Re: [PATCH bpf-next 2/3] bpf, sockmap: Restrict iter-context sockmap updates to iter/sockmap

[Michal Luczaj]

On 10/19/26 13:16, Jakub Sitnicki wrote:
> On Fri, Oct 16, 2026 at 11:09 PM +02, Michal Luczaj wrote:
>> @@ -10341,7 +10342,12 @@ static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id)
>>  	 */
>>  	switch (type) {
>>  	case BPF_PROG_TYPE_TRACING:
>> -		if (eatype == BPF_TRACE_ITER)
>> +		/* iter/sockmap only; type check rejects a freplace of any
>> +		 * iterator's bpf_iter_sockmap() subprog.
>> +		 */
>> +		if (eatype == BPF_TRACE_ITER &&
>> +		    env->prog->type == BPF_PROG_TYPE_TRACING &&
>> +		    !strcmp(afname + strlen(BPF_ITER_FUNC_PREFIX), "sockmap"))
>>  			return true;
>>  		break;
>>  	case BPF_PROG_TYPE_SOCK_OPS:
> 
> Explicit bailout when prog->type == BPF_PROG_TYPE_EXT might be more
> self-explanatory.

I just though that such explicit allow-criteria approach is safer than a
deny-criteria (should other special prog types come along). But I agree
that would be more self-explanatory.