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Message-Id: <20220112193152.3058718-6-haoluo@google.com>
Date: Wed, 12 Jan 2022 11:31:49 -0800
From: Hao Luo <haoluo@...gle.com>
To: Alexei Starovoitov <ast@...nel.org>,
Andrii Nakryiko <andrii@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>
Cc: Martin KaFai Lau <kafai@...com>, Song Liu <songliubraving@...com>,
Yonghong Song <yhs@...com>, KP Singh <kpsingh@...nel.org>,
Shakeel Butt <shakeelb@...gle.com>,
Joe Burton <jevburton.kernel@...il.com>,
Tejun Heo <tj@...nel.org>, bpf@...r.kernel.org,
linux-kernel@...r.kernel.org, Hao Luo <haoluo@...gle.com>
Subject: [PATCH RESEND RFC bpf-next v1 5/8] bpf: Introduce a new program type bpf_view.
Introduce a new program type called "bpf_view", which can be used to
print out a kernel object's state to a seq file. So the signature of
this program consists of two parameters: a seq file and a kernel object.
Currently only 'struct cgroup' is supported.
The following patches will introduce a call site for this program type
and allow users to customize the format of printing out the state of
kernel objects to userspace.
Signed-off-by: Hao Luo <haoluo@...gle.com>
---
include/linux/bpf.h | 4 +
include/uapi/linux/bpf.h | 2 +
kernel/bpf/Makefile | 2 +-
kernel/bpf/bpf_view.c | 179 +++++++++++++++++++++++++++++++++
kernel/bpf/bpf_view.h | 24 +++++
kernel/bpf/syscall.c | 3 +
kernel/bpf/verifier.c | 6 ++
kernel/trace/bpf_trace.c | 12 ++-
tools/include/uapi/linux/bpf.h | 2 +
9 files changed, 230 insertions(+), 4 deletions(-)
create mode 100644 kernel/bpf/bpf_view.c
create mode 100644 kernel/bpf/bpf_view.h
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 2ec693c3d6f6..16f582dfff7e 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1622,6 +1622,10 @@ void bpf_iter_map_show_fdinfo(const struct bpf_iter_aux_info *aux,
int bpf_iter_map_fill_link_info(const struct bpf_iter_aux_info *aux,
struct bpf_link_info *info);
+bool bpf_view_prog_supported(struct bpf_prog *prog);
+int bpf_view_link_attach(const union bpf_attr *attr, bpfptr_t uattr,
+ struct bpf_prog *prog);
+
int map_set_for_each_callback_args(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index b0383d371b9a..efa0f21d13ba 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -982,6 +982,7 @@ enum bpf_attach_type {
BPF_MODIFY_RETURN,
BPF_LSM_MAC,
BPF_TRACE_ITER,
+ BPF_TRACE_VIEW,
BPF_CGROUP_INET4_GETPEERNAME,
BPF_CGROUP_INET6_GETPEERNAME,
BPF_CGROUP_INET4_GETSOCKNAME,
@@ -1009,6 +1010,7 @@ enum bpf_link_type {
BPF_LINK_TYPE_NETNS = 5,
BPF_LINK_TYPE_XDP = 6,
BPF_LINK_TYPE_PERF_EVENT = 7,
+ BPF_LINK_TYPE_VIEW = 8,
MAX_BPF_LINK_TYPE,
};
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index b1abf0d94b5b..c662734d83c5 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -8,7 +8,7 @@ CFLAGS_core.o += $(call cc-disable-warning, override-init) $(cflags-nogcse-yy)
obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o bpf_iter.o map_iter.o task_iter.o prog_iter.o
obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o bloom_filter.o
-obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o ringbuf.o kernfs_node.o
+obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o ringbuf.o kernfs_node.o bpf_view.o
obj-$(CONFIG_BPF_SYSCALL) += bpf_local_storage.o bpf_task_storage.o
obj-${CONFIG_BPF_LSM} += bpf_inode_storage.o
obj-$(CONFIG_BPF_SYSCALL) += disasm.o
diff --git a/kernel/bpf/bpf_view.c b/kernel/bpf/bpf_view.c
new file mode 100644
index 000000000000..967a9240bab4
--- /dev/null
+++ b/kernel/bpf/bpf_view.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/bpf.h>
+#include <linux/btf_ids.h>
+#include <linux/cgroup.h>
+#include <linux/filter.h>
+#include "bpf_view.h"
+
+static struct list_head targets = LIST_HEAD_INIT(targets);
+
+/* bpf_view_link operations */
+
+struct bpf_view_target_info {
+ struct list_head list;
+ const char *target;
+ u32 ctx_arg_info_size;
+ struct bpf_ctx_arg_aux ctx_arg_info[BPF_VIEW_CTX_ARG_MAX];
+ u32 btf_id;
+};
+
+struct bpf_view_link {
+ struct bpf_link link;
+ struct bpf_view_target_info *tinfo;
+};
+
+static void bpf_view_link_release(struct bpf_link *link)
+{
+}
+
+static void bpf_view_link_dealloc(struct bpf_link *link)
+{
+ struct bpf_view_link *view_link =
+ container_of(link, struct bpf_view_link, link);
+ kfree(view_link);
+}
+
+static void bpf_view_link_show_fdinfo(const struct bpf_link *link,
+ struct seq_file *seq)
+{
+ struct bpf_view_link *view_link =
+ container_of(link, struct bpf_view_link, link);
+
+ seq_printf(seq, "attach_target:\t%s\n", view_link->tinfo->target);
+}
+
+static const struct bpf_link_ops bpf_view_link_lops = {
+ .release = bpf_view_link_release,
+ .dealloc = bpf_view_link_dealloc,
+ .show_fdinfo = bpf_view_link_show_fdinfo,
+};
+
+bool bpf_link_is_view(struct bpf_link *link)
+{
+ return link->ops == &bpf_view_link_lops;
+}
+
+int bpf_view_link_attach(const union bpf_attr *attr, bpfptr_t uattr,
+ struct bpf_prog *prog)
+{
+ struct bpf_link_primer link_primer;
+ struct bpf_view_target_info *tinfo;
+ struct bpf_view_link *link;
+ u32 prog_btf_id;
+ bool existed = false;
+ int err;
+
+ prog_btf_id = prog->aux->attach_btf_id;
+ list_for_each_entry(tinfo, &targets, list) {
+ if (tinfo->btf_id == prog_btf_id) {
+ existed = true;
+ break;
+ }
+ }
+ if (!existed)
+ return -ENOENT;
+
+ link = kzalloc(sizeof(*link), GFP_USER | __GFP_NOWARN);
+ if (!link)
+ return -ENOMEM;
+
+ bpf_link_init(&link->link, BPF_LINK_TYPE_VIEW, &bpf_view_link_lops, prog);
+ link->tinfo = tinfo;
+ err = bpf_link_prime(&link->link, &link_primer);
+ if (err) {
+ kfree(link);
+ return err;
+ }
+
+ return bpf_link_settle(&link_primer);
+}
+
+int run_view_prog(struct bpf_prog *prog, void *ctx)
+{
+ int ret;
+
+ rcu_read_lock();
+ migrate_disable();
+ ret = bpf_prog_run(prog, ctx);
+ migrate_enable();
+ rcu_read_unlock();
+
+ return ret;
+}
+
+bool bpf_view_prog_supported(struct bpf_prog *prog)
+{
+ const char *attach_fname = prog->aux->attach_func_name;
+ const char *prefix = BPF_VIEW_FUNC_PREFIX;
+ u32 prog_btf_id = prog->aux->attach_btf_id;
+ struct bpf_view_target_info *tinfo;
+ int prefix_len = strlen(prefix);
+ bool supported = false;
+
+ if (strncmp(attach_fname, prefix, prefix_len))
+ return false;
+
+ list_for_each_entry(tinfo, &targets, list) {
+ if (tinfo->btf_id && tinfo->btf_id == prog_btf_id) {
+ supported = true;
+ break;
+ }
+ if (!strcmp(attach_fname + prefix_len, tinfo->target)) {
+ tinfo->btf_id = prog->aux->attach_btf_id;
+ supported = true;
+ break;
+ }
+ }
+ if (supported) {
+ prog->aux->ctx_arg_info_size = tinfo->ctx_arg_info_size;
+ prog->aux->ctx_arg_info = tinfo->ctx_arg_info;
+ }
+ return supported;
+}
+
+/* Generate BTF_IDs */
+BTF_ID_LIST(bpf_view_btf_ids)
+BTF_ID(struct, seq_file)
+BTF_ID(struct, cgroup)
+
+/* Index of bpf_view_btf_ids */
+enum {
+ BTF_ID_SEQ_FILE = 0,
+ BTF_ID_CGROUP,
+};
+
+static void register_bpf_view_target(struct bpf_view_target_info *target,
+ int idx[BPF_VIEW_CTX_ARG_MAX])
+{
+ int i;
+
+ for (i = 0; i < target->ctx_arg_info_size; ++i)
+ target->ctx_arg_info[i].btf_id = bpf_view_btf_ids[idx[i]];
+
+ INIT_LIST_HEAD(&target->list);
+ list_add(&target->list, &targets);
+}
+
+DEFINE_BPF_VIEW_FUNC(cgroup, struct seq_file *seq, struct cgroup *cgroup)
+
+static struct bpf_view_target_info cgroup_view_tinfo = {
+ .target = "cgroup",
+ .ctx_arg_info_size = 2,
+ .ctx_arg_info = {
+ { offsetof(struct bpf_view_cgroup_ctx, seq), PTR_TO_BTF_ID },
+ { offsetof(struct bpf_view_cgroup_ctx, cgroup), PTR_TO_BTF_ID },
+ },
+ .btf_id = 0,
+};
+
+static int __init bpf_view_init(void)
+{
+ int cgroup_view_idx[BPF_VIEW_CTX_ARG_MAX] = {
+ BTF_ID_SEQ_FILE, BTF_ID_CGROUP };
+
+ register_bpf_view_target(&cgroup_view_tinfo, cgroup_view_idx);
+
+ return 0;
+}
+late_initcall(bpf_view_init);
+
diff --git a/kernel/bpf/bpf_view.h b/kernel/bpf/bpf_view.h
new file mode 100644
index 000000000000..1a1110a5727f
--- /dev/null
+++ b/kernel/bpf/bpf_view.h
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#ifndef _BPF_VIEW_H_
+#define _BPF_VIEW_H_
+
+#include <linux/bpf.h>
+
+#define BPF_VIEW_FUNC_PREFIX "bpf_view_"
+#define DEFINE_BPF_VIEW_FUNC(target, args...) \
+ extern int bpf_view_ ## target(args); \
+ int __init bpf_view_ ## target(args) { return 0; }
+
+#define BPF_VIEW_CTX_ARG_MAX 2
+
+struct bpf_view_cgroup_ctx {
+ __bpf_md_ptr(struct seq_file *, seq);
+ __bpf_md_ptr(struct cgroup *, cgroup);
+};
+
+bool bpf_link_is_view(struct bpf_link *link);
+
+/* Run a bpf_view program */
+int run_view_prog(struct bpf_prog *prog, void *ctx);
+
+#endif // _BPF_VIEW_H_
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index fa4505f9b611..32ac84d3ac0b 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3175,6 +3175,7 @@ attach_type_to_prog_type(enum bpf_attach_type attach_type)
case BPF_CGROUP_SETSOCKOPT:
return BPF_PROG_TYPE_CGROUP_SOCKOPT;
case BPF_TRACE_ITER:
+ case BPF_TRACE_VIEW:
return BPF_PROG_TYPE_TRACING;
case BPF_SK_LOOKUP:
return BPF_PROG_TYPE_SK_LOOKUP;
@@ -4235,6 +4236,8 @@ static int tracing_bpf_link_attach(const union bpf_attr *attr, bpfptr_t uattr,
if (prog->expected_attach_type == BPF_TRACE_ITER)
return bpf_iter_link_attach(attr, uattr, prog);
+ else if (prog->expected_attach_type == BPF_TRACE_VIEW)
+ return bpf_view_link_attach(attr, uattr, prog);
else if (prog->type == BPF_PROG_TYPE_EXT)
return bpf_tracing_prog_attach(prog,
attr->link_create.target_fd,
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index bfb45381fb3f..ce7816519c93 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9770,6 +9770,7 @@ static int check_return_code(struct bpf_verifier_env *env)
case BPF_MODIFY_RETURN:
return 0;
case BPF_TRACE_ITER:
+ case BPF_TRACE_VIEW:
break;
default:
return -ENOTSUPP;
@@ -13971,6 +13972,7 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
break;
case BPF_TRACE_ITER:
+ case BPF_TRACE_VIEW:
if (!btf_type_is_func(t)) {
bpf_log(log, "attach_btf_id %u is not a function\n",
btf_id);
@@ -14147,6 +14149,10 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
if (!bpf_iter_prog_supported(prog))
return -EINVAL;
return 0;
+ } else if (prog->expected_attach_type == BPF_TRACE_VIEW) {
+ if (!bpf_view_prog_supported(prog))
+ return -EINVAL;
+ return 0;
}
if (prog->type == BPF_PROG_TYPE_LSM) {
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 21aa30644219..9413b5af6e2c 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1630,6 +1630,12 @@ raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
}
}
+static inline bool prog_support_seq_helpers(const struct bpf_prog *prog)
+{
+ return prog->expected_attach_type == BPF_TRACE_ITER ||
+ prog->expected_attach_type == BPF_TRACE_VIEW;
+}
+
const struct bpf_func_proto *
tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
@@ -1663,15 +1669,15 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_get_socket_ptr_cookie_proto;
#endif
case BPF_FUNC_seq_printf:
- return prog->expected_attach_type == BPF_TRACE_ITER ?
+ return prog_support_seq_helpers(prog) ?
&bpf_seq_printf_proto :
NULL;
case BPF_FUNC_seq_write:
- return prog->expected_attach_type == BPF_TRACE_ITER ?
+ return prog_support_seq_helpers(prog) ?
&bpf_seq_write_proto :
NULL;
case BPF_FUNC_seq_printf_btf:
- return prog->expected_attach_type == BPF_TRACE_ITER ?
+ return prog_support_seq_helpers(prog) ?
&bpf_seq_printf_btf_proto :
NULL;
case BPF_FUNC_d_path:
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index b0383d371b9a..efa0f21d13ba 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -982,6 +982,7 @@ enum bpf_attach_type {
BPF_MODIFY_RETURN,
BPF_LSM_MAC,
BPF_TRACE_ITER,
+ BPF_TRACE_VIEW,
BPF_CGROUP_INET4_GETPEERNAME,
BPF_CGROUP_INET6_GETPEERNAME,
BPF_CGROUP_INET4_GETSOCKNAME,
@@ -1009,6 +1010,7 @@ enum bpf_link_type {
BPF_LINK_TYPE_NETNS = 5,
BPF_LINK_TYPE_XDP = 6,
BPF_LINK_TYPE_PERF_EVENT = 7,
+ BPF_LINK_TYPE_VIEW = 8,
MAX_BPF_LINK_TYPE,
};
--
2.34.1.448.ga2b2bfdf31-goog
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