| Message ID | tencent_7DD02046A8398BE3324F85E0F56ED41EB105@qq.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf-next] samples/bpf: Fix sockex3: missing BPF prog type | expand |
On Sat, Oct 29, 2022 at 12:53 AM Rong Tao <rtoax@foxmail.com> wrote: > > From: Rong Tao <rongtao@cestc.cn> > > since commit 450b167fb9be("libbpf: clean up SEC() handling"), > sec_def_matches() does not recognize "socket/xxx" as "socket", therefore, > the BPF program type is not recognized, set "socket/xxx" to SOCKET_FILTER > solves this error. > > $ cd samples/bpf > $ sudo ./sockex3 > libbpf: prog 'bpf_func_PARSE_IP': missing BPF prog type, check ELF section name 'socket/3' > libbpf: prog 'bpf_func_PARSE_IP': failed to load: -22 > libbpf: failed to load object './sockex3_kern.o' > ERROR: loading BPF object file failed > > Signed-off-by: Rong Tao <rongtao@cestc.cn> > --- You need to do changes like this: diff --git a/samples/bpf/sockex3_kern.c b/samples/bpf/sockex3_kern.c index b363503357e5..db6a93e7ec53 100644 --- a/samples/bpf/sockex3_kern.c +++ b/samples/bpf/sockex3_kern.c @@ -17,7 +17,7 @@ #define IP_MF 0x2000 #define IP_OFFSET 0x1FFF -#define PROG(F) SEC("socket/"__stringify(F)) int bpf_func_##F +#define PROG(F) SEC("socket_filter") int bpf_func_##F struct { __uint(type, BPF_MAP_TYPE_PROG_ARRAY); @@ -279,7 +279,7 @@ PROG(PARSE_MPLS)(struct __sk_buff *skb) return 0; } -SEC("socket/0") +SEC("socket_filter") int main_prog(struct __sk_buff *skb) { __u32 nhoff = ETH_HLEN; Why fixing up after the fact at runtime, if you can just make those BPF programs conform to libbpf rules? > samples/bpf/sockex3_user.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/samples/bpf/sockex3_user.c b/samples/bpf/sockex3_user.c > index cd6fa79df900..dc79c17ad195 100644 > --- a/samples/bpf/sockex3_user.c > +++ b/samples/bpf/sockex3_user.c > @@ -39,6 +39,9 @@ int main(int argc, char **argv) > return 0; > } > > + bpf_object__for_each_program(prog, obj) > + bpf_program__set_type(prog, BPF_PROG_TYPE_SOCKET_FILTER); > + > /* load BPF program */ > if (bpf_object__load(obj)) { > fprintf(stderr, "ERROR: loading BPF object file failed\n"); > -- > 2.31.1 >
We can not just remove the number of program like:
-#define PROG(F) SEC("socket/"__stringify(F)) int bpf_func_##F
+#define PROG(F) SEC("socket_filter") int bpf_func_##F
because "sockex3" use the _NUMBER_ as index(see map "jmp_table"), if we
apply the following patch, it's still not recognize "socket_filter/xxx"
as "socket_filter", still have "missing BPF prog type" error:
diff --git a/samples/bpf/sockex3_kern.c b/samples/bpf/sockex3_kern.c
index b363503357e5..ab5a7bde66d0 100644
--- a/samples/bpf/sockex3_kern.c
+++ b/samples/bpf/sockex3_kern.c
@@ -17,7 +17,7 @@
#define IP_MF 0x2000
#define IP_OFFSET 0x1FFF
-#define PROG(F) SEC("socket/"__stringify(F)) int bpf_func_##F
+#define PROG(F) SEC("socket_filter/"__stringify(F)) int bpf_func_##F
struct {
__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
@@ -279,7 +279,7 @@ PROG(PARSE_MPLS)(struct __sk_buff *skb)
return 0;
}
-SEC("socket/0")
+SEC("socket_filter/0")
int main_prog(struct __sk_buff *skb)
{
__u32 nhoff = ETH_HLEN;
diff --git a/samples/bpf/sockex3_user.c b/samples/bpf/sockex3_user.c
index cd6fa79df900..63fc9a8077b1 100644
--- a/samples/bpf/sockex3_user.c
+++ b/samples/bpf/sockex3_user.c
@@ -56,7 +56,7 @@ int main(int argc, char **argv)
fd = bpf_program__fd(prog);
section = bpf_program__section_name(prog);
- if (sscanf(section, "socket/%d", &key) != 1) {
+ if (sscanf(section, "socket_filter/%d", &key) != 1) {
fprintf(stderr, "ERROR: finding prog failed\n");
goto cleanup;
}
For a reason, in sockex3_kern.c only have five PROGs, list all five:
#define PROG(F) SEC("socket/"__stringify(F)) int bpf_func_##F
PROG(PARSE_IP)(struct __sk_buff *skb)
PROG(PARSE_IPV6)(struct __sk_buff *skb)
PROG(PARSE_VLAN)(struct __sk_buff *skb)
PROG(PARSE_MPLS)(struct __sk_buff *skb)
SEC("socket/0") int main_prog(struct __sk_buff *skb)
As you can see, all those PROGs are BPF_PROG_TYPE_SOCKET_FILTER, so we can
use the follow patch specify bpf program type as SOCKET_FILTER:
https://lore.kernel.org/lkml/tencent_7DD02046A8398BE3324F85E0F56ED41EB105@qq.com/
diff --git a/samples/bpf/sockex3_user.c b/samples/bpf/sockex3_user.c
index cd6fa79df900..dc79c17ad195 100644
--- a/samples/bpf/sockex3_user.c
+++ b/samples/bpf/sockex3_user.c
@@ -39,6 +39,9 @@ int main(int argc, char **argv)
return 0;
}
+ bpf_object__for_each_program(prog, obj)
+ bpf_program__set_type(prog, BPF_PROG_TYPE_SOCKET_FILTER);
+
/* load BPF program */
if (bpf_object__load(obj)) {
fprintf(stderr, "ERROR: loading BPF object file failed\n");
This patch above totally solved the compile error.
On Thu, Nov 3, 2022 at 8:17 PM Rong Tao <rtoax@foxmail.com> wrote: > > We can not just remove the number of program like: > > -#define PROG(F) SEC("socket/"__stringify(F)) int bpf_func_##F > +#define PROG(F) SEC("socket_filter") int bpf_func_##F > > because "sockex3" use the _NUMBER_ as index(see map "jmp_table"), if we > apply the following patch, it's still not recognize "socket_filter/xxx" > as "socket_filter", still have "missing BPF prog type" error: Ok, let's keep unwinding this. This is an old and manual way to set up tail call map. Libbpf supports declarative way to do, so sockex3_user.c won't have to do anything at all. See progs/test_prog_array_init.c for an example. Let's convert samples to use this as well. This programmatic setting of program type works, there is no doubt about this. But it's a signal that something is not exactly how it should be. So let's use this as an opportunity to modernize samples, instead of adding workarounds. I hope you sympathize with this goal. > > diff --git a/samples/bpf/sockex3_kern.c b/samples/bpf/sockex3_kern.c > index b363503357e5..ab5a7bde66d0 100644 > --- a/samples/bpf/sockex3_kern.c > +++ b/samples/bpf/sockex3_kern.c > @@ -17,7 +17,7 @@ > #define IP_MF 0x2000 > #define IP_OFFSET 0x1FFF > [...]
diff --git a/samples/bpf/sockex3_user.c b/samples/bpf/sockex3_user.c index cd6fa79df900..dc79c17ad195 100644 --- a/samples/bpf/sockex3_user.c +++ b/samples/bpf/sockex3_user.c @@ -39,6 +39,9 @@ int main(int argc, char **argv) return 0; } + bpf_object__for_each_program(prog, obj) + bpf_program__set_type(prog, BPF_PROG_TYPE_SOCKET_FILTER); + /* load BPF program */ if (bpf_object__load(obj)) { fprintf(stderr, "ERROR: loading BPF object file failed\n");