Add code generation support for TC hooks.
Co-developed-by: Dmitrii Banshchikov <[email protected]>
Signed-off-by: Dmitrii Banshchikov <[email protected]>
Signed-off-by: Quentin Deslandes <[email protected]>
---
net/bpfilter/codegen.c | 151 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 151 insertions(+)
diff --git a/net/bpfilter/codegen.c b/net/bpfilter/codegen.c
index 545bc7aeb77c..e7ae7dfa5118 100644
--- a/net/bpfilter/codegen.c
+++ b/net/bpfilter/codegen.c
@@ -8,6 +8,8 @@
#include "../../include/uapi/linux/bpfilter.h"
+#include <linux/pkt_cls.h>
+
#include <unistd.h>
#include <sys/syscall.h>
@@ -15,6 +17,8 @@
#include <stdlib.h>
#include <string.h>
+#include <bpf/libbpf.h>
+
#include "logger.h"
enum fixup_insn_type {
@@ -390,6 +394,150 @@ static void unload_maps(struct codegen *codegen)
}
}
+static int tc_gen_inline_prologue(struct codegen *codegen)
+{
+ EMIT(codegen, BPF_MOV64_REG(CODEGEN_REG_CTX, BPF_REG_ARG1));
+ EMIT(codegen, BPF_MOV64_REG(CODEGEN_REG_RUNTIME_CTX, BPF_REG_FP));
+ EMIT(codegen, BPF_MOV32_IMM(CODEGEN_REG_RETVAL, TC_ACT_OK));
+
+ return 0;
+}
+
+static int tc_load_packet_data(struct codegen *codegen, int dst_reg)
+{
+ EMIT(codegen, BPF_LDX_MEM(BPF_W, dst_reg, CODEGEN_REG_CTX,
+ offsetof(struct __sk_buff, data)));
+
+ return 0;
+}
+
+static int tc_load_packet_data_end(struct codegen *codegen, int dst_reg)
+{
+ EMIT(codegen, BPF_LDX_MEM(BPF_W, CODEGEN_REG_DATA_END, CODEGEN_REG_CTX,
+ offsetof(struct __sk_buff, data_end)));
+
+ return 0;
+}
+
+static int tc_emit_ret_code(struct codegen *codegen, int ret_code)
+{
+ int tc_ret_code;
+
+ if (ret_code == BPFILTER_NF_ACCEPT)
+ tc_ret_code = TC_ACT_UNSPEC;
+ else if (ret_code == BPFILTER_NF_DROP)
+ tc_ret_code = TC_ACT_SHOT;
+ else
+ return -EINVAL;
+
+ EMIT(codegen, BPF_MOV32_IMM(BPF_REG_0, tc_ret_code));
+
+ return 0;
+}
+
+static int tc_gen_inline_epilogue(struct codegen *codegen)
+{
+ EMIT(codegen, BPF_EXIT_INSN());
+
+ return 0;
+}
+
+struct tc_img_ctx {
+ int fd;
+ struct bpf_tc_hook hook;
+ struct bpf_tc_opts opts;
+};
+
+static int tc_load_img(struct codegen *codegen)
+{
+ struct tc_img_ctx *img_ctx;
+ int fd;
+ int r;
+
+ if (codegen->img_ctx) {
+ BFLOG_ERR("TC context missing from codegen");
+ return -EINVAL;
+ }
+
+ img_ctx = calloc(1, sizeof(*img_ctx));
+ if (!img_ctx) {
+ BFLOG_ERR("out of memory");
+ return -ENOMEM;
+ }
+
+ img_ctx->hook.sz = sizeof(img_ctx->hook);
+ img_ctx->hook.ifindex = 2;
+ img_ctx->hook.attach_point = codegen->bpf_tc_hook;
+
+ fd = load_img(codegen);
+ if (fd < 0) {
+ BFLOG_ERR("failed to load TC codegen image: %s", STRERR(fd));
+ r = fd;
+ goto err_free;
+ }
+
+ r = bpf_tc_hook_create(&img_ctx->hook);
+ if (r && r != -EEXIST) {
+ BFLOG_ERR("failed to create TC hook: %s\n", STRERR(r));
+ goto err_free;
+ }
+
+ img_ctx->opts.sz = sizeof(img_ctx->opts);
+ img_ctx->opts.handle = codegen->iptables_hook;
+ img_ctx->opts.priority = 0;
+ img_ctx->opts.prog_fd = fd;
+ r = bpf_tc_attach(&img_ctx->hook, &img_ctx->opts);
+ if (r) {
+ BFLOG_ERR("failed to attach TC program: %s", STRERR(r));
+ goto err_free;
+ }
+
+ img_ctx->fd = fd;
+ codegen->img_ctx = img_ctx;
+
+ return fd;
+
+err_free:
+ if (fd > -1)
+ close(fd);
+ free(img_ctx);
+ return r;
+}
+
+static void tc_unload_img(struct codegen *codegen)
+{
+ struct tc_img_ctx *img_ctx;
+ int r;
+
+ BUG_ON(!codegen->img_ctx);
+
+ img_ctx = (struct tc_img_ctx *)codegen->img_ctx;
+ img_ctx->opts.flags = 0;
+ img_ctx->opts.prog_fd = 0;
+ img_ctx->opts.prog_id = 0;
+ r = bpf_tc_detach(&img_ctx->hook, &img_ctx->opts);
+ if (r)
+ BFLOG_EMERG("failed to detach TC program: %s", STRERR(r));
+
+ BUG_ON(img_ctx->fd < 0);
+ close(img_ctx->fd);
+ free(img_ctx);
+
+ codegen->img_ctx = NULL;
+
+ unload_img(codegen);
+}
+
+static const struct codegen_ops tc_codegen_ops = {
+ .gen_inline_prologue = tc_gen_inline_prologue,
+ .load_packet_data = tc_load_packet_data,
+ .load_packet_data_end = tc_load_packet_data_end,
+ .emit_ret_code = tc_emit_ret_code,
+ .gen_inline_epilogue = tc_gen_inline_epilogue,
+ .load_img = tc_load_img,
+ .unload_img = tc_unload_img,
+};
+
void create_shared_codegen(struct shared_codegen *shared_codegen)
{
shared_codegen->maps_refcnt = 0;
@@ -413,6 +561,9 @@ int create_codegen(struct codegen *codegen, enum bpf_prog_type type)
memset(codegen, 0, sizeof(*codegen));
switch (type) {
+ case BPF_PROG_TYPE_SCHED_CLS:
+ codegen->codegen_ops = &tc_codegen_ops;
+ break;
default:
BFLOG_ERR("unsupported BPF program type %d", type);
return -EINVAL;
--
2.38.1