From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: brouer@redhat.com,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"Toke Høiland-Jørgensen" <toke@redhat.com>
Subject: Better ways to validate map via BTF?
Date: Thu, 28 Nov 2019 17:08:37 +0100 [thread overview]
Message-ID: <20191128170837.2236713b@carbon> (raw)
[-- Attachment #1: Type: text/plain, Size: 1429 bytes --]
Hi Andrii,
Is there are better way to validate that a userspace BPF-program uses
the correct map via BTF?
Below and in attached patch, I'm using bpf_obj_get_info_by_fd() to get
some map-info, and check info.value_size and info.max_entries match
what I expect. What I really want, is to check that "map-value" have
same struct layout as:
struct config {
__u32 action;
int ifindex;
__u32 options;
};
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
static void check_config_map_fd_info(int map_fd) {
struct bpf_map_info info = { 0 };
__u32 info_len = sizeof(info);
__u32 exp_value_size = sizeof(struct config);
__u32 exp_entries = 1;
int err;
/* BPF-info via bpf-syscall */
err = bpf_obj_get_info_by_fd(map_fd, &info, &info_len);
if (err) {
fprintf(stderr, "ERR: %s() can't get info - %s\n",
__func__, strerror(errno));
exit(EXIT_FAIL_BPF);
}
if (exp_value_size != info.value_size) {
fprintf(stderr, "ERR: %s() "
"Map value size(%d) mismatch expected size(%d)\n",
__func__, info.value_size, exp_value_size);
exit(EXIT_FAIL_BPF);
}
if (exp_entries != info.max_entries) {
fprintf(stderr, "ERR: %s() "
"Map max_entries(%d) mismatch expected entries(%d)\n",
__func__, info.max_entries, exp_entries);
exit(EXIT_FAIL_BPF);
}
}
struct config {
__u32 action;
int ifindex;
__u32 options;
};
[-- Attachment #2: 02-detect_map_mismatch --]
[-- Type: application/octet-stream, Size: 2423 bytes --]
samples/bpf: xdp_rxq_info check that map have expected size
From: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
samples/bpf/xdp_rxq_info_user.c | 33 ++++++++++++++++++++++++++++++++-
1 file changed, 32 insertions(+), 1 deletion(-)
diff --git a/samples/bpf/xdp_rxq_info_user.c b/samples/bpf/xdp_rxq_info_user.c
index 51e0d810e070..fa60731fdbad 100644
--- a/samples/bpf/xdp_rxq_info_user.c
+++ b/samples/bpf/xdp_rxq_info_user.c
@@ -453,6 +453,35 @@ static void stats_poll(int interval, int action, __u32 cfg_opt)
free_stats_record(prev);
}
+static void check_config_map_fd_info(int map_fd) {
+ struct bpf_map_info info = { 0 };
+ __u32 info_len = sizeof(info);
+ __u32 exp_value_size = sizeof(struct config);
+ __u32 exp_entries = 1;
+ int err;
+
+ /* BPF-info via bpf-syscall */
+ err = bpf_obj_get_info_by_fd(map_fd, &info, &info_len);
+ if (err) {
+ fprintf(stderr, "ERR: %s() can't get info - %s\n",
+ __func__, strerror(errno));
+ exit(EXIT_FAIL_BPF);
+ }
+
+ if (exp_value_size != info.value_size) {
+ fprintf(stderr, "ERR: %s() "
+ "Map value size(%d) mismatch expected size(%d)\n",
+ __func__, info.value_size, exp_value_size);
+ exit(EXIT_FAIL_BPF);
+ }
+
+ if (exp_entries != info.max_entries) {
+ fprintf(stderr, "ERR: %s() "
+ "Map max_entries(%d) mismatch expected entries(%d)\n",
+ __func__, info.max_entries, exp_entries);
+ exit(EXIT_FAIL_BPF);
+ }
+}
int main(int argc, char **argv)
{
@@ -461,7 +490,7 @@ int main(int argc, char **argv)
struct bpf_prog_load_attr prog_load_attr = {
.prog_type = BPF_PROG_TYPE_XDP,
};
- struct bpf_prog_info info = {};
+ struct bpf_prog_info info = { 0 };
__u32 info_len = sizeof(info);
int prog_fd, map_fd, opt, err;
bool use_separators = true;
@@ -490,6 +519,7 @@ int main(int argc, char **argv)
return EXIT_FAIL;
map = bpf_map__next(NULL, obj);
+// map = bpf_object__find_map_by_name(obj, "config");
stats_global_map = bpf_map__next(map, obj);
rx_queue_index_map = bpf_map__next(stats_global_map, obj);
if (!map || !stats_global_map || !rx_queue_index_map) {
@@ -581,6 +611,7 @@ int main(int argc, char **argv)
setlocale(LC_NUMERIC, "en_US");
/* User-side setup ifindex in config_map */
+ check_config_map_fd_info(map_fd);
err = bpf_map_update_elem(map_fd, &key, &cfg, 0);
if (err) {
fprintf(stderr, "Store config failed (err:%d)\n", err);
next reply other threads:[~2019-11-28 16:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-28 16:08 Jesper Dangaard Brouer [this message]
2019-11-29 5:27 ` Better ways to validate map via BTF? Andrii Nakryiko
2019-11-29 8:27 ` Toke Høiland-Jørgensen
2019-12-02 20:03 ` Andrii Nakryiko
2019-12-03 11:05 ` Toke Høiland-Jørgensen
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