diff options
| author | Kui-Feng Lee <thinker.li@gmail.com> | 2024-01-19 14:49:59 -0800 |
|---|---|---|
| committer | Martin KaFai Lau <martin.lau@kernel.org> | 2024-01-23 16:37:44 -0800 |
| commit | fcc2c1fb0651477c8ed78a3a293c175ccd70697a (patch) | |
| tree | 5db50a9fefdd357c802c97bfe3962f1c6e0fee90 /kernel/bpf/verifier.c | |
| parent | 689423db3bda2244c24db8a64de4cdb37be1de41 (diff) | |
bpf: pass attached BTF to the bpf_struct_ops subsystem
Pass the fd of a btf from the userspace to the bpf() syscall, and then
convert the fd into a btf. The btf is generated from the module that
defines the target BPF struct_ops type.
In order to inform the kernel about the module that defines the target
struct_ops type, the userspace program needs to provide a btf fd for the
respective module's btf. This btf contains essential information on the
types defined within the module, including the target struct_ops type.
A btf fd must be provided to the kernel for struct_ops maps and for the bpf
programs attached to those maps.
In the case of the bpf programs, the attach_btf_obj_fd parameter is passed
as part of the bpf_attr and is converted into a btf. This btf is then
stored in the prog->aux->attach_btf field. Here, it just let the verifier
access attach_btf directly.
In the case of struct_ops maps, a btf fd is passed as value_type_btf_obj_fd
of bpf_attr. The bpf_struct_ops_map_alloc() function converts the fd to a
btf and stores it as st_map->btf. A flag BPF_F_VTYPE_BTF_OBJ_FD is added
for map_flags to indicate that the value of value_type_btf_obj_fd is set.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240119225005.668602-9-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 2a0fd2ccdb11..6081512deb79 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20290,6 +20290,7 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) const struct btf_member *member; struct bpf_prog *prog = env->prog; u32 btf_id, member_idx; + struct btf *btf; const char *mname; if (!prog->gpl_compatible) { @@ -20297,8 +20298,10 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) return -EINVAL; } + btf = prog->aux->attach_btf ?: bpf_get_btf_vmlinux(); + btf_id = prog->aux->attach_btf_id; - st_ops_desc = bpf_struct_ops_find(btf_vmlinux, btf_id); + st_ops_desc = bpf_struct_ops_find(btf, btf_id); if (!st_ops_desc) { verbose(env, "attach_btf_id %u is not a supported struct\n", btf_id); @@ -20315,8 +20318,8 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env) } member = &btf_type_member(t)[member_idx]; - mname = btf_name_by_offset(btf_vmlinux, member->name_off); - func_proto = btf_type_resolve_func_ptr(btf_vmlinux, member->type, + mname = btf_name_by_offset(btf, member->name_off); + func_proto = btf_type_resolve_func_ptr(btf, member->type, NULL); if (!func_proto) { verbose(env, "attach to invalid member %s(@idx %u) of struct %s\n", |