[PATCH v3 07/15] commoncap: Move cap_elevated calculation into bprm_set_creds

On Tue, Jul 18, 2017 at 3:25 PM, Kees Cook [off-list ref] wrote:

Instead of a separate function, open-code the cap_elevated test, which
lets us entirely remove bprm->cap_effective (to use the local "effective"
variable instead), and more accurately examine euid/egid changes via the
existing local "is_setid".

...

-static int is_secureexec(struct linux_binprm *bprm)
-{
-       const struct cred *cred = bprm->cred;
-       kuid_t root_uid = make_kuid(cred->user_ns, 0);
-
-       if (!uid_eq(cred->uid, root_uid)) {
-               if (bprm->cap_effective)
-                       return 1;
-               if (!cap_issubset(cred->cap_permitted, cred->cap_ambient))
-                       return 1;
+       bprm->cap_elevated = 0;
+       if (is_setid) {
+               bprm->cap_elevated = 1;
+       } else if (!uid_eq(new->uid, root_uid)) {
+               if (effective ||
+                   !cap_issubset(new->cap_permitted, new->cap_ambient))
+                       bprm->cap_elevated = 1;
        }

-       return (!uid_eq(cred->euid, cred->uid) ||
-               !gid_eq(cred->egid, cred->gid));
+       return 0;

I think this matches the old behavior.  IOW it looks right.
--
To unsubscribe from this list: send the line "unsubscribe linux-security-module" in
the body of a message to majordomo at vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html