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 --- samples/bpf/test_probe_write_user_kern.c | 56 ++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 samples/bpf/test_probe_write_user_kern.c (limited to 'samples/bpf/test_probe_write_user_kern.c') diff --git a/samples/bpf/test_probe_write_user_kern.c b/samples/bpf/test_probe_write_user_kern.c new file mode 100644 index 000000000..220a96438 --- /dev/null +++ b/samples/bpf/test_probe_write_user_kern.c @@ -0,0 +1,56 @@ +/* Copyright (c) 2016 Sargun Dhillon + * + * 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. + */ +#include +#include +#include +#include +#include +#include +#include +#include "trace_common.h" + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __type(key, struct sockaddr_in); + __type(value, struct sockaddr_in); + __uint(max_entries, 256); +} dnat_map SEC(".maps"); + +/* kprobe is NOT a stable ABI + * kernel functions can be removed, renamed or completely change semantics. + * Number of arguments and their positions can change, etc. + * In such case this bpf+kprobe example will no longer be meaningful + * + * This example sits on a syscall, and the syscall ABI is relatively stable + * of course, across platforms, and over time, the ABI may change. + */ +SEC("kprobe/" SYSCALL(sys_connect)) +int bpf_prog1(struct pt_regs *ctx) +{ + struct pt_regs *real_regs = (struct pt_regs *)PT_REGS_PARM1_CORE(ctx); + void *sockaddr_arg = (void *)PT_REGS_PARM2_CORE(real_regs); + int sockaddr_len = (int)PT_REGS_PARM3_CORE(real_regs); + struct sockaddr_in new_addr, orig_addr = {}; + struct sockaddr_in *mapped_addr; + + if (sockaddr_len > sizeof(orig_addr)) + return 0; + + if (bpf_probe_read_user(&orig_addr, sizeof(orig_addr), sockaddr_arg) != 0) + return 0; + + mapped_addr = bpf_map_lookup_elem(&dnat_map, &orig_addr); + if (mapped_addr != NULL) { + memcpy(&new_addr, mapped_addr, sizeof(new_addr)); + bpf_probe_write_user(sockaddr_arg, &new_addr, + sizeof(new_addr)); + } + return 0; +} + +char _license[] SEC("license") = "GPL"; +u32 _version SEC("version") = LINUX_VERSION_CODE; -- cgit v1.2.3