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Date: Tue, 12 May 2020 08:52:39 -0700
From: Yonghong Song <yhs@...com>
To: Andrii Nakryiko <andriin@...com>, <bpf@...r.kernel.org>,
Martin KaFai Lau <kafai@...com>, <netdev@...r.kernel.org>
CC: Alexei Starovoitov <ast@...com>,
Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>
Subject: [PATCH bpf-next 7/8] bpf: enable bpf_iter targets registering ctx argument types
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@...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(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index ad1bd13cd34c..da36cdb410bb 100644
--- 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;
+ 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 *pathname, int flags);
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 {
diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 80262d2980f5..870b646c5797 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -540,6 +540,13 @@ static inline bool fib6_metric_locked(struct fib6_info *f6i, int metric)
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)
{
diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c
index 041f97dcec39..a6db83f41c50 100644
--- a/kernel/bpf/bpf_iter.c
+++ b/kernel/bpf/bpf_iter.c
@@ -305,6 +305,11 @@ bool bpf_iter_prog_supported(struct bpf_prog *prog)
}
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;
}
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index dcd233139294..ec587628a02f 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3694,7 +3694,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
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",
@@ -3790,10 +3790,15 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
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++) {
+ 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);
diff --git a/kernel/bpf/map_iter.c b/kernel/bpf/map_iter.c
index 545c7dbb13c9..66e1691e7ee7 100644
--- a/kernel/bpf/map_iter.c
+++ b/kernel/bpf/map_iter.c
@@ -87,6 +87,11 @@ static struct bpf_iter_reg bpf_map_reg_info = {
.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)
diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index ed0b1d6ce688..3621e1979c39 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -312,6 +312,11 @@ static struct bpf_iter_reg task_reg_info = {
.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 struct bpf_iter_reg task_file_reg_info = {
@@ -320,6 +325,13 @@ static struct bpf_iter_reg task_file_reg_info = {
.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)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2a1826c76bb6..a3f2af756fd6 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -10652,7 +10652,6 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
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;
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index a1fcc0ca21af..250ff52c674e 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -2638,11 +2638,6 @@ static void ipv6_route_native_seq_stop(struct seq_file *seq, void *v)
}
#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)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index bb8581f9b448..94b6aaa84db3 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -6403,6 +6403,11 @@ static struct bpf_iter_reg ipv6_route_reg_info = {
.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)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 1e2f5ab8c7d7..3fe1979c0088 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2809,6 +2809,11 @@ static struct bpf_iter_reg netlink_reg_info = {
.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)
--
2.24.1
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