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.fastab...@gmail.com>
Acked-by: Yonghong Song <y...@fb.com>
---
kernel/bpf/helpers.c | 27 +++++++++++++++++++++++++++
kernel/trace/bpf_trace.c | 16 ++++++++--------
2 files changed, 35 insertions(+), 8 deletions(-)
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 886949f..ee992dd 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -601,6 +601,13 @@ const struct bpf_func_proto bpf_event_output_data_proto =
{
.arg5_type = ARG_CONST_SIZE_OR_ZERO,
};
+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_base_func_proto(enum bpf_func_id func_id)
{
@@ -648,6 +655,26 @@ 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_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_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..6fabbc4 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,
@@ -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,
@@ -928,7 +928,7 @@ 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,
