diff options
| -rw-r--r-- | net/xfrm/xfrm_policy.c | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index f35bc67..3da67ca 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -1134,12 +1134,33 @@ int __xfrm_route_forward(struct sk_buff *skb, unsigned short family) } EXPORT_SYMBOL(__xfrm_route_forward); +/* Optimize later using cookies and generation ids. */ + static struct dst_entry *xfrm_dst_check(struct dst_entry *dst, u32 cookie) { - /* If it is marked obsolete, which is how we even get here, - * then we have purged it from the policy bundle list and we - * did that for a good reason. + /* Code (such as __xfrm4_bundle_create()) sets dst->obsolete + * to "-1" to force all XFRM destinations to get validated by + * dst_ops->check on every use. We do this because when a + * normal route referenced by an XFRM dst is obsoleted we do + * not go looking around for all parent referencing XFRM dsts + * so that we can invalidate them. It is just too much work. + * Instead we make the checks here on every use. For example: + * + * XFRM dst A --> IPv4 dst X + * + * X is the "xdst->route" of A (X is also the "dst->path" of A + * in this example). If X is marked obsolete, "A" will not + * notice. That's what we are validating here via the + * stale_bundle() check. + * + * When a policy's bundle is pruned, we dst_free() the XFRM + * dst which causes it's ->obsolete field to be set to a + * positive non-zero integer. If an XFRM dst has been pruned + * like this, we want to force a new route lookup. */ + if (dst->obsolete < 0 && !stale_bundle(dst)) + return dst; + return NULL; } |