From afc154e978de1eb11c555bc8bcec1552f75ebc43 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Thu, 11 Jul 2013 12:43:42 +0200 Subject: [PATCH] ipv6: fix route selection if kernel is not compiled with CONFIG_IPV6_ROUTER_PREF This is a follow-up patch to 3630d40067a21d4dfbadc6002bb469ce26ac5d52 ("ipv6: rt6_check_neigh should successfully verify neigh if no NUD information are available"). Since the removal of rt->n in rt6_info we can end up with a dst == NULL in rt6_check_neigh. In case the kernel is not compiled with CONFIG_IPV6_ROUTER_PREF we should also select a route with unkown NUD state but we must not avoid doing round robin selection on routes with the same target. So introduce and pass down a boolean ``do_rr'' to indicate when we should update rt->rr_ptr. As soon as no route is valid we do backtracking and do a lookup on a higher level in the fib trie. v2: a) Improved rt6_check_neigh logic (no need to create neighbour there) and documented return values. v3: a) Introduce enum rt6_nud_state to get rid of the magic numbers (thanks to David Miller). b) Update and shorten commit message a bit to actualy reflect the source. Reported-by: Pierre Emeriaud Cc: YOSHIFUJI Hideaki Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/ipv6/route.c | 63 ++++++++++++++++++++++++++++++------------------ 1 file changed, 40 insertions(+), 23 deletions(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 5b127e09c22..a8c891aa246 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -65,6 +65,12 @@ #include #endif +enum rt6_nud_state { + RT6_NUD_FAIL_HARD = -2, + RT6_NUD_FAIL_SOFT = -1, + RT6_NUD_SUCCEED = 1 +}; + static struct rt6_info *ip6_rt_copy(struct rt6_info *ort, const struct in6_addr *dest); static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie); @@ -531,28 +537,29 @@ static inline int rt6_check_dev(struct rt6_info *rt, int oif) return 0; } -static inline bool rt6_check_neigh(struct rt6_info *rt) +static inline enum rt6_nud_state rt6_check_neigh(struct rt6_info *rt) { struct neighbour *neigh; - bool ret = false; + enum rt6_nud_state ret = RT6_NUD_FAIL_HARD; if (rt->rt6i_flags & RTF_NONEXTHOP || !(rt->rt6i_flags & RTF_GATEWAY)) - return true; + return RT6_NUD_SUCCEED; rcu_read_lock_bh(); neigh = __ipv6_neigh_lookup_noref(rt->dst.dev, &rt->rt6i_gateway); if (neigh) { read_lock(&neigh->lock); if (neigh->nud_state & NUD_VALID) - ret = true; + ret = RT6_NUD_SUCCEED; #ifdef CONFIG_IPV6_ROUTER_PREF else if (!(neigh->nud_state & NUD_FAILED)) - ret = true; + ret = RT6_NUD_SUCCEED; #endif read_unlock(&neigh->lock); - } else if (IS_ENABLED(CONFIG_IPV6_ROUTER_PREF)) { - ret = true; + } else { + ret = IS_ENABLED(CONFIG_IPV6_ROUTER_PREF) ? + RT6_NUD_SUCCEED : RT6_NUD_FAIL_SOFT; } rcu_read_unlock_bh(); @@ -566,43 +573,52 @@ static int rt6_score_route(struct rt6_info *rt, int oif, m = rt6_check_dev(rt, oif); if (!m && (strict & RT6_LOOKUP_F_IFACE)) - return -1; + return RT6_NUD_FAIL_HARD; #ifdef CONFIG_IPV6_ROUTER_PREF m |= IPV6_DECODE_PREF(IPV6_EXTRACT_PREF(rt->rt6i_flags)) << 2; #endif - if (!rt6_check_neigh(rt) && (strict & RT6_LOOKUP_F_REACHABLE)) - return -1; + if (strict & RT6_LOOKUP_F_REACHABLE) { + int n = rt6_check_neigh(rt); + if (n < 0) + return n; + } return m; } static struct rt6_info *find_match(struct rt6_info *rt, int oif, int strict, - int *mpri, struct rt6_info *match) + int *mpri, struct rt6_info *match, + bool *do_rr) { int m; + bool match_do_rr = false; if (rt6_check_expired(rt)) goto out; m = rt6_score_route(rt, oif, strict); - if (m < 0) + if (m == RT6_NUD_FAIL_SOFT && !IS_ENABLED(CONFIG_IPV6_ROUTER_PREF)) { + match_do_rr = true; + m = 0; /* lowest valid score */ + } else if (m < 0) { goto out; + } + + if (strict & RT6_LOOKUP_F_REACHABLE) + rt6_probe(rt); if (m > *mpri) { - if (strict & RT6_LOOKUP_F_REACHABLE) - rt6_probe(match); + *do_rr = match_do_rr; *mpri = m; match = rt; - } else if (strict & RT6_LOOKUP_F_REACHABLE) { - rt6_probe(rt); } - out: return match; } static struct rt6_info *find_rr_leaf(struct fib6_node *fn, struct rt6_info *rr_head, - u32 metric, int oif, int strict) + u32 metric, int oif, int strict, + bool *do_rr) { struct rt6_info *rt, *match; int mpri = -1; @@ -610,10 +626,10 @@ static struct rt6_info *find_rr_leaf(struct fib6_node *fn, match = NULL; for (rt = rr_head; rt && rt->rt6i_metric == metric; rt = rt->dst.rt6_next) - match = find_match(rt, oif, strict, &mpri, match); + match = find_match(rt, oif, strict, &mpri, match, do_rr); for (rt = fn->leaf; rt && rt != rr_head && rt->rt6i_metric == metric; rt = rt->dst.rt6_next) - match = find_match(rt, oif, strict, &mpri, match); + match = find_match(rt, oif, strict, &mpri, match, do_rr); return match; } @@ -622,15 +638,16 @@ static struct rt6_info *rt6_select(struct fib6_node *fn, int oif, int strict) { struct rt6_info *match, *rt0; struct net *net; + bool do_rr = false; rt0 = fn->rr_ptr; if (!rt0) fn->rr_ptr = rt0 = fn->leaf; - match = find_rr_leaf(fn, rt0, rt0->rt6i_metric, oif, strict); + match = find_rr_leaf(fn, rt0, rt0->rt6i_metric, oif, strict, + &do_rr); - if (!match && - (strict & RT6_LOOKUP_F_REACHABLE)) { + if (do_rr) { struct rt6_info *next = rt0->dst.rt6_next; /* no entries matched; do round-robin */ -- 2.34.1