From: Alexei Starovoitov ast@kernel.org
mainline inclusion from mainline-5.14-rc1 commit 3d78417b60fba249cc555468cb72d96f5cde2964 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Add new helper: long bpf_btf_find_by_name_kind(char *name, int name_sz, u32 kind, int flags) Description Find BTF type with given name and kind in vmlinux BTF or in module's BTFs. Return Returns btf_id and btf_obj_fd in lower and upper 32 bits.
It will be used by loader program to find btf_id to attach the program to and to find btf_ids of ksyms.
Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20210514003623.28033-10-alexei.starovoitov@gmail... (cherry picked from commit 3d78417b60fba249cc555468cb72d96f5cde2964) Signed-off-by: Wang Yufen wangyufen@huawei.com --- include/linux/bpf.h | 1 + include/uapi/linux/bpf.h | 7 ++++ kernel/bpf/btf.c | 62 ++++++++++++++++++++++++++++++++++ kernel/bpf/syscall.c | 2 ++ tools/include/uapi/linux/bpf.h | 7 ++++ 5 files changed, 79 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 143c187dc4f0..ce82ba540afa 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2052,6 +2052,7 @@ extern const struct bpf_func_proto bpf_snprintf_proto; extern const struct bpf_func_proto bpf_per_cpu_ptr_proto; extern const struct bpf_func_proto bpf_this_cpu_ptr_proto; extern const struct bpf_func_proto bpf_for_each_map_elem_proto; +extern const struct bpf_func_proto bpf_btf_find_by_name_kind_proto;
const struct bpf_func_proto *bpf_tracing_func_proto( enum bpf_func_id func_id, const struct bpf_prog *prog); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 18061388dd1b..0e88c9c8552e 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3886,6 +3886,12 @@ union bpf_attr { * Execute bpf syscall with given arguments. * Return * A syscall result. + * + * long bpf_btf_find_by_name_kind(char *name, int name_sz, u32 kind, int flags) + * Description + * Find BTF type with given name and kind in vmlinux BTF or in module's BTFs. + * Return + * Returns btf_id and btf_obj_fd in lower and upper 32 bits. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -4052,6 +4058,7 @@ union bpf_attr { FN(for_each_map_elem), \ FN(snprintf), \ FN(sys_bpf), \ + FN(btf_find_by_name_kind), \ /* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 390e9186371b..cd3c1a11fef1 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6021,3 +6021,65 @@ struct module *btf_try_get_module(const struct btf *btf)
return res; } + +BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags) +{ + struct btf *btf; + long ret; + + if (flags) + return -EINVAL; + + if (name_sz <= 1 || name[name_sz - 1]) + return -EINVAL; + + btf = bpf_get_btf_vmlinux(); + if (IS_ERR(btf)) + return PTR_ERR(btf); + + ret = btf_find_by_name_kind(btf, name, kind); + /* ret is never zero, since btf_find_by_name_kind returns + * positive btf_id or negative error. + */ + if (ret < 0) { + struct btf *mod_btf; + int id; + + /* If name is not found in vmlinux's BTF then search in module's BTFs */ + spin_lock_bh(&btf_idr_lock); + idr_for_each_entry(&btf_idr, mod_btf, id) { + if (!btf_is_module(mod_btf)) + continue; + /* linear search could be slow hence unlock/lock + * the IDR to avoiding holding it for too long + */ + btf_get(mod_btf); + spin_unlock_bh(&btf_idr_lock); + ret = btf_find_by_name_kind(mod_btf, name, kind); + if (ret > 0) { + int btf_obj_fd; + + btf_obj_fd = __btf_new_fd(mod_btf); + if (btf_obj_fd < 0) { + btf_put(mod_btf); + return btf_obj_fd; + } + return ret | (((u64)btf_obj_fd) << 32); + } + spin_lock_bh(&btf_idr_lock); + btf_put(mod_btf); + } + spin_unlock_bh(&btf_idr_lock); + } + return ret; +} + +const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = { + .func = bpf_btf_find_by_name_kind, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_MEM, + .arg2_type = ARG_CONST_SIZE, + .arg3_type = ARG_ANYTHING, + .arg4_type = ARG_ANYTHING, +}; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index cb40f29c4603..a9c1fa6d05a7 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -4671,6 +4671,8 @@ syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) switch (func_id) { case BPF_FUNC_sys_bpf: return &bpf_sys_bpf_proto; + case BPF_FUNC_btf_find_by_name_kind: + return &bpf_btf_find_by_name_kind_proto; default: return tracing_prog_func_proto(func_id, prog); } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index d7ba96b3bf9e..f9d82a60d26b 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -4596,6 +4596,12 @@ union bpf_attr { * Execute bpf syscall with given arguments. * Return * A syscall result. + * + * long bpf_btf_find_by_name_kind(char *name, int name_sz, u32 kind, int flags) + * Description + * Find BTF type with given name and kind in vmlinux BTF or in module's BTFs. + * Return + * Returns btf_id and btf_obj_fd in lower and upper 32 bits. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -4762,6 +4768,7 @@ union bpf_attr { FN(for_each_map_elem), \ FN(snprintf), \ FN(sys_bpf), \ + FN(btf_find_by_name_kind), \ /* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper