Messages in this thread | | | Subject | Re: [PATCH] selinux: stricter parsing in mls_context_to_sid() | From | Stephen Smalley <> | Date | Mon, 6 Aug 2018 08:58:47 -0400 |
| |
On 08/03/2018 05:36 AM, Jann Horn wrote: > mls_context_to_sid incorrectly accepted MLS context strings that are > followed by a dash and trailing garbage. > > Before this change, the following command works: > > # mount -t tmpfs -o 'context=system_u:object_r:tmp_t:s0-s0:c0-BLAH' \ > none mount > > After this change, it fails with the following error message in dmesg: > > SELinux: security_context_str_to_sid(system_u:object_r:tmp_t:s0-s0:c0-BLAH) > failed for (dev tmpfs, type tmpfs) errno=-22 > > This is not an important bug; but it is a small quirk that was useful for > exploiting a vulnerability in fusermount. > > This patch does not change the behavior when the policy does not have MLS > enabled. > > Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
> --- > security/selinux/ss/mls.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c > index 39475fb455bc..2c73d612d2ee 100644 > --- a/security/selinux/ss/mls.c > +++ b/security/selinux/ss/mls.c > @@ -344,7 +344,7 @@ int mls_context_to_sid(struct policydb *pol, > break; > } > } > - if (delim == '-') { > + if (delim == '-' && l == 0) { > /* Extract high sensitivity. */ > scontextp = p; > while (*p && *p != ':') >
| |