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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Kuniyuki Iwashima](/assets/img/avatar_default.png)
This commit adds two stats for the socket migration feature to evaluate the effectiveness: LINUX_MIB_TCPMIGRATEREQ(SUCCESS|FAILURE). If the migration fails because of the own_req race in receiving ACK and sending SYN+ACK paths, we do not increment the failure stat. Then another CPU is responsible for the req. Link: https://lore.kernel.org/bpf/CAK6E8=cgFKuGecTzSCSQ8z3YJ_163C0uwO9yRvfDSE7vOe9mJA@mail.gmail.com/ Suggested-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
649 lines
16 KiB
C
649 lines
16 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* To speed up listener socket lookup, create an array to store all sockets
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* listening on the same port. This allows a decision to be made after finding
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* the first socket. An optional BPF program can also be configured for
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* selecting the socket index from the array of available sockets.
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*/
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#include <net/ip.h>
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#include <net/sock_reuseport.h>
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#include <linux/bpf.h>
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#include <linux/idr.h>
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#include <linux/filter.h>
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#include <linux/rcupdate.h>
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#define INIT_SOCKS 128
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DEFINE_SPINLOCK(reuseport_lock);
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static DEFINE_IDA(reuseport_ida);
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static int reuseport_resurrect(struct sock *sk, struct sock_reuseport *old_reuse,
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struct sock_reuseport *reuse, bool bind_inany);
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static int reuseport_sock_index(struct sock *sk,
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const struct sock_reuseport *reuse,
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bool closed)
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{
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int left, right;
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if (!closed) {
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left = 0;
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right = reuse->num_socks;
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} else {
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left = reuse->max_socks - reuse->num_closed_socks;
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right = reuse->max_socks;
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}
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for (; left < right; left++)
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if (reuse->socks[left] == sk)
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return left;
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return -1;
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}
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static void __reuseport_add_sock(struct sock *sk,
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struct sock_reuseport *reuse)
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{
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reuse->socks[reuse->num_socks] = sk;
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/* paired with smp_rmb() in reuseport_(select|migrate)_sock() */
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smp_wmb();
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reuse->num_socks++;
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}
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static bool __reuseport_detach_sock(struct sock *sk,
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struct sock_reuseport *reuse)
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{
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int i = reuseport_sock_index(sk, reuse, false);
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if (i == -1)
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return false;
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reuse->socks[i] = reuse->socks[reuse->num_socks - 1];
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reuse->num_socks--;
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return true;
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}
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static void __reuseport_add_closed_sock(struct sock *sk,
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struct sock_reuseport *reuse)
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{
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reuse->socks[reuse->max_socks - reuse->num_closed_socks - 1] = sk;
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/* paired with READ_ONCE() in inet_csk_bind_conflict() */
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WRITE_ONCE(reuse->num_closed_socks, reuse->num_closed_socks + 1);
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}
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static bool __reuseport_detach_closed_sock(struct sock *sk,
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struct sock_reuseport *reuse)
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{
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int i = reuseport_sock_index(sk, reuse, true);
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if (i == -1)
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return false;
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reuse->socks[i] = reuse->socks[reuse->max_socks - reuse->num_closed_socks];
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/* paired with READ_ONCE() in inet_csk_bind_conflict() */
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WRITE_ONCE(reuse->num_closed_socks, reuse->num_closed_socks - 1);
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return true;
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}
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static struct sock_reuseport *__reuseport_alloc(unsigned int max_socks)
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{
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unsigned int size = sizeof(struct sock_reuseport) +
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sizeof(struct sock *) * max_socks;
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struct sock_reuseport *reuse = kzalloc(size, GFP_ATOMIC);
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if (!reuse)
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return NULL;
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reuse->max_socks = max_socks;
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RCU_INIT_POINTER(reuse->prog, NULL);
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return reuse;
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}
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int reuseport_alloc(struct sock *sk, bool bind_inany)
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{
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struct sock_reuseport *reuse;
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int id, ret = 0;
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/* bh lock used since this function call may precede hlist lock in
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* soft irq of receive path or setsockopt from process context
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*/
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spin_lock_bh(&reuseport_lock);
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/* Allocation attempts can occur concurrently via the setsockopt path
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* and the bind/hash path. Nothing to do when we lose the race.
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*/
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reuse = rcu_dereference_protected(sk->sk_reuseport_cb,
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lockdep_is_held(&reuseport_lock));
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if (reuse) {
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if (reuse->num_closed_socks) {
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/* sk was shutdown()ed before */
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ret = reuseport_resurrect(sk, reuse, NULL, bind_inany);
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goto out;
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}
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/* Only set reuse->bind_inany if the bind_inany is true.
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* Otherwise, it will overwrite the reuse->bind_inany
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* which was set by the bind/hash path.
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*/
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if (bind_inany)
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reuse->bind_inany = bind_inany;
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goto out;
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}
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reuse = __reuseport_alloc(INIT_SOCKS);
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if (!reuse) {
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ret = -ENOMEM;
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goto out;
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}
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id = ida_alloc(&reuseport_ida, GFP_ATOMIC);
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if (id < 0) {
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kfree(reuse);
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ret = id;
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goto out;
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}
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reuse->reuseport_id = id;
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reuse->bind_inany = bind_inany;
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reuse->socks[0] = sk;
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reuse->num_socks = 1;
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rcu_assign_pointer(sk->sk_reuseport_cb, reuse);
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out:
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spin_unlock_bh(&reuseport_lock);
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return ret;
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}
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EXPORT_SYMBOL(reuseport_alloc);
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static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse)
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{
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struct sock_reuseport *more_reuse;
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u32 more_socks_size, i;
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more_socks_size = reuse->max_socks * 2U;
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if (more_socks_size > U16_MAX) {
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if (reuse->num_closed_socks) {
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/* Make room by removing a closed sk.
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* The child has already been migrated.
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* Only reqsk left at this point.
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*/
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struct sock *sk;
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sk = reuse->socks[reuse->max_socks - reuse->num_closed_socks];
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RCU_INIT_POINTER(sk->sk_reuseport_cb, NULL);
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__reuseport_detach_closed_sock(sk, reuse);
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return reuse;
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}
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return NULL;
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}
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more_reuse = __reuseport_alloc(more_socks_size);
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if (!more_reuse)
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return NULL;
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more_reuse->num_socks = reuse->num_socks;
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more_reuse->num_closed_socks = reuse->num_closed_socks;
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more_reuse->prog = reuse->prog;
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more_reuse->reuseport_id = reuse->reuseport_id;
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more_reuse->bind_inany = reuse->bind_inany;
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more_reuse->has_conns = reuse->has_conns;
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memcpy(more_reuse->socks, reuse->socks,
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reuse->num_socks * sizeof(struct sock *));
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memcpy(more_reuse->socks +
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(more_reuse->max_socks - more_reuse->num_closed_socks),
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reuse->socks + (reuse->max_socks - reuse->num_closed_socks),
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reuse->num_closed_socks * sizeof(struct sock *));
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more_reuse->synq_overflow_ts = READ_ONCE(reuse->synq_overflow_ts);
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for (i = 0; i < reuse->max_socks; ++i)
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rcu_assign_pointer(reuse->socks[i]->sk_reuseport_cb,
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more_reuse);
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/* Note: we use kfree_rcu here instead of reuseport_free_rcu so
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* that reuse and more_reuse can temporarily share a reference
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* to prog.
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*/
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kfree_rcu(reuse, rcu);
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return more_reuse;
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}
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static void reuseport_free_rcu(struct rcu_head *head)
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{
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struct sock_reuseport *reuse;
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reuse = container_of(head, struct sock_reuseport, rcu);
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sk_reuseport_prog_free(rcu_dereference_protected(reuse->prog, 1));
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ida_free(&reuseport_ida, reuse->reuseport_id);
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kfree(reuse);
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}
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/**
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* reuseport_add_sock - Add a socket to the reuseport group of another.
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* @sk: New socket to add to the group.
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* @sk2: Socket belonging to the existing reuseport group.
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* @bind_inany: Whether or not the group is bound to a local INANY address.
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*
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* May return ENOMEM and not add socket to group under memory pressure.
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*/
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int reuseport_add_sock(struct sock *sk, struct sock *sk2, bool bind_inany)
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{
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struct sock_reuseport *old_reuse, *reuse;
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if (!rcu_access_pointer(sk2->sk_reuseport_cb)) {
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int err = reuseport_alloc(sk2, bind_inany);
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if (err)
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return err;
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}
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spin_lock_bh(&reuseport_lock);
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reuse = rcu_dereference_protected(sk2->sk_reuseport_cb,
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lockdep_is_held(&reuseport_lock));
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old_reuse = rcu_dereference_protected(sk->sk_reuseport_cb,
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lockdep_is_held(&reuseport_lock));
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if (old_reuse && old_reuse->num_closed_socks) {
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/* sk was shutdown()ed before */
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int err = reuseport_resurrect(sk, old_reuse, reuse, reuse->bind_inany);
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spin_unlock_bh(&reuseport_lock);
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return err;
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}
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if (old_reuse && old_reuse->num_socks != 1) {
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spin_unlock_bh(&reuseport_lock);
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return -EBUSY;
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}
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if (reuse->num_socks + reuse->num_closed_socks == reuse->max_socks) {
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reuse = reuseport_grow(reuse);
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if (!reuse) {
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spin_unlock_bh(&reuseport_lock);
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return -ENOMEM;
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}
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}
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__reuseport_add_sock(sk, reuse);
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rcu_assign_pointer(sk->sk_reuseport_cb, reuse);
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spin_unlock_bh(&reuseport_lock);
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if (old_reuse)
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call_rcu(&old_reuse->rcu, reuseport_free_rcu);
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return 0;
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}
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EXPORT_SYMBOL(reuseport_add_sock);
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static int reuseport_resurrect(struct sock *sk, struct sock_reuseport *old_reuse,
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struct sock_reuseport *reuse, bool bind_inany)
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{
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if (old_reuse == reuse) {
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/* If sk was in the same reuseport group, just pop sk out of
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* the closed section and push sk into the listening section.
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*/
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__reuseport_detach_closed_sock(sk, old_reuse);
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__reuseport_add_sock(sk, old_reuse);
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return 0;
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}
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if (!reuse) {
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/* In bind()/listen() path, we cannot carry over the eBPF prog
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* for the shutdown()ed socket. In setsockopt() path, we should
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* not change the eBPF prog of listening sockets by attaching a
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* prog to the shutdown()ed socket. Thus, we will allocate a new
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* reuseport group and detach sk from the old group.
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*/
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int id;
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reuse = __reuseport_alloc(INIT_SOCKS);
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if (!reuse)
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return -ENOMEM;
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id = ida_alloc(&reuseport_ida, GFP_ATOMIC);
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if (id < 0) {
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kfree(reuse);
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return id;
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}
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reuse->reuseport_id = id;
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reuse->bind_inany = bind_inany;
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} else {
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/* Move sk from the old group to the new one if
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* - all the other listeners in the old group were close()d or
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* shutdown()ed, and then sk2 has listen()ed on the same port
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* OR
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* - sk listen()ed without bind() (or with autobind), was
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* shutdown()ed, and then listen()s on another port which
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* sk2 listen()s on.
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*/
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if (reuse->num_socks + reuse->num_closed_socks == reuse->max_socks) {
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reuse = reuseport_grow(reuse);
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if (!reuse)
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return -ENOMEM;
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}
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}
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__reuseport_detach_closed_sock(sk, old_reuse);
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__reuseport_add_sock(sk, reuse);
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rcu_assign_pointer(sk->sk_reuseport_cb, reuse);
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if (old_reuse->num_socks + old_reuse->num_closed_socks == 0)
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call_rcu(&old_reuse->rcu, reuseport_free_rcu);
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return 0;
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}
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void reuseport_detach_sock(struct sock *sk)
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{
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struct sock_reuseport *reuse;
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spin_lock_bh(&reuseport_lock);
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reuse = rcu_dereference_protected(sk->sk_reuseport_cb,
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lockdep_is_held(&reuseport_lock));
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/* reuseport_grow() has detached a closed sk */
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if (!reuse)
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goto out;
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/* Notify the bpf side. The sk may be added to a sockarray
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* map. If so, sockarray logic will remove it from the map.
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*
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* Other bpf map types that work with reuseport, like sockmap,
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* don't need an explicit callback from here. They override sk
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* unhash/close ops to remove the sk from the map before we
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* get to this point.
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*/
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bpf_sk_reuseport_detach(sk);
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rcu_assign_pointer(sk->sk_reuseport_cb, NULL);
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if (!__reuseport_detach_closed_sock(sk, reuse))
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__reuseport_detach_sock(sk, reuse);
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if (reuse->num_socks + reuse->num_closed_socks == 0)
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call_rcu(&reuse->rcu, reuseport_free_rcu);
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out:
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spin_unlock_bh(&reuseport_lock);
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}
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EXPORT_SYMBOL(reuseport_detach_sock);
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void reuseport_stop_listen_sock(struct sock *sk)
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{
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if (sk->sk_protocol == IPPROTO_TCP) {
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struct sock_reuseport *reuse;
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struct bpf_prog *prog;
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spin_lock_bh(&reuseport_lock);
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reuse = rcu_dereference_protected(sk->sk_reuseport_cb,
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lockdep_is_held(&reuseport_lock));
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prog = rcu_dereference_protected(reuse->prog,
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lockdep_is_held(&reuseport_lock));
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if (sock_net(sk)->ipv4.sysctl_tcp_migrate_req ||
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(prog && prog->expected_attach_type == BPF_SK_REUSEPORT_SELECT_OR_MIGRATE)) {
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/* Migration capable, move sk from the listening section
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* to the closed section.
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*/
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bpf_sk_reuseport_detach(sk);
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__reuseport_detach_sock(sk, reuse);
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__reuseport_add_closed_sock(sk, reuse);
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spin_unlock_bh(&reuseport_lock);
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return;
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}
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spin_unlock_bh(&reuseport_lock);
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}
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/* Not capable to do migration, detach immediately */
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reuseport_detach_sock(sk);
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}
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EXPORT_SYMBOL(reuseport_stop_listen_sock);
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static struct sock *run_bpf_filter(struct sock_reuseport *reuse, u16 socks,
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struct bpf_prog *prog, struct sk_buff *skb,
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int hdr_len)
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{
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struct sk_buff *nskb = NULL;
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u32 index;
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if (skb_shared(skb)) {
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nskb = skb_clone(skb, GFP_ATOMIC);
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if (!nskb)
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return NULL;
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skb = nskb;
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}
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/* temporarily advance data past protocol header */
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if (!pskb_pull(skb, hdr_len)) {
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kfree_skb(nskb);
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return NULL;
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}
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index = bpf_prog_run_save_cb(prog, skb);
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__skb_push(skb, hdr_len);
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consume_skb(nskb);
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if (index >= socks)
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return NULL;
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return reuse->socks[index];
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}
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static struct sock *reuseport_select_sock_by_hash(struct sock_reuseport *reuse,
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u32 hash, u16 num_socks)
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{
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int i, j;
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i = j = reciprocal_scale(hash, num_socks);
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while (reuse->socks[i]->sk_state == TCP_ESTABLISHED) {
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i++;
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if (i >= num_socks)
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i = 0;
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if (i == j)
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return NULL;
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}
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return reuse->socks[i];
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}
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/**
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* reuseport_select_sock - Select a socket from an SO_REUSEPORT group.
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* @sk: First socket in the group.
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* @hash: When no BPF filter is available, use this hash to select.
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* @skb: skb to run through BPF filter.
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* @hdr_len: BPF filter expects skb data pointer at payload data. If
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* the skb does not yet point at the payload, this parameter represents
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* how far the pointer needs to advance to reach the payload.
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* Returns a socket that should receive the packet (or NULL on error).
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*/
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struct sock *reuseport_select_sock(struct sock *sk,
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u32 hash,
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struct sk_buff *skb,
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int hdr_len)
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{
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struct sock_reuseport *reuse;
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struct bpf_prog *prog;
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struct sock *sk2 = NULL;
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u16 socks;
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rcu_read_lock();
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reuse = rcu_dereference(sk->sk_reuseport_cb);
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/* if memory allocation failed or add call is not yet complete */
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if (!reuse)
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goto out;
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prog = rcu_dereference(reuse->prog);
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socks = READ_ONCE(reuse->num_socks);
|
|
if (likely(socks)) {
|
|
/* paired with smp_wmb() in __reuseport_add_sock() */
|
|
smp_rmb();
|
|
|
|
if (!prog || !skb)
|
|
goto select_by_hash;
|
|
|
|
if (prog->type == BPF_PROG_TYPE_SK_REUSEPORT)
|
|
sk2 = bpf_run_sk_reuseport(reuse, sk, prog, skb, NULL, hash);
|
|
else
|
|
sk2 = run_bpf_filter(reuse, socks, prog, skb, hdr_len);
|
|
|
|
select_by_hash:
|
|
/* no bpf or invalid bpf result: fall back to hash usage */
|
|
if (!sk2)
|
|
sk2 = reuseport_select_sock_by_hash(reuse, hash, socks);
|
|
}
|
|
|
|
out:
|
|
rcu_read_unlock();
|
|
return sk2;
|
|
}
|
|
EXPORT_SYMBOL(reuseport_select_sock);
|
|
|
|
/**
|
|
* reuseport_migrate_sock - Select a socket from an SO_REUSEPORT group.
|
|
* @sk: close()ed or shutdown()ed socket in the group.
|
|
* @migrating_sk: ESTABLISHED/SYN_RECV full socket in the accept queue or
|
|
* NEW_SYN_RECV request socket during 3WHS.
|
|
* @skb: skb to run through BPF filter.
|
|
* Returns a socket (with sk_refcnt +1) that should accept the child socket
|
|
* (or NULL on error).
|
|
*/
|
|
struct sock *reuseport_migrate_sock(struct sock *sk,
|
|
struct sock *migrating_sk,
|
|
struct sk_buff *skb)
|
|
{
|
|
struct sock_reuseport *reuse;
|
|
struct sock *nsk = NULL;
|
|
bool allocated = false;
|
|
struct bpf_prog *prog;
|
|
u16 socks;
|
|
u32 hash;
|
|
|
|
rcu_read_lock();
|
|
|
|
reuse = rcu_dereference(sk->sk_reuseport_cb);
|
|
if (!reuse)
|
|
goto out;
|
|
|
|
socks = READ_ONCE(reuse->num_socks);
|
|
if (unlikely(!socks))
|
|
goto failure;
|
|
|
|
/* paired with smp_wmb() in __reuseport_add_sock() */
|
|
smp_rmb();
|
|
|
|
hash = migrating_sk->sk_hash;
|
|
prog = rcu_dereference(reuse->prog);
|
|
if (!prog || prog->expected_attach_type != BPF_SK_REUSEPORT_SELECT_OR_MIGRATE) {
|
|
if (sock_net(sk)->ipv4.sysctl_tcp_migrate_req)
|
|
goto select_by_hash;
|
|
goto failure;
|
|
}
|
|
|
|
if (!skb) {
|
|
skb = alloc_skb(0, GFP_ATOMIC);
|
|
if (!skb)
|
|
goto failure;
|
|
allocated = true;
|
|
}
|
|
|
|
nsk = bpf_run_sk_reuseport(reuse, sk, prog, skb, migrating_sk, hash);
|
|
|
|
if (allocated)
|
|
kfree_skb(skb);
|
|
|
|
select_by_hash:
|
|
if (!nsk)
|
|
nsk = reuseport_select_sock_by_hash(reuse, hash, socks);
|
|
|
|
if (IS_ERR_OR_NULL(nsk) || unlikely(!refcount_inc_not_zero(&nsk->sk_refcnt))) {
|
|
nsk = NULL;
|
|
goto failure;
|
|
}
|
|
|
|
out:
|
|
rcu_read_unlock();
|
|
return nsk;
|
|
|
|
failure:
|
|
__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
|
|
goto out;
|
|
}
|
|
EXPORT_SYMBOL(reuseport_migrate_sock);
|
|
|
|
int reuseport_attach_prog(struct sock *sk, struct bpf_prog *prog)
|
|
{
|
|
struct sock_reuseport *reuse;
|
|
struct bpf_prog *old_prog;
|
|
|
|
if (sk_unhashed(sk)) {
|
|
int err;
|
|
|
|
if (!sk->sk_reuseport)
|
|
return -EINVAL;
|
|
|
|
err = reuseport_alloc(sk, false);
|
|
if (err)
|
|
return err;
|
|
} else if (!rcu_access_pointer(sk->sk_reuseport_cb)) {
|
|
/* The socket wasn't bound with SO_REUSEPORT */
|
|
return -EINVAL;
|
|
}
|
|
|
|
spin_lock_bh(&reuseport_lock);
|
|
reuse = rcu_dereference_protected(sk->sk_reuseport_cb,
|
|
lockdep_is_held(&reuseport_lock));
|
|
old_prog = rcu_dereference_protected(reuse->prog,
|
|
lockdep_is_held(&reuseport_lock));
|
|
rcu_assign_pointer(reuse->prog, prog);
|
|
spin_unlock_bh(&reuseport_lock);
|
|
|
|
sk_reuseport_prog_free(old_prog);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(reuseport_attach_prog);
|
|
|
|
int reuseport_detach_prog(struct sock *sk)
|
|
{
|
|
struct sock_reuseport *reuse;
|
|
struct bpf_prog *old_prog;
|
|
|
|
old_prog = NULL;
|
|
spin_lock_bh(&reuseport_lock);
|
|
reuse = rcu_dereference_protected(sk->sk_reuseport_cb,
|
|
lockdep_is_held(&reuseport_lock));
|
|
|
|
/* reuse must be checked after acquiring the reuseport_lock
|
|
* because reuseport_grow() can detach a closed sk.
|
|
*/
|
|
if (!reuse) {
|
|
spin_unlock_bh(&reuseport_lock);
|
|
return sk->sk_reuseport ? -ENOENT : -EINVAL;
|
|
}
|
|
|
|
if (sk_unhashed(sk) && reuse->num_closed_socks) {
|
|
spin_unlock_bh(&reuseport_lock);
|
|
return -ENOENT;
|
|
}
|
|
|
|
old_prog = rcu_replace_pointer(reuse->prog, old_prog,
|
|
lockdep_is_held(&reuseport_lock));
|
|
spin_unlock_bh(&reuseport_lock);
|
|
|
|
if (!old_prog)
|
|
return -ENOENT;
|
|
|
|
sk_reuseport_prog_free(old_prog);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(reuseport_detach_prog);
|