Implement support for source and destination addresses and ports matching.
Co-developed-by: Dmitrii Banshchikov me@ubique.spb.ru Signed-off-by: Dmitrii Banshchikov me@ubique.spb.ru Signed-off-by: Quentin Deslandes qde@naccy.de --- net/bpfilter/Makefile | 2 +- net/bpfilter/context.c | 2 +- net/bpfilter/match.h | 2 + net/bpfilter/xt_udp.c | 111 ++++++++++++++++++ .../testing/selftests/bpf/bpfilter/.gitignore | 1 + tools/testing/selftests/bpf/bpfilter/Makefile | 6 +- .../selftests/bpf/bpfilter/test_xt_udp.c | 48 ++++++++ 7 files changed, 168 insertions(+), 4 deletions(-) create mode 100644 net/bpfilter/xt_udp.c create mode 100644 tools/testing/selftests/bpf/bpfilter/test_xt_udp.c
diff --git a/net/bpfilter/Makefile b/net/bpfilter/Makefile index 2f8d867a6038..345341a9ee30 100644 --- a/net/bpfilter/Makefile +++ b/net/bpfilter/Makefile @@ -13,7 +13,7 @@ $(LIBBPF_A): userprogs := bpfilter_umh bpfilter_umh-objs := main.o logger.o map-common.o bpfilter_umh-objs += context.o codegen.o -bpfilter_umh-objs += match.o +bpfilter_umh-objs += match.o xt_udp.o bpfilter_umh-userldlibs := $(LIBBPF_A) -lelf -lz userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi
diff --git a/net/bpfilter/context.c b/net/bpfilter/context.c index b5e172412fab..f420fb8b6507 100644 --- a/net/bpfilter/context.c +++ b/net/bpfilter/context.c @@ -16,7 +16,7 @@ #include "map-common.h" #include "match.h"
-static const struct match_ops *match_ops[] = { }; +static const struct match_ops *match_ops[] = { &xt_udp };
static int init_match_ops_map(struct context *ctx) { diff --git a/net/bpfilter/match.h b/net/bpfilter/match.h index c6541e6a6567..7de3d2a07dc5 100644 --- a/net/bpfilter/match.h +++ b/net/bpfilter/match.h @@ -29,6 +29,8 @@ struct match { const struct bpfilter_ipt_match *ipt_match; };
+extern const struct match_ops xt_udp; + int init_match(struct context *ctx, const struct bpfilter_ipt_match *ipt_match, struct match *match);
diff --git a/net/bpfilter/xt_udp.c b/net/bpfilter/xt_udp.c new file mode 100644 index 000000000000..c78cd4341f81 --- /dev/null +++ b/net/bpfilter/xt_udp.c @@ -0,0 +1,111 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2021 Telegram FZ-LLC + * Copyright (c) 2022 Meta Platforms, Inc. and affiliates. + */ + +#define _GNU_SOURCE + +#include <linux/filter.h> +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter/xt_tcpudp.h> +#include <linux/udp.h> + +#include <arpa/inet.h> +#include <errno.h> + +#include "codegen.h" +#include "context.h" +#include "logger.h" +#include "match.h" + +static int xt_udp_check(struct context *ctx, + const struct bpfilter_ipt_match *ipt_match) +{ + const struct xt_udp *udp; + + udp = (const struct xt_udp *)&ipt_match->data; + + if (udp->invflags & XT_UDP_INV_MASK) { + BFLOG_ERR("cannot check match 'udp': invalid flags\n"); + return -EINVAL; + } + + return 0; +} + +static int xt_udp_gen_inline_ports(struct codegen *ctx, int regno, bool inv, + const u16 (*ports)[2]) +{ + if ((*ports)[0] == 0 && (*ports)[1] == 65535) { + if (inv) + EMIT_FIXUP(ctx, CODEGEN_FIXUP_NEXT_RULE, + BPF_JMP_IMM(BPF_JA, 0, 0, 0)); + } else if ((*ports)[0] == (*ports)[1]) { + const u16 port = htons((*ports)[0]); + + EMIT_FIXUP(ctx, CODEGEN_FIXUP_NEXT_RULE, + BPF_JMP_IMM((inv ? BPF_JEQ : BPF_JNE), regno, port, 0)); + } else { + EMIT_LITTLE_ENDIAN(ctx, BPF_ENDIAN(BPF_TO_BE, regno, 16)); + EMIT_FIXUP(ctx, CODEGEN_FIXUP_NEXT_RULE, + BPF_JMP_IMM(inv ? BPF_JGT : BPF_JLT, regno, (*ports)[0], 0)); + EMIT_FIXUP(ctx, CODEGEN_FIXUP_NEXT_RULE, + BPF_JMP_IMM(inv ? BPF_JLT : BPF_JGT, regno, (*ports)[1], 0)); + } + + return 0; +} + +static int xt_udp_gen_inline(struct codegen *ctx, const struct match *match) +{ + const struct xt_udp *udp; + int r; + + udp = (const struct xt_udp *)&match->ipt_match->data; + + EMIT(ctx, BPF_MOV64_REG(CODEGEN_REG_SCRATCH1, CODEGEN_REG_L4)); + EMIT(ctx, BPF_ALU64_IMM(BPF_ADD, CODEGEN_REG_SCRATCH1, sizeof(struct udphdr))); + r = ctx->codegen_ops->load_packet_data_end(ctx, CODEGEN_REG_DATA_END); + if (r) { + BFLOG_ERR("failed to generate code to load packet data end: %s", + STRERR(r)); + return r; + } + + EMIT_FIXUP(ctx, CODEGEN_FIXUP_NEXT_RULE, + BPF_JMP_REG(BPF_JGT, CODEGEN_REG_SCRATCH1, CODEGEN_REG_DATA_END, 0)); + + EMIT(ctx, BPF_LDX_MEM(BPF_H, CODEGEN_REG_SCRATCH4, CODEGEN_REG_L4, + offsetof(struct udphdr, source))); + EMIT(ctx, BPF_LDX_MEM(BPF_H, CODEGEN_REG_SCRATCH5, CODEGEN_REG_L4, + offsetof(struct udphdr, dest))); + + r = xt_udp_gen_inline_ports(ctx, CODEGEN_REG_SCRATCH4, + udp->invflags & XT_UDP_INV_SRCPT, + &udp->spts); + if (r) { + BFLOG_ERR("failed to generate code to match source ports: %s", + STRERR(r)); + return r; + } + + r = xt_udp_gen_inline_ports(ctx, CODEGEN_REG_SCRATCH5, + udp->invflags & XT_UDP_INV_DSTPT, + &udp->dpts); + if (r) { + BFLOG_ERR("failed to generate code to match destination ports: %s", + STRERR(r)); + return r; + } + + return 0; +} + +const struct match_ops xt_udp = { + .name = "udp", + .size = XT_ALIGN(sizeof(struct xt_udp)), + .revision = 0, + .check = xt_udp_check, + .gen_inline = xt_udp_gen_inline +}; diff --git a/tools/testing/selftests/bpf/bpfilter/.gitignore b/tools/testing/selftests/bpf/bpfilter/.gitignore index 9ac1b3caf246..f84cc86493df 100644 --- a/tools/testing/selftests/bpf/bpfilter/.gitignore +++ b/tools/testing/selftests/bpf/bpfilter/.gitignore @@ -2,3 +2,4 @@ tools/** test_map test_match +test_xt_udp diff --git a/tools/testing/selftests/bpf/bpfilter/Makefile b/tools/testing/selftests/bpf/bpfilter/Makefile index 10642c1d6a87..97f8d596de36 100644 --- a/tools/testing/selftests/bpf/bpfilter/Makefile +++ b/tools/testing/selftests/bpf/bpfilter/Makefile @@ -12,6 +12,7 @@ CFLAGS += -Wall -g -pthread -I$(TOOLSINCDIR) -I$(APIDIR) -I$(BPFILTERSRCDIR)
TEST_GEN_PROGS += test_map TEST_GEN_PROGS += test_match +TEST_GEN_PROGS += test_xt_udp
KSFT_KHDR_INSTALL := 1
@@ -35,11 +36,12 @@ $(BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile) \
BPFILTER_MAP_SRCS := $(BPFILTERSRCDIR)/map-common.c BPFILTER_CODEGEN_SRCS := $(BPFILTERSRCDIR)/codegen.c $(BPFOBJ) -lelf -lz -BPFILTER_MATCH_SRCS := $(BPFILTERSRCDIR)/match.c +BPFILTER_MATCH_SRCS := $(BPFILTERSRCDIR)/match.c $(BPFILTERSRCDIR)/xt_udp.c
-BPFILTER_COMMON_SRCS := $(BPFILTER_MAP_SRCS) +BPFILTER_COMMON_SRCS := $(BPFILTER_MAP_SRCS) $(BPFILTER_CODEGEN_SRCS) BPFILTER_COMMON_SRCS += $(BPFILTERSRCDIR)/context.c $(BPFILTERSRCDIR)/logger.c BPFILTER_COMMON_SRCS += $(BPFILTER_MATCH_SRCS)
$(OUTPUT)/test_map: test_map.c $(BPFILTER_MAP_SRCS) $(OUTPUT)/test_match: test_match.c $(BPFILTER_COMMON_SRCS) +$(OUTPUT)/test_xt_udp: test_xt_udp.c $(BPFILTER_COMMON_SRCS) diff --git a/tools/testing/selftests/bpf/bpfilter/test_xt_udp.c b/tools/testing/selftests/bpf/bpfilter/test_xt_udp.c new file mode 100644 index 000000000000..c0898b0eca30 --- /dev/null +++ b/tools/testing/selftests/bpf/bpfilter/test_xt_udp.c @@ -0,0 +1,48 @@ +// SPDX-License-Identifier: GPL-2.0 + +#define _GNU_SOURCE + +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter/xt_tcpudp.h> + +#include "../../kselftest_harness.h" + +#include "context.h" +#include "logger.h" +#include "match.h" + +#include "bpfilter_util.h" + +FIXTURE(test_xt_udp) +{ + struct context ctx; + struct { + struct xt_entry_match match; + struct xt_udp udp; + + } ipt_match; + struct match match; +}; + +FIXTURE_SETUP(test_xt_udp) +{ + logger_set_file(stderr); + ASSERT_EQ(0, create_context(&self->ctx)); +}; + +FIXTURE_TEARDOWN(test_xt_udp) +{ + free_context(&self->ctx); +}; + +TEST_F(test_xt_udp, init) +{ + init_entry_match((struct xt_entry_match *)&self->ipt_match, + sizeof(self->ipt_match), 0, "udp"); + ASSERT_EQ(init_match(&self->ctx, + (const struct bpfilter_ipt_match *)&self->ipt_match, + &self->match), + 0); +} + +TEST_HARNESS_MAIN