cregit-Linux how code gets into the kernel

Release 4.17 samples/sockmap/sockmap_kern.c

Directory: samples/sockmap
/* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 */
#include <uapi/linux/bpf.h>
#include <uapi/linux/if_ether.h>
#include <uapi/linux/if_packet.h>
#include <uapi/linux/ip.h>
#include "../../tools/testing/selftests/bpf/bpf_helpers.h"
#include "../../tools/testing/selftests/bpf/bpf_endian.h"

/* Sockmap sample program connects a client and a backend together
 * using cgroups.
 *
 *    client:X <---> frontend:80 client:X <---> backend:80
 *
 * For simplicity we hard code values here and bind 1:1. The hard
 * coded values are part of the setup in sockmap.sh script that
 * is associated with this BPF program.
 *
 * The bpf_printk is verbose and prints information as connections
 * are established and verdicts are decided.
 */


#define bpf_printk(fmt, ...)					\
({                                                              \
               char ____fmt[] = fmt;                            \
               bpf_trace_printk(____fmt, sizeof(____fmt),       \
                                ##__VA_ARGS__);                 \
})

struct bpf_map_def SEC("maps") sock_map = {
	.type = BPF_MAP_TYPE_SOCKMAP,
	.key_size = sizeof(int),
	.value_size = sizeof(int),
	.max_entries = 20,
};

struct bpf_map_def SEC("maps") sock_map_txmsg = {
	.type = BPF_MAP_TYPE_SOCKMAP,
	.key_size = sizeof(int),
	.value_size = sizeof(int),
	.max_entries = 20,
};

struct bpf_map_def SEC("maps") sock_map_redir = {
	.type = BPF_MAP_TYPE_SOCKMAP,
	.key_size = sizeof(int),
	.value_size = sizeof(int),
	.max_entries = 20,
};

struct bpf_map_def SEC("maps") sock_apply_bytes = {
	.type = BPF_MAP_TYPE_ARRAY,
	.key_size = sizeof(int),
	.value_size = sizeof(int),
	.max_entries = 1
};

struct bpf_map_def SEC("maps") sock_cork_bytes = {
	.type = BPF_MAP_TYPE_ARRAY,
	.key_size = sizeof(int),
	.value_size = sizeof(int),
	.max_entries = 1
};

struct bpf_map_def SEC("maps") sock_pull_bytes = {
	.type = BPF_MAP_TYPE_ARRAY,
	.key_size = sizeof(int),
	.value_size = sizeof(int),
	.max_entries = 2
};

struct bpf_map_def SEC("maps") sock_redir_flags = {
	.type = BPF_MAP_TYPE_ARRAY,
	.key_size = sizeof(int),
	.value_size = sizeof(int),
	.max_entries = 1
};

struct bpf_map_def SEC("maps") sock_skb_opts = {
	.type = BPF_MAP_TYPE_ARRAY,
	.key_size = sizeof(int),
	.value_size = sizeof(int),
	.max_entries = 1
};

SEC("sk_skb1")

int bpf_prog1(struct __sk_buff *skb) { return skb->len; }

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SEC("sk_skb2")
int bpf_prog2(struct __sk_buff *skb) { __u32 lport = skb->local_port; __u32 rport = skb->remote_port; int len, *f, ret, zero = 0; __u64 flags = 0; if (lport == 10000) ret = 10; else ret = 1; len = (__u32)skb->data_end - (__u32)skb->data; f = bpf_map_lookup_elem(&sock_skb_opts, &zero); if (f && *f) { ret = 3; flags = *f; } bpf_printk("sk_skb2: redirect(%iB) flags=%i\n", len, flags); return bpf_sk_redirect_map(skb, &sock_map, ret, flags); }

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SEC("sockops")
int bpf_sockmap(struct bpf_sock_ops *skops) { __u32 lport, rport; int op, err = 0, index, key, ret; op = (int) skops->op; switch (op) { case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: lport = skops->local_port; rport = skops->remote_port; if (lport == 10000) { ret = 1; err = bpf_sock_map_update(skops, &sock_map, &ret, BPF_NOEXIST); bpf_printk("passive(%i -> %i) map ctx update err: %d\n", lport, bpf_ntohl(rport), err); } break; case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB: lport = skops->local_port; rport = skops->remote_port; if (bpf_ntohl(rport) == 10001) { ret = 10; err = bpf_sock_map_update(skops, &sock_map, &ret, BPF_NOEXIST); bpf_printk("active(%i -> %i) map ctx update err: %d\n", lport, bpf_ntohl(rport), err); } break; default: break; } return 0; }

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SEC("sk_msg1")
int bpf_prog4(struct sk_msg_md *msg) { int *bytes, zero = 0, one = 1; int *start, *end; bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero); if (bytes) bpf_msg_apply_bytes(msg, *bytes); bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero); if (bytes) bpf_msg_cork_bytes(msg, *bytes); start = bpf_map_lookup_elem(&sock_pull_bytes, &zero); end = bpf_map_lookup_elem(&sock_pull_bytes, &one); if (start && end) bpf_msg_pull_data(msg, *start, *end, 0); return SK_PASS; }

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SEC("sk_msg2")
int bpf_prog5(struct sk_msg_md *msg) { int err1 = -1, err2 = -1, zero = 0, one = 1; int *bytes, *start, *end, len1, len2; bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero); if (bytes) err1 = bpf_msg_apply_bytes(msg, *bytes); bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero); if (bytes) err2 = bpf_msg_cork_bytes(msg, *bytes); len1 = (__u64)msg->data_end - (__u64)msg->data; start = bpf_map_lookup_elem(&sock_pull_bytes, &zero); end = bpf_map_lookup_elem(&sock_pull_bytes, &one); if (start && end) { int err; bpf_printk("sk_msg2: pull(%i:%i)\n", start ? *start : 0, end ? *end : 0); err = bpf_msg_pull_data(msg, *start, *end, 0); if (err) bpf_printk("sk_msg2: pull_data err %i\n", err); len2 = (__u64)msg->data_end - (__u64)msg->data; bpf_printk("sk_msg2: length update %i->%i\n", len1, len2); } bpf_printk("sk_msg2: data length %i err1 %i err2 %i\n", len1, err1, err2); return SK_PASS; }

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SEC("sk_msg3")
int bpf_prog6(struct sk_msg_md *msg) { int *bytes, zero = 0, one = 1, key = 0; int *start, *end, *f; __u64 flags = 0; bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero); if (bytes) bpf_msg_apply_bytes(msg, *bytes); bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero); if (bytes) bpf_msg_cork_bytes(msg, *bytes); start = bpf_map_lookup_elem(&sock_pull_bytes, &zero); end = bpf_map_lookup_elem(&sock_pull_bytes, &one); if (start && end) bpf_msg_pull_data(msg, *start, *end, 0); f = bpf_map_lookup_elem(&sock_redir_flags, &zero); if (f && *f) { key = 2; flags = *f; } return bpf_msg_redirect_map(msg, &sock_map_redir, key, flags); }

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SEC("sk_msg4")
int bpf_prog7(struct sk_msg_md *msg) { int err1 = 0, err2 = 0, zero = 0, one = 1, key = 0; int *f, *bytes, *start, *end, len1, len2; __u64 flags = 0; int err; bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero); if (bytes) err1 = bpf_msg_apply_bytes(msg, *bytes); bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero); if (bytes) err2 = bpf_msg_cork_bytes(msg, *bytes); len1 = (__u64)msg->data_end - (__u64)msg->data; start = bpf_map_lookup_elem(&sock_pull_bytes, &zero); end = bpf_map_lookup_elem(&sock_pull_bytes, &one); if (start && end) { bpf_printk("sk_msg2: pull(%i:%i)\n", start ? *start : 0, end ? *end : 0); err = bpf_msg_pull_data(msg, *start, *end, 0); if (err) bpf_printk("sk_msg2: pull_data err %i\n", err); len2 = (__u64)msg->data_end - (__u64)msg->data; bpf_printk("sk_msg2: length update %i->%i\n", len1, len2); } f = bpf_map_lookup_elem(&sock_redir_flags, &zero); if (f && *f) { key = 2; flags = *f; } bpf_printk("sk_msg3: redirect(%iB) flags=%i err=%i\n", len1, flags, err1 ? err1 : err2); err = bpf_msg_redirect_map(msg, &sock_map_redir, key, flags); bpf_printk("sk_msg3: err %i\n", err); return err; }

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SEC("sk_msg5")
int bpf_prog8(struct sk_msg_md *msg) { void *data_end = (void *)(long) msg->data_end; void *data = (void *)(long) msg->data; int ret = 0, *bytes, zero = 0; bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero); if (bytes) { ret = bpf_msg_apply_bytes(msg, *bytes); if (ret) return SK_DROP; } else { return SK_DROP; } return SK_PASS; }

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SEC("sk_msg6")
int bpf_prog9(struct sk_msg_md *msg) { void *data_end = (void *)(long) msg->data_end; void *data = (void *)(long) msg->data; int ret = 0, *bytes, zero = 0; bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero); if (bytes) { if (((__u64)data_end - (__u64)data) >= *bytes) return SK_PASS; ret = bpf_msg_cork_bytes(msg, *bytes); if (ret) return SK_DROP; } return SK_PASS; }

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SEC("sk_msg7")
int bpf_prog10(struct sk_msg_md *msg) { int *bytes, zero = 0, one = 1; int *start, *end; bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero); if (bytes) bpf_msg_apply_bytes(msg, *bytes); bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero); if (bytes) bpf_msg_cork_bytes(msg, *bytes); start = bpf_map_lookup_elem(&sock_pull_bytes, &zero); end = bpf_map_lookup_elem(&sock_pull_bytes, &one); if (start && end) bpf_msg_pull_data(msg, *start, *end, 0); return SK_DROP; }

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char _license[] SEC("license") = "GPL";

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Directory: samples/sockmap
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