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tools/bpf: add log_level to bpf_load_program_attr

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The kernel verifier has three levels of logs:
    0: no logs
    1: logs mostly useful
  > 1: verbose

Current libbpf API functions bpf_load_program_xattr() and
bpf_load_program() cannot specify log_level.
The bcc, however, provides an interface for user to
specify log_level 2 for verbose output.

This patch added log_level into structure
bpf_load_program_attr, so users, including bcc, can use
bpf_load_program_xattr() to change log_level. The
supported log_level is 0, 1, and 2.

The bpf selftest test_sock.c is modified to enable log_level = 2.
If the "verbose" in test_sock.c is changed to true,
the test will output logs like below:
  $ ./test_sock
  func#0 @0
  0: R1=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
  0: (bf) r6 = r1
  1: R1=ctx(id=0,off=0,imm=0) R6_w=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
  1: (61) r7 = *(u32 *)(r6 +28)
  invalid bpf_context access off=28 size=4

  Test case: bind4 load with invalid access: src_ip6 .. [PASS]
  ...
  Test case: bind6 allow all .. [PASS]
  Summary: 16 PASSED, 0 FAILED

Some test_sock tests are negative tests and verbose verifier
log will be printed out as shown in the above.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song 2019-02-07 09:34:51 -08:00 committed by Alexei Starovoitov
parent 62b8cea62e
commit a4021a3579
3 changed files with 26 additions and 6 deletions
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18
tools/lib/bpf/bpf.c
View File

@ -215,10 +215,15 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
{
void *finfo = NULL, *linfo = NULL;
union bpf_attr attr;
__u32 log_level;
__u32 name_len;
int fd;
if (!load_attr)
if (!load_attr || !log_buf != !log_buf_sz)
return -EINVAL;
log_level = load_attr->log_level;
if (log_level > 2 || (log_level && !log_buf))
return -EINVAL;
name_len = load_attr->name ? strlen(load_attr->name) : 0;
@ -229,9 +234,16 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
attr.insn_cnt = (__u32)load_attr->insns_cnt;
attr.insns = ptr_to_u64(load_attr->insns);
attr.license = ptr_to_u64(load_attr->license);
attr.log_level = log_level;
if (log_level) {
attr.log_buf = ptr_to_u64(log_buf);
attr.log_size = log_buf_sz;
} else {
attr.log_buf = ptr_to_u64(NULL);
attr.log_size = 0;
attr.log_level = 0;
}
attr.kern_version = load_attr->kern_version;
attr.prog_ifindex = load_attr->prog_ifindex;
attr.prog_btf_fd = load_attr->prog_btf_fd;
@ -287,7 +299,7 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
goto done;
}
if (!log_buf || !log_buf_sz)
if (log_level || !log_buf)
goto done;
/* Try again with log */

1
tools/lib/bpf/bpf.h
View File

@ -85,6 +85,7 @@ struct bpf_load_program_attr {
__u32 line_info_rec_size;
const void *line_info;
__u32 line_info_cnt;
__u32 log_level;
};
/* Flags to direct loading requirements */

9
tools/testing/selftests/bpf/test_sock.c
View File

@ -20,6 +20,7 @@
#define MAX_INSNS 512
char bpf_log_buf[BPF_LOG_BUF_SIZE];
static bool verbose = false;
struct sock_test {
const char *descr;
@ -325,6 +326,7 @@ static int load_sock_prog(const struct bpf_insn *prog,
enum bpf_attach_type attach_type)
{
struct bpf_load_program_attr attr;
int ret;
memset(&attr, 0, sizeof(struct bpf_load_program_attr));
attr.prog_type = BPF_PROG_TYPE_CGROUP_SOCK;
@ -332,8 +334,13 @@ static int load_sock_prog(const struct bpf_insn *prog,
attr.insns = prog;
attr.insns_cnt = probe_prog_length(attr.insns);
attr.license = "GPL";
attr.log_level = 2;
return bpf_load_program_xattr(&attr, bpf_log_buf, BPF_LOG_BUF_SIZE);
ret = bpf_load_program_xattr(&attr, bpf_log_buf, BPF_LOG_BUF_SIZE);
if (verbose && ret < 0)
fprintf(stderr, "%s\n", bpf_log_buf);
return ret;
}
static int attach_sock_prog(int cgfd, int progfd,