From: Marcelo Ricardo Leitner marcelo.leitner@gmail.com
[ Upstream commit 582eea230536a6f104097dd46205822005d5fe3a ]
Under certain circumstances, depending on the order of addresses on the interfaces, it could be that sctp_v[46]_get_dst() would return a dst with a mismatched struct flowi.
For example, if when walking through the bind addresses and the first one is not a match, it saves the dst as a fallback (added in 410f03831c07), but not the flowi. Then if the next one is also not a match, the previous dst will be returned but with the flowi information for the 2nd address, which is wrong.
The fix is to use a locally stored flowi that can be used for such attempts, and copy it to the parameter only in case it is a possible match, together with the corresponding dst entry.
The patch updates IPv6 code mostly just to be in sync. Even though the issue is also present there, it fallback is not expected to work with IPv6.
Fixes: 410f03831c07 ("sctp: add routing output fallback") Reported-by: Jin Meng meng.a.jin@nokia-sbell.com Signed-off-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Tested-by: Xin Long lucien.xin@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sctp/ipv6.c | 20 ++++++++++++++------ net/sctp/protocol.c | 28 +++++++++++++++++++--------- 2 files changed, 33 insertions(+), 15 deletions(-)
--- a/net/sctp/ipv6.c +++ b/net/sctp/ipv6.c @@ -235,7 +235,8 @@ static void sctp_v6_get_dst(struct sctp_ { struct sctp_association *asoc = t->asoc; struct dst_entry *dst = NULL; - struct flowi6 *fl6 = &fl->u.ip6; + struct flowi _fl; + struct flowi6 *fl6 = &_fl.u.ip6; struct sctp_bind_addr *bp; struct ipv6_pinfo *np = inet6_sk(sk); struct sctp_sockaddr_entry *laddr; @@ -245,7 +246,7 @@ static void sctp_v6_get_dst(struct sctp_ enum sctp_scope scope; __u8 matchlen = 0;
- memset(fl6, 0, sizeof(struct flowi6)); + memset(&_fl, 0, sizeof(_fl)); fl6->daddr = daddr->v6.sin6_addr; fl6->fl6_dport = daddr->v6.sin6_port; fl6->flowi6_proto = IPPROTO_SCTP; @@ -271,8 +272,11 @@ static void sctp_v6_get_dst(struct sctp_ rcu_read_unlock();
dst = ip6_dst_lookup_flow(sk, fl6, final_p); - if (!asoc || saddr) + if (!asoc || saddr) { + t->dst = dst; + memcpy(fl, &_fl, sizeof(_fl)); goto out; + }
bp = &asoc->base.bind_addr; scope = sctp_scope(daddr); @@ -295,6 +299,8 @@ static void sctp_v6_get_dst(struct sctp_ if ((laddr->a.sa.sa_family == AF_INET6) && (sctp_v6_cmp_addr(&dst_saddr, &laddr->a))) { rcu_read_unlock(); + t->dst = dst; + memcpy(fl, &_fl, sizeof(_fl)); goto out; } } @@ -333,6 +339,8 @@ static void sctp_v6_get_dst(struct sctp_ if (!IS_ERR_OR_NULL(dst)) dst_release(dst); dst = bdst; + t->dst = dst; + memcpy(fl, &_fl, sizeof(_fl)); break; }
@@ -346,6 +354,8 @@ static void sctp_v6_get_dst(struct sctp_ dst_release(dst); dst = bdst; matchlen = bmatchlen; + t->dst = dst; + memcpy(fl, &_fl, sizeof(_fl)); } rcu_read_unlock();
@@ -354,14 +364,12 @@ out: struct rt6_info *rt;
rt = (struct rt6_info *)dst; - t->dst = dst; t->dst_cookie = rt6_get_cookie(rt); pr_debug("rt6_dst:%pI6/%d rt6_src:%pI6\n", &rt->rt6i_dst.addr, rt->rt6i_dst.plen, - &fl6->saddr); + &fl->u.ip6.saddr); } else { t->dst = NULL; - pr_debug("no route\n"); } } --- a/net/sctp/protocol.c +++ b/net/sctp/protocol.c @@ -435,14 +435,15 @@ static void sctp_v4_get_dst(struct sctp_ { struct sctp_association *asoc = t->asoc; struct rtable *rt; - struct flowi4 *fl4 = &fl->u.ip4; + struct flowi _fl; + struct flowi4 *fl4 = &_fl.u.ip4; struct sctp_bind_addr *bp; struct sctp_sockaddr_entry *laddr; struct dst_entry *dst = NULL; union sctp_addr *daddr = &t->ipaddr; union sctp_addr dst_saddr;
- memset(fl4, 0x0, sizeof(struct flowi4)); + memset(&_fl, 0x0, sizeof(_fl)); fl4->daddr = daddr->v4.sin_addr.s_addr; fl4->fl4_dport = daddr->v4.sin_port; fl4->flowi4_proto = IPPROTO_SCTP; @@ -460,8 +461,11 @@ static void sctp_v4_get_dst(struct sctp_ &fl4->saddr);
rt = ip_route_output_key(sock_net(sk), fl4); - if (!IS_ERR(rt)) + if (!IS_ERR(rt)) { dst = &rt->dst; + t->dst = dst; + memcpy(fl, &_fl, sizeof(_fl)); + }
/* If there is no association or if a source address is passed, no * more validation is required. @@ -524,27 +528,33 @@ static void sctp_v4_get_dst(struct sctp_ odev = __ip_dev_find(sock_net(sk), laddr->a.v4.sin_addr.s_addr, false); if (!odev || odev->ifindex != fl4->flowi4_oif) { - if (!dst) + if (!dst) { dst = &rt->dst; - else + t->dst = dst; + memcpy(fl, &_fl, sizeof(_fl)); + } else { dst_release(&rt->dst); + } continue; }
dst_release(dst); dst = &rt->dst; + t->dst = dst; + memcpy(fl, &_fl, sizeof(_fl)); break; }
out_unlock: rcu_read_unlock(); out: - t->dst = dst; - if (dst) + if (dst) { pr_debug("rt_dst:%pI4, rt_src:%pI4\n", - &fl4->daddr, &fl4->saddr); - else + &fl->u.ip4.daddr, &fl->u.ip4.saddr); + } else { + t->dst = NULL; pr_debug("no route\n"); + } }
/* For v4, the source address is cached in the route entry(dst). So no need