kernel/linux.git/net/core/dst.c, branch v6.1.168

net: do not delay dst_entries_add() in dst_release()

2024-11-14T12:15:17+00:00

commit ac888d58869bb99753e7652be19a151df9ecb35d upstream. dst_entries_add() uses per-cpu data that might be freed at netns dismantle from ip6_route_net_exit() calling dst_entries_destroy() Before ip6_route_net_exit() can be called, we release all the dsts associated with this netns, via calls to dst_release(), which waits an rcu grace period before calling dst_destroy() dst_entries_add() use in dst_destroy() is racy, because dst_entries_destroy() could have been called already. Decrementing the number of dsts must happen sooner. Notes: 1) in CONFIG_XFRM case, dst_destroy() can call dst_release_immediate(child), this might also cause UAF if the child does not have DST_NOCOUNT set. IPSEC maintainers might take a look and see how to address this. 2) There is also discussion about removing this count of dst, which might happen in future kernels. Fixes: f88649721268 ("ipv4: fix dst race in sk_dst_get()") Closes: https://lore.kernel.org/lkml/CANn89iLCCGsP7SFn9HKpvnKu96Td4KD08xf7aGtiYgZnkjaL=w@mail.gmail.com/T/ Reported-by: Naresh Kamboju Tested-by: Linux Kernel Functional Testing Tested-by: Naresh Kamboju Signed-off-by: Eric Dumazet Cc: Xin Long Cc: Steffen Klassert Reviewed-by: Xin Long Link: https://patch.msgid.link/20241008143110.1064899-1-edumazet@google.com Signed-off-by: Paolo Abeni [ resolved conflict due to bc9d3a9f2afc ("net: dst: Switch to rcuref_t reference counting") is not in the tree ] Signed-off-by: Abdelkareem Abdelsaamad Signed-off-by: Greg Kroah-Hartman

ipv6: remove max_size check inline with ipv4

2024-01-15T17:54:51+00:00

commit af6d10345ca76670c1b7c37799f0d5576ccef277 upstream. In ip6_dst_gc() replace: if (entries > gc_thresh) With: if (entries > ops->gc_thresh) Sending Ipv6 packets in a loop via a raw socket triggers an issue where a route is cloned by ip6_rt_cache_alloc() for each packet sent. This quickly consumes the Ipv6 max_size threshold which defaults to 4096 resulting in these warnings: [1] 99.187805] dst_alloc: 7728 callbacks suppressed [2] Route cache is full: consider increasing sysctl net.ipv6.route.max_size. . . [300] Route cache is full: consider increasing sysctl net.ipv6.route.max_size. When this happens the packet is dropped and sendto() gets a network is unreachable error: remaining pkt 200557 errno 101 remaining pkt 196462 errno 101 . . remaining pkt 126821 errno 101 Implement David Aherns suggestion to remove max_size check seeing that Ipv6 has a GC to manage memory usage. Ipv4 already does not check max_size. Here are some memory comparisons for Ipv4 vs Ipv6 with the patch: Test by running 5 instances of a program that sends UDP packets to a raw socket 5000000 times. Compare Ipv4 and Ipv6 performance with a similar program. Ipv4: Before test: MemFree: 29427108 kB Slab: 237612 kB ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0 xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0 ip_dst_cache 2881 3990 192 42 2 : tunables 0 0 0 During test: MemFree: 29417608 kB Slab: 247712 kB ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0 xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0 ip_dst_cache 44394 44394 192 42 2 : tunables 0 0 0 After test: MemFree: 29422308 kB Slab: 238104 kB ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0 xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0 ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0 Ipv6 with patch: Errno 101 errors are not observed anymore with the patch. Before test: MemFree: 29422308 kB Slab: 238104 kB ip6_dst_cache 1912 2528 256 32 2 : tunables 0 0 0 xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0 ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0 During Test: MemFree: 29431516 kB Slab: 240940 kB ip6_dst_cache 11980 12064 256 32 2 : tunables 0 0 0 xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0 ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0 After Test: MemFree: 29441816 kB Slab: 238132 kB ip6_dst_cache 1902 2432 256 32 2 : tunables 0 0 0 xfrm_dst_cache 0 0 320 25 2 : tunables 0 0 0 ip_dst_cache 3048 4116 192 42 2 : tunables 0 0 0 Tested-by: Andrea Mayer Signed-off-by: Jon Maxwell Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20230112012532.311021-1-jmaxwell37@gmail.com Signed-off-by: Jakub Kicinski Cc: "Jitindar Singh, Suraj" Signed-off-by: Greg Kroah-Hartman

net: rename reference+tracking helpers

2022-06-10T04:52:55+00:00

Netdev reference helpers have a dev_ prefix for historic reasons. Renaming the old helpers would be too much churn but we can rename the tracking ones which are relatively recent and should be the default for new code. Rename: dev_hold_track() -> netdev_hold() dev_put_track() -> netdev_put() dev_replace_track() -> netdev_ref_replace() Link: https://lore.kernel.org/r/20220608043955.919359-1-kuba@kernel.org Signed-off-by: Jakub Kicinski

net: dst: add net device refcount tracking to dst_entry

2021-12-07T00:05:10+00:00

We want to track all dev_hold()/dev_put() to ease leak hunting. Signed-off-by: Eric Dumazet Signed-off-by: Jakub Kicinski

net: Remove redundant if statements

2021-08-05T12:27:50+00:00

The 'if (dev)' statement already move into dev_{put , hold}, so remove redundant if statements. Signed-off-by: Yajun Deng Signed-off-by: David S. Miller

net, bpf: Fix ip6ip6 crash with collect_md populated skbs

2021-03-10T20:24:18+00:00

I ran into a crash where setting up a ip6ip6 tunnel device which was /not/ set to collect_md mode was receiving collect_md populated skbs for xmit. The BPF prog was populating the skb via bpf_skb_set_tunnel_key() which is assigning special metadata dst entry and then redirecting the skb to the device, taking ip6_tnl_start_xmit() -> ipxip6_tnl_xmit() -> ip6_tnl_xmit() and in the latter it performs a neigh lookup based on skb_dst(skb) where we trigger a NULL pointer dereference on dst->ops->neigh_lookup() since the md_dst_ops do not populate neigh_lookup callback with a fake handler. Transform the md_dst_ops into generic dst_blackhole_ops that can also be reused elsewhere when needed, and use them for the metadata dst entries as callback ops. Also, remove the dst_md_discard{,_out}() ops and rely on dst_discard{,_out}() from dst_init() which free the skb the same way modulo the splat. Given we will be able to recover just fine from there, avoid any potential splats iff this gets ever triggered in future (or worse, panic on warns when set). Fixes: f38a9eb1f77b ("dst: Metadata destinations") Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller

net: Consolidate common blackhole dst ops

2021-03-10T20:24:18+00:00

Move generic blackhole dst ops to the core and use them from both ipv4_dst_blackhole_ops and ip6_dst_blackhole_ops where possible. No functional change otherwise. We need these also in other locations and having to define them over and over again is not great. Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller

net: Correct the comment of dst_dev_put()

2020-09-10T20:28:57+00:00

Since commit 8d7017fd621d ("blackhole_netdev: use blackhole_netdev to invalidate dst entries"), we use blackhole_netdev to invalidate dst entries instead of loopback device anymore. Signed-off-by: Miaohe Lin Signed-off-by: David S. Miller

net/dst: use a smaller percpu_counter batch for dst entries accounting

2020-05-09T04:33:33+00:00

percpu_counter_add() uses a default batch size which is quite big on platforms with 256 cpus. (2*256 -> 512) This means dst_entries_get_fast() can be off by +/- 2*(nr_cpus^2) (131072 on servers with 256 cpus) Reduce the batch size to something more reasonable, and add logic to ip6_dst_gc() to call dst_entries_get_slow() before calling the _very_ expensive fib6_run_gc() function. Signed-off-by: Eric Dumazet Signed-off-by: Jakub Kicinski

net: print proper warning on dst underflow

2019-09-26T07:05:56+00:00

Proper warnings with stack traces make it much easier to figure out what's doing the double free and create more meaningful bug reports from users. Signed-off-by: Jason A. Donenfeld Signed-off-by: David S. Miller