From: Eyal Birger eyal.birger@gmail.com
[ Upstream commit e6175a2ed1f18bf2f649625bf725e07adcfa6a28 ]
In IPv4 setting the "disable_policy" flag on a device means no policy should be enforced for traffic originating from the device. This was implemented by seting the DST_NOPOLICY flag in the dst based on the originating device.
However, dsts are cached in nexthops regardless of the originating devices, in which case, the DST_NOPOLICY flag value may be incorrect.
Consider the following setup:
+------------------------------+ | ROUTER | +-------------+ | +-----------------+ | | ipsec src |----|-|ipsec0 | | +-------------+ | |disable_policy=0 | +----+ | | +-----------------+ |eth1|-|----- +-------------+ | +-----------------+ +----+ | | noipsec src |----|-|eth0 | | +-------------+ | |disable_policy=1 | | | +-----------------+ | +------------------------------+
Where ROUTER has a default route towards eth1.
dst entries for traffic arriving from eth0 would have DST_NOPOLICY and would be cached and therefore can be reused by traffic originating from ipsec0, skipping policy check.
Fix by setting a IPSKB_NOPOLICY flag in IPCB and observing it instead of the DST in IN/FWD IPv4 policy checks.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Shmulik Ladkani shmulik.ladkani@gmail.com Signed-off-by: Eyal Birger eyal.birger@gmail.com Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/ip.h | 1 + include/net/xfrm.h | 14 +++++++++++++- net/ipv4/route.c | 23 ++++++++++++++++++----- 3 files changed, 32 insertions(+), 6 deletions(-)
diff --git a/include/net/ip.h b/include/net/ip.h index 0106c6590ee7..a77a9e1c6c04 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -55,6 +55,7 @@ struct inet_skb_parm { #define IPSKB_DOREDIRECT BIT(5) #define IPSKB_FRAG_PMTU BIT(6) #define IPSKB_L3SLAVE BIT(7) +#define IPSKB_NOPOLICY BIT(8)
u16 frag_max_size; }; diff --git a/include/net/xfrm.h b/include/net/xfrm.h index e03f0f882226..65242172e41c 100644 --- a/include/net/xfrm.h +++ b/include/net/xfrm.h @@ -1092,6 +1092,18 @@ static inline bool __xfrm_check_nopolicy(struct net *net, struct sk_buff *skb, return false; }
+static inline bool __xfrm_check_dev_nopolicy(struct sk_buff *skb, + int dir, unsigned short family) +{ + if (dir != XFRM_POLICY_OUT && family == AF_INET) { + /* same dst may be used for traffic originating from + * devices with different policy settings. + */ + return IPCB(skb)->flags & IPSKB_NOPOLICY; + } + return skb_dst(skb) && (skb_dst(skb)->flags & DST_NOPOLICY); +} + static inline int __xfrm_policy_check2(struct sock *sk, int dir, struct sk_buff *skb, unsigned int family, int reverse) @@ -1103,7 +1115,7 @@ static inline int __xfrm_policy_check2(struct sock *sk, int dir, return __xfrm_policy_check(sk, ndir, skb, family);
return __xfrm_check_nopolicy(net, skb, dir) || - (skb_dst(skb) && (skb_dst(skb)->flags & DST_NOPOLICY)) || + __xfrm_check_dev_nopolicy(skb, dir, family) || __xfrm_policy_check(sk, ndir, skb, family); }
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 6e8020a3bd67..1db2fda22830 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1727,6 +1727,7 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr, struct in_device *in_dev = __in_dev_get_rcu(dev); unsigned int flags = RTCF_MULTICAST; struct rtable *rth; + bool no_policy; u32 itag = 0; int err;
@@ -1737,8 +1738,12 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr, if (our) flags |= RTCF_LOCAL;
+ no_policy = IN_DEV_ORCONF(in_dev, NOPOLICY); + if (no_policy) + IPCB(skb)->flags |= IPSKB_NOPOLICY; + rth = rt_dst_alloc(dev_net(dev)->loopback_dev, flags, RTN_MULTICAST, - IN_DEV_ORCONF(in_dev, NOPOLICY), false); + no_policy, false); if (!rth) return -ENOBUFS;
@@ -1797,7 +1802,7 @@ static int __mkroute_input(struct sk_buff *skb, struct rtable *rth; int err; struct in_device *out_dev; - bool do_cache; + bool do_cache, no_policy; u32 itag = 0;
/* get a working reference to the output device */ @@ -1842,6 +1847,10 @@ static int __mkroute_input(struct sk_buff *skb, } }
+ no_policy = IN_DEV_ORCONF(in_dev, NOPOLICY); + if (no_policy) + IPCB(skb)->flags |= IPSKB_NOPOLICY; + fnhe = find_exception(nhc, daddr); if (do_cache) { if (fnhe) @@ -1854,8 +1863,7 @@ static int __mkroute_input(struct sk_buff *skb, } }
- rth = rt_dst_alloc(out_dev->dev, 0, res->type, - IN_DEV_ORCONF(in_dev, NOPOLICY), + rth = rt_dst_alloc(out_dev->dev, 0, res->type, no_policy, IN_DEV_ORCONF(out_dev, NOXFRM)); if (!rth) { err = -ENOBUFS; @@ -2230,6 +2238,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr, struct rtable *rth; struct flowi4 fl4; bool do_cache = true; + bool no_policy;
/* IP on this device is disabled. */
@@ -2347,6 +2356,10 @@ out: return err; RT_CACHE_STAT_INC(in_brd);
local_input: + no_policy = IN_DEV_ORCONF(in_dev, NOPOLICY); + if (no_policy) + IPCB(skb)->flags |= IPSKB_NOPOLICY; + do_cache &= res->fi && !itag; if (do_cache) { struct fib_nh_common *nhc = FIB_RES_NHC(*res); @@ -2361,7 +2374,7 @@ out: return err;
rth = rt_dst_alloc(ip_rt_get_dev(net, res), flags | RTCF_LOCAL, res->type, - IN_DEV_ORCONF(in_dev, NOPOLICY), false); + no_policy, false); if (!rth) goto e_nobufs;