libbpf: Tie struct_ops programs to kernel BTF ids, not to local ids
Enforce the following existing limitation on struct_ops programs based on kernel BTF id instead of program-local BTF id: struct_ops BPF prog can be re-used between multiple .struct_ops & .struct_ops.link as long as it's the same struct_ops struct definition and the same function pointer field This allows reusing same BPF program for versioned struct_ops map definitions, e.g.: SEC("struct_ops/test") int BPF_PROG(foo) { ... } struct some_ops___v1 { int (*test)(void); }; struct some_ops___v2 { int (*test)(void); }; SEC(".struct_ops.link") struct some_ops___v1 a = { .test = foo } SEC(".struct_ops.link") struct some_ops___v2 b = { .test = foo } Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240306104529.6453-3-eddyz87@gmail.com
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@ -1146,8 +1146,32 @@ static int bpf_map__init_kern_struct_ops(struct bpf_map *map)
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if (mod_btf)
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if (mod_btf)
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prog->attach_btf_obj_fd = mod_btf->fd;
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prog->attach_btf_obj_fd = mod_btf->fd;
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prog->attach_btf_id = kern_type_id;
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prog->expected_attach_type = kern_member_idx;
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/* if we haven't yet processed this BPF program, record proper
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* attach_btf_id and member_idx
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*/
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if (!prog->attach_btf_id) {
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prog->attach_btf_id = kern_type_id;
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prog->expected_attach_type = kern_member_idx;
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}
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/* struct_ops BPF prog can be re-used between multiple
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* .struct_ops & .struct_ops.link as long as it's the
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* same struct_ops struct definition and the same
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* function pointer field
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*/
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if (prog->attach_btf_id != kern_type_id) {
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pr_warn("struct_ops init_kern %s func ptr %s: invalid reuse of prog %s in sec %s with type %u: attach_btf_id %u != kern_type_id %u\n",
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map->name, mname, prog->name, prog->sec_name, prog->type,
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prog->attach_btf_id, kern_type_id);
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return -EINVAL;
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}
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if (prog->expected_attach_type != kern_member_idx) {
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pr_warn("struct_ops init_kern %s func ptr %s: invalid reuse of prog %s in sec %s with type %u: expected_attach_type %u != kern_member_idx %u\n",
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map->name, mname, prog->name, prog->sec_name, prog->type,
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prog->expected_attach_type, kern_member_idx);
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return -EINVAL;
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}
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st_ops->kern_func_off[i] = kern_data_off + kern_moff;
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st_ops->kern_func_off[i] = kern_data_off + kern_moff;
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@ -9428,27 +9452,6 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
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return -EINVAL;
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return -EINVAL;
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}
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}
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/* if we haven't yet processed this BPF program, record proper
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* attach_btf_id and member_idx
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*/
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if (!prog->attach_btf_id) {
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prog->attach_btf_id = st_ops->type_id;
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prog->expected_attach_type = member_idx;
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}
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/* struct_ops BPF prog can be re-used between multiple
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* .struct_ops & .struct_ops.link as long as it's the
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* same struct_ops struct definition and the same
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* function pointer field
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*/
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if (prog->attach_btf_id != st_ops->type_id ||
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prog->expected_attach_type != member_idx) {
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pr_warn("struct_ops reloc %s: cannot use prog %s in sec %s with type %u attach_btf_id %u expected_attach_type %u for func ptr %s\n",
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map->name, prog->name, prog->sec_name, prog->type,
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prog->attach_btf_id, prog->expected_attach_type, name);
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return -EINVAL;
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}
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st_ops->progs[member_idx] = prog;
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st_ops->progs[member_idx] = prog;
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/* st_ops->data will be exposed to users, being returned by
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/* st_ops->data will be exposed to users, being returned by
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