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Message-ID: <158939787911.17281.887645911866087465.stgit@john-Precision-5820-Tower>
Date: Wed, 13 May 2020 12:24:39 -0700
From: John Fastabend <john.fastabend@...il.com>
To: ast@...nel.org, daniel@...earbox.net
Cc: lmb@...udflare.com, bpf@...r.kernel.org, john.fastabend@...il.com,
jakub@...udflare.com, netdev@...r.kernel.org
Subject: [bpf-next PATCH 2/3] bpf: sk_msg helpers for probe_* and
*current_task*
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 + sk_msg and link the two programs together to accomplish
this. However, this is a bit clunky and also means we have to call
sk_msg program and kprobe program when we could just use a single
program and avoid passing metadata through sk_msg/skb, socket, etc.
To accomplish this add probe_* helpers to sk_msg programs guarded
by a CAP_SYS_ADMIN 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
BPF_FUNC_probe_read_user_str
BPF_FUNC_probe_read_kernel_str
BPF_FUNC_probe_read_str
Signed-off-by: John Fastabend <john.fastabend@...il.com>
---
kernel/trace/bpf_trace.c | 16 ++++++++--------
net/core/filter.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 42 insertions(+), 8 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index d961428..abe6721 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,
@@ -213,7 +213,7 @@ BPF_CALL_3(bpf_probe_read_compat, void *, dst, u32, size,
return bpf_probe_read_kernel_common(dst, size, unsafe_ptr, true);
}
-static const struct bpf_func_proto bpf_probe_read_compat_proto = {
+const struct bpf_func_proto bpf_probe_read_compat_proto = {
.func = bpf_probe_read_compat,
.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,
@@ -268,7 +268,7 @@ BPF_CALL_3(bpf_probe_read_compat_str, void *, dst, u32, size,
return bpf_probe_read_kernel_str_common(dst, size, unsafe_ptr, true);
}
-static const struct bpf_func_proto bpf_probe_read_compat_str_proto = {
+const struct bpf_func_proto bpf_probe_read_compat_str_proto = {
.func = bpf_probe_read_compat_str,
.gpl_only = true,
.ret_type = RET_INTEGER,
@@ -874,7 +874,7 @@ 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,
@@ -895,7 +895,7 @@ BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx)
return task_under_cgroup_hierarchy(current, cgrp);
}
-static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
+const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
.func = bpf_current_task_under_cgroup,
.gpl_only = false,
.ret_type = RET_INTEGER,
diff --git a/net/core/filter.c b/net/core/filter.c
index 45b4a16..d1c4739 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6362,6 +6362,15 @@ sock_ops_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
const struct bpf_func_proto bpf_msg_redirect_map_proto __weak;
const struct bpf_func_proto bpf_msg_redirect_hash_proto __weak;
+const struct bpf_func_proto bpf_current_task_under_cgroup_proto __weak;
+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_probe_read_compat_proto __weak;
+const struct bpf_func_proto bpf_probe_read_compat_str_proto __weak;
+
static const struct bpf_func_proto *
sk_msg_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
@@ -6397,6 +6406,31 @@ sk_msg_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_get_cgroup_classid_curr_proto;
#endif
default:
+ break;
+ }
+
+ if (!capable(CAP_SYS_ADMIN))
+ return bpf_base_func_proto(func_id);
+
+ /* All helpers below are for CAP_SYS_ADMIN only */
+ switch (func_id) {
+ case BPF_FUNC_get_current_task:
+ return &bpf_get_current_task_proto;
+ case BPF_FUNC_current_task_under_cgroup:
+ return &bpf_current_task_under_cgroup_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:
+ return &bpf_probe_read_compat_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;
+ case BPF_FUNC_probe_read_str:
+ return &bpf_probe_read_compat_str_proto;
+ default:
return bpf_base_func_proto(func_id);
}
}
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