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Message-ID: <20191114185720.1641606-16-ast@kernel.org>
Date: Thu, 14 Nov 2019 10:57:15 -0800
From: Alexei Starovoitov <ast@...nel.org>
To: <davem@...emloft.net>
CC: <daniel@...earbox.net>, <x86@...nel.org>, <netdev@...r.kernel.org>,
<bpf@...r.kernel.org>, <kernel-team@...com>
Subject: [PATCH v4 bpf-next 15/20] bpf: Annotate context types
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@...nel.org>
---
include/linux/bpf.h | 11 +++-
include/linux/bpf_types.h | 78 +++++++++++++++++---------
kernel/bpf/btf.c | 114 +++++++++++++++++++++++++++++++++++++-
kernel/bpf/syscall.c | 4 +-
kernel/bpf/verifier.c | 2 +-
net/core/filter.c | 10 ----
6 files changed, 176 insertions(+), 43 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index cb5a356381f5..9c48f11fe56e 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -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);
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index de14872b01ba..93740b3614d7 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -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)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 033d071eb59c..4b7c8bd423d6 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -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)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index e2e37bea86bc..05a0ee75eca0 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -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>
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index e78ec7990767..7395d6bebefd 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -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>
diff --git a/net/core/filter.c b/net/core/filter.c
index f72face90659..49ded4a7588a 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -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,
--
2.23.0
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