fd75733da2
BPF type compatibility checks (bpf_core_types_are_compat()) are currently duplicated between kernel and user space. That's a historical artifact more than intentional doing and can lead to subtle bugs where one implementation is adjusted but another is forgotten. That happened with the enum64 work, for example, where the libbpf side was changed (commit23b2a3a8f6("libbpf: Add enum64 relocation support")) to use the btf_kind_core_compat() helper function but the kernel side was not (commit6089fb325c("bpf: Add btf enum64 support")). This patch addresses both the duplication issue, by merging both implementations and moving them into relo_core.c, and fixes the alluded to kind check (by giving preference to libbpf's already adjusted logic). For discussion of the topic, please refer to: https://lore.kernel.org/bpf/CAADnVQKbWR7oarBdewgOBZUPzryhRYvEbkhyPJQHHuxq=0K1gw@mail.gmail.com/T/#mcc99f4a33ad9a322afaf1b9276fb1f0b7add9665 Changelog: v1 -> v2: - limited libbpf recursion limit to 32 - changed name to __bpf_core_types_are_compat - included warning previously present in libbpf version - merged kernel and user space changes into a single patch Signed-off-by: Daniel Müller <deso@posteo.net> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20220623182934.2582827-1-deso@posteo.net
96 lines
3.0 KiB
C
96 lines
3.0 KiB
C
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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/* Copyright (c) 2019 Facebook */
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#ifndef __RELO_CORE_H
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#define __RELO_CORE_H
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#include <linux/bpf.h>
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struct bpf_core_cand {
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const struct btf *btf;
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__u32 id;
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};
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/* dynamically sized list of type IDs and its associated struct btf */
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struct bpf_core_cand_list {
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struct bpf_core_cand *cands;
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int len;
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};
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#define BPF_CORE_SPEC_MAX_LEN 64
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/* represents BPF CO-RE field or array element accessor */
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struct bpf_core_accessor {
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__u32 type_id; /* struct/union type or array element type */
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__u32 idx; /* field index or array index */
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const char *name; /* field name or NULL for array accessor */
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};
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struct bpf_core_spec {
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const struct btf *btf;
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/* high-level spec: named fields and array indices only */
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struct bpf_core_accessor spec[BPF_CORE_SPEC_MAX_LEN];
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/* original unresolved (no skip_mods_or_typedefs) root type ID */
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__u32 root_type_id;
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/* CO-RE relocation kind */
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enum bpf_core_relo_kind relo_kind;
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/* high-level spec length */
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int len;
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/* raw, low-level spec: 1-to-1 with accessor spec string */
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int raw_spec[BPF_CORE_SPEC_MAX_LEN];
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/* raw spec length */
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int raw_len;
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/* field bit offset represented by spec */
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__u32 bit_offset;
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};
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struct bpf_core_relo_res {
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/* expected value in the instruction, unless validate == false */
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__u64 orig_val;
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/* new value that needs to be patched up to */
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__u64 new_val;
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/* relocation unsuccessful, poison instruction, but don't fail load */
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bool poison;
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/* some relocations can't be validated against orig_val */
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bool validate;
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/* for field byte offset relocations or the forms:
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* *(T *)(rX + <off>) = rY
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* rX = *(T *)(rY + <off>),
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* we remember original and resolved field size to adjust direct
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* memory loads of pointers and integers; this is necessary for 32-bit
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* host kernel architectures, but also allows to automatically
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* relocate fields that were resized from, e.g., u32 to u64, etc.
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*/
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bool fail_memsz_adjust;
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__u32 orig_sz;
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__u32 orig_type_id;
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__u32 new_sz;
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__u32 new_type_id;
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};
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int __bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
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const struct btf *targ_btf, __u32 targ_id, int level);
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int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
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const struct btf *targ_btf, __u32 targ_id);
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size_t bpf_core_essential_name_len(const char *name);
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int bpf_core_calc_relo_insn(const char *prog_name,
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const struct bpf_core_relo *relo, int relo_idx,
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const struct btf *local_btf,
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struct bpf_core_cand_list *cands,
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struct bpf_core_spec *specs_scratch,
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struct bpf_core_relo_res *targ_res);
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int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn,
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int insn_idx, const struct bpf_core_relo *relo,
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int relo_idx, const struct bpf_core_relo_res *res);
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int bpf_core_parse_spec(const char *prog_name, const struct btf *btf,
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const struct bpf_core_relo *relo,
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struct bpf_core_spec *spec);
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int bpf_core_format_spec(char *buf, size_t buf_sz, const struct bpf_core_spec *spec);
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#endif
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