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authorJohn Fastabend <john.fastabend@gmail.com>2020-05-24 18:50:55 +0200
committerAlexei Starovoitov <ast@kernel.org>2020-06-01 23:38:20 +0200
commitf470378c7562a2818b45ed11c98973f2b89eedd3 (patch)
tree644a058b0dd4945cc4fe53c4e07c299ba68d16a7 /kernel/bpf
parentbpf, sk_msg: Add some generic helpers that may be useful from sk_msg (diff)
downloadlinux-f470378c7562a2818b45ed11c98973f2b89eedd3.tar.xz
linux-f470378c7562a2818b45ed11c98973f2b89eedd3.zip
bpf: Extend bpf_base_func_proto helpers with 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 + 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_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> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/159033905529.12355.4368381069655254932.stgit@john-Precision-5820-Tower Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/helpers.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 886949fdcece..bb4fb634275e 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;
}
}