", Opt_fsfloor),
+ fsparam_string("smackfshat", Opt_fshat),
+ fsparam_string("smackfsroot", Opt_fsroot),
+ fsparam_string("smackfstransmute", Opt_fstransmute),
{}
};