kernel/git/stable/linux.git/include/net/dst.h, branch linux-4.3.y

net: fix IP early demux races

2016-01-23T04:55:48+00:00

[ Upstream commit 5037e9ef9454917b047f9f3a19b4dd179fbf7cd4 ] David Wilder reported crashes caused by dst reuse. I am seeing a crash on a distro V4.2.3 kernel caused by a double release of a dst_entry. In ipv4_dst_destroy() the call to list_empty() finds a poisoned next pointer, indicating the dst_entry has already been removed from the list and freed. The crash occurs 18 to 24 hours into a run of a network stress exerciser. Thanks to his detailed report and analysis, we were able to understand the core issue. IP early demux can associate a dst to skb, after a lookup in TCP/UDP sockets. When socket cache is not properly set, we want to store into sk->sk_dst_cache the dst for future IP early demux lookups, by acquiring a stable refcount on the dst. Problem is this acquisition is simply using an atomic_inc(), which works well, unless the dst was queued for destruction from dst_release() noticing dst refcount went to zero, if DST_NOCACHE was set on dst. We need to make sure current refcount is not zero before incrementing it, or risk double free as David reported. This patch, being a stable candidate, adds two new helpers, and use them only from IP early demux problematic paths. It might be possible to merge in net-next skb_dst_force() and skb_dst_force_safe(), but I prefer having the smallest patch for stable kernels : Maybe some skb_dst_force() callers do not expect skb->dst can suddenly be cleared. Can probably be backported back to linux-3.6 kernels Reported-by: David J. Wilder Tested-by: David J. Wilder Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

tcp: use dctcp if enabled on the route to the initiator

2015-08-31T19:34:00+00:00

Currently, the following case doesn't use DCTCP, even if it should: A responder has f.e. Cubic as system wide default, but for a specific route to the initiating host, DCTCP is being set in RTAX_CC_ALGO. The initiating host then uses DCTCP as congestion control, but since the initiator sets ECT(0), tcp_ecn_create_request() doesn't set ecn_ok, and we have to fall back to Reno after 3WHS completes. We were thinking on how to solve this in a minimal, non-intrusive way without bloating tcp_ecn_create_request() needlessly: lets cache the CA ecn option flag in RTAX_FEATURES. In other words, when ECT(0) is set on the SYN packet, set ecn_ok=1 iff route RTAX_FEATURES contains the unexposed (internal-only) DST_FEATURE_ECN_CA. This allows to only do a single metric feature lookup inside tcp_ecn_create_request(). Joint work with Florian Westphal. Signed-off-by: Daniel Borkmann Signed-off-by: Florian Westphal Signed-off-by: David S. Miller

dst: Add __skb_dst_copy() variation

2015-08-27T18:40:42+00:00

This variation on skb_dst_copy() doesn't require two skbs. Signed-off-by: Joe Stringer Acked-by: Pravin B Shelar Acked-by: Thomas Graf Signed-off-by: David S. Miller

route: fix breakage after moving lwtunnel state

2015-08-23T23:51:17+00:00

__recnt and related fields need to be in its own cacheline for performance reasons. Commit 61adedf3e3f1 ("route: move lwtunnel state to dst_entry") broke that on 32bit archs, causing BUILD_BUG_ON in dst_hold to be triggered. This patch fixes the breakage by moving the lwtunnel state to the end of dst_entry on 32bit archs. Unfortunately, this makes it share the cacheline with __refcnt and may affect performance, thus further patches may be needed. Reported-by: kbuild test robot Fixes: 61adedf3e3f1 ("route: move lwtunnel state to dst_entry") Signed-off-by: Jiri Benc Signed-off-by: David S. Miller

route: move lwtunnel state to dst_entry

2015-08-20T22:42:36+00:00

Currently, the lwtunnel state resides in per-protocol data. This is a problem if we encapsulate ipv6 traffic in an ipv4 tunnel (or vice versa). The xmit function of the tunnel does not know whether the packet has been routed to it by ipv4 or ipv6, yet it needs the lwtstate data. Moving the lwtstate data to dst_entry makes such inter-protocol tunneling possible. As a bonus, this brings a nice diffstat. Signed-off-by: Jiri Benc Acked-by: Roopa Prabhu Acked-by: Thomas Graf Signed-off-by: David S. Miller

dst: Metadata destinations

2015-07-21T17:39:05+00:00

Introduces a new dst_metadata which enables to carry per packet metadata between forwarding and processing elements via the skb->dst pointer. The structure is set up to be a union. Thus, each separate type of metadata requires its own dst instance. If demand arises to carry multiple types of metadata concurrently, metadata dst entries can be made stackable. The metadata dst entry is refcnt'ed as expected for now but a non reference counted use is possible if the reference is forced before queueing the skb. In order to allow allocating dsts with variable length, the existing dst_alloc() is split into a dst_alloc() and dst_init() function. The existing dst_init() function to initialize the subsystem is being renamed to dst_subsys_init() to make it clear what is what. The check before ip_route_input() is changed to ignore metadata dsts and drop the dst inside the routing function thus allowing to interpret metadata in a later commit. Signed-off-by: Thomas Graf Signed-off-by: David S. Miller

net: make skb_dst_pop routine static

2015-05-13T03:19:49+00:00

As xfrm_output_one() is the only caller of skb_dst_pop(), we should make skb_dst_pop() localized. Signed-off-by: Ying Xue Signed-off-by: David S. Miller

ipv6: Remove DST_METRICS_FORCE_OVERWRITE and _rt6i_peer

2015-05-02T00:57:06+00:00

_rt6i_peer is no longer needed after the last patch, 'ipv6: Stop rt6_info from using inet_peer's metrics'. DST_METRICS_FORCE_OVERWRITE is added by commit e5fd387ad5b3 ("ipv6: do not overwrite inetpeer metrics prematurely"). Since inetpeer is no longer used for metrics, this bit is also not needed. Signed-off-by: Martin KaFai Lau Reviewed-by: Hannes Frederic Sowa Cc: Michal Kubeček Cc: Steffen Klassert Signed-off-by: David S. Miller

xfrm: release dst_orig in case of error in xfrm_lookup()

2015-02-12T06:10:56+00:00

dst_orig should be released on error. Function like __xfrm_route_forward() expects that behavior. Since a recent commit, xfrm_lookup() may also be called by xfrm_lookup_route(), which expects the opposite. Let's introduce a new flag (XFRM_LOOKUP_KEEP_DST_REF) to tell what should be done in case of error. Fixes: f92ee61982d("xfrm: Generate blackhole routes only from route lookup functions") Signed-off-by: huaibin Wang Signed-off-by: Nicolas Dichtel Signed-off-by: Steffen Klassert

xfrm: Generate queueing routes only from route lookup functions

2014-09-16T08:08:49+00:00

Currently we genarate a queueing route if we have matching policies but can not resolve the states and the sysctl xfrm_larval_drop is disabled. Here we assume that dst_output() is called to kill the queued packets. Unfortunately this assumption is not true in all cases, so it is possible that these packets leave the system unwanted. We fix this by generating queueing routes only from the route lookup functions, here we can guarantee a call to dst_output() afterwards. Fixes: a0073fe18e71 ("xfrm: Add a state resolution packet queue") Reported-by: Konstantinos Kolelis Signed-off-by: Steffen Klassert