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a6f190630d
Add a new SKB drop reason (SKB_DROP_REASON_PFMEMALLOC) to track packets dropped due to memory pressure. In production environments, we've observed memory exhaustion reported by memory layer stack traces, but these drops were not properly tracked in the SKB drop reason infrastructure. While most network code paths now properly report pfmemalloc drops, some protocol-specific socket implementations still use sk_filter() without drop reason tracking: - Bluetooth L2CAP sockets - CAIF sockets - IUCV sockets - Netlink sockets - SCTP sockets - Unix domain sockets These remaining cases represent less common paths and could be converted in a follow-up patch if needed. The current implementation provides significantly improved observability into memory pressure events in the network stack, especially for key protocols like TCP and UDP, helping to diagnose problems in production environments. Reported-by: Matt Fleming <mfleming@cloudflare.com> Signed-off-by: Jesper Dangaard Brouer <hawk@kernel.org> Link: https://patch.msgid.link/175268316579.2407873.11634752355644843509.stgit@firesoul Signed-off-by: Jakub Kicinski <kuba@kernel.org>
295 lines
7.4 KiB
C
295 lines
7.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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*
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* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
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*
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* Most of this code is based on the SDL diagrams published in the 7th ARRL
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* Computer Networking Conference papers. The diagrams have mistakes in them,
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* but are mostly correct. Before you modify the code could you read the SDL
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* diagrams as the code is not obvious and probably very easy to break.
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*/
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#include <linux/errno.h>
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#include <linux/filter.h>
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/kernel.h>
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#include <linux/timer.h>
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#include <linux/string.h>
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#include <linux/sockios.h>
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#include <linux/net.h>
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#include <net/ax25.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <net/tcp_states.h>
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#include <linux/fcntl.h>
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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#include <net/rose.h>
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/*
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* State machine for state 1, Awaiting Call Accepted State.
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* The handling of the timer(s) is in file rose_timer.c.
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* Handling of state 0 and connection release is in af_rose.c.
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*/
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static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
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{
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struct rose_sock *rose = rose_sk(sk);
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switch (frametype) {
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case ROSE_CALL_ACCEPTED:
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rose_stop_timer(sk);
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rose_start_idletimer(sk);
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rose->condition = 0x00;
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rose->vs = 0;
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rose->va = 0;
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rose->vr = 0;
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rose->vl = 0;
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rose->state = ROSE_STATE_3;
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sk->sk_state = TCP_ESTABLISHED;
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if (!sock_flag(sk, SOCK_DEAD))
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sk->sk_state_change(sk);
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break;
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case ROSE_CLEAR_REQUEST:
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rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
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rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
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rose->neighbour->use--;
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break;
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default:
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break;
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}
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return 0;
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}
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/*
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* State machine for state 2, Awaiting Clear Confirmation State.
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* The handling of the timer(s) is in file rose_timer.c
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* Handling of state 0 and connection release is in af_rose.c.
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*/
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static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
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{
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struct rose_sock *rose = rose_sk(sk);
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switch (frametype) {
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case ROSE_CLEAR_REQUEST:
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rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
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rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
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rose->neighbour->use--;
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break;
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case ROSE_CLEAR_CONFIRMATION:
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rose_disconnect(sk, 0, -1, -1);
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rose->neighbour->use--;
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break;
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default:
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break;
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}
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return 0;
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}
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/*
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* State machine for state 3, Connected State.
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* The handling of the timer(s) is in file rose_timer.c
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* Handling of state 0 and connection release is in af_rose.c.
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*/
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static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
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{
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enum skb_drop_reason dr; /* ignored */
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struct rose_sock *rose = rose_sk(sk);
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int queued = 0;
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switch (frametype) {
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case ROSE_RESET_REQUEST:
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rose_stop_timer(sk);
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rose_start_idletimer(sk);
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rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
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rose->condition = 0x00;
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rose->vs = 0;
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rose->vr = 0;
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rose->va = 0;
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rose->vl = 0;
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rose_requeue_frames(sk);
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break;
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case ROSE_CLEAR_REQUEST:
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rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
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rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
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rose->neighbour->use--;
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break;
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case ROSE_RR:
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case ROSE_RNR:
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if (!rose_validate_nr(sk, nr)) {
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rose_write_internal(sk, ROSE_RESET_REQUEST);
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rose->condition = 0x00;
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rose->vs = 0;
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rose->vr = 0;
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rose->va = 0;
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rose->vl = 0;
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rose->state = ROSE_STATE_4;
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rose_start_t2timer(sk);
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rose_stop_idletimer(sk);
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} else {
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rose_frames_acked(sk, nr);
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if (frametype == ROSE_RNR) {
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rose->condition |= ROSE_COND_PEER_RX_BUSY;
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} else {
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rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
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}
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}
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break;
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case ROSE_DATA: /* XXX */
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rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
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if (!rose_validate_nr(sk, nr)) {
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rose_write_internal(sk, ROSE_RESET_REQUEST);
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rose->condition = 0x00;
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rose->vs = 0;
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rose->vr = 0;
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rose->va = 0;
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rose->vl = 0;
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rose->state = ROSE_STATE_4;
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rose_start_t2timer(sk);
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rose_stop_idletimer(sk);
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break;
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}
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rose_frames_acked(sk, nr);
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if (ns == rose->vr) {
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rose_start_idletimer(sk);
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if (!sk_filter_trim_cap(sk, skb, ROSE_MIN_LEN, &dr) &&
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__sock_queue_rcv_skb(sk, skb) == 0) {
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rose->vr = (rose->vr + 1) % ROSE_MODULUS;
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queued = 1;
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} else {
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/* Should never happen ! */
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rose_write_internal(sk, ROSE_RESET_REQUEST);
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rose->condition = 0x00;
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rose->vs = 0;
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rose->vr = 0;
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rose->va = 0;
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rose->vl = 0;
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rose->state = ROSE_STATE_4;
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rose_start_t2timer(sk);
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rose_stop_idletimer(sk);
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break;
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}
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if (atomic_read(&sk->sk_rmem_alloc) >
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(sk->sk_rcvbuf >> 1))
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rose->condition |= ROSE_COND_OWN_RX_BUSY;
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}
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/*
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* If the window is full, ack the frame, else start the
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* acknowledge hold back timer.
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*/
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if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) {
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rose->condition &= ~ROSE_COND_ACK_PENDING;
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rose_stop_timer(sk);
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rose_enquiry_response(sk);
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} else {
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rose->condition |= ROSE_COND_ACK_PENDING;
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rose_start_hbtimer(sk);
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}
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break;
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default:
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printk(KERN_WARNING "ROSE: unknown %02X in state 3\n", frametype);
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break;
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}
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return queued;
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}
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/*
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* State machine for state 4, Awaiting Reset Confirmation State.
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* The handling of the timer(s) is in file rose_timer.c
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* Handling of state 0 and connection release is in af_rose.c.
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*/
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static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
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{
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struct rose_sock *rose = rose_sk(sk);
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switch (frametype) {
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case ROSE_RESET_REQUEST:
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rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
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fallthrough;
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case ROSE_RESET_CONFIRMATION:
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rose_stop_timer(sk);
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rose_start_idletimer(sk);
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rose->condition = 0x00;
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rose->va = 0;
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rose->vr = 0;
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rose->vs = 0;
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rose->vl = 0;
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rose->state = ROSE_STATE_3;
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rose_requeue_frames(sk);
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break;
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case ROSE_CLEAR_REQUEST:
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rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
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rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
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rose->neighbour->use--;
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break;
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default:
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break;
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}
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return 0;
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}
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/*
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* State machine for state 5, Awaiting Call Acceptance State.
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* The handling of the timer(s) is in file rose_timer.c
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* Handling of state 0 and connection release is in af_rose.c.
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*/
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static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype)
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{
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if (frametype == ROSE_CLEAR_REQUEST) {
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rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
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rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
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rose_sk(sk)->neighbour->use--;
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}
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return 0;
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}
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/* Higher level upcall for a LAPB frame */
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int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb)
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{
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struct rose_sock *rose = rose_sk(sk);
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int queued = 0, frametype, ns, nr, q, d, m;
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if (rose->state == ROSE_STATE_0)
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return 0;
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frametype = rose_decode(skb, &ns, &nr, &q, &d, &m);
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switch (rose->state) {
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case ROSE_STATE_1:
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queued = rose_state1_machine(sk, skb, frametype);
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break;
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case ROSE_STATE_2:
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queued = rose_state2_machine(sk, skb, frametype);
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break;
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case ROSE_STATE_3:
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queued = rose_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
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break;
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case ROSE_STATE_4:
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queued = rose_state4_machine(sk, skb, frametype);
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break;
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case ROSE_STATE_5:
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queued = rose_state5_machine(sk, skb, frametype);
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break;
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}
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rose_kick(sk);
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return queued;
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}
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