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 <y...@fb.com>
---
tools/lib/bpf/bpf.c | 22 +++++++++++++++++-----
tools/lib/bpf/bpf.h | 1 +
tools/testing/selftests/bpf/test_sock.c | 9 ++++++++-
3 files changed, 26 insertions(+), 6 deletions(-)
Changelog:
v2 -> v3:
. returning error immediately for inconsistent log_level/log_buf/log_buf_sz
values
. for log_level=1/2, always doing logging during bpf_prog_load.
v1 -> v2:
. make log_level as the last member of struct bpf_load_program_attr.
. return -EINVAL if bpf_load_program_attr.log_level > 2.
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 3defad77dc7a..3f5290ee1b47 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -214,10 +214,15 @@ 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;
@@ -228,9 +233,16 @@ 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_buf = ptr_to_u64(NULL);
- attr.log_size = 0;
- attr.log_level = 0;
+
+ 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.kern_version = load_attr->kern_version;
attr.prog_ifindex = load_attr->prog_ifindex;
attr.prog_btf_fd = load_attr->prog_btf_fd;
@@ -286,7 +298,7 @@ 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 */
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index ed09eed2dc3b..6ffdd79bea89 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -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 */
diff --git a/tools/testing/selftests/bpf/test_sock.c
b/tools/testing/selftests/bpf/test_sock.c
index 561ffb6d6433..fb679ac3d4b0 100644
--- a/tools/testing/selftests/bpf/test_sock.c
+++ b/tools/testing/selftests/bpf/test_sock.c
@@ -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,
--
2.17.1
