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bpf: Annotate context types

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Annotate BPF program context types with program-side type and kernel-side type.
This type information is used by the verifier. btf_get_prog_ctx_type() is
used in the later patches to verify that BTF type of ctx in BPF program matches to
kernel expected ctx type. For example, the XDP program type is:
BPF_PROG_TYPE(BPF_PROG_TYPE_XDP, xdp, struct xdp_md, struct xdp_buff)
That means that XDP program should be written as:
int xdp_prog(struct xdp_md *ctx) { ... }

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20191114185720.1641606-16-ast@kernel.org
This commit is contained in:
Alexei Starovoitov 2019-11-14 10:57:15 -08:00 committed by Daniel Borkmann
parent 9cc31b3a09
commit 91cc1a9974
6 changed files with 176 additions and 43 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

11
include/linux/bpf.h
View file

@ -747,7 +747,7 @@ DECLARE_PER_CPU(int, bpf_prog_active);
extern const struct file_operations bpf_map_fops;
extern const struct file_operations bpf_prog_fops;
#define BPF_PROG_TYPE(_id, _name) \
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
extern const struct bpf_prog_ops _name ## _prog_ops; \
extern const struct bpf_verifier_ops _name ## _verifier_ops;
#define BPF_MAP_TYPE(_id, _ops) \
@ -1213,6 +1213,15 @@ static inline u32 bpf_sock_convert_ctx_access(enum bpf_access_type type,
#endif
#ifdef CONFIG_INET
struct sk_reuseport_kern {
struct sk_buff *skb;
struct sock *sk;
struct sock *selected_sk;
void *data_end;
u32 hash;
u32 reuseport_id;
bool bind_inany;
};
bool bpf_tcp_sock_is_valid_access(int off, int size, enum bpf_access_type type,
struct bpf_insn_access_aux *info);

78
include/linux/bpf_types.h
View file

@ -2,42 +2,68 @@
/* internal file - do not include directly */
#ifdef CONFIG_NET
BPF_PROG_TYPE(BPF_PROG_TYPE_SOCKET_FILTER, sk_filter)
BPF_PROG_TYPE(BPF_PROG_TYPE_SCHED_CLS, tc_cls_act)
BPF_PROG_TYPE(BPF_PROG_TYPE_SCHED_ACT, tc_cls_act)
BPF_PROG_TYPE(BPF_PROG_TYPE_XDP, xdp)
BPF_PROG_TYPE(BPF_PROG_TYPE_SOCKET_FILTER, sk_filter,
struct __sk_buff, struct sk_buff)
BPF_PROG_TYPE(BPF_PROG_TYPE_SCHED_CLS, tc_cls_act,
struct __sk_buff, struct sk_buff)
BPF_PROG_TYPE(BPF_PROG_TYPE_SCHED_ACT, tc_cls_act,
struct __sk_buff, struct sk_buff)
BPF_PROG_TYPE(BPF_PROG_TYPE_XDP, xdp,
struct xdp_md, struct xdp_buff)
#ifdef CONFIG_CGROUP_BPF
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SKB, cg_skb)
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SOCK, cg_sock)
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SOCK_ADDR, cg_sock_addr)
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SKB, cg_skb,
struct __sk_buff, struct sk_buff)
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SOCK, cg_sock,
struct bpf_sock, struct sock)
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SOCK_ADDR, cg_sock_addr,
struct bpf_sock_addr, struct bpf_sock_addr_kern)
#endif
BPF_PROG_TYPE(BPF_PROG_TYPE_LWT_IN, lwt_in)
BPF_PROG_TYPE(BPF_PROG_TYPE_LWT_OUT, lwt_out)
BPF_PROG_TYPE(BPF_PROG_TYPE_LWT_XMIT, lwt_xmit)
BPF_PROG_TYPE(BPF_PROG_TYPE_LWT_SEG6LOCAL, lwt_seg6local)
BPF_PROG_TYPE(BPF_PROG_TYPE_SOCK_OPS, sock_ops)
BPF_PROG_TYPE(BPF_PROG_TYPE_SK_SKB, sk_skb)
BPF_PROG_TYPE(BPF_PROG_TYPE_SK_MSG, sk_msg)
BPF_PROG_TYPE(BPF_PROG_TYPE_FLOW_DISSECTOR, flow_dissector)
BPF_PROG_TYPE(BPF_PROG_TYPE_LWT_IN, lwt_in,
struct __sk_buff, struct sk_buff)
BPF_PROG_TYPE(BPF_PROG_TYPE_LWT_OUT, lwt_out,
struct __sk_buff, struct sk_buff)
BPF_PROG_TYPE(BPF_PROG_TYPE_LWT_XMIT, lwt_xmit,
struct __sk_buff, struct sk_buff)
BPF_PROG_TYPE(BPF_PROG_TYPE_LWT_SEG6LOCAL, lwt_seg6local,
struct __sk_buff, struct sk_buff)
BPF_PROG_TYPE(BPF_PROG_TYPE_SOCK_OPS, sock_ops,
struct bpf_sock_ops, struct bpf_sock_ops_kern)
BPF_PROG_TYPE(BPF_PROG_TYPE_SK_SKB, sk_skb,
struct __sk_buff, struct sk_buff)
BPF_PROG_TYPE(BPF_PROG_TYPE_SK_MSG, sk_msg,
struct sk_msg_md, struct sk_msg)
BPF_PROG_TYPE(BPF_PROG_TYPE_FLOW_DISSECTOR, flow_dissector,
struct __sk_buff, struct bpf_flow_dissector)
#endif
#ifdef CONFIG_BPF_EVENTS
BPF_PROG_TYPE(BPF_PROG_TYPE_KPROBE, kprobe)
BPF_PROG_TYPE(BPF_PROG_TYPE_TRACEPOINT, tracepoint)
BPF_PROG_TYPE(BPF_PROG_TYPE_PERF_EVENT, perf_event)
BPF_PROG_TYPE(BPF_PROG_TYPE_RAW_TRACEPOINT, raw_tracepoint)
BPF_PROG_TYPE(BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE, raw_tracepoint_writable)
BPF_PROG_TYPE(BPF_PROG_TYPE_TRACING, tracing)
BPF_PROG_TYPE(BPF_PROG_TYPE_KPROBE, kprobe,
bpf_user_pt_regs_t, struct pt_regs)
BPF_PROG_TYPE(BPF_PROG_TYPE_TRACEPOINT, tracepoint,
__u64, u64)
BPF_PROG_TYPE(BPF_PROG_TYPE_PERF_EVENT, perf_event,
struct bpf_perf_event_data, struct bpf_perf_event_data_kern)
BPF_PROG_TYPE(BPF_PROG_TYPE_RAW_TRACEPOINT, raw_tracepoint,
struct bpf_raw_tracepoint_args, u64)
BPF_PROG_TYPE(BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE, raw_tracepoint_writable,
struct bpf_raw_tracepoint_args, u64)
BPF_PROG_TYPE(BPF_PROG_TYPE_TRACING, tracing,
void *, void *)
#endif
#ifdef CONFIG_CGROUP_BPF
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_DEVICE, cg_dev)
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SYSCTL, cg_sysctl)
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SOCKOPT, cg_sockopt)
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_DEVICE, cg_dev,
struct bpf_cgroup_dev_ctx, struct bpf_cgroup_dev_ctx)
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SYSCTL, cg_sysctl,
struct bpf_sysctl, struct bpf_sysctl_kern)
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_SOCKOPT, cg_sockopt,
struct bpf_sockopt, struct bpf_sockopt_kern)
#endif
#ifdef CONFIG_BPF_LIRC_MODE2
BPF_PROG_TYPE(BPF_PROG_TYPE_LIRC_MODE2, lirc_mode2)
BPF_PROG_TYPE(BPF_PROG_TYPE_LIRC_MODE2, lirc_mode2,
__u32, u32)
#endif
#ifdef CONFIG_INET
BPF_PROG_TYPE(BPF_PROG_TYPE_SK_REUSEPORT, sk_reuseport)
BPF_PROG_TYPE(BPF_PROG_TYPE_SK_REUSEPORT, sk_reuseport,
struct sk_reuseport_md, struct sk_reuseport_kern)
#endif
BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)

114
kernel/bpf/btf.c
View file

@ -2,6 +2,8 @@
/* Copyright (c) 2018 Facebook */
#include <uapi/linux/btf.h>
#include <uapi/linux/bpf.h>
#include <uapi/linux/bpf_perf_event.h>
#include <uapi/linux/types.h>
#include <linux/seq_file.h>
#include <linux/compiler.h>
@ -16,6 +18,9 @@
#include <linux/sort.h>
#include <linux/bpf_verifier.h>
#include <linux/btf.h>
#include <linux/skmsg.h>
#include <linux/perf_event.h>
#include <net/sock.h>
/* BTF (BPF Type Format) is the meta data format which describes
* the data types of BPF program/map. Hence, it basically focus
@ -3439,13 +3444,98 @@ static struct btf *btf_parse(void __user *btf_data, u32 btf_data_size,
extern char __weak _binary__btf_vmlinux_bin_start[];
extern char __weak _binary__btf_vmlinux_bin_end[];
extern struct btf *btf_vmlinux;
#define BPF_MAP_TYPE(_id, _ops)
static union {
struct bpf_ctx_convert {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
prog_ctx_type _id##_prog; \
kern_ctx_type _id##_kern;
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
} *__t;
/* 't' is written once under lock. Read many times. */
const struct btf_type *t;
} bpf_ctx_convert;
enum {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
__ctx_convert##_id,
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
};
static u8 bpf_ctx_convert_map[] = {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
[_id] = __ctx_convert##_id,
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
};
#undef BPF_MAP_TYPE
static const struct btf_member *
btf_get_prog_ctx_type(struct bpf_verifier_log *log, struct btf *btf,
const struct btf_type *t, enum bpf_prog_type prog_type)
{
const struct btf_type *conv_struct;
const struct btf_type *ctx_struct;
const struct btf_member *ctx_type;
const char *tname, *ctx_tname;
conv_struct = bpf_ctx_convert.t;
if (!conv_struct) {
bpf_log(log, "btf_vmlinux is malformed\n");
return NULL;
}
t = btf_type_by_id(btf, t->type);
while (btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (!btf_type_is_struct(t)) {
/* Only pointer to struct is supported for now.
* That means that BPF_PROG_TYPE_TRACEPOINT with BTF
* is not supported yet.
* BPF_PROG_TYPE_RAW_TRACEPOINT is fine.
*/
bpf_log(log, "BPF program ctx type is not a struct\n");
return NULL;
}
tname = btf_name_by_offset(btf, t->name_off);
if (!tname) {
bpf_log(log, "BPF program ctx struct doesn't have a name\n");
return NULL;
}
/* prog_type is valid bpf program type. No need for bounds check. */
ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2;
/* ctx_struct is a pointer to prog_ctx_type in vmlinux.
* Like 'struct __sk_buff'
*/
ctx_struct = btf_type_by_id(btf_vmlinux, ctx_type->type);
if (!ctx_struct)
/* should not happen */
return NULL;
ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_struct->name_off);
if (!ctx_tname) {
/* should not happen */
bpf_log(log, "Please fix kernel include/linux/bpf_types.h\n");
return NULL;
}
/* only compare that prog's ctx type name is the same as
* kernel expects. No need to compare field by field.
* It's ok for bpf prog to do:
* struct __sk_buff {};
* int socket_filter_bpf_prog(struct __sk_buff *skb)
* { // no fields of skb are ever used }
*/
if (strcmp(ctx_tname, tname))
return NULL;
return ctx_type;
}
struct btf *btf_parse_vmlinux(void)
{
struct btf_verifier_env *env = NULL;
struct bpf_verifier_log *log;
struct btf *btf = NULL;
int err;
int err, i;
env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
if (!env)
@ -3479,6 +3569,26 @@ struct btf *btf_parse_vmlinux(void)
if (err)
goto errout;
/* find struct bpf_ctx_convert for type checking later */
for (i = 1; i <= btf->nr_types; i++) {
const struct btf_type *t;
const char *tname;
t = btf_type_by_id(btf, i);
if (!__btf_type_is_struct(t))
continue;
tname = __btf_name_by_offset(btf, t->name_off);
if (!strcmp(tname, "bpf_ctx_convert")) {
/* btf_parse_vmlinux() runs under bpf_verifier_lock */
bpf_ctx_convert.t = t;
break;
}
}
if (i > btf->nr_types) {
err = -ENOENT;
goto errout;
}
btf_verifier_env_free(env);
refcount_set(&btf->refcnt, 1);
return btf;
@ -3492,8 +3602,6 @@ struct btf *btf_parse_vmlinux(void)
return ERR_PTR(err);
}
extern struct btf *btf_vmlinux;
bool btf_ctx_access(int off, int size, enum bpf_access_type type,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)

4
kernel/bpf/syscall.c
View file

@ -43,7 +43,7 @@ static DEFINE_SPINLOCK(map_idr_lock);
int sysctl_unprivileged_bpf_disabled __read_mostly;
static const struct bpf_map_ops * const bpf_map_types[] = {
#define BPF_PROG_TYPE(_id, _ops)
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type)
#define BPF_MAP_TYPE(_id, _ops) \
[_id] = &_ops,
#include <linux/bpf_types.h>
@ -1189,7 +1189,7 @@ static int map_freeze(const union bpf_attr *attr)
}
static const struct bpf_prog_ops * const bpf_prog_types[] = {
#define BPF_PROG_TYPE(_id, _name) \
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
[_id] = & _name ## _prog_ops,
#define BPF_MAP_TYPE(_id, _ops)
#include <linux/bpf_types.h>

2
kernel/bpf/verifier.c
View file

@ -23,7 +23,7 @@
#include "disasm.h"
static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
#define BPF_PROG_TYPE(_id, _name) \
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
[_id] = & _name ## _verifier_ops,
#define BPF_MAP_TYPE(_id, _ops)
#include <linux/bpf_types.h>

10
net/core/filter.c
View file

@ -8684,16 +8684,6 @@ int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf,
}
#ifdef CONFIG_INET
struct sk_reuseport_kern {
struct sk_buff *skb;
struct sock *sk;
struct sock *selected_sk;
void *data_end;
u32 hash;
u32 reuseport_id;
bool bind_inany;
};
static void bpf_init_reuseport_kern(struct sk_reuseport_kern *reuse_kern,
struct sock_reuseport *reuse,
struct sock *sk, struct sk_buff *skb,