NACK: [PATCH][SRU][bionic] UBUNTU: SAUCE: apparmor: fix nnp subset test for unconfined

[Tyler Hicks]

On 2019-10-03 16:26:12, John Johansen wrote:
> On 10/3/19 2:13 PM, Tyler Hicks wrote:
> > On 2019-10-03 12:14:58, John Johansen wrote:
> >> The subset test is not taking into account the unconfined exception
> >> which will cause profile transitions in the stacked confinement
> >> case to fail when no_new_privs is applied.
> >>
> >> This fixes a regression introduced in the fix for
> >> https://bugs.launchpad.net/bugs/1839037
> >>
> >> Fixes: d9b32413d82a ("UBUNTU: SAUCE: apparmor: fix nnp subset check failure when, stacking")
> >> BugLink: https://bugs.launchpad.net/bugs/1844186
> >> Signed-off-by: John Johansen <john.johansen at canonical.com>
> >> ---
> >>  security/apparmor/domain.c        |  4 ++--
> >>  security/apparmor/include/label.h |  1 +
> >>  security/apparmor/label.c         | 33 +++++++++++++++++++++++++++++++
> >>  3 files changed, 36 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
> >> index 76cebad829fa..442550b13775 100644
> >> --- a/security/apparmor/domain.c
> >> +++ b/security/apparmor/domain.c
> >> @@ -797,7 +797,7 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
> >>  	 * aways results in a further reduction of permissions.
> >>  	 */
> >>  	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
> >> -	    !unconfined(label) && !aa_label_is_subset(new, label)) {
> >> +	    !unconfined(label) && !aa_label_is_unconfined_subset(new, label)) {
> >>  		error = -EPERM;
> >>  		info = "no new privs";
> >>  		goto audit;
> >> @@ -1136,7 +1136,7 @@ static int change_profile_perms_wrapper(const char *op, const char *name,
> >>  	 */
> >>  	if (task_no_new_privs(current) && !stack &&
> >>  	    !profile_unconfined(profile) &&
> >> -	    !aa_label_is_subset(target, &profile->label)) {
> >> +	    !aa_label_is_unconfined_subset(target, &profile->label)) {
> >>  		info = "no new privs";
> >>  		error = -EPERM;
> >>  	}
> > 
> > aa_change_hat() in Bionic is still affected by 1839037 which is why this
> > regression fix doesn't include a hunk for aa_change_hat(). Is it worth
> > sending a second revision for Bionic that has a patch that fixes 1839037
> > for aa_change_hat() and then revise this patch to fix the
> > aa_change_hat() fix?
> > 
> 
> yeah, probably. I get that together and resend

Thanks, John. I'm marking this thread with an explicit NACK to help the
stable team know to skip over this revision.

Tyler

> 
> > Tyler
> > 
> >> diff --git a/security/apparmor/include/label.h b/security/apparmor/include/label.h
> >> index af22dcbbcb8a..95075bd908f3 100644
> >> --- a/security/apparmor/include/label.h
> >> +++ b/security/apparmor/include/label.h
> >> @@ -285,6 +285,7 @@ bool aa_label_init(struct aa_label *label, int size);
> >>  struct aa_label *aa_label_alloc(int size, struct aa_proxy *proxy, gfp_t gfp);
> >>  
> >>  bool aa_label_is_subset(struct aa_label *set, struct aa_label *sub);
> >> +bool aa_label_is_unconfined_subset(struct aa_label *set, struct aa_label *sub);
> >>  struct aa_profile *__aa_label_next_not_in_set(struct label_it *I,
> >>  					     struct aa_label *set,
> >>  					     struct aa_label *sub);
> >> diff --git a/security/apparmor/label.c b/security/apparmor/label.c
> >> index 324fe5c60f87..0d9741f6d860 100644
> >> --- a/security/apparmor/label.c
> >> +++ b/security/apparmor/label.c
> >> @@ -555,6 +555,39 @@ bool aa_label_is_subset(struct aa_label *set, struct aa_label *sub)
> >>  	return __aa_label_next_not_in_set(&i, set, sub) == NULL;
> >>  }
> >>  
> >> +/**
> >> + * aa_label_is_unconfined_subset - test if @sub is a subset of @set
> >> + * @set: label to test against
> >> + * @sub: label to test if is subset of @set
> >> + *
> >> + * This checks for subset but taking into account unconfined. IF
> >> + * @sub contains an unconfined profile that does not have a matching
> >> + * unconfined in @set then this will not cause the test to fail.
> >> + * Conversely we don't care about an unconfined in @set that is not in
> >> + * @sub
> >> + *
> >> + * Returns: true if @sub is special_subset of @set
> >> + *     else false
> >> + */
> >> +bool aa_label_is_unconfined_subset(struct aa_label *set, struct aa_label *sub)
> >> +{
> >> +	struct label_it i = { };
> >> +	struct aa_profile *p;
> >> +
> >> +	AA_BUG(!set);
> >> +	AA_BUG(!sub);
> >> +
> >> +	if (sub == set)
> >> +		return true;
> >> +
> >> +	do {
> >> +		p = __aa_label_next_not_in_set(&i, set, sub);
> >> +		if (p && !profile_unconfined(p))
> >> +			break;
> >> +	} while (p);
> >> +
> >> +	return p == NULL;
> >> +}
> >>  
> >>  
> >>  /**
> >> -- 
> >> 2.17.1
> >>
> >>
> >> -- 
> >> kernel-team mailing list
> >> kernel-team at lists.ubuntu.com
> >> https://lists.ubuntu.com/mailman/listinfo/kernel-team
>