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From: John Fastabend <john.fastabend@gmail.com>
To: yhs@fb.com, andrii.nakryiko@gmail.com, ast@kernel.org,
	daniel@iogearbox.net
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, john.fastabend@gmail.com
Subject: [bpf-next PATCH v5 2/5] bpf: extend bpf_base_func_proto helpers with probe_* and *current_task*
Date: Sun, 24 May 2020 09:50:55 -0700
Message-ID: <159033905529.12355.4368381069655254932.stgit@john-Precision-5820-Tower> (raw)
In-Reply-To: <159033879471.12355.1236562159278890735.stgit@john-Precision-5820-Tower>

Often it is useful when applying policy to know something about the
task. If the administrator has CAP_SYS_ADMIN rights then they can
use kprobe + networking hook and link the two programs together to
accomplish this. However, this is a bit clunky and also means we have
to call both the network program and kprobe program when we could just
use a single program and avoid passing metadata through sk_msg/skb->cb,
socket, maps, etc.

To accomplish this add probe_* helpers to bpf_base_func_proto programs
guarded by a perfmon_capable() check. New supported helpers are the
following,

 BPF_FUNC_get_current_task
 BPF_FUNC_current_task_under_cgroup
 BPF_FUNC_probe_read_user
 BPF_FUNC_probe_read_kernel
 BPF_FUNC_probe_read_user_str
 BPF_FUNC_probe_read_kernel_str

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
---
 kernel/bpf/helpers.c     |   24 ++++++++++++++++++++++++
 kernel/trace/bpf_trace.c |   10 +++++-----
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 886949f..bb4fb63 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -601,6 +601,12 @@ const struct bpf_func_proto bpf_event_output_data_proto =  {
 	.arg5_type      = ARG_CONST_SIZE_OR_ZERO,
 };
 
+const struct bpf_func_proto bpf_get_current_task_proto __weak;
+const struct bpf_func_proto bpf_probe_read_user_proto __weak;
+const struct bpf_func_proto bpf_probe_read_user_str_proto __weak;
+const struct bpf_func_proto bpf_probe_read_kernel_proto __weak;
+const struct bpf_func_proto bpf_probe_read_kernel_str_proto __weak;
+
 const struct bpf_func_proto *
 bpf_base_func_proto(enum bpf_func_id func_id)
 {
@@ -648,6 +654,24 @@ bpf_base_func_proto(enum bpf_func_id func_id)
 	case BPF_FUNC_jiffies64:
 		return &bpf_jiffies64_proto;
 	default:
+		break;
+	}
+
+	if (!perfmon_capable())
+		return NULL;
+
+	switch (func_id) {
+	case BPF_FUNC_get_current_task:
+		return &bpf_get_current_task_proto;
+	case BPF_FUNC_probe_read_user:
+		return &bpf_probe_read_user_proto;
+	case BPF_FUNC_probe_read_kernel:
+		return &bpf_probe_read_kernel_proto;
+	case BPF_FUNC_probe_read_user_str:
+		return &bpf_probe_read_user_str_proto;
+	case BPF_FUNC_probe_read_kernel_str:
+		return &bpf_probe_read_kernel_str_proto;
+	default:
 		return NULL;
 	}
 }
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 9531f54..187cd69 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -147,7 +147,7 @@ BPF_CALL_3(bpf_probe_read_user, void *, dst, u32, size,
 	return ret;
 }
 
-static const struct bpf_func_proto bpf_probe_read_user_proto = {
+const struct bpf_func_proto bpf_probe_read_user_proto = {
 	.func		= bpf_probe_read_user,
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
@@ -167,7 +167,7 @@ BPF_CALL_3(bpf_probe_read_user_str, void *, dst, u32, size,
 	return ret;
 }
 
-static const struct bpf_func_proto bpf_probe_read_user_str_proto = {
+const struct bpf_func_proto bpf_probe_read_user_str_proto = {
 	.func		= bpf_probe_read_user_str,
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
@@ -198,7 +198,7 @@ BPF_CALL_3(bpf_probe_read_kernel, void *, dst, u32, size,
 	return bpf_probe_read_kernel_common(dst, size, unsafe_ptr, false);
 }
 
-static const struct bpf_func_proto bpf_probe_read_kernel_proto = {
+const struct bpf_func_proto bpf_probe_read_kernel_proto = {
 	.func		= bpf_probe_read_kernel,
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
@@ -253,7 +253,7 @@ BPF_CALL_3(bpf_probe_read_kernel_str, void *, dst, u32, size,
 	return bpf_probe_read_kernel_str_common(dst, size, unsafe_ptr, false);
 }
 
-static const struct bpf_func_proto bpf_probe_read_kernel_str_proto = {
+const struct bpf_func_proto bpf_probe_read_kernel_str_proto = {
 	.func		= bpf_probe_read_kernel_str,
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
@@ -907,7 +907,7 @@ BPF_CALL_0(bpf_get_current_task)
 	return (long) current;
 }
 
-static const struct bpf_func_proto bpf_get_current_task_proto = {
+const struct bpf_func_proto bpf_get_current_task_proto = {
 	.func		= bpf_get_current_task,
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,


  parent reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-24 16:50 [bpf-next PATCH v5 0/5] bpf: Add sk_msg and networking helpers John Fastabend
2020-05-24 16:50 ` [bpf-next PATCH v5 1/5] bpf, sk_msg: add some generic helpers that may be useful from sk_msg John Fastabend
2020-05-25 21:51   ` Daniel Borkmann
2020-05-25 22:57     ` John Fastabend
2020-05-26 18:33       ` Andrii Nakryiko
2020-05-26 20:51         ` John Fastabend
2020-05-26 21:29           ` Andrii Nakryiko
2020-05-26 23:12             ` Daniel Borkmann
2020-05-24 16:50 ` John Fastabend [this message]
2020-05-25 21:52   ` [bpf-next PATCH v5 2/5] bpf: extend bpf_base_func_proto helpers with probe_* and *current_task* Daniel Borkmann
2020-05-25 22:58     ` John Fastabend
2020-05-24 16:51 ` [bpf-next PATCH v5 3/5] bpf, sk_msg: add get socket storage helpers John Fastabend
2020-05-24 16:51 ` [bpf-next PATCH v5 4/5] bpf, selftests: add sk_msg helpers load and attach test John Fastabend
2020-05-26 18:07   ` Andrii Nakryiko
2020-05-24 16:51 ` [bpf-next PATCH v5 5/5] bpf, selftests: test probe_* helpers from SCHED_CLS John Fastabend
2020-05-26 18:09   ` Andrii Nakryiko

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