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apparmor: fix nnp subset test for unconfined

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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

BugLink: https://bugs.launchpad.net/bugs/1844186
Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
John Johansen 2019-09-25 08:02:48 -07:00
parent a68d59ff4d
commit 3ed4aaa94f
3 changed files with 39 additions and 4 deletions
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9
security/apparmor/domain.c
View File

@ -929,7 +929,8 @@ 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, ctx->nnp)) {
!unconfined(label) &&
!aa_label_is_unconfined_subset(new, ctx->nnp)) {
error = -EPERM;
info = "no new privs";
goto audit;
@ -1207,7 +1208,7 @@ int aa_change_hat(const char *hats[], int count, u64 token, int flags)
* reduce restrictions.
*/
if (task_no_new_privs(current) && !unconfined(label) &&
!aa_label_is_subset(new, ctx->nnp)) {
!aa_label_is_unconfined_subset(new, ctx->nnp)) {
/* not an apparmor denial per se, so don't log it */
AA_DEBUG("no_new_privs - change_hat denied");
error = -EPERM;
@ -1228,7 +1229,7 @@ int aa_change_hat(const char *hats[], int count, u64 token, int flags)
* reduce restrictions.
*/
if (task_no_new_privs(current) && !unconfined(label) &&
!aa_label_is_subset(previous, ctx->nnp)) {
!aa_label_is_unconfined_subset(previous, ctx->nnp)) {
/* not an apparmor denial per se, so don't log it */
AA_DEBUG("no_new_privs - change_hat denied");
error = -EPERM;
@ -1424,7 +1425,7 @@ int aa_change_profile(const char *fqname, int flags)
* reduce restrictions.
*/
if (task_no_new_privs(current) && !unconfined(label) &&
!aa_label_is_subset(new, ctx->nnp)) {
!aa_label_is_unconfined_subset(new, ctx->nnp)) {
/* not an apparmor denial per se, so don't log it */
AA_DEBUG("no_new_privs - change_hat denied");
error = -EPERM;

1
security/apparmor/include/label.h
View File

@ -281,6 +281,7 @@ bool aa_label_init(struct aa_label *label, int size, gfp_t gfp);
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);

33
security/apparmor/label.c
View File

@ -550,6 +550,39 @@ 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;
}
/**