2021-07-21 00:08:22 +00:00
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// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
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/* Copyright (c) 2019 Facebook */
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2021-12-01 18:10:26 +00:00
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#ifdef __KERNEL__
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#include <linux/bpf.h>
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#include <linux/btf.h>
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#include <linux/string.h>
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#include <linux/bpf_verifier.h>
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#include "relo_core.h"
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static const char *btf_kind_str(const struct btf_type *t)
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{
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return btf_type_str(t);
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}
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static bool is_ldimm64_insn(struct bpf_insn *insn)
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{
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return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
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}
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static const struct btf_type *
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skip_mods_and_typedefs(const struct btf *btf, u32 id, u32 *res_id)
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{
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return btf_type_skip_modifiers(btf, id, res_id);
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}
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static const char *btf__name_by_offset(const struct btf *btf, u32 offset)
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{
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return btf_name_by_offset(btf, offset);
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}
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static s64 btf__resolve_size(const struct btf *btf, u32 type_id)
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{
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const struct btf_type *t;
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int size;
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t = btf_type_by_id(btf, type_id);
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t = btf_resolve_size(btf, t, &size);
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if (IS_ERR(t))
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return PTR_ERR(t);
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return size;
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}
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enum libbpf_print_level {
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LIBBPF_WARN,
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LIBBPF_INFO,
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LIBBPF_DEBUG,
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};
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#undef pr_warn
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#undef pr_info
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#undef pr_debug
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#define pr_warn(fmt, log, ...) bpf_log((void *)log, fmt, "", ##__VA_ARGS__)
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#define pr_info(fmt, log, ...) bpf_log((void *)log, fmt, "", ##__VA_ARGS__)
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#define pr_debug(fmt, log, ...) bpf_log((void *)log, fmt, "", ##__VA_ARGS__)
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#define libbpf_print(level, fmt, ...) bpf_log((void *)prog_name, fmt, ##__VA_ARGS__)
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#else
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2021-07-21 00:08:22 +00:00
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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#include <ctype.h>
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#include <linux/err.h>
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#include "libbpf.h"
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#include "bpf.h"
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#include "btf.h"
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#include "str_error.h"
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#include "libbpf_internal.h"
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2021-12-01 18:10:26 +00:00
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#endif
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2021-07-21 00:08:22 +00:00
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static bool is_flex_arr(const struct btf *btf,
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const struct bpf_core_accessor *acc,
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const struct btf_array *arr)
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{
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const struct btf_type *t;
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/* not a flexible array, if not inside a struct or has non-zero size */
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if (!acc->name || arr->nelems > 0)
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return false;
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/* has to be the last member of enclosing struct */
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2021-12-01 18:10:24 +00:00
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t = btf_type_by_id(btf, acc->type_id);
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2021-07-21 00:08:22 +00:00
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return acc->idx == btf_vlen(t) - 1;
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}
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static const char *core_relo_kind_str(enum bpf_core_relo_kind kind)
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{
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switch (kind) {
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2021-12-01 18:10:27 +00:00
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case BPF_CORE_FIELD_BYTE_OFFSET: return "byte_off";
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case BPF_CORE_FIELD_BYTE_SIZE: return "byte_sz";
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case BPF_CORE_FIELD_EXISTS: return "field_exists";
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case BPF_CORE_FIELD_SIGNED: return "signed";
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case BPF_CORE_FIELD_LSHIFT_U64: return "lshift_u64";
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case BPF_CORE_FIELD_RSHIFT_U64: return "rshift_u64";
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case BPF_CORE_TYPE_ID_LOCAL: return "local_type_id";
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case BPF_CORE_TYPE_ID_TARGET: return "target_type_id";
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case BPF_CORE_TYPE_EXISTS: return "type_exists";
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case BPF_CORE_TYPE_SIZE: return "type_size";
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case BPF_CORE_ENUMVAL_EXISTS: return "enumval_exists";
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case BPF_CORE_ENUMVAL_VALUE: return "enumval_value";
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2021-07-21 00:08:22 +00:00
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default: return "unknown";
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}
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}
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static bool core_relo_is_field_based(enum bpf_core_relo_kind kind)
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{
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switch (kind) {
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2021-12-01 18:10:27 +00:00
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case BPF_CORE_FIELD_BYTE_OFFSET:
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case BPF_CORE_FIELD_BYTE_SIZE:
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case BPF_CORE_FIELD_EXISTS:
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case BPF_CORE_FIELD_SIGNED:
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case BPF_CORE_FIELD_LSHIFT_U64:
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case BPF_CORE_FIELD_RSHIFT_U64:
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2021-07-21 00:08:22 +00:00
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return true;
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default:
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return false;
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}
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}
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static bool core_relo_is_type_based(enum bpf_core_relo_kind kind)
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{
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switch (kind) {
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2021-12-01 18:10:27 +00:00
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case BPF_CORE_TYPE_ID_LOCAL:
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case BPF_CORE_TYPE_ID_TARGET:
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case BPF_CORE_TYPE_EXISTS:
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case BPF_CORE_TYPE_SIZE:
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2021-07-21 00:08:22 +00:00
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return true;
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default:
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return false;
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}
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}
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static bool core_relo_is_enumval_based(enum bpf_core_relo_kind kind)
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{
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switch (kind) {
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2021-12-01 18:10:27 +00:00
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case BPF_CORE_ENUMVAL_EXISTS:
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case BPF_CORE_ENUMVAL_VALUE:
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2021-07-21 00:08:22 +00:00
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return true;
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default:
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return false;
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}
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}
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/*
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* Turn bpf_core_relo into a low- and high-level spec representation,
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* validating correctness along the way, as well as calculating resulting
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* field bit offset, specified by accessor string. Low-level spec captures
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* every single level of nestedness, including traversing anonymous
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* struct/union members. High-level one only captures semantically meaningful
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* "turning points": named fields and array indicies.
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* E.g., for this case:
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*
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* struct sample {
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* int __unimportant;
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* struct {
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* int __1;
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* int __2;
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* int a[7];
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* };
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* };
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*
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* struct sample *s = ...;
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*
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* int x = &s->a[3]; // access string = '0:1:2:3'
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*
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* Low-level spec has 1:1 mapping with each element of access string (it's
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* just a parsed access string representation): [0, 1, 2, 3].
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*
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* High-level spec will capture only 3 points:
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* - intial zero-index access by pointer (&s->... is the same as &s[0]...);
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* - field 'a' access (corresponds to '2' in low-level spec);
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* - array element #3 access (corresponds to '3' in low-level spec).
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*
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* Type-based relocations (TYPE_EXISTS/TYPE_SIZE,
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* TYPE_ID_LOCAL/TYPE_ID_TARGET) don't capture any field information. Their
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* spec and raw_spec are kept empty.
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*
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* Enum value-based relocations (ENUMVAL_EXISTS/ENUMVAL_VALUE) use access
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* string to specify enumerator's value index that need to be relocated.
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*/
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2022-04-26 00:45:10 +00:00
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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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2021-07-21 00:08:22 +00:00
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{
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int access_idx, parsed_len, i;
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struct bpf_core_accessor *acc;
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const struct btf_type *t;
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2022-04-26 00:45:09 +00:00
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const char *name, *spec_str;
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2021-07-21 00:08:22 +00:00
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__u32 id;
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__s64 sz;
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2022-04-26 00:45:09 +00:00
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spec_str = btf__name_by_offset(btf, relo->access_str_off);
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2021-07-21 00:08:22 +00:00
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if (str_is_empty(spec_str) || *spec_str == ':')
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return -EINVAL;
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memset(spec, 0, sizeof(*spec));
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spec->btf = btf;
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2022-04-26 00:45:09 +00:00
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spec->root_type_id = relo->type_id;
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spec->relo_kind = relo->kind;
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2021-07-21 00:08:22 +00:00
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/* type-based relocations don't have a field access string */
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2022-04-26 00:45:09 +00:00
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if (core_relo_is_type_based(relo->kind)) {
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2021-07-21 00:08:22 +00:00
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if (strcmp(spec_str, "0"))
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return -EINVAL;
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return 0;
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}
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/* parse spec_str="0:1:2:3:4" into array raw_spec=[0, 1, 2, 3, 4] */
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while (*spec_str) {
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if (*spec_str == ':')
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++spec_str;
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if (sscanf(spec_str, "%d%n", &access_idx, &parsed_len) != 1)
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return -EINVAL;
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if (spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
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return -E2BIG;
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spec_str += parsed_len;
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spec->raw_spec[spec->raw_len++] = access_idx;
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}
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if (spec->raw_len == 0)
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return -EINVAL;
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2022-04-26 00:45:09 +00:00
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t = skip_mods_and_typedefs(btf, relo->type_id, &id);
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2021-07-21 00:08:22 +00:00
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if (!t)
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return -EINVAL;
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access_idx = spec->raw_spec[0];
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acc = &spec->spec[0];
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acc->type_id = id;
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acc->idx = access_idx;
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spec->len++;
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2022-04-26 00:45:09 +00:00
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if (core_relo_is_enumval_based(relo->kind)) {
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2021-07-21 00:08:22 +00:00
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if (!btf_is_enum(t) || spec->raw_len > 1 || access_idx >= btf_vlen(t))
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return -EINVAL;
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/* record enumerator name in a first accessor */
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acc->name = btf__name_by_offset(btf, btf_enum(t)[access_idx].name_off);
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return 0;
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}
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2022-04-26 00:45:09 +00:00
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if (!core_relo_is_field_based(relo->kind))
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2021-07-21 00:08:22 +00:00
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return -EINVAL;
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sz = btf__resolve_size(btf, id);
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if (sz < 0)
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return sz;
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spec->bit_offset = access_idx * sz * 8;
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for (i = 1; i < spec->raw_len; i++) {
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t = skip_mods_and_typedefs(btf, id, &id);
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if (!t)
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return -EINVAL;
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access_idx = spec->raw_spec[i];
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acc = &spec->spec[spec->len];
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if (btf_is_composite(t)) {
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const struct btf_member *m;
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__u32 bit_offset;
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if (access_idx >= btf_vlen(t))
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return -EINVAL;
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bit_offset = btf_member_bit_offset(t, access_idx);
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spec->bit_offset += bit_offset;
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m = btf_members(t) + access_idx;
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if (m->name_off) {
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name = btf__name_by_offset(btf, m->name_off);
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if (str_is_empty(name))
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return -EINVAL;
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acc->type_id = id;
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acc->idx = access_idx;
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acc->name = name;
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spec->len++;
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}
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id = m->type;
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} else if (btf_is_array(t)) {
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const struct btf_array *a = btf_array(t);
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bool flex;
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t = skip_mods_and_typedefs(btf, a->type, &id);
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if (!t)
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return -EINVAL;
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flex = is_flex_arr(btf, acc - 1, a);
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if (!flex && access_idx >= a->nelems)
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return -EINVAL;
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spec->spec[spec->len].type_id = id;
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spec->spec[spec->len].idx = access_idx;
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spec->len++;
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sz = btf__resolve_size(btf, id);
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if (sz < 0)
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return sz;
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spec->bit_offset += access_idx * sz * 8;
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} else {
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2021-12-01 18:10:26 +00:00
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pr_warn("prog '%s': relo for [%u] %s (at idx %d) captures type [%d] of unexpected kind %s\n",
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2022-04-26 00:45:09 +00:00
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prog_name, relo->type_id, spec_str, i, id, btf_kind_str(t));
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2021-07-21 00:08:22 +00:00
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return -EINVAL;
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}
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}
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return 0;
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}
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/* Check two types for compatibility for the purpose of field access
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* relocation. const/volatile/restrict and typedefs are skipped to ensure we
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* are relocating semantically compatible entities:
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* - any two STRUCTs/UNIONs are compatible and can be mixed;
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* - any two FWDs are compatible, if their names match (modulo flavor suffix);
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* - any two PTRs are always compatible;
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* - for ENUMs, names should be the same (ignoring flavor suffix) or at
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* least one of enums should be anonymous;
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* - for ENUMs, check sizes, names are ignored;
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* - for INT, size and signedness are ignored;
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* - any two FLOATs are always compatible;
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* - for ARRAY, dimensionality is ignored, element types are checked for
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* compatibility recursively;
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* - everything else shouldn't be ever a target of relocation.
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* These rules are not set in stone and probably will be adjusted as we get
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* more experience with using BPF CO-RE relocations.
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*/
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static int bpf_core_fields_are_compat(const struct btf *local_btf,
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__u32 local_id,
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const struct btf *targ_btf,
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__u32 targ_id)
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{
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const struct btf_type *local_type, *targ_type;
|
|
|
|
|
|
|
|
recur:
|
|
|
|
local_type = skip_mods_and_typedefs(local_btf, local_id, &local_id);
|
|
|
|
targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
|
|
|
|
if (!local_type || !targ_type)
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
if (btf_is_composite(local_type) && btf_is_composite(targ_type))
|
|
|
|
return 1;
|
|
|
|
if (btf_kind(local_type) != btf_kind(targ_type))
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
switch (btf_kind(local_type)) {
|
|
|
|
case BTF_KIND_PTR:
|
|
|
|
case BTF_KIND_FLOAT:
|
|
|
|
return 1;
|
|
|
|
case BTF_KIND_FWD:
|
|
|
|
case BTF_KIND_ENUM: {
|
|
|
|
const char *local_name, *targ_name;
|
|
|
|
size_t local_len, targ_len;
|
|
|
|
|
|
|
|
local_name = btf__name_by_offset(local_btf,
|
|
|
|
local_type->name_off);
|
|
|
|
targ_name = btf__name_by_offset(targ_btf, targ_type->name_off);
|
|
|
|
local_len = bpf_core_essential_name_len(local_name);
|
|
|
|
targ_len = bpf_core_essential_name_len(targ_name);
|
|
|
|
/* one of them is anonymous or both w/ same flavor-less names */
|
|
|
|
return local_len == 0 || targ_len == 0 ||
|
|
|
|
(local_len == targ_len &&
|
|
|
|
strncmp(local_name, targ_name, local_len) == 0);
|
|
|
|
}
|
|
|
|
case BTF_KIND_INT:
|
|
|
|
/* just reject deprecated bitfield-like integers; all other
|
|
|
|
* integers are by default compatible between each other
|
|
|
|
*/
|
|
|
|
return btf_int_offset(local_type) == 0 &&
|
|
|
|
btf_int_offset(targ_type) == 0;
|
|
|
|
case BTF_KIND_ARRAY:
|
|
|
|
local_id = btf_array(local_type)->type;
|
|
|
|
targ_id = btf_array(targ_type)->type;
|
|
|
|
goto recur;
|
|
|
|
default:
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Given single high-level named field accessor in local type, find
|
|
|
|
* corresponding high-level accessor for a target type. Along the way,
|
|
|
|
* maintain low-level spec for target as well. Also keep updating target
|
|
|
|
* bit offset.
|
|
|
|
*
|
|
|
|
* Searching is performed through recursive exhaustive enumeration of all
|
|
|
|
* fields of a struct/union. If there are any anonymous (embedded)
|
|
|
|
* structs/unions, they are recursively searched as well. If field with
|
|
|
|
* desired name is found, check compatibility between local and target types,
|
|
|
|
* before returning result.
|
|
|
|
*
|
|
|
|
* 1 is returned, if field is found.
|
|
|
|
* 0 is returned if no compatible field is found.
|
|
|
|
* <0 is returned on error.
|
|
|
|
*/
|
|
|
|
static int bpf_core_match_member(const struct btf *local_btf,
|
|
|
|
const struct bpf_core_accessor *local_acc,
|
|
|
|
const struct btf *targ_btf,
|
|
|
|
__u32 targ_id,
|
|
|
|
struct bpf_core_spec *spec,
|
|
|
|
__u32 *next_targ_id)
|
|
|
|
{
|
|
|
|
const struct btf_type *local_type, *targ_type;
|
|
|
|
const struct btf_member *local_member, *m;
|
|
|
|
const char *local_name, *targ_name;
|
|
|
|
__u32 local_id;
|
|
|
|
int i, n, found;
|
|
|
|
|
|
|
|
targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
|
|
|
|
if (!targ_type)
|
|
|
|
return -EINVAL;
|
|
|
|
if (!btf_is_composite(targ_type))
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
local_id = local_acc->type_id;
|
2021-12-01 18:10:24 +00:00
|
|
|
local_type = btf_type_by_id(local_btf, local_id);
|
2021-07-21 00:08:22 +00:00
|
|
|
local_member = btf_members(local_type) + local_acc->idx;
|
|
|
|
local_name = btf__name_by_offset(local_btf, local_member->name_off);
|
|
|
|
|
|
|
|
n = btf_vlen(targ_type);
|
|
|
|
m = btf_members(targ_type);
|
|
|
|
for (i = 0; i < n; i++, m++) {
|
|
|
|
__u32 bit_offset;
|
|
|
|
|
|
|
|
bit_offset = btf_member_bit_offset(targ_type, i);
|
|
|
|
|
|
|
|
/* too deep struct/union/array nesting */
|
|
|
|
if (spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
|
|
|
|
return -E2BIG;
|
|
|
|
|
|
|
|
/* speculate this member will be the good one */
|
|
|
|
spec->bit_offset += bit_offset;
|
|
|
|
spec->raw_spec[spec->raw_len++] = i;
|
|
|
|
|
|
|
|
targ_name = btf__name_by_offset(targ_btf, m->name_off);
|
|
|
|
if (str_is_empty(targ_name)) {
|
|
|
|
/* embedded struct/union, we need to go deeper */
|
|
|
|
found = bpf_core_match_member(local_btf, local_acc,
|
|
|
|
targ_btf, m->type,
|
|
|
|
spec, next_targ_id);
|
|
|
|
if (found) /* either found or error */
|
|
|
|
return found;
|
|
|
|
} else if (strcmp(local_name, targ_name) == 0) {
|
|
|
|
/* matching named field */
|
|
|
|
struct bpf_core_accessor *targ_acc;
|
|
|
|
|
|
|
|
targ_acc = &spec->spec[spec->len++];
|
|
|
|
targ_acc->type_id = targ_id;
|
|
|
|
targ_acc->idx = i;
|
|
|
|
targ_acc->name = targ_name;
|
|
|
|
|
|
|
|
*next_targ_id = m->type;
|
|
|
|
found = bpf_core_fields_are_compat(local_btf,
|
|
|
|
local_member->type,
|
|
|
|
targ_btf, m->type);
|
|
|
|
if (!found)
|
|
|
|
spec->len--; /* pop accessor */
|
|
|
|
return found;
|
|
|
|
}
|
|
|
|
/* member turned out not to be what we looked for */
|
|
|
|
spec->bit_offset -= bit_offset;
|
|
|
|
spec->raw_len--;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Try to match local spec to a target type and, if successful, produce full
|
|
|
|
* target spec (high-level, low-level + bit offset).
|
|
|
|
*/
|
|
|
|
static int bpf_core_spec_match(struct bpf_core_spec *local_spec,
|
|
|
|
const struct btf *targ_btf, __u32 targ_id,
|
|
|
|
struct bpf_core_spec *targ_spec)
|
|
|
|
{
|
|
|
|
const struct btf_type *targ_type;
|
|
|
|
const struct bpf_core_accessor *local_acc;
|
|
|
|
struct bpf_core_accessor *targ_acc;
|
|
|
|
int i, sz, matched;
|
|
|
|
|
|
|
|
memset(targ_spec, 0, sizeof(*targ_spec));
|
|
|
|
targ_spec->btf = targ_btf;
|
|
|
|
targ_spec->root_type_id = targ_id;
|
|
|
|
targ_spec->relo_kind = local_spec->relo_kind;
|
|
|
|
|
|
|
|
if (core_relo_is_type_based(local_spec->relo_kind)) {
|
|
|
|
return bpf_core_types_are_compat(local_spec->btf,
|
|
|
|
local_spec->root_type_id,
|
|
|
|
targ_btf, targ_id);
|
|
|
|
}
|
|
|
|
|
|
|
|
local_acc = &local_spec->spec[0];
|
|
|
|
targ_acc = &targ_spec->spec[0];
|
|
|
|
|
|
|
|
if (core_relo_is_enumval_based(local_spec->relo_kind)) {
|
|
|
|
size_t local_essent_len, targ_essent_len;
|
|
|
|
const struct btf_enum *e;
|
|
|
|
const char *targ_name;
|
|
|
|
|
|
|
|
/* has to resolve to an enum */
|
|
|
|
targ_type = skip_mods_and_typedefs(targ_spec->btf, targ_id, &targ_id);
|
|
|
|
if (!btf_is_enum(targ_type))
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
local_essent_len = bpf_core_essential_name_len(local_acc->name);
|
|
|
|
|
|
|
|
for (i = 0, e = btf_enum(targ_type); i < btf_vlen(targ_type); i++, e++) {
|
|
|
|
targ_name = btf__name_by_offset(targ_spec->btf, e->name_off);
|
|
|
|
targ_essent_len = bpf_core_essential_name_len(targ_name);
|
|
|
|
if (targ_essent_len != local_essent_len)
|
|
|
|
continue;
|
|
|
|
if (strncmp(local_acc->name, targ_name, local_essent_len) == 0) {
|
|
|
|
targ_acc->type_id = targ_id;
|
|
|
|
targ_acc->idx = i;
|
|
|
|
targ_acc->name = targ_name;
|
|
|
|
targ_spec->len++;
|
|
|
|
targ_spec->raw_spec[targ_spec->raw_len] = targ_acc->idx;
|
|
|
|
targ_spec->raw_len++;
|
|
|
|
return 1;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (!core_relo_is_field_based(local_spec->relo_kind))
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
for (i = 0; i < local_spec->len; i++, local_acc++, targ_acc++) {
|
|
|
|
targ_type = skip_mods_and_typedefs(targ_spec->btf, targ_id,
|
|
|
|
&targ_id);
|
|
|
|
if (!targ_type)
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
if (local_acc->name) {
|
|
|
|
matched = bpf_core_match_member(local_spec->btf,
|
|
|
|
local_acc,
|
|
|
|
targ_btf, targ_id,
|
|
|
|
targ_spec, &targ_id);
|
|
|
|
if (matched <= 0)
|
|
|
|
return matched;
|
|
|
|
} else {
|
|
|
|
/* for i=0, targ_id is already treated as array element
|
|
|
|
* type (because it's the original struct), for others
|
|
|
|
* we should find array element type first
|
|
|
|
*/
|
|
|
|
if (i > 0) {
|
|
|
|
const struct btf_array *a;
|
|
|
|
bool flex;
|
|
|
|
|
|
|
|
if (!btf_is_array(targ_type))
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
a = btf_array(targ_type);
|
|
|
|
flex = is_flex_arr(targ_btf, targ_acc - 1, a);
|
|
|
|
if (!flex && local_acc->idx >= a->nelems)
|
|
|
|
return 0;
|
|
|
|
if (!skip_mods_and_typedefs(targ_btf, a->type,
|
|
|
|
&targ_id))
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* too deep struct/union/array nesting */
|
|
|
|
if (targ_spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
|
|
|
|
return -E2BIG;
|
|
|
|
|
|
|
|
targ_acc->type_id = targ_id;
|
|
|
|
targ_acc->idx = local_acc->idx;
|
|
|
|
targ_acc->name = NULL;
|
|
|
|
targ_spec->len++;
|
|
|
|
targ_spec->raw_spec[targ_spec->raw_len] = targ_acc->idx;
|
|
|
|
targ_spec->raw_len++;
|
|
|
|
|
|
|
|
sz = btf__resolve_size(targ_btf, targ_id);
|
|
|
|
if (sz < 0)
|
|
|
|
return sz;
|
|
|
|
targ_spec->bit_offset += local_acc->idx * sz * 8;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
return 1;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int bpf_core_calc_field_relo(const char *prog_name,
|
|
|
|
const struct bpf_core_relo *relo,
|
|
|
|
const struct bpf_core_spec *spec,
|
|
|
|
__u32 *val, __u32 *field_sz, __u32 *type_id,
|
|
|
|
bool *validate)
|
|
|
|
{
|
|
|
|
const struct bpf_core_accessor *acc;
|
|
|
|
const struct btf_type *t;
|
|
|
|
__u32 byte_off, byte_sz, bit_off, bit_sz, field_type_id;
|
|
|
|
const struct btf_member *m;
|
|
|
|
const struct btf_type *mt;
|
|
|
|
bool bitfield;
|
|
|
|
__s64 sz;
|
|
|
|
|
|
|
|
*field_sz = 0;
|
|
|
|
|
2021-12-01 18:10:27 +00:00
|
|
|
if (relo->kind == BPF_CORE_FIELD_EXISTS) {
|
2021-07-21 00:08:22 +00:00
|
|
|
*val = spec ? 1 : 0;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (!spec)
|
|
|
|
return -EUCLEAN; /* request instruction poisoning */
|
|
|
|
|
|
|
|
acc = &spec->spec[spec->len - 1];
|
2021-12-01 18:10:24 +00:00
|
|
|
t = btf_type_by_id(spec->btf, acc->type_id);
|
2021-07-21 00:08:22 +00:00
|
|
|
|
|
|
|
/* a[n] accessor needs special handling */
|
|
|
|
if (!acc->name) {
|
2021-12-01 18:10:27 +00:00
|
|
|
if (relo->kind == BPF_CORE_FIELD_BYTE_OFFSET) {
|
2021-07-21 00:08:22 +00:00
|
|
|
*val = spec->bit_offset / 8;
|
|
|
|
/* remember field size for load/store mem size */
|
|
|
|
sz = btf__resolve_size(spec->btf, acc->type_id);
|
|
|
|
if (sz < 0)
|
|
|
|
return -EINVAL;
|
|
|
|
*field_sz = sz;
|
|
|
|
*type_id = acc->type_id;
|
2021-12-01 18:10:27 +00:00
|
|
|
} else if (relo->kind == BPF_CORE_FIELD_BYTE_SIZE) {
|
2021-07-21 00:08:22 +00:00
|
|
|
sz = btf__resolve_size(spec->btf, acc->type_id);
|
|
|
|
if (sz < 0)
|
|
|
|
return -EINVAL;
|
|
|
|
*val = sz;
|
|
|
|
} else {
|
|
|
|
pr_warn("prog '%s': relo %d at insn #%d can't be applied to array access\n",
|
|
|
|
prog_name, relo->kind, relo->insn_off / 8);
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
if (validate)
|
|
|
|
*validate = true;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
m = btf_members(t) + acc->idx;
|
|
|
|
mt = skip_mods_and_typedefs(spec->btf, m->type, &field_type_id);
|
|
|
|
bit_off = spec->bit_offset;
|
|
|
|
bit_sz = btf_member_bitfield_size(t, acc->idx);
|
|
|
|
|
|
|
|
bitfield = bit_sz > 0;
|
|
|
|
if (bitfield) {
|
|
|
|
byte_sz = mt->size;
|
|
|
|
byte_off = bit_off / 8 / byte_sz * byte_sz;
|
|
|
|
/* figure out smallest int size necessary for bitfield load */
|
|
|
|
while (bit_off + bit_sz - byte_off * 8 > byte_sz * 8) {
|
|
|
|
if (byte_sz >= 8) {
|
|
|
|
/* bitfield can't be read with 64-bit read */
|
|
|
|
pr_warn("prog '%s': relo %d at insn #%d can't be satisfied for bitfield\n",
|
|
|
|
prog_name, relo->kind, relo->insn_off / 8);
|
|
|
|
return -E2BIG;
|
|
|
|
}
|
|
|
|
byte_sz *= 2;
|
|
|
|
byte_off = bit_off / 8 / byte_sz * byte_sz;
|
|
|
|
}
|
|
|
|
} else {
|
|
|
|
sz = btf__resolve_size(spec->btf, field_type_id);
|
|
|
|
if (sz < 0)
|
|
|
|
return -EINVAL;
|
|
|
|
byte_sz = sz;
|
|
|
|
byte_off = spec->bit_offset / 8;
|
|
|
|
bit_sz = byte_sz * 8;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* for bitfields, all the relocatable aspects are ambiguous and we
|
|
|
|
* might disagree with compiler, so turn off validation of expected
|
|
|
|
* value, except for signedness
|
|
|
|
*/
|
|
|
|
if (validate)
|
|
|
|
*validate = !bitfield;
|
|
|
|
|
|
|
|
switch (relo->kind) {
|
2021-12-01 18:10:27 +00:00
|
|
|
case BPF_CORE_FIELD_BYTE_OFFSET:
|
2021-07-21 00:08:22 +00:00
|
|
|
*val = byte_off;
|
|
|
|
if (!bitfield) {
|
|
|
|
*field_sz = byte_sz;
|
|
|
|
*type_id = field_type_id;
|
|
|
|
}
|
|
|
|
break;
|
2021-12-01 18:10:27 +00:00
|
|
|
case BPF_CORE_FIELD_BYTE_SIZE:
|
2021-07-21 00:08:22 +00:00
|
|
|
*val = byte_sz;
|
|
|
|
break;
|
2021-12-01 18:10:27 +00:00
|
|
|
case BPF_CORE_FIELD_SIGNED:
|
2021-07-21 00:08:22 +00:00
|
|
|
/* enums will be assumed unsigned */
|
|
|
|
*val = btf_is_enum(mt) ||
|
|
|
|
(btf_int_encoding(mt) & BTF_INT_SIGNED);
|
|
|
|
if (validate)
|
|
|
|
*validate = true; /* signedness is never ambiguous */
|
|
|
|
break;
|
2021-12-01 18:10:27 +00:00
|
|
|
case BPF_CORE_FIELD_LSHIFT_U64:
|
2021-10-26 01:08:27 +00:00
|
|
|
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
|
2021-07-21 00:08:22 +00:00
|
|
|
*val = 64 - (bit_off + bit_sz - byte_off * 8);
|
|
|
|
#else
|
|
|
|
*val = (8 - byte_sz) * 8 + (bit_off - byte_off * 8);
|
|
|
|
#endif
|
|
|
|
break;
|
2021-12-01 18:10:27 +00:00
|
|
|
case BPF_CORE_FIELD_RSHIFT_U64:
|
2021-07-21 00:08:22 +00:00
|
|
|
*val = 64 - bit_sz;
|
|
|
|
if (validate)
|
|
|
|
*validate = true; /* right shift is never ambiguous */
|
|
|
|
break;
|
2021-12-01 18:10:27 +00:00
|
|
|
case BPF_CORE_FIELD_EXISTS:
|
2021-07-21 00:08:22 +00:00
|
|
|
default:
|
|
|
|
return -EOPNOTSUPP;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int bpf_core_calc_type_relo(const struct bpf_core_relo *relo,
|
|
|
|
const struct bpf_core_spec *spec,
|
2021-12-13 01:07:06 +00:00
|
|
|
__u32 *val, bool *validate)
|
2021-07-21 00:08:22 +00:00
|
|
|
{
|
|
|
|
__s64 sz;
|
|
|
|
|
2021-12-13 01:07:06 +00:00
|
|
|
/* by default, always check expected value in bpf_insn */
|
|
|
|
if (validate)
|
|
|
|
*validate = true;
|
|
|
|
|
2021-07-21 00:08:22 +00:00
|
|
|
/* type-based relos return zero when target type is not found */
|
|
|
|
if (!spec) {
|
|
|
|
*val = 0;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
switch (relo->kind) {
|
2021-12-01 18:10:27 +00:00
|
|
|
case BPF_CORE_TYPE_ID_TARGET:
|
2021-07-21 00:08:22 +00:00
|
|
|
*val = spec->root_type_id;
|
2021-12-13 01:07:06 +00:00
|
|
|
/* type ID, embedded in bpf_insn, might change during linking,
|
|
|
|
* so enforcing it is pointless
|
|
|
|
*/
|
|
|
|
if (validate)
|
|
|
|
*validate = false;
|
2021-07-21 00:08:22 +00:00
|
|
|
break;
|
2021-12-01 18:10:27 +00:00
|
|
|
case BPF_CORE_TYPE_EXISTS:
|
2021-07-21 00:08:22 +00:00
|
|
|
*val = 1;
|
|
|
|
break;
|
2021-12-01 18:10:27 +00:00
|
|
|
case BPF_CORE_TYPE_SIZE:
|
2021-07-21 00:08:22 +00:00
|
|
|
sz = btf__resolve_size(spec->btf, spec->root_type_id);
|
|
|
|
if (sz < 0)
|
|
|
|
return -EINVAL;
|
|
|
|
*val = sz;
|
|
|
|
break;
|
2021-12-01 18:10:27 +00:00
|
|
|
case BPF_CORE_TYPE_ID_LOCAL:
|
|
|
|
/* BPF_CORE_TYPE_ID_LOCAL is handled specially and shouldn't get here */
|
2021-07-21 00:08:22 +00:00
|
|
|
default:
|
|
|
|
return -EOPNOTSUPP;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int bpf_core_calc_enumval_relo(const struct bpf_core_relo *relo,
|
|
|
|
const struct bpf_core_spec *spec,
|
|
|
|
__u32 *val)
|
|
|
|
{
|
|
|
|
const struct btf_type *t;
|
|
|
|
const struct btf_enum *e;
|
|
|
|
|
|
|
|
switch (relo->kind) {
|
2021-12-01 18:10:27 +00:00
|
|
|
case BPF_CORE_ENUMVAL_EXISTS:
|
2021-07-21 00:08:22 +00:00
|
|
|
*val = spec ? 1 : 0;
|
|
|
|
break;
|
2021-12-01 18:10:27 +00:00
|
|
|
case BPF_CORE_ENUMVAL_VALUE:
|
2021-07-21 00:08:22 +00:00
|
|
|
if (!spec)
|
|
|
|
return -EUCLEAN; /* request instruction poisoning */
|
2021-12-01 18:10:24 +00:00
|
|
|
t = btf_type_by_id(spec->btf, spec->spec[0].type_id);
|
2021-07-21 00:08:22 +00:00
|
|
|
e = btf_enum(t) + spec->spec[0].idx;
|
|
|
|
*val = e->val;
|
|
|
|
break;
|
|
|
|
default:
|
|
|
|
return -EOPNOTSUPP;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Calculate original and target relocation values, given local and target
|
|
|
|
* specs and relocation kind. These values are calculated for each candidate.
|
|
|
|
* If there are multiple candidates, resulting values should all be consistent
|
|
|
|
* with each other. Otherwise, libbpf will refuse to proceed due to ambiguity.
|
|
|
|
* If instruction has to be poisoned, *poison will be set to true.
|
|
|
|
*/
|
|
|
|
static int bpf_core_calc_relo(const char *prog_name,
|
|
|
|
const struct bpf_core_relo *relo,
|
|
|
|
int relo_idx,
|
|
|
|
const struct bpf_core_spec *local_spec,
|
|
|
|
const struct bpf_core_spec *targ_spec,
|
|
|
|
struct bpf_core_relo_res *res)
|
|
|
|
{
|
|
|
|
int err = -EOPNOTSUPP;
|
|
|
|
|
|
|
|
res->orig_val = 0;
|
|
|
|
res->new_val = 0;
|
|
|
|
res->poison = false;
|
|
|
|
res->validate = true;
|
|
|
|
res->fail_memsz_adjust = false;
|
|
|
|
res->orig_sz = res->new_sz = 0;
|
|
|
|
res->orig_type_id = res->new_type_id = 0;
|
|
|
|
|
|
|
|
if (core_relo_is_field_based(relo->kind)) {
|
|
|
|
err = bpf_core_calc_field_relo(prog_name, relo, local_spec,
|
|
|
|
&res->orig_val, &res->orig_sz,
|
|
|
|
&res->orig_type_id, &res->validate);
|
|
|
|
err = err ?: bpf_core_calc_field_relo(prog_name, relo, targ_spec,
|
|
|
|
&res->new_val, &res->new_sz,
|
|
|
|
&res->new_type_id, NULL);
|
|
|
|
if (err)
|
|
|
|
goto done;
|
|
|
|
/* Validate if it's safe to adjust load/store memory size.
|
|
|
|
* Adjustments are performed only if original and new memory
|
|
|
|
* sizes differ.
|
|
|
|
*/
|
|
|
|
res->fail_memsz_adjust = false;
|
|
|
|
if (res->orig_sz != res->new_sz) {
|
|
|
|
const struct btf_type *orig_t, *new_t;
|
|
|
|
|
2021-12-01 18:10:24 +00:00
|
|
|
orig_t = btf_type_by_id(local_spec->btf, res->orig_type_id);
|
|
|
|
new_t = btf_type_by_id(targ_spec->btf, res->new_type_id);
|
2021-07-21 00:08:22 +00:00
|
|
|
|
|
|
|
/* There are two use cases in which it's safe to
|
|
|
|
* adjust load/store's mem size:
|
|
|
|
* - reading a 32-bit kernel pointer, while on BPF
|
|
|
|
* size pointers are always 64-bit; in this case
|
|
|
|
* it's safe to "downsize" instruction size due to
|
|
|
|
* pointer being treated as unsigned integer with
|
|
|
|
* zero-extended upper 32-bits;
|
|
|
|
* - reading unsigned integers, again due to
|
|
|
|
* zero-extension is preserving the value correctly.
|
|
|
|
*
|
|
|
|
* In all other cases it's incorrect to attempt to
|
|
|
|
* load/store field because read value will be
|
|
|
|
* incorrect, so we poison relocated instruction.
|
|
|
|
*/
|
|
|
|
if (btf_is_ptr(orig_t) && btf_is_ptr(new_t))
|
|
|
|
goto done;
|
|
|
|
if (btf_is_int(orig_t) && btf_is_int(new_t) &&
|
|
|
|
btf_int_encoding(orig_t) != BTF_INT_SIGNED &&
|
|
|
|
btf_int_encoding(new_t) != BTF_INT_SIGNED)
|
|
|
|
goto done;
|
|
|
|
|
|
|
|
/* mark as invalid mem size adjustment, but this will
|
|
|
|
* only be checked for LDX/STX/ST insns
|
|
|
|
*/
|
|
|
|
res->fail_memsz_adjust = true;
|
|
|
|
}
|
|
|
|
} else if (core_relo_is_type_based(relo->kind)) {
|
2021-12-13 01:07:06 +00:00
|
|
|
err = bpf_core_calc_type_relo(relo, local_spec, &res->orig_val, &res->validate);
|
|
|
|
err = err ?: bpf_core_calc_type_relo(relo, targ_spec, &res->new_val, NULL);
|
2021-07-21 00:08:22 +00:00
|
|
|
} else if (core_relo_is_enumval_based(relo->kind)) {
|
|
|
|
err = bpf_core_calc_enumval_relo(relo, local_spec, &res->orig_val);
|
|
|
|
err = err ?: bpf_core_calc_enumval_relo(relo, targ_spec, &res->new_val);
|
|
|
|
}
|
|
|
|
|
|
|
|
done:
|
|
|
|
if (err == -EUCLEAN) {
|
|
|
|
/* EUCLEAN is used to signal instruction poisoning request */
|
|
|
|
res->poison = true;
|
|
|
|
err = 0;
|
|
|
|
} else if (err == -EOPNOTSUPP) {
|
|
|
|
/* EOPNOTSUPP means unknown/unsupported relocation */
|
|
|
|
pr_warn("prog '%s': relo #%d: unrecognized CO-RE relocation %s (%d) at insn #%d\n",
|
|
|
|
prog_name, relo_idx, core_relo_kind_str(relo->kind),
|
|
|
|
relo->kind, relo->insn_off / 8);
|
|
|
|
}
|
|
|
|
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Turn instruction for which CO_RE relocation failed into invalid one with
|
|
|
|
* distinct signature.
|
|
|
|
*/
|
|
|
|
static void bpf_core_poison_insn(const char *prog_name, int relo_idx,
|
|
|
|
int insn_idx, struct bpf_insn *insn)
|
|
|
|
{
|
|
|
|
pr_debug("prog '%s': relo #%d: substituting insn #%d w/ invalid insn\n",
|
|
|
|
prog_name, relo_idx, insn_idx);
|
|
|
|
insn->code = BPF_JMP | BPF_CALL;
|
|
|
|
insn->dst_reg = 0;
|
|
|
|
insn->src_reg = 0;
|
|
|
|
insn->off = 0;
|
|
|
|
/* if this instruction is reachable (not a dead code),
|
|
|
|
* verifier will complain with the following message:
|
|
|
|
* invalid func unknown#195896080
|
|
|
|
*/
|
|
|
|
insn->imm = 195896080; /* => 0xbad2310 => "bad relo" */
|
|
|
|
}
|
|
|
|
|
|
|
|
static int insn_bpf_size_to_bytes(struct bpf_insn *insn)
|
|
|
|
{
|
|
|
|
switch (BPF_SIZE(insn->code)) {
|
|
|
|
case BPF_DW: return 8;
|
|
|
|
case BPF_W: return 4;
|
|
|
|
case BPF_H: return 2;
|
|
|
|
case BPF_B: return 1;
|
|
|
|
default: return -1;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
static int insn_bytes_to_bpf_size(__u32 sz)
|
|
|
|
{
|
|
|
|
switch (sz) {
|
|
|
|
case 8: return BPF_DW;
|
|
|
|
case 4: return BPF_W;
|
|
|
|
case 2: return BPF_H;
|
|
|
|
case 1: return BPF_B;
|
|
|
|
default: return -1;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Patch relocatable BPF instruction.
|
|
|
|
*
|
|
|
|
* Patched value is determined by relocation kind and target specification.
|
|
|
|
* For existence relocations target spec will be NULL if field/type is not found.
|
|
|
|
* Expected insn->imm value is determined using relocation kind and local
|
|
|
|
* spec, and is checked before patching instruction. If actual insn->imm value
|
|
|
|
* is wrong, bail out with error.
|
|
|
|
*
|
|
|
|
* Currently supported classes of BPF instruction are:
|
|
|
|
* 1. rX = <imm> (assignment with immediate operand);
|
|
|
|
* 2. rX += <imm> (arithmetic operations with immediate operand);
|
|
|
|
* 3. rX = <imm64> (load with 64-bit immediate value);
|
|
|
|
* 4. rX = *(T *)(rY + <off>), where T is one of {u8, u16, u32, u64};
|
|
|
|
* 5. *(T *)(rX + <off>) = rY, where T is one of {u8, u16, u32, u64};
|
|
|
|
* 6. *(T *)(rX + <off>) = <imm>, where T is one of {u8, u16, u32, u64}.
|
|
|
|
*/
|
2022-02-15 22:58:50 +00:00
|
|
|
int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn,
|
|
|
|
int insn_idx, const struct bpf_core_relo *relo,
|
|
|
|
int relo_idx, const struct bpf_core_relo_res *res)
|
2021-07-21 00:08:22 +00:00
|
|
|
{
|
|
|
|
__u32 orig_val, new_val;
|
|
|
|
__u8 class;
|
|
|
|
|
|
|
|
class = BPF_CLASS(insn->code);
|
|
|
|
|
|
|
|
if (res->poison) {
|
|
|
|
poison:
|
|
|
|
/* poison second part of ldimm64 to avoid confusing error from
|
|
|
|
* verifier about "unknown opcode 00"
|
|
|
|
*/
|
|
|
|
if (is_ldimm64_insn(insn))
|
|
|
|
bpf_core_poison_insn(prog_name, relo_idx, insn_idx + 1, insn + 1);
|
|
|
|
bpf_core_poison_insn(prog_name, relo_idx, insn_idx, insn);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
orig_val = res->orig_val;
|
|
|
|
new_val = res->new_val;
|
|
|
|
|
|
|
|
switch (class) {
|
|
|
|
case BPF_ALU:
|
|
|
|
case BPF_ALU64:
|
|
|
|
if (BPF_SRC(insn->code) != BPF_K)
|
|
|
|
return -EINVAL;
|
|
|
|
if (res->validate && insn->imm != orig_val) {
|
|
|
|
pr_warn("prog '%s': relo #%d: unexpected insn #%d (ALU/ALU64) value: got %u, exp %u -> %u\n",
|
|
|
|
prog_name, relo_idx,
|
|
|
|
insn_idx, insn->imm, orig_val, new_val);
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
orig_val = insn->imm;
|
|
|
|
insn->imm = new_val;
|
|
|
|
pr_debug("prog '%s': relo #%d: patched insn #%d (ALU/ALU64) imm %u -> %u\n",
|
|
|
|
prog_name, relo_idx, insn_idx,
|
|
|
|
orig_val, new_val);
|
|
|
|
break;
|
|
|
|
case BPF_LDX:
|
|
|
|
case BPF_ST:
|
|
|
|
case BPF_STX:
|
|
|
|
if (res->validate && insn->off != orig_val) {
|
|
|
|
pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDX/ST/STX) value: got %u, exp %u -> %u\n",
|
|
|
|
prog_name, relo_idx, insn_idx, insn->off, orig_val, new_val);
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
if (new_val > SHRT_MAX) {
|
|
|
|
pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) value too big: %u\n",
|
|
|
|
prog_name, relo_idx, insn_idx, new_val);
|
|
|
|
return -ERANGE;
|
|
|
|
}
|
|
|
|
if (res->fail_memsz_adjust) {
|
|
|
|
pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) accesses field incorrectly. "
|
|
|
|
"Make sure you are accessing pointers, unsigned integers, or fields of matching type and size.\n",
|
|
|
|
prog_name, relo_idx, insn_idx);
|
|
|
|
goto poison;
|
|
|
|
}
|
|
|
|
|
|
|
|
orig_val = insn->off;
|
|
|
|
insn->off = new_val;
|
|
|
|
pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) off %u -> %u\n",
|
|
|
|
prog_name, relo_idx, insn_idx, orig_val, new_val);
|
|
|
|
|
|
|
|
if (res->new_sz != res->orig_sz) {
|
|
|
|
int insn_bytes_sz, insn_bpf_sz;
|
|
|
|
|
|
|
|
insn_bytes_sz = insn_bpf_size_to_bytes(insn);
|
|
|
|
if (insn_bytes_sz != res->orig_sz) {
|
|
|
|
pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) unexpected mem size: got %d, exp %u\n",
|
|
|
|
prog_name, relo_idx, insn_idx, insn_bytes_sz, res->orig_sz);
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
insn_bpf_sz = insn_bytes_to_bpf_size(res->new_sz);
|
|
|
|
if (insn_bpf_sz < 0) {
|
|
|
|
pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) invalid new mem size: %u\n",
|
|
|
|
prog_name, relo_idx, insn_idx, res->new_sz);
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
insn->code = BPF_MODE(insn->code) | insn_bpf_sz | BPF_CLASS(insn->code);
|
|
|
|
pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) mem_sz %u -> %u\n",
|
|
|
|
prog_name, relo_idx, insn_idx, res->orig_sz, res->new_sz);
|
|
|
|
}
|
|
|
|
break;
|
|
|
|
case BPF_LD: {
|
|
|
|
__u64 imm;
|
|
|
|
|
|
|
|
if (!is_ldimm64_insn(insn) ||
|
|
|
|
insn[0].src_reg != 0 || insn[0].off != 0 ||
|
|
|
|
insn[1].code != 0 || insn[1].dst_reg != 0 ||
|
|
|
|
insn[1].src_reg != 0 || insn[1].off != 0) {
|
|
|
|
pr_warn("prog '%s': relo #%d: insn #%d (LDIMM64) has unexpected form\n",
|
|
|
|
prog_name, relo_idx, insn_idx);
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
imm = insn[0].imm + ((__u64)insn[1].imm << 32);
|
|
|
|
if (res->validate && imm != orig_val) {
|
|
|
|
pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDIMM64) value: got %llu, exp %u -> %u\n",
|
|
|
|
prog_name, relo_idx,
|
|
|
|
insn_idx, (unsigned long long)imm,
|
|
|
|
orig_val, new_val);
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
insn[0].imm = new_val;
|
|
|
|
insn[1].imm = 0; /* currently only 32-bit values are supported */
|
|
|
|
pr_debug("prog '%s': relo #%d: patched insn #%d (LDIMM64) imm64 %llu -> %u\n",
|
|
|
|
prog_name, relo_idx, insn_idx,
|
|
|
|
(unsigned long long)imm, new_val);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
default:
|
|
|
|
pr_warn("prog '%s': relo #%d: trying to relocate unrecognized insn #%d, code:0x%x, src:0x%x, dst:0x%x, off:0x%x, imm:0x%x\n",
|
|
|
|
prog_name, relo_idx, insn_idx, insn->code,
|
|
|
|
insn->src_reg, insn->dst_reg, insn->off, insn->imm);
|
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Output spec definition in the format:
|
|
|
|
* [<type-id>] (<type-name>) + <raw-spec> => <offset>@<spec>,
|
|
|
|
* where <spec> is a C-syntax view of recorded field access, e.g.: x.a[3].b
|
|
|
|
*/
|
2022-04-26 00:45:10 +00:00
|
|
|
int bpf_core_format_spec(char *buf, size_t buf_sz, const struct bpf_core_spec *spec)
|
2021-07-21 00:08:22 +00:00
|
|
|
{
|
|
|
|
const struct btf_type *t;
|
|
|
|
const struct btf_enum *e;
|
|
|
|
const char *s;
|
|
|
|
__u32 type_id;
|
2022-04-26 00:45:08 +00:00
|
|
|
int i, len = 0;
|
|
|
|
|
|
|
|
#define append_buf(fmt, args...) \
|
|
|
|
({ \
|
|
|
|
int r; \
|
|
|
|
r = snprintf(buf, buf_sz, fmt, ##args); \
|
|
|
|
len += r; \
|
|
|
|
if (r >= buf_sz) \
|
|
|
|
r = buf_sz; \
|
|
|
|
buf += r; \
|
|
|
|
buf_sz -= r; \
|
|
|
|
})
|
2021-07-21 00:08:22 +00:00
|
|
|
|
|
|
|
type_id = spec->root_type_id;
|
2021-12-01 18:10:24 +00:00
|
|
|
t = btf_type_by_id(spec->btf, type_id);
|
2021-07-21 00:08:22 +00:00
|
|
|
s = btf__name_by_offset(spec->btf, t->name_off);
|
|
|
|
|
2022-04-26 00:45:08 +00:00
|
|
|
append_buf("<%s> [%u] %s %s",
|
|
|
|
core_relo_kind_str(spec->relo_kind),
|
|
|
|
type_id, btf_kind_str(t), str_is_empty(s) ? "<anon>" : s);
|
2021-07-21 00:08:22 +00:00
|
|
|
|
|
|
|
if (core_relo_is_type_based(spec->relo_kind))
|
2022-04-26 00:45:08 +00:00
|
|
|
return len;
|
2021-07-21 00:08:22 +00:00
|
|
|
|
|
|
|
if (core_relo_is_enumval_based(spec->relo_kind)) {
|
|
|
|
t = skip_mods_and_typedefs(spec->btf, type_id, NULL);
|
|
|
|
e = btf_enum(t) + spec->raw_spec[0];
|
|
|
|
s = btf__name_by_offset(spec->btf, e->name_off);
|
|
|
|
|
2022-04-26 00:45:08 +00:00
|
|
|
append_buf("::%s = %u", s, e->val);
|
|
|
|
return len;
|
2021-07-21 00:08:22 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
if (core_relo_is_field_based(spec->relo_kind)) {
|
|
|
|
for (i = 0; i < spec->len; i++) {
|
|
|
|
if (spec->spec[i].name)
|
2022-04-26 00:45:08 +00:00
|
|
|
append_buf(".%s", spec->spec[i].name);
|
2021-07-21 00:08:22 +00:00
|
|
|
else if (i > 0 || spec->spec[i].idx > 0)
|
2022-04-26 00:45:08 +00:00
|
|
|
append_buf("[%u]", spec->spec[i].idx);
|
2021-07-21 00:08:22 +00:00
|
|
|
}
|
|
|
|
|
2022-04-26 00:45:08 +00:00
|
|
|
append_buf(" (");
|
2021-07-21 00:08:22 +00:00
|
|
|
for (i = 0; i < spec->raw_len; i++)
|
2022-04-26 00:45:08 +00:00
|
|
|
append_buf("%s%d", i == 0 ? "" : ":", spec->raw_spec[i]);
|
2021-07-21 00:08:22 +00:00
|
|
|
|
|
|
|
if (spec->bit_offset % 8)
|
2022-04-26 00:45:08 +00:00
|
|
|
append_buf(" @ offset %u.%u)", spec->bit_offset / 8, spec->bit_offset % 8);
|
2021-07-21 00:08:22 +00:00
|
|
|
else
|
2022-04-26 00:45:08 +00:00
|
|
|
append_buf(" @ offset %u)", spec->bit_offset / 8);
|
|
|
|
return len;
|
2021-07-21 00:08:22 +00:00
|
|
|
}
|
2022-04-26 00:45:08 +00:00
|
|
|
|
|
|
|
return len;
|
|
|
|
#undef append_buf
|
2021-07-21 00:08:22 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
2022-02-15 22:58:50 +00:00
|
|
|
* Calculate CO-RE relocation target result.
|
2021-07-21 00:08:22 +00:00
|
|
|
*
|
|
|
|
* The outline and important points of the algorithm:
|
|
|
|
* 1. For given local type, find corresponding candidate target types.
|
|
|
|
* Candidate type is a type with the same "essential" name, ignoring
|
|
|
|
* everything after last triple underscore (___). E.g., `sample`,
|
|
|
|
* `sample___flavor_one`, `sample___flavor_another_one`, are all candidates
|
|
|
|
* for each other. Names with triple underscore are referred to as
|
|
|
|
* "flavors" and are useful, among other things, to allow to
|
|
|
|
* specify/support incompatible variations of the same kernel struct, which
|
|
|
|
* might differ between different kernel versions and/or build
|
|
|
|
* configurations.
|
|
|
|
*
|
|
|
|
* N.B. Struct "flavors" could be generated by bpftool's BTF-to-C
|
|
|
|
* converter, when deduplicated BTF of a kernel still contains more than
|
|
|
|
* one different types with the same name. In that case, ___2, ___3, etc
|
|
|
|
* are appended starting from second name conflict. But start flavors are
|
|
|
|
* also useful to be defined "locally", in BPF program, to extract same
|
|
|
|
* data from incompatible changes between different kernel
|
|
|
|
* versions/configurations. For instance, to handle field renames between
|
|
|
|
* kernel versions, one can use two flavors of the struct name with the
|
|
|
|
* same common name and use conditional relocations to extract that field,
|
|
|
|
* depending on target kernel version.
|
|
|
|
* 2. For each candidate type, try to match local specification to this
|
|
|
|
* candidate target type. Matching involves finding corresponding
|
|
|
|
* high-level spec accessors, meaning that all named fields should match,
|
|
|
|
* as well as all array accesses should be within the actual bounds. Also,
|
|
|
|
* types should be compatible (see bpf_core_fields_are_compat for details).
|
|
|
|
* 3. It is supported and expected that there might be multiple flavors
|
|
|
|
* matching the spec. As long as all the specs resolve to the same set of
|
|
|
|
* offsets across all candidates, there is no error. If there is any
|
|
|
|
* ambiguity, CO-RE relocation will fail. This is necessary to accomodate
|
|
|
|
* imprefection of BTF deduplication, which can cause slight duplication of
|
|
|
|
* the same BTF type, if some directly or indirectly referenced (by
|
|
|
|
* pointer) type gets resolved to different actual types in different
|
|
|
|
* object files. If such situation occurs, deduplicated BTF will end up
|
|
|
|
* with two (or more) structurally identical types, which differ only in
|
|
|
|
* types they refer to through pointer. This should be OK in most cases and
|
|
|
|
* is not an error.
|
|
|
|
* 4. Candidate types search is performed by linearly scanning through all
|
|
|
|
* types in target BTF. It is anticipated that this is overall more
|
|
|
|
* efficient memory-wise and not significantly worse (if not better)
|
|
|
|
* CPU-wise compared to prebuilding a map from all local type names to
|
|
|
|
* a list of candidate type names. It's also sped up by caching resolved
|
|
|
|
* list of matching candidates per each local "root" type ID, that has at
|
|
|
|
* least one bpf_core_relo associated with it. This list is shared
|
|
|
|
* between multiple relocations for the same type ID and is updated as some
|
|
|
|
* of the candidates are pruned due to structural incompatibility.
|
|
|
|
*/
|
2022-02-15 22:58:50 +00:00
|
|
|
int bpf_core_calc_relo_insn(const char *prog_name,
|
|
|
|
const struct bpf_core_relo *relo,
|
|
|
|
int relo_idx,
|
|
|
|
const struct btf *local_btf,
|
|
|
|
struct bpf_core_cand_list *cands,
|
|
|
|
struct bpf_core_spec *specs_scratch,
|
|
|
|
struct bpf_core_relo_res *targ_res)
|
2021-07-21 00:08:22 +00:00
|
|
|
{
|
2021-12-03 18:28:36 +00:00
|
|
|
struct bpf_core_spec *local_spec = &specs_scratch[0];
|
|
|
|
struct bpf_core_spec *cand_spec = &specs_scratch[1];
|
|
|
|
struct bpf_core_spec *targ_spec = &specs_scratch[2];
|
2022-02-15 22:58:50 +00:00
|
|
|
struct bpf_core_relo_res cand_res;
|
2021-07-21 00:08:22 +00:00
|
|
|
const struct btf_type *local_type;
|
|
|
|
const char *local_name;
|
|
|
|
__u32 local_id;
|
2022-04-26 00:45:08 +00:00
|
|
|
char spec_buf[256];
|
2021-07-21 00:08:22 +00:00
|
|
|
int i, j, err;
|
|
|
|
|
|
|
|
local_id = relo->type_id;
|
2021-12-01 18:10:24 +00:00
|
|
|
local_type = btf_type_by_id(local_btf, local_id);
|
2021-07-21 00:08:22 +00:00
|
|
|
local_name = btf__name_by_offset(local_btf, local_type->name_off);
|
|
|
|
if (!local_name)
|
|
|
|
return -EINVAL;
|
|
|
|
|
2022-04-26 00:45:09 +00:00
|
|
|
err = bpf_core_parse_spec(prog_name, local_btf, relo, local_spec);
|
2021-07-21 00:08:22 +00:00
|
|
|
if (err) {
|
2022-04-26 00:45:09 +00:00
|
|
|
const char *spec_str;
|
|
|
|
|
|
|
|
spec_str = btf__name_by_offset(local_btf, relo->access_str_off);
|
2021-07-21 00:08:22 +00:00
|
|
|
pr_warn("prog '%s': relo #%d: parsing [%d] %s %s + %s failed: %d\n",
|
|
|
|
prog_name, relo_idx, local_id, btf_kind_str(local_type),
|
|
|
|
str_is_empty(local_name) ? "<anon>" : local_name,
|
2022-04-26 00:45:09 +00:00
|
|
|
spec_str ?: "<?>", err);
|
2021-07-21 00:08:22 +00:00
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
|
2022-04-26 00:45:08 +00:00
|
|
|
bpf_core_format_spec(spec_buf, sizeof(spec_buf), local_spec);
|
|
|
|
pr_debug("prog '%s': relo #%d: %s\n", prog_name, relo_idx, spec_buf);
|
2021-07-21 00:08:22 +00:00
|
|
|
|
|
|
|
/* TYPE_ID_LOCAL relo is special and doesn't need candidate search */
|
2021-12-01 18:10:27 +00:00
|
|
|
if (relo->kind == BPF_CORE_TYPE_ID_LOCAL) {
|
2021-12-13 01:07:06 +00:00
|
|
|
/* bpf_insn's imm value could get out of sync during linking */
|
2022-02-15 22:58:50 +00:00
|
|
|
memset(targ_res, 0, sizeof(*targ_res));
|
|
|
|
targ_res->validate = false;
|
|
|
|
targ_res->poison = false;
|
|
|
|
targ_res->orig_val = local_spec->root_type_id;
|
|
|
|
targ_res->new_val = local_spec->root_type_id;
|
|
|
|
return 0;
|
2021-07-21 00:08:22 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
/* libbpf doesn't support candidate search for anonymous types */
|
2022-04-26 00:45:02 +00:00
|
|
|
if (str_is_empty(local_name)) {
|
2021-07-21 00:08:22 +00:00
|
|
|
pr_warn("prog '%s': relo #%d: <%s> (%d) relocation doesn't support anonymous types\n",
|
|
|
|
prog_name, relo_idx, core_relo_kind_str(relo->kind), relo->kind);
|
|
|
|
return -EOPNOTSUPP;
|
|
|
|
}
|
|
|
|
|
|
|
|
for (i = 0, j = 0; i < cands->len; i++) {
|
2021-12-03 18:28:36 +00:00
|
|
|
err = bpf_core_spec_match(local_spec, cands->cands[i].btf,
|
|
|
|
cands->cands[i].id, cand_spec);
|
2021-07-21 00:08:22 +00:00
|
|
|
if (err < 0) {
|
2022-04-26 00:45:08 +00:00
|
|
|
bpf_core_format_spec(spec_buf, sizeof(spec_buf), cand_spec);
|
|
|
|
pr_warn("prog '%s': relo #%d: error matching candidate #%d %s: %d\n ",
|
|
|
|
prog_name, relo_idx, i, spec_buf, err);
|
2021-07-21 00:08:22 +00:00
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
2022-04-26 00:45:08 +00:00
|
|
|
bpf_core_format_spec(spec_buf, sizeof(spec_buf), cand_spec);
|
|
|
|
pr_debug("prog '%s': relo #%d: %s candidate #%d %s\n", prog_name,
|
|
|
|
relo_idx, err == 0 ? "non-matching" : "matching", i, spec_buf);
|
2021-07-21 00:08:22 +00:00
|
|
|
|
|
|
|
if (err == 0)
|
|
|
|
continue;
|
|
|
|
|
2021-12-03 18:28:36 +00:00
|
|
|
err = bpf_core_calc_relo(prog_name, relo, relo_idx, local_spec, cand_spec, &cand_res);
|
2021-07-21 00:08:22 +00:00
|
|
|
if (err)
|
|
|
|
return err;
|
|
|
|
|
|
|
|
if (j == 0) {
|
2022-02-15 22:58:50 +00:00
|
|
|
*targ_res = cand_res;
|
2021-12-03 18:28:36 +00:00
|
|
|
*targ_spec = *cand_spec;
|
|
|
|
} else if (cand_spec->bit_offset != targ_spec->bit_offset) {
|
2021-07-21 00:08:22 +00:00
|
|
|
/* if there are many field relo candidates, they
|
|
|
|
* should all resolve to the same bit offset
|
|
|
|
*/
|
|
|
|
pr_warn("prog '%s': relo #%d: field offset ambiguity: %u != %u\n",
|
2021-12-03 18:28:36 +00:00
|
|
|
prog_name, relo_idx, cand_spec->bit_offset,
|
|
|
|
targ_spec->bit_offset);
|
2021-07-21 00:08:22 +00:00
|
|
|
return -EINVAL;
|
2022-02-15 22:58:50 +00:00
|
|
|
} else if (cand_res.poison != targ_res->poison ||
|
|
|
|
cand_res.new_val != targ_res->new_val) {
|
2021-07-21 00:08:22 +00:00
|
|
|
/* all candidates should result in the same relocation
|
|
|
|
* decision and value, otherwise it's dangerous to
|
|
|
|
* proceed due to ambiguity
|
|
|
|
*/
|
|
|
|
pr_warn("prog '%s': relo #%d: relocation decision ambiguity: %s %u != %s %u\n",
|
|
|
|
prog_name, relo_idx,
|
|
|
|
cand_res.poison ? "failure" : "success", cand_res.new_val,
|
2022-02-15 22:58:50 +00:00
|
|
|
targ_res->poison ? "failure" : "success", targ_res->new_val);
|
2021-07-21 00:08:22 +00:00
|
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
cands->cands[j++] = cands->cands[i];
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
2021-12-01 18:10:27 +00:00
|
|
|
* For BPF_CORE_FIELD_EXISTS relo or when used BPF program has field
|
2021-07-21 00:08:22 +00:00
|
|
|
* existence checks or kernel version/config checks, it's expected
|
|
|
|
* that we might not find any candidates. In this case, if field
|
|
|
|
* wasn't found in any candidate, the list of candidates shouldn't
|
|
|
|
* change at all, we'll just handle relocating appropriately,
|
|
|
|
* depending on relo's kind.
|
|
|
|
*/
|
|
|
|
if (j > 0)
|
|
|
|
cands->len = j;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* If no candidates were found, it might be both a programmer error,
|
|
|
|
* as well as expected case, depending whether instruction w/
|
|
|
|
* relocation is guarded in some way that makes it unreachable (dead
|
|
|
|
* code) if relocation can't be resolved. This is handled in
|
|
|
|
* bpf_core_patch_insn() uniformly by replacing that instruction with
|
|
|
|
* BPF helper call insn (using invalid helper ID). If that instruction
|
|
|
|
* is indeed unreachable, then it will be ignored and eliminated by
|
|
|
|
* verifier. If it was an error, then verifier will complain and point
|
|
|
|
* to a specific instruction number in its log.
|
|
|
|
*/
|
|
|
|
if (j == 0) {
|
|
|
|
pr_debug("prog '%s': relo #%d: no matching targets found\n",
|
|
|
|
prog_name, relo_idx);
|
|
|
|
|
|
|
|
/* calculate single target relo result explicitly */
|
2022-02-15 22:58:50 +00:00
|
|
|
err = bpf_core_calc_relo(prog_name, relo, relo_idx, local_spec, NULL, targ_res);
|
2021-07-21 00:08:22 +00:00
|
|
|
if (err)
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|