Commit fa553d9b authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Alexei Starovoitov

bpf, testing: Add selftest to read/write sockaddr from user space

Tested on x86-64 and Ilya was also kind enough to give it a spin on
s390x, both passing with probe_user:OK there. The test is using the
newly added bpf_probe_read_user() to dump sockaddr from connect call
into .bss BPF map and overrides the user buffer via bpf_probe_write_user():

  # ./test_progs
  [...]
  #17 pkt_md_access:OK
  #18 probe_user:OK
  #19 prog_run_xattr:OK
  [...]
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Tested-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/90f449d8af25354e05080e82fc6e2d3179da30ea.1572649915.git.daniel@iogearbox.net
parent 50f9aa44
// SPDX-License-Identifier: GPL-2.0
#include <test_progs.h>
void test_probe_user(void)
{
#define kprobe_name "__sys_connect"
const char *prog_name = "kprobe/" kprobe_name;
const char *obj_file = "./test_probe_user.o";
DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts, );
int err, results_map_fd, sock_fd, duration = 0;
struct sockaddr curr, orig, tmp;
struct sockaddr_in *in = (struct sockaddr_in *)&curr;
struct bpf_link *kprobe_link = NULL;
struct bpf_program *kprobe_prog;
struct bpf_object *obj;
static const int zero = 0;
obj = bpf_object__open_file(obj_file, &opts);
if (CHECK(IS_ERR(obj), "obj_open_file", "err %ld\n", PTR_ERR(obj)))
return;
kprobe_prog = bpf_object__find_program_by_title(obj, prog_name);
if (CHECK(!kprobe_prog, "find_probe",
"prog '%s' not found\n", prog_name))
goto cleanup;
err = bpf_object__load(obj);
if (CHECK(err, "obj_load", "err %d\n", err))
goto cleanup;
results_map_fd = bpf_find_map(__func__, obj, "test_pro.bss");
if (CHECK(results_map_fd < 0, "find_bss_map",
"err %d\n", results_map_fd))
goto cleanup;
kprobe_link = bpf_program__attach_kprobe(kprobe_prog, false,
kprobe_name);
if (CHECK(IS_ERR(kprobe_link), "attach_kprobe",
"err %ld\n", PTR_ERR(kprobe_link))) {
kprobe_link = NULL;
goto cleanup;
}
memset(&curr, 0, sizeof(curr));
in->sin_family = AF_INET;
in->sin_port = htons(5555);
in->sin_addr.s_addr = inet_addr("255.255.255.255");
memcpy(&orig, &curr, sizeof(curr));
sock_fd = socket(AF_INET, SOCK_STREAM, 0);
if (CHECK(sock_fd < 0, "create_sock_fd", "err %d\n", sock_fd))
goto cleanup;
connect(sock_fd, &curr, sizeof(curr));
close(sock_fd);
err = bpf_map_lookup_elem(results_map_fd, &zero, &tmp);
if (CHECK(err, "get_kprobe_res",
"failed to get kprobe res: %d\n", err))
goto cleanup;
in = (struct sockaddr_in *)&tmp;
if (CHECK(memcmp(&tmp, &orig, sizeof(orig)), "check_kprobe_res",
"wrong kprobe res from probe read: %s:%u\n",
inet_ntoa(in->sin_addr), ntohs(in->sin_port)))
goto cleanup;
memset(&tmp, 0xab, sizeof(tmp));
in = (struct sockaddr_in *)&curr;
if (CHECK(memcmp(&curr, &tmp, sizeof(tmp)), "check_kprobe_res",
"wrong kprobe res from probe write: %s:%u\n",
inet_ntoa(in->sin_addr), ntohs(in->sin_port)))
goto cleanup;
cleanup:
bpf_link__destroy(kprobe_link);
bpf_object__close(obj);
}
// SPDX-License-Identifier: GPL-2.0
#include <linux/ptrace.h>
#include <linux/bpf.h>
#include <netinet/in.h>
#include "bpf_helpers.h"
#include "bpf_tracing.h"
static struct sockaddr_in old;
SEC("kprobe/__sys_connect")
int handle_sys_connect(struct pt_regs *ctx)
{
void *ptr = (void *)PT_REGS_PARM2(ctx);
struct sockaddr_in new;
bpf_probe_read_user(&old, sizeof(old), ptr);
__builtin_memset(&new, 0xab, sizeof(new));
bpf_probe_write_user(ptr, &new, sizeof(new));
return 0;
}
char _license[] SEC("license") = "GPL";
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment