On 2/11/20 5:14 AM, Petr Lautrbach wrote:
get_ordered_context_list() code used to ask the kernel to compute the complete
set of reachable contexts using /sys/fs/selinux/user aka
security_compute_user(). This set can be so huge so that it doesn't fit into a
kernel page and security_compute_user() fails. Even if it doesn't fail,
get_ordered_context_list() throws away the vast majority of the returned
contexts because they don't match anything in
/etc/selinux/targeted/contexts/default_contexts or
/etc/selinux/targeted/contexts/users/
get_ordered_context_list() is rewritten to compute set of contexts based on
/etc/selinux/targeted/contexts/users/ and
/etc/selinux/targeted/contexts/default_contexts files and to return only valid
contexts, using security_check_context(), from this set.
Fixes: https://github.com/SELinuxProject/selinux/issues/28
Signed-off-by: Petr Lautrbach <plautrba@xxxxxxxxxx>
---
diff --git a/libselinux/src/get_context_list.c b/libselinux/src/get_context_list.c
index 689e46589f30..6078d980cde1 100644
--- a/libselinux/src/get_context_list.c
+++ b/libselinux/src/get_context_list.c
@@ -463,40 +467,18 @@ int get_ordered_context_list(const char *user,
__FUNCTION__, selinux_default_context_path());
/* Fall through */
}
- rc = 0;
+ rc = nreachable;
Shouldn't we do this outside the if (fp) statement? Otherwise, if we
got some reachable contexts from the per-user contexts file but the
global default_contexts file was missing, we'll end up freeing the
reachable contexts and returning 0 on the out path.
}
- if (!nordered)
+ if (!nreachable)
goto failsafe;
- /* Apply the ordering. */
- co = malloc(nreach * sizeof(struct context_order));
- if (!co)
- goto failsafe;
- for (i = 0; i < nreach; i++) {
- co[i].con = reachable[i];
- co[i].order = ordering[i];
- }
- qsort(co, nreach, sizeof(struct context_order), order_compare);
- for (i = 0; i < nreach; i++)
- reachable[i] = co[i].con;
- free(co);
-
- /* Only report the ordered entries to the caller. */
- if (nordered <= nreach) {
- for (i = nordered; i < nreach; i++)
- free(reachable[i]);
- reachable[nordered] = NULL;
- rc = nordered;
- }
-
out:
if (rc > 0)
*list = reachable;
else
freeconary(reachable);
- free(ordering);
if (freefrom)
freecon(fromcon);
