Re: [PATCH iproute2 -master] bpf: also check elf for official e_machine value

[Alexei Starovoitov]

On Tue, Jul 19, 2016 at 01:09:52AM +0200, Daniel Borkmann wrote:
> Use the official BPF ELF e_machine value that was assigned recently [1]
> and will be propagated to glibc, libelf et al. LLVM will switch to it
> in 3.9 release, therefore we need to prepare tc to check for EM_ELF as
> well, older version still have the EM_NONE.
> 
>   [1] 
> https://github.com/llvm-mirror/llvm/commit/36b9c09330bfb5e771914cfe307588f30d5510d2
> 
> Signed-off-by: Daniel Borkmann 

Thank you for fixing it.
Acked-by: Alexei Starovoitov 

[PATCH iproute2 -master] bpf: also check elf for official e_machine value

[Daniel Borkmann]

Use the official BPF ELF e_machine value that was assigned recently [1]
and will be propagated to glibc, libelf et al. LLVM will switch to it
in 3.9 release, therefore we need to prepare tc to check for EM_ELF as
well, older version still have the EM_NONE.

  [1] 
https://github.com/llvm-mirror/llvm/commit/36b9c09330bfb5e771914cfe307588f30d5510d2

Signed-off-by: Daniel Borkmann 
---
 tc/tc_bpf.c | 7 ++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tc/tc_bpf.c b/tc/tc_bpf.c
index 86c6069..7eb1cd7 100644
--- a/tc/tc_bpf.c
+++ b/tc/tc_bpf.c
@@ -54,6 +54,10 @@
 #define AF_ALG 38
 #endif
 
+#ifndef EM_BPF
+#define EM_BPF 247
+#endif
+
 #ifdef HAVE_ELF
 static int bpf_obj_open(const char *path, enum bpf_prog_type type,
const char *sec, bool verbose);
@@ -1690,7 +1694,8 @@ static void bpf_hash_destroy(struct bpf_elf_ctx *ctx)
 static int bpf_elf_check_ehdr(const struct bpf_elf_ctx *ctx)
 {
if (ctx->elf_hdr.e_type != ET_REL ||
-   ctx->elf_hdr.e_machine != 0 ||
+   (ctx->elf_hdr.e_machine != EM_NONE &&
+ctx->elf_hdr.e_machine != EM_BPF) ||
ctx->elf_hdr.e_version != EV_CURRENT) {
fprintf(stderr, "ELF format error, ELF file not for eBPF?\n");
return -EINVAL;
-- 
1.9.3