[PATCH] Completely honor prctl(PR_SET_KEEPCAPS, 1)

From: Dax Kelson (dax@gurulabs.com)
Date: Wed May 08 2002 - 04:40:11 EST


Originally when a process set*uided all capabilities bits were cleared.
Then sometime later (wish BK went back 3 years), the behaviour was
modified according to the comment "A process may, via prctl(), elect to
keep its capabilites when it calls setuid() and switches away from
uid==0. Both permitted and effective sets will be retained."

The current behavior/implementation doesn't match the comment. Only
permitted capabilities are retained.

This patch against 2.4.18-3 (RHL7.3 kernel, should apply against stock)
fixes it. Now both permitted and effective capabilities are retained.

--- kernel/sys.c-org Wed May 8 01:20:37 2002
+++ kernel/sys.c Wed May 8 01:35:04 2002
@@ -482,7 +482,7 @@
                 cap_clear(current->cap_permitted);
                 cap_clear(current->cap_effective);
         }
- if (old_euid == 0 && current->euid != 0) {
+ if ((old_euid == 0 && current->euid != 0) && !current->keep_capabilities) {
                 cap_clear(current->cap_effective);
         }
         if (old_euid != 0 && current->euid == 0) {

-
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