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https://github.com/torvalds/linux
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20ae1d6aa1
Each peer's endpoint contains a dst_cache entry that takes a reference
to another netdev. When the containing namespace exits, we take down the
socket and prevent future sockets from being created (by setting
creating_net to NULL), which removes that potential reference on the
netns. However, it doesn't release references to the netns that a netdev
cached in dst_cache might be taking, so the netns still might fail to
exit. Since the socket is gimped anyway, we can simply clear all the
dst_caches (by way of clearing the endpoint src), which will release all
references.
However, the current dst_cache_reset function only releases those
references lazily. But it turns out that all of our usages of
wg_socket_clear_peer_endpoint_src are called from contexts that are not
exactly high-speed or bottle-necked. For example, when there's
connection difficulty, or when userspace is reconfiguring the interface.
And in particular for this patch, when the netns is exiting. So for
those cases, it makes more sense to call dst_release immediately. For
that, we add a small helper function to dst_cache.
This patch also adds a test to netns.sh from Hangbin Liu to ensure this
doesn't regress.
Tested-by: Hangbin Liu <liuhangbin@gmail.com>
Reported-by: Xiumei Mu <xmu@redhat.com>
Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Fixes: 900575aa33 ("wireguard: device: avoid circular netns references")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
184 lines
3.9 KiB
C
184 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* net/core/dst_cache.c - dst entry cache
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*
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* Copyright (c) 2016 Paolo Abeni <pabeni@redhat.com>
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*/
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#include <linux/kernel.h>
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#include <linux/percpu.h>
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#include <net/dst_cache.h>
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#include <net/route.h>
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#if IS_ENABLED(CONFIG_IPV6)
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#include <net/ip6_fib.h>
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#endif
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#include <uapi/linux/in.h>
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struct dst_cache_pcpu {
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unsigned long refresh_ts;
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struct dst_entry *dst;
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u32 cookie;
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union {
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struct in_addr in_saddr;
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struct in6_addr in6_saddr;
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};
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};
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static void dst_cache_per_cpu_dst_set(struct dst_cache_pcpu *dst_cache,
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struct dst_entry *dst, u32 cookie)
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{
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dst_release(dst_cache->dst);
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if (dst)
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dst_hold(dst);
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dst_cache->cookie = cookie;
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dst_cache->dst = dst;
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}
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static struct dst_entry *dst_cache_per_cpu_get(struct dst_cache *dst_cache,
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struct dst_cache_pcpu *idst)
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{
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struct dst_entry *dst;
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dst = idst->dst;
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if (!dst)
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goto fail;
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/* the cache already hold a dst reference; it can't go away */
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dst_hold(dst);
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if (unlikely(!time_after(idst->refresh_ts, dst_cache->reset_ts) ||
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(dst->obsolete && !dst->ops->check(dst, idst->cookie)))) {
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dst_cache_per_cpu_dst_set(idst, NULL, 0);
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dst_release(dst);
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goto fail;
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}
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return dst;
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fail:
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idst->refresh_ts = jiffies;
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return NULL;
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}
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struct dst_entry *dst_cache_get(struct dst_cache *dst_cache)
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{
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if (!dst_cache->cache)
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return NULL;
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return dst_cache_per_cpu_get(dst_cache, this_cpu_ptr(dst_cache->cache));
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}
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EXPORT_SYMBOL_GPL(dst_cache_get);
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struct rtable *dst_cache_get_ip4(struct dst_cache *dst_cache, __be32 *saddr)
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{
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struct dst_cache_pcpu *idst;
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struct dst_entry *dst;
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if (!dst_cache->cache)
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return NULL;
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idst = this_cpu_ptr(dst_cache->cache);
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dst = dst_cache_per_cpu_get(dst_cache, idst);
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if (!dst)
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return NULL;
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*saddr = idst->in_saddr.s_addr;
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return container_of(dst, struct rtable, dst);
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}
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EXPORT_SYMBOL_GPL(dst_cache_get_ip4);
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void dst_cache_set_ip4(struct dst_cache *dst_cache, struct dst_entry *dst,
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__be32 saddr)
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{
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struct dst_cache_pcpu *idst;
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if (!dst_cache->cache)
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return;
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idst = this_cpu_ptr(dst_cache->cache);
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dst_cache_per_cpu_dst_set(idst, dst, 0);
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idst->in_saddr.s_addr = saddr;
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}
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EXPORT_SYMBOL_GPL(dst_cache_set_ip4);
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#if IS_ENABLED(CONFIG_IPV6)
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void dst_cache_set_ip6(struct dst_cache *dst_cache, struct dst_entry *dst,
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const struct in6_addr *saddr)
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{
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struct dst_cache_pcpu *idst;
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if (!dst_cache->cache)
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return;
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idst = this_cpu_ptr(dst_cache->cache);
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dst_cache_per_cpu_dst_set(this_cpu_ptr(dst_cache->cache), dst,
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rt6_get_cookie((struct rt6_info *)dst));
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idst->in6_saddr = *saddr;
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}
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EXPORT_SYMBOL_GPL(dst_cache_set_ip6);
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struct dst_entry *dst_cache_get_ip6(struct dst_cache *dst_cache,
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struct in6_addr *saddr)
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{
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struct dst_cache_pcpu *idst;
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struct dst_entry *dst;
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if (!dst_cache->cache)
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return NULL;
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idst = this_cpu_ptr(dst_cache->cache);
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dst = dst_cache_per_cpu_get(dst_cache, idst);
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if (!dst)
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return NULL;
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*saddr = idst->in6_saddr;
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return dst;
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}
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EXPORT_SYMBOL_GPL(dst_cache_get_ip6);
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#endif
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int dst_cache_init(struct dst_cache *dst_cache, gfp_t gfp)
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{
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dst_cache->cache = alloc_percpu_gfp(struct dst_cache_pcpu,
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gfp | __GFP_ZERO);
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if (!dst_cache->cache)
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return -ENOMEM;
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dst_cache_reset(dst_cache);
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return 0;
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}
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EXPORT_SYMBOL_GPL(dst_cache_init);
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void dst_cache_destroy(struct dst_cache *dst_cache)
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{
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int i;
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if (!dst_cache->cache)
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return;
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for_each_possible_cpu(i)
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dst_release(per_cpu_ptr(dst_cache->cache, i)->dst);
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free_percpu(dst_cache->cache);
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}
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EXPORT_SYMBOL_GPL(dst_cache_destroy);
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void dst_cache_reset_now(struct dst_cache *dst_cache)
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{
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int i;
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if (!dst_cache->cache)
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return;
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dst_cache->reset_ts = jiffies;
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for_each_possible_cpu(i) {
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struct dst_cache_pcpu *idst = per_cpu_ptr(dst_cache->cache, i);
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struct dst_entry *dst = idst->dst;
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idst->cookie = 0;
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idst->dst = NULL;
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dst_release(dst);
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}
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}
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EXPORT_SYMBOL_GPL(dst_cache_reset_now);
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