From: Yonghong Song <yhs@fb.com>
Date: Wed, 13 May 2020 11:02:21 -0700
Subject: bpf: Enable bpf_iter targets registering ctx argument types
Patch-mainline: v5.8-rc1
Git-commit: 3c32cc1bceba8a1755dc35cd97516f6c67856844
References: bsc#1177028
Commit b121b341e598 ("bpf: Add PTR_TO_BTF_ID_OR_NULL
support") adds a field btf_id_or_null_non0_off to
bpf_prog->aux structure to indicate that the
first ctx argument is PTR_TO_BTF_ID reg_type and
all others are PTR_TO_BTF_ID_OR_NULL.
This approach does not really scale if we have
other different reg types in the future, e.g.,
a pointer to a buffer.
This patch enables bpf_iter targets registering ctx argument
reg types which may be different from the default one.
For example, for pointers to structures, the default reg_type
is PTR_TO_BTF_ID for tracing program. The target can register
a particular pointer type as PTR_TO_BTF_ID_OR_NULL which can
be used by the verifier to enforce accesses.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200513180221.2949882-1-yhs@fb.com
Acked-by: Gary Lin <glin@suse.com>
---
include/linux/bpf.h | 12 +++++++++++-
include/net/ip6_fib.h | 7 +++++++
kernel/bpf/bpf_iter.c | 5 +++++
kernel/bpf/btf.c | 15 ++++++++++-----
kernel/bpf/map_iter.c | 5 +++++
kernel/bpf/task_iter.c | 12 ++++++++++++
kernel/bpf/verifier.c | 1 -
net/ipv6/ip6_fib.c | 5 -----
net/ipv6/route.c | 5 +++++
net/netlink/af_netlink.c | 5 +++++
10 files changed, 60 insertions(+), 12 deletions(-)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -643,6 +643,12 @@ struct bpf_jit_poke_descriptor {
u16 reason;
};
+/* reg_type info for ctx arguments */
+struct bpf_ctx_arg_aux {
+ u32 offset;
+ enum bpf_reg_type reg_type;
+};
+
struct bpf_prog_aux {
atomic64_t refcnt;
u32 used_map_cnt;
@@ -654,12 +660,13 @@ struct bpf_prog_aux {
u32 func_cnt; /* used by non-func prog as the number of func progs */
u32 func_idx; /* 0 for non-func prog, the index in func array for func prog */
u32 attach_btf_id; /* in-kernel BTF type id to attach to */
+ u32 ctx_arg_info_size;
+ const struct bpf_ctx_arg_aux *ctx_arg_info;
struct bpf_prog *linked_prog;
bool verifier_zext; /* Zero extensions has been inserted by verifier. */
bool offload_requested;
bool attach_btf_trace; /* true if attaching to BTF-enabled raw tp */
bool func_proto_unreliable;
- bool btf_id_or_null_non0_off;
enum bpf_tramp_prog_type trampoline_prog_type;
struct bpf_trampoline *trampoline;
struct hlist_node tramp_hlist;
@@ -1139,12 +1146,15 @@ int bpf_obj_get_user(const char __user *
typedef int (*bpf_iter_init_seq_priv_t)(void *private_data);
typedef void (*bpf_iter_fini_seq_priv_t)(void *private_data);
+#define BPF_ITER_CTX_ARG_MAX 2
struct bpf_iter_reg {
const char *target;
const struct seq_operations *seq_ops;
bpf_iter_init_seq_priv_t init_seq_private;
bpf_iter_fini_seq_priv_t fini_seq_private;
u32 seq_priv_size;
+ u32 ctx_arg_info_size;
+ struct bpf_ctx_arg_aux ctx_arg_info[BPF_ITER_CTX_ARG_MAX];
};
struct bpf_iter_meta {
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -540,6 +540,13 @@ static inline bool fib6_metric_locked(st
return !!(f6i->fib6_metrics->metrics[RTAX_LOCK - 1] & (1 << metric));
}
+#if IS_BUILTIN(CONFIG_IPV6) && defined(CONFIG_BPF_SYSCALL)
+struct bpf_iter__ipv6_route {
+ __bpf_md_ptr(struct bpf_iter_meta *, meta);
+ __bpf_md_ptr(struct fib6_info *, rt);
+};
+#endif
+
#ifdef CONFIG_IPV6_MULTIPLE_TABLES
static inline bool fib6_has_custom_rules(const struct net *net)
{
--- a/kernel/bpf/bpf_iter.c
+++ b/kernel/bpf/bpf_iter.c
@@ -308,6 +308,11 @@ bool bpf_iter_prog_supported(struct bpf_
}
mutex_unlock(&targets_mutex);
+ if (supported) {
+ prog->aux->ctx_arg_info_size = tinfo->reg_info->ctx_arg_info_size;
+ prog->aux->ctx_arg_info = tinfo->reg_info->ctx_arg_info;
+ }
+
return supported;
}
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3695,7 +3695,7 @@ bool btf_ctx_access(int off, int size, e
struct bpf_verifier_log *log = info->log;
const struct btf_param *args;
u32 nr_args, arg;
- int ret;
+ int i, ret;
if (off % 8) {
bpf_log(log, "func '%s' offset %d is not multiple of 8\n",
@@ -3791,10 +3791,15 @@ bool btf_ctx_access(int off, int size, e
return true;
/* this is a pointer to another type */
- if (off != 0 && prog->aux->btf_id_or_null_non0_off)
- info->reg_type = PTR_TO_BTF_ID_OR_NULL;
- else
- info->reg_type = PTR_TO_BTF_ID;
+ info->reg_type = PTR_TO_BTF_ID;
+ for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {
+ const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];
+
+ if (ctx_arg_info->offset == off) {
+ info->reg_type = ctx_arg_info->reg_type;
+ break;
+ }
+ }
if (tgt_prog) {
ret = btf_translate_to_vmlinux(log, btf, t, tgt_prog->type, arg);
--- a/kernel/bpf/map_iter.c
+++ b/kernel/bpf/map_iter.c
@@ -87,6 +87,11 @@ static const struct bpf_iter_reg bpf_map
.init_seq_private = NULL,
.fini_seq_private = NULL,
.seq_priv_size = sizeof(struct bpf_iter_seq_map_info),
+ .ctx_arg_info_size = 1,
+ .ctx_arg_info = {
+ { offsetof(struct bpf_iter__bpf_map, map),
+ PTR_TO_BTF_ID_OR_NULL },
+ },
};
static int __init bpf_map_iter_init(void)
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -312,6 +312,11 @@ static const struct bpf_iter_reg task_re
.init_seq_private = init_seq_pidns,
.fini_seq_private = fini_seq_pidns,
.seq_priv_size = sizeof(struct bpf_iter_seq_task_info),
+ .ctx_arg_info_size = 1,
+ .ctx_arg_info = {
+ { offsetof(struct bpf_iter__task, task),
+ PTR_TO_BTF_ID_OR_NULL },
+ },
};
static const struct bpf_iter_reg task_file_reg_info = {
@@ -320,6 +325,13 @@ static const struct bpf_iter_reg task_fi
.init_seq_private = init_seq_pidns,
.fini_seq_private = fini_seq_pidns,
.seq_priv_size = sizeof(struct bpf_iter_seq_task_file_info),
+ .ctx_arg_info_size = 2,
+ .ctx_arg_info = {
+ { offsetof(struct bpf_iter__task_file, task),
+ PTR_TO_BTF_ID_OR_NULL },
+ { offsetof(struct bpf_iter__task_file, file),
+ PTR_TO_BTF_ID_OR_NULL },
+ },
};
static int __init task_iter_init(void)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -10658,7 +10658,6 @@ static int check_attach_btf_id(struct bp
prog->aux->attach_func_proto = t;
if (!bpf_iter_prog_supported(prog))
return -EINVAL;
- prog->aux->btf_id_or_null_non0_off = true;
ret = btf_distill_func_proto(&env->log, btf, t,
tname, &fmodel);
return ret;
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -2638,11 +2638,6 @@ static void ipv6_route_native_seq_stop(s
}
#if IS_BUILTIN(CONFIG_IPV6) && defined(CONFIG_BPF_SYSCALL)
-struct bpf_iter__ipv6_route {
- __bpf_md_ptr(struct bpf_iter_meta *, meta);
- __bpf_md_ptr(struct fib6_info *, rt);
-};
-
static int ipv6_route_prog_seq_show(struct bpf_prog *prog,
struct bpf_iter_meta *meta,
void *v)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -6408,6 +6408,11 @@ static const struct bpf_iter_reg ipv6_ro
.init_seq_private = bpf_iter_init_seq_net,
.fini_seq_private = bpf_iter_fini_seq_net,
.seq_priv_size = sizeof(struct ipv6_route_iter),
+ .ctx_arg_info_size = 1,
+ .ctx_arg_info = {
+ { offsetof(struct bpf_iter__ipv6_route, rt),
+ PTR_TO_BTF_ID_OR_NULL },
+ },
};
static int __init bpf_iter_register(void)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2807,6 +2807,11 @@ static const struct bpf_iter_reg netlink
.init_seq_private = bpf_iter_init_seq_net,
.fini_seq_private = bpf_iter_fini_seq_net,
.seq_priv_size = sizeof(struct nl_seq_iter),
+ .ctx_arg_info_size = 1,
+ .ctx_arg_info = {
+ { offsetof(struct bpf_iter__netlink, sk),
+ PTR_TO_BTF_ID_OR_NULL },
+ },
};
static int __init bpf_iter_register(void)