From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- net/core/sock_reuseport.c | 749 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 749 insertions(+) create mode 100644 net/core/sock_reuseport.c (limited to 'net/core/sock_reuseport.c') diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c new file mode 100644 index 000000000..5a165286e --- /dev/null +++ b/net/core/sock_reuseport.c @@ -0,0 +1,749 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * To speed up listener socket lookup, create an array to store all sockets + * listening on the same port. This allows a decision to be made after finding + * the first socket. An optional BPF program can also be configured for + * selecting the socket index from the array of available sockets. + */ + +#include +#include +#include +#include +#include +#include + +#define INIT_SOCKS 128 + +DEFINE_SPINLOCK(reuseport_lock); + +static DEFINE_IDA(reuseport_ida); +static int reuseport_resurrect(struct sock *sk, struct sock_reuseport *old_reuse, + struct sock_reuseport *reuse, bool bind_inany); + +void reuseport_has_conns_set(struct sock *sk) +{ + struct sock_reuseport *reuse; + + if (!rcu_access_pointer(sk->sk_reuseport_cb)) + return; + + spin_lock_bh(&reuseport_lock); + reuse = rcu_dereference_protected(sk->sk_reuseport_cb, + lockdep_is_held(&reuseport_lock)); + if (likely(reuse)) + reuse->has_conns = 1; + spin_unlock_bh(&reuseport_lock); +} +EXPORT_SYMBOL(reuseport_has_conns_set); + +static void __reuseport_get_incoming_cpu(struct sock_reuseport *reuse) +{ + /* Paired with READ_ONCE() in reuseport_select_sock_by_hash(). */ + WRITE_ONCE(reuse->incoming_cpu, reuse->incoming_cpu + 1); +} + +static void __reuseport_put_incoming_cpu(struct sock_reuseport *reuse) +{ + /* Paired with READ_ONCE() in reuseport_select_sock_by_hash(). */ + WRITE_ONCE(reuse->incoming_cpu, reuse->incoming_cpu - 1); +} + +static void reuseport_get_incoming_cpu(struct sock *sk, struct sock_reuseport *reuse) +{ + if (sk->sk_incoming_cpu >= 0) + __reuseport_get_incoming_cpu(reuse); +} + +static void reuseport_put_incoming_cpu(struct sock *sk, struct sock_reuseport *reuse) +{ + if (sk->sk_incoming_cpu >= 0) + __reuseport_put_incoming_cpu(reuse); +} + +void reuseport_update_incoming_cpu(struct sock *sk, int val) +{ + struct sock_reuseport *reuse; + int old_sk_incoming_cpu; + + if (unlikely(!rcu_access_pointer(sk->sk_reuseport_cb))) { + /* Paired with REAE_ONCE() in sk_incoming_cpu_update() + * and compute_score(). + */ + WRITE_ONCE(sk->sk_incoming_cpu, val); + return; + } + + spin_lock_bh(&reuseport_lock); + + /* This must be done under reuseport_lock to avoid a race with + * reuseport_grow(), which accesses sk->sk_incoming_cpu without + * lock_sock() when detaching a shutdown()ed sk. + * + * Paired with READ_ONCE() in reuseport_select_sock_by_hash(). + */ + old_sk_incoming_cpu = sk->sk_incoming_cpu; + WRITE_ONCE(sk->sk_incoming_cpu, val); + + reuse = rcu_dereference_protected(sk->sk_reuseport_cb, + lockdep_is_held(&reuseport_lock)); + + /* reuseport_grow() has detached a closed sk. */ + if (!reuse) + goto out; + + if (old_sk_incoming_cpu < 0 && val >= 0) + __reuseport_get_incoming_cpu(reuse); + else if (old_sk_incoming_cpu >= 0 && val < 0) + __reuseport_put_incoming_cpu(reuse); + +out: + spin_unlock_bh(&reuseport_lock); +} + +static int reuseport_sock_index(struct sock *sk, + const struct sock_reuseport *reuse, + bool closed) +{ + int left, right; + + if (!closed) { + left = 0; + right = reuse->num_socks; + } else { + left = reuse->max_socks - reuse->num_closed_socks; + right = reuse->max_socks; + } + + for (; left < right; left++) + if (reuse->socks[left] == sk) + return left; + return -1; +} + +static void __reuseport_add_sock(struct sock *sk, + struct sock_reuseport *reuse) +{ + reuse->socks[reuse->num_socks] = sk; + /* paired with smp_rmb() in reuseport_(select|migrate)_sock() */ + smp_wmb(); + reuse->num_socks++; + reuseport_get_incoming_cpu(sk, reuse); +} + +static bool __reuseport_detach_sock(struct sock *sk, + struct sock_reuseport *reuse) +{ + int i = reuseport_sock_index(sk, reuse, false); + + if (i == -1) + return false; + + reuse->socks[i] = reuse->socks[reuse->num_socks - 1]; + reuse->num_socks--; + reuseport_put_incoming_cpu(sk, reuse); + + return true; +} + +static void __reuseport_add_closed_sock(struct sock *sk, + struct sock_reuseport *reuse) +{ + reuse->socks[reuse->max_socks - reuse->num_closed_socks - 1] = sk; + /* paired with READ_ONCE() in inet_csk_bind_conflict() */ + WRITE_ONCE(reuse->num_closed_socks, reuse->num_closed_socks + 1); + reuseport_get_incoming_cpu(sk, reuse); +} + +static bool __reuseport_detach_closed_sock(struct sock *sk, + struct sock_reuseport *reuse) +{ + int i = reuseport_sock_index(sk, reuse, true); + + if (i == -1) + return false; + + reuse->socks[i] = reuse->socks[reuse->max_socks - reuse->num_closed_socks]; + /* paired with READ_ONCE() in inet_csk_bind_conflict() */ + WRITE_ONCE(reuse->num_closed_socks, reuse->num_closed_socks - 1); + reuseport_put_incoming_cpu(sk, reuse); + + return true; +} + +static struct sock_reuseport *__reuseport_alloc(unsigned int max_socks) +{ + unsigned int size = sizeof(struct sock_reuseport) + + sizeof(struct sock *) * max_socks; + struct sock_reuseport *reuse = kzalloc(size, GFP_ATOMIC); + + if (!reuse) + return NULL; + + reuse->max_socks = max_socks; + + RCU_INIT_POINTER(reuse->prog, NULL); + return reuse; +} + +int reuseport_alloc(struct sock *sk, bool bind_inany) +{ + struct sock_reuseport *reuse; + int id, ret = 0; + + /* bh lock used since this function call may precede hlist lock in + * soft irq of receive path or setsockopt from process context + */ + spin_lock_bh(&reuseport_lock); + + /* Allocation attempts can occur concurrently via the setsockopt path + * and the bind/hash path. Nothing to do when we lose the race. + */ + reuse = rcu_dereference_protected(sk->sk_reuseport_cb, + lockdep_is_held(&reuseport_lock)); + if (reuse) { + if (reuse->num_closed_socks) { + /* sk was shutdown()ed before */ + ret = reuseport_resurrect(sk, reuse, NULL, bind_inany); + goto out; + } + + /* Only set reuse->bind_inany if the bind_inany is true. + * Otherwise, it will overwrite the reuse->bind_inany + * which was set by the bind/hash path. + */ + if (bind_inany) + reuse->bind_inany = bind_inany; + goto out; + } + + reuse = __reuseport_alloc(INIT_SOCKS); + if (!reuse) { + ret = -ENOMEM; + goto out; + } + + id = ida_alloc(&reuseport_ida, GFP_ATOMIC); + if (id < 0) { + kfree(reuse); + ret = id; + goto out; + } + + reuse->reuseport_id = id; + reuse->bind_inany = bind_inany; + reuse->socks[0] = sk; + reuse->num_socks = 1; + reuseport_get_incoming_cpu(sk, reuse); + rcu_assign_pointer(sk->sk_reuseport_cb, reuse); + +out: + spin_unlock_bh(&reuseport_lock); + + return ret; +} +EXPORT_SYMBOL(reuseport_alloc); + +static struct sock_reuseport *reuseport_grow(struct sock_reuseport *reuse) +{ + struct sock_reuseport *more_reuse; + u32 more_socks_size, i; + + more_socks_size = reuse->max_socks * 2U; + if (more_socks_size > U16_MAX) { + if (reuse->num_closed_socks) { + /* Make room by removing a closed sk. + * The child has already been migrated. + * Only reqsk left at this point. + */ + struct sock *sk; + + sk = reuse->socks[reuse->max_socks - reuse->num_closed_socks]; + RCU_INIT_POINTER(sk->sk_reuseport_cb, NULL); + __reuseport_detach_closed_sock(sk, reuse); + + return reuse; + } + + return NULL; + } + + more_reuse = __reuseport_alloc(more_socks_size); + if (!more_reuse) + return NULL; + + more_reuse->num_socks = reuse->num_socks; + more_reuse->num_closed_socks = reuse->num_closed_socks; + more_reuse->prog = reuse->prog; + more_reuse->reuseport_id = reuse->reuseport_id; + more_reuse->bind_inany = reuse->bind_inany; + more_reuse->has_conns = reuse->has_conns; + more_reuse->incoming_cpu = reuse->incoming_cpu; + + memcpy(more_reuse->socks, reuse->socks, + reuse->num_socks * sizeof(struct sock *)); + memcpy(more_reuse->socks + + (more_reuse->max_socks - more_reuse->num_closed_socks), + reuse->socks + (reuse->max_socks - reuse->num_closed_socks), + reuse->num_closed_socks * sizeof(struct sock *)); + more_reuse->synq_overflow_ts = READ_ONCE(reuse->synq_overflow_ts); + + for (i = 0; i < reuse->max_socks; ++i) + rcu_assign_pointer(reuse->socks[i]->sk_reuseport_cb, + more_reuse); + + /* Note: we use kfree_rcu here instead of reuseport_free_rcu so + * that reuse and more_reuse can temporarily share a reference + * to prog. + */ + kfree_rcu(reuse, rcu); + return more_reuse; +} + +static void reuseport_free_rcu(struct rcu_head *head) +{ + struct sock_reuseport *reuse; + + reuse = container_of(head, struct sock_reuseport, rcu); + sk_reuseport_prog_free(rcu_dereference_protected(reuse->prog, 1)); + ida_free(&reuseport_ida, reuse->reuseport_id); + kfree(reuse); +} + +/** + * reuseport_add_sock - Add a socket to the reuseport group of another. + * @sk: New socket to add to the group. + * @sk2: Socket belonging to the existing reuseport group. + * @bind_inany: Whether or not the group is bound to a local INANY address. + * + * May return ENOMEM and not add socket to group under memory pressure. + */ +int reuseport_add_sock(struct sock *sk, struct sock *sk2, bool bind_inany) +{ + struct sock_reuseport *old_reuse, *reuse; + + if (!rcu_access_pointer(sk2->sk_reuseport_cb)) { + int err = reuseport_alloc(sk2, bind_inany); + + if (err) + return err; + } + + spin_lock_bh(&reuseport_lock); + reuse = rcu_dereference_protected(sk2->sk_reuseport_cb, + lockdep_is_held(&reuseport_lock)); + old_reuse = rcu_dereference_protected(sk->sk_reuseport_cb, + lockdep_is_held(&reuseport_lock)); + if (old_reuse && old_reuse->num_closed_socks) { + /* sk was shutdown()ed before */ + int err = reuseport_resurrect(sk, old_reuse, reuse, reuse->bind_inany); + + spin_unlock_bh(&reuseport_lock); + return err; + } + + if (old_reuse && old_reuse->num_socks != 1) { + spin_unlock_bh(&reuseport_lock); + return -EBUSY; + } + + if (reuse->num_socks + reuse->num_closed_socks == reuse->max_socks) { + reuse = reuseport_grow(reuse); + if (!reuse) { + spin_unlock_bh(&reuseport_lock); + return -ENOMEM; + } + } + + __reuseport_add_sock(sk, reuse); + rcu_assign_pointer(sk->sk_reuseport_cb, reuse); + + spin_unlock_bh(&reuseport_lock); + + if (old_reuse) + call_rcu(&old_reuse->rcu, reuseport_free_rcu); + return 0; +} +EXPORT_SYMBOL(reuseport_add_sock); + +static int reuseport_resurrect(struct sock *sk, struct sock_reuseport *old_reuse, + struct sock_reuseport *reuse, bool bind_inany) +{ + if (old_reuse == reuse) { + /* If sk was in the same reuseport group, just pop sk out of + * the closed section and push sk into the listening section. + */ + __reuseport_detach_closed_sock(sk, old_reuse); + __reuseport_add_sock(sk, old_reuse); + return 0; + } + + if (!reuse) { + /* In bind()/listen() path, we cannot carry over the eBPF prog + * for the shutdown()ed socket. In setsockopt() path, we should + * not change the eBPF prog of listening sockets by attaching a + * prog to the shutdown()ed socket. Thus, we will allocate a new + * reuseport group and detach sk from the old group. + */ + int id; + + reuse = __reuseport_alloc(INIT_SOCKS); + if (!reuse) + return -ENOMEM; + + id = ida_alloc(&reuseport_ida, GFP_ATOMIC); + if (id < 0) { + kfree(reuse); + return id; + } + + reuse->reuseport_id = id; + reuse->bind_inany = bind_inany; + } else { + /* Move sk from the old group to the new one if + * - all the other listeners in the old group were close()d or + * shutdown()ed, and then sk2 has listen()ed on the same port + * OR + * - sk listen()ed without bind() (or with autobind), was + * shutdown()ed, and then listen()s on another port which + * sk2 listen()s on. + */ + if (reuse->num_socks + reuse->num_closed_socks == reuse->max_socks) { + reuse = reuseport_grow(reuse); + if (!reuse) + return -ENOMEM; + } + } + + __reuseport_detach_closed_sock(sk, old_reuse); + __reuseport_add_sock(sk, reuse); + rcu_assign_pointer(sk->sk_reuseport_cb, reuse); + + if (old_reuse->num_socks + old_reuse->num_closed_socks == 0) + call_rcu(&old_reuse->rcu, reuseport_free_rcu); + + return 0; +} + +void reuseport_detach_sock(struct sock *sk) +{ + struct sock_reuseport *reuse; + + spin_lock_bh(&reuseport_lock); + reuse = rcu_dereference_protected(sk->sk_reuseport_cb, + lockdep_is_held(&reuseport_lock)); + + /* reuseport_grow() has detached a closed sk */ + if (!reuse) + goto out; + + /* Notify the bpf side. The sk may be added to a sockarray + * map. If so, sockarray logic will remove it from the map. + * + * Other bpf map types that work with reuseport, like sockmap, + * don't need an explicit callback from here. They override sk + * unhash/close ops to remove the sk from the map before we + * get to this point. + */ + bpf_sk_reuseport_detach(sk); + + rcu_assign_pointer(sk->sk_reuseport_cb, NULL); + + if (!__reuseport_detach_closed_sock(sk, reuse)) + __reuseport_detach_sock(sk, reuse); + + if (reuse->num_socks + reuse->num_closed_socks == 0) + call_rcu(&reuse->rcu, reuseport_free_rcu); + +out: + spin_unlock_bh(&reuseport_lock); +} +EXPORT_SYMBOL(reuseport_detach_sock); + +void reuseport_stop_listen_sock(struct sock *sk) +{ + if (sk->sk_protocol == IPPROTO_TCP) { + struct sock_reuseport *reuse; + struct bpf_prog *prog; + + spin_lock_bh(&reuseport_lock); + + reuse = rcu_dereference_protected(sk->sk_reuseport_cb, + lockdep_is_held(&reuseport_lock)); + prog = rcu_dereference_protected(reuse->prog, + lockdep_is_held(&reuseport_lock)); + + if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_migrate_req) || + (prog && prog->expected_attach_type == BPF_SK_REUSEPORT_SELECT_OR_MIGRATE)) { + /* Migration capable, move sk from the listening section + * to the closed section. + */ + bpf_sk_reuseport_detach(sk); + + __reuseport_detach_sock(sk, reuse); + __reuseport_add_closed_sock(sk, reuse); + + spin_unlock_bh(&reuseport_lock); + return; + } + + spin_unlock_bh(&reuseport_lock); + } + + /* Not capable to do migration, detach immediately */ + reuseport_detach_sock(sk); +} +EXPORT_SYMBOL(reuseport_stop_listen_sock); + +static struct sock *run_bpf_filter(struct sock_reuseport *reuse, u16 socks, + struct bpf_prog *prog, struct sk_buff *skb, + int hdr_len) +{ + struct sk_buff *nskb = NULL; + u32 index; + + if (skb_shared(skb)) { + nskb = skb_clone(skb, GFP_ATOMIC); + if (!nskb) + return NULL; + skb = nskb; + } + + /* temporarily advance data past protocol header */ + if (!pskb_pull(skb, hdr_len)) { + kfree_skb(nskb); + return NULL; + } + index = bpf_prog_run_save_cb(prog, skb); + __skb_push(skb, hdr_len); + + consume_skb(nskb); + + if (index >= socks) + return NULL; + + return reuse->socks[index]; +} + +static struct sock *reuseport_select_sock_by_hash(struct sock_reuseport *reuse, + u32 hash, u16 num_socks) +{ + struct sock *first_valid_sk = NULL; + int i, j; + + i = j = reciprocal_scale(hash, num_socks); + do { + struct sock *sk = reuse->socks[i]; + + if (sk->sk_state != TCP_ESTABLISHED) { + /* Paired with WRITE_ONCE() in __reuseport_(get|put)_incoming_cpu(). */ + if (!READ_ONCE(reuse->incoming_cpu)) + return sk; + + /* Paired with WRITE_ONCE() in reuseport_update_incoming_cpu(). */ + if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id()) + return sk; + + if (!first_valid_sk) + first_valid_sk = sk; + } + + i++; + if (i >= num_socks) + i = 0; + } while (i != j); + + return first_valid_sk; +} + +/** + * reuseport_select_sock - Select a socket from an SO_REUSEPORT group. + * @sk: First socket in the group. + * @hash: When no BPF filter is available, use this hash to select. + * @skb: skb to run through BPF filter. + * @hdr_len: BPF filter expects skb data pointer at payload data. If + * the skb does not yet point at the payload, this parameter represents + * how far the pointer needs to advance to reach the payload. + * Returns a socket that should receive the packet (or NULL on error). + */ +struct sock *reuseport_select_sock(struct sock *sk, + u32 hash, + struct sk_buff *skb, + int hdr_len) +{ + struct sock_reuseport *reuse; + struct bpf_prog *prog; + struct sock *sk2 = NULL; + u16 socks; + + rcu_read_lock(); + reuse = rcu_dereference(sk->sk_reuseport_cb); + + /* if memory allocation failed or add call is not yet complete */ + if (!reuse) + goto out; + + prog = rcu_dereference(reuse->prog); + 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 (READ_ONCE(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); -- cgit v1.2.3