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![John Fastabend](/assets/img/avatar_default.png)
To ensure btf_ctx_access() is safe the verifier checks that the BTF
arg type is an int, enum, or pointer. When the function does the
BTF arg lookup it uses the calculation 'arg = off / 8' using the
fact that registers are 8B. This requires that the first arg is
in the first reg, the second in the second, and so on. However,
for __int128 the arg will consume two registers by default LLVM
implementation. So this will cause the arg layout assumed by the
'arg = off / 8' calculation to be incorrect.
Because __int128 is uncommon this patch applies the easiest fix and
will force int types to be sizeof(u64) or smaller so that they will
fit in a single register.
v2: remove unneeded parens per Andrii's feedback
Fixes: 9e15db6613
("bpf: Implement accurate raw_tp context access via BTF")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/159303723962.11287.13309537171132420717.stgit@john-Precision-5820-Tower
162 lines
4.8 KiB
C
162 lines
4.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright (c) 2018 Facebook */
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#ifndef _LINUX_BTF_H
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#define _LINUX_BTF_H 1
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#include <linux/types.h>
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#include <uapi/linux/btf.h>
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#define BTF_TYPE_EMIT(type) ((void)(type *)0)
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struct btf;
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struct btf_member;
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struct btf_type;
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union bpf_attr;
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extern const struct file_operations btf_fops;
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void btf_put(struct btf *btf);
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int btf_new_fd(const union bpf_attr *attr);
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struct btf *btf_get_by_fd(int fd);
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int btf_get_info_by_fd(const struct btf *btf,
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const union bpf_attr *attr,
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union bpf_attr __user *uattr);
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/* Figure out the size of a type_id. If type_id is a modifier
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* (e.g. const), it will be resolved to find out the type with size.
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*
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* For example:
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* In describing "const void *", type_id is "const" and "const"
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* refers to "void *". The return type will be "void *".
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*
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* If type_id is a simple "int", then return type will be "int".
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*
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* @btf: struct btf object
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* @type_id: Find out the size of type_id. The type_id of the return
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* type is set to *type_id.
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* @ret_size: It can be NULL. If not NULL, the size of the return
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* type is set to *ret_size.
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* Return: The btf_type (resolved to another type with size info if needed).
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* NULL is returned if type_id itself does not have size info
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* (e.g. void) or it cannot be resolved to another type that
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* has size info.
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* *type_id and *ret_size will not be changed in the
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* NULL return case.
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*/
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const struct btf_type *btf_type_id_size(const struct btf *btf,
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u32 *type_id,
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u32 *ret_size);
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void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
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struct seq_file *m);
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int btf_get_fd_by_id(u32 id);
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u32 btf_id(const struct btf *btf);
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bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
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const struct btf_member *m,
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u32 expected_offset, u32 expected_size);
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int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t);
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bool btf_type_is_void(const struct btf_type *t);
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s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind);
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const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
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u32 id, u32 *res_id);
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const struct btf_type *btf_type_resolve_ptr(const struct btf *btf,
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u32 id, u32 *res_id);
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const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf,
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u32 id, u32 *res_id);
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const struct btf_type *
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btf_resolve_size(const struct btf *btf, const struct btf_type *type,
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u32 *type_size, const struct btf_type **elem_type,
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u32 *total_nelems);
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#define for_each_member(i, struct_type, member) \
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for (i = 0, member = btf_type_member(struct_type); \
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i < btf_type_vlen(struct_type); \
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i++, member++)
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static inline bool btf_type_is_ptr(const struct btf_type *t)
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{
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return BTF_INFO_KIND(t->info) == BTF_KIND_PTR;
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}
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static inline bool btf_type_is_int(const struct btf_type *t)
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{
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return BTF_INFO_KIND(t->info) == BTF_KIND_INT;
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}
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static inline bool btf_type_is_small_int(const struct btf_type *t)
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{
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return btf_type_is_int(t) && t->size <= sizeof(u64);
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}
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static inline bool btf_type_is_enum(const struct btf_type *t)
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{
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return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM;
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}
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static inline bool btf_type_is_typedef(const struct btf_type *t)
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{
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return BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF;
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}
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static inline bool btf_type_is_func(const struct btf_type *t)
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{
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return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC;
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}
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static inline bool btf_type_is_func_proto(const struct btf_type *t)
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{
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return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC_PROTO;
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}
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static inline u16 btf_type_vlen(const struct btf_type *t)
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{
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return BTF_INFO_VLEN(t->info);
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}
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static inline u16 btf_func_linkage(const struct btf_type *t)
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{
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return BTF_INFO_VLEN(t->info);
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}
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static inline bool btf_type_kflag(const struct btf_type *t)
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{
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return BTF_INFO_KFLAG(t->info);
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}
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static inline u32 btf_member_bit_offset(const struct btf_type *struct_type,
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const struct btf_member *member)
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{
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return btf_type_kflag(struct_type) ? BTF_MEMBER_BIT_OFFSET(member->offset)
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: member->offset;
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}
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static inline u32 btf_member_bitfield_size(const struct btf_type *struct_type,
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const struct btf_member *member)
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{
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return btf_type_kflag(struct_type) ? BTF_MEMBER_BITFIELD_SIZE(member->offset)
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: 0;
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}
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static inline const struct btf_member *btf_type_member(const struct btf_type *t)
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{
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return (const struct btf_member *)(t + 1);
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}
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#ifdef CONFIG_BPF_SYSCALL
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const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);
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const char *btf_name_by_offset(const struct btf *btf, u32 offset);
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struct btf *btf_parse_vmlinux(void);
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struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog);
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#else
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static inline const struct btf_type *btf_type_by_id(const struct btf *btf,
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u32 type_id)
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{
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return NULL;
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}
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static inline const char *btf_name_by_offset(const struct btf *btf,
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u32 offset)
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{
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return NULL;
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}
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#endif
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#endif
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