Add target structure, containing a pointer to a target_ops structure and a pointer to an xt_entry_target structure. The later containing the payload for the target's type.
target_ops structure provides two operations: - check: validates the target. - gen_inline: generate the eBPF bytecode for the target.
All target_ops are kept in a map by their name.
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 | 42 ++++ net/bpfilter/context.h | 1 + net/bpfilter/target.c | 203 ++++++++++++++++++ net/bpfilter/target.h | 57 +++++ .../testing/selftests/bpf/bpfilter/.gitignore | 1 + tools/testing/selftests/bpf/bpfilter/Makefile | 5 +- .../selftests/bpf/bpfilter/bpfilter_util.h | 23 ++ .../selftests/bpf/bpfilter/test_target.c | 83 +++++++ 9 files changed, 415 insertions(+), 2 deletions(-) create mode 100644 net/bpfilter/target.c create mode 100644 net/bpfilter/target.h create mode 100644 tools/testing/selftests/bpf/bpfilter/test_target.c
diff --git a/net/bpfilter/Makefile b/net/bpfilter/Makefile index 345341a9ee30..7e642e0ae932 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 xt_udp.o +bpfilter_umh-objs += match.o xt_udp.o target.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 f420fb8b6507..ac07b678baa7 100644 --- a/net/bpfilter/context.c +++ b/net/bpfilter/context.c @@ -15,6 +15,7 @@ #include "logger.h" #include "map-common.h" #include "match.h" +#include "target.h"
static const struct match_ops *match_ops[] = { &xt_udp };
@@ -42,6 +43,35 @@ static int init_match_ops_map(struct context *ctx) return 0; }
+static const struct target_ops *target_ops[] = { + &standard_target_ops, + &error_target_ops +}; + +static int init_target_ops_map(struct context *ctx) +{ + int r; + + r = create_map(&ctx->target_ops_map, ARRAY_SIZE(target_ops)); + if (r) { + BFLOG_ERR("failed to create targets map: %s", STRERR(r)); + return r; + } + + for (int i = 0; i < ARRAY_SIZE(target_ops); ++i) { + const struct target_ops *t = target_ops[i]; + + r = map_upsert(&ctx->target_ops_map, t->name, (void *)t); + if (r) { + BFLOG_ERR("failed to upsert in targets map: %s", + STRERR(r)); + return r; + } + } + + return 0; +} + int create_context(struct context *ctx) { int r; @@ -52,10 +82,22 @@ int create_context(struct context *ctx) return r; }
+ r = init_target_ops_map(ctx); + if (r) { + BFLOG_ERR("failed to initialize targets map: %s", STRERR(r)); + goto err_free_match_ops_map; + } + return 0; + +err_free_match_ops_map: + free_map(&ctx->match_ops_map); + + return r; }
void free_context(struct context *ctx) { + free_map(&ctx->target_ops_map); free_map(&ctx->match_ops_map); } diff --git a/net/bpfilter/context.h b/net/bpfilter/context.h index e36aa8ebf57e..f9c34a9968b8 100644 --- a/net/bpfilter/context.h +++ b/net/bpfilter/context.h @@ -11,6 +11,7 @@
struct context { struct hsearch_data match_ops_map; + struct hsearch_data target_ops_map; };
int create_context(struct context *ctx); diff --git a/net/bpfilter/target.c b/net/bpfilter/target.c new file mode 100644 index 000000000000..a96ec7735c0e --- /dev/null +++ b/net/bpfilter/target.c @@ -0,0 +1,203 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2021 Telegram FZ-LLC + * Copyright (c) 2022 Meta Platforms, Inc. and affiliates. + */ + +#define _GNU_SOURCE + +#include "target.h" + +#include <linux/err.h> +#include <linux/filter.h> +#include <linux/list.h> +#include <linux/netfilter/x_tables.h> + +#include <errno.h> +#include <string.h> + +#include "codegen.h" +#include "context.h" +#include "logger.h" +#include "map-common.h" + +static const struct target_ops *target_ops_map_find(struct hsearch_data *map, + const char *name) +{ + const size_t len = strnlen(name, BPFILTER_EXTENSION_MAXNAMELEN); + + if (len < BPFILTER_EXTENSION_MAXNAMELEN) + return map_find(map, name); + + return ERR_PTR(-EINVAL); +} + +static int standard_target_check(struct context *ctx, + const struct bpfilter_ipt_target *ipt_target) +{ + const struct bpfilter_ipt_standard_target *standard_target; + + standard_target = (const struct bpfilter_ipt_standard_target *)ipt_target; + + // Positive values of verdict denote a jump offset into a blob. + if (standard_target->verdict > 0) + return 0; + + // Special values like ACCEPT, DROP, RETURN are encoded as negative values. + if (standard_target->verdict < 0) { + if (standard_target->verdict == BPFILTER_RETURN) + return 0; + + switch (convert_verdict(standard_target->verdict)) { + case BPFILTER_NF_ACCEPT: + case BPFILTER_NF_DROP: + case BPFILTER_NF_QUEUE: + return 0; + } + } + + BFLOG_ERR("unsupported verdict: %d", standard_target->verdict); + + return -EINVAL; +} + +static int standard_target_gen_inline(struct codegen *ctx, + const struct target *target) +{ + const struct bpfilter_ipt_standard_target *standard_target; + int r; + + standard_target = (const struct bpfilter_ipt_standard_target *)target->ipt_target; + + if (standard_target->verdict >= 0) { + struct codegen_subprog_desc *subprog; + struct codegen_fixup_desc *fixup; + + subprog = malloc(sizeof(*subprog)); + if (!subprog) { + BFLOG_ERR("out of memory"); + return -ENOMEM; + } + + INIT_LIST_HEAD(&subprog->list); + subprog->type = CODEGEN_SUBPROG_USER_CHAIN; + subprog->insn = 0; + subprog->offset = standard_target->verdict; + + fixup = malloc(sizeof(*fixup)); + if (!fixup) { + BFLOG_ERR("out of memory"); + free(subprog); + return -ENOMEM; + } + + INIT_LIST_HEAD(&fixup->list); + fixup->type = CODEGEN_FIXUP_JUMP_TO_CHAIN; + fixup->insn = ctx->len_cur; + fixup->offset = standard_target->verdict; + + list_add_tail(&fixup->list, &ctx->fixup); + + r = codegen_push_awaiting_subprog(ctx, subprog); + if (r) { + BFLOG_ERR("failed to push awaiting subprog: %s", + STRERR(r)); + return r; + } + + EMIT(ctx, BPF_JMP_IMM(BPF_JA, 0, 0, 0)); + + return 0; + } + + if (standard_target->verdict == BPFILTER_RETURN) { + EMIT(ctx, BPF_EXIT_INSN()); + return 0; + } + + r = ctx->codegen_ops->emit_ret_code(ctx, convert_verdict(standard_target->verdict)); + if (r) { + BFLOG_ERR("failed to emit return code: %s", STRERR(r)); + return r; + } + + EMIT(ctx, BPF_EXIT_INSN()); + + return 0; +} + +const struct target_ops standard_target_ops = { + .name = "", + .revision = 0, + .size = sizeof(struct xt_standard_target), + .check = standard_target_check, + .gen_inline = standard_target_gen_inline, +}; + +static int error_target_check(struct context *ctx, + const struct bpfilter_ipt_target *ipt_target) +{ + const struct bpfilter_ipt_error_target *error_target; + size_t maxlen; + + error_target = (const struct bpfilter_ipt_error_target *)ipt_target; + maxlen = sizeof(error_target->error_name); + if (strnlen(error_target->error_name, maxlen) == maxlen) { + BFLOG_ERR("failed to check error target: too long errorname"); + return -EINVAL; + } + + return 0; +} + +static int error_target_gen_inline(struct codegen *ctx, + const struct target *target) +{ + return -EINVAL; +} + +const struct target_ops error_target_ops = { + .name = "ERROR", + .revision = 0, + .size = sizeof(struct xt_error_target), + .check = error_target_check, + .gen_inline = error_target_gen_inline, +}; + +int init_target(struct context *ctx, + const struct bpfilter_ipt_target *ipt_target, + struct target *target) +{ + const size_t maxlen = sizeof(ipt_target->u.user.name); + const struct target_ops *found; + int r; + + if (strnlen(ipt_target->u.user.name, maxlen) == maxlen) { + BFLOG_ERR("cannot init target: too long target name '%s'", + ipt_target->u.user.name); + return -EINVAL; + } + + found = target_ops_map_find(&ctx->target_ops_map, + ipt_target->u.user.name); + if (IS_ERR(found)) { + BFLOG_ERR("cannot find target by name '%s' in map", + ipt_target->u.user.name); + return PTR_ERR(found); + } + + if (found->size != ipt_target->u.target_size || + found->revision != ipt_target->u.user.revision) { + BFLOG_ERR("invalid target size: '%s'", ipt_target->u.user.name); + return -EINVAL; + } + + r = found->check(ctx, ipt_target); + if (r) + return r; + + target->target_ops = found; + target->ipt_target = ipt_target; + + return 0; +} diff --git a/net/bpfilter/target.h b/net/bpfilter/target.h new file mode 100644 index 000000000000..57bae658b6a2 --- /dev/null +++ b/net/bpfilter/target.h @@ -0,0 +1,57 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (c) 2021 Telegram FZ-LLC + * Copyright (c) 2022 Meta Platforms, Inc. and affiliates. + */ + +#ifndef NET_BPFILTER_TARGET_H +#define NET_BPFILTER_TARGET_H + +#include "../../include/uapi/linux/bpfilter.h" + +#include <stdint.h> + +struct codegen; +struct context; +struct target; +struct target_ops_map; + +struct target_ops { + char name[BPFILTER_EXTENSION_MAXNAMELEN]; + uint8_t revision; + uint16_t size; + int (*check)(struct context *ctx, + const struct bpfilter_ipt_target *ipt_target); + int (*gen_inline)(struct codegen *ctx, const struct target *target); +}; + +struct target { + const struct target_ops *target_ops; + const struct bpfilter_ipt_target *ipt_target; +}; + +extern const struct target_ops standard_target_ops; +extern const struct target_ops error_target_ops; + +/* Restore verdict's special value(ACCEPT, DROP, etc.) from its negative + * representation. + */ +static inline int convert_verdict(int verdict) +{ + return -verdict - 1; +} + +static inline int standard_target_verdict(const struct bpfilter_ipt_target *ipt_target) +{ + const struct bpfilter_ipt_standard_target *standard_target; + + standard_target = (const struct bpfilter_ipt_standard_target *)ipt_target; + + return standard_target->verdict; +} + +int init_target(struct context *ctx, + const struct bpfilter_ipt_target *ipt_target, + struct target *target); + +#endif // NET_BPFILTER_TARGET_H diff --git a/tools/testing/selftests/bpf/bpfilter/.gitignore b/tools/testing/selftests/bpf/bpfilter/.gitignore index f84cc86493df..89912a44109f 100644 --- a/tools/testing/selftests/bpf/bpfilter/.gitignore +++ b/tools/testing/selftests/bpf/bpfilter/.gitignore @@ -3,3 +3,4 @@ tools/** test_map test_match test_xt_udp +test_target diff --git a/tools/testing/selftests/bpf/bpfilter/Makefile b/tools/testing/selftests/bpf/bpfilter/Makefile index 97f8d596de36..587951d14c0c 100644 --- a/tools/testing/selftests/bpf/bpfilter/Makefile +++ b/tools/testing/selftests/bpf/bpfilter/Makefile @@ -13,6 +13,7 @@ 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 +TEST_GEN_PROGS += test_target
KSFT_KHDR_INSTALL := 1
@@ -37,11 +38,13 @@ $(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 $(BPFILTERSRCDIR)/xt_udp.c +BPFILTER_TARGET_SRCS := $(BPFILTERSRCDIR)/target.c
BPFILTER_COMMON_SRCS := $(BPFILTER_MAP_SRCS) $(BPFILTER_CODEGEN_SRCS) BPFILTER_COMMON_SRCS += $(BPFILTERSRCDIR)/context.c $(BPFILTERSRCDIR)/logger.c -BPFILTER_COMMON_SRCS += $(BPFILTER_MATCH_SRCS) +BPFILTER_COMMON_SRCS += $(BPFILTER_MATCH_SRCS) $(BPFILTER_TARGET_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 $(BPFILTER_COMMON_SRCS) +$(OUTPUT)/test_target: test_target.c $(BPFILTER_COMMON_SRCS) diff --git a/tools/testing/selftests/bpf/bpfilter/bpfilter_util.h b/tools/testing/selftests/bpf/bpfilter/bpfilter_util.h index 705fd1777a67..0d6a6bee5514 100644 --- a/tools/testing/selftests/bpf/bpfilter/bpfilter_util.h +++ b/tools/testing/selftests/bpf/bpfilter/bpfilter_util.h @@ -19,4 +19,27 @@ static inline void init_entry_match(struct xt_entry_match *match, match->u.user.revision = revision; }
+static inline void init_standard_target(struct xt_standard_target *ipt_target, + int revision, int verdict) +{ + snprintf(ipt_target->target.u.user.name, + sizeof(ipt_target->target.u.user.name), "%s", + BPFILTER_STANDARD_TARGET); + ipt_target->target.u.user.revision = revision; + ipt_target->target.u.user.target_size = sizeof(*ipt_target); + ipt_target->verdict = verdict; +} + +static inline void init_error_target(struct xt_error_target *ipt_target, + int revision, const char *error_name) +{ + snprintf(ipt_target->target.u.user.name, + sizeof(ipt_target->target.u.user.name), "%s", + BPFILTER_ERROR_TARGET); + ipt_target->target.u.user.revision = revision; + ipt_target->target.u.user.target_size = sizeof(*ipt_target); + snprintf(ipt_target->errorname, sizeof(ipt_target->errorname), "%s", + error_name); +} + #endif // BPFILTER_UTIL_H diff --git a/tools/testing/selftests/bpf/bpfilter/test_target.c b/tools/testing/selftests/bpf/bpfilter/test_target.c new file mode 100644 index 000000000000..0ebe4b052a9b --- /dev/null +++ b/tools/testing/selftests/bpf/bpfilter/test_target.c @@ -0,0 +1,83 @@ +// SPDX-License-Identifier: GPL-2.0 + +#define _GNU_SOURCE + +#include <linux/bpfilter.h> +#include <linux/netfilter/x_tables.h> + +#include "../../kselftest_harness.h" + +#include "context.h" +#include "logger.h" +#include "target.h" + +#include "bpfilter_util.h" + +FIXTURE(test_standard_target) +{ + struct context ctx; + struct xt_standard_target ipt_target; + struct target target; +}; + +FIXTURE_VARIANT(test_standard_target) +{ + int verdict; +}; + +FIXTURE_VARIANT_ADD(test_standard_target, accept) { + .verdict = -BPFILTER_NF_ACCEPT - 1, +}; + +FIXTURE_VARIANT_ADD(test_standard_target, drop) { + .verdict = -BPFILTER_NF_DROP - 1, +}; + +FIXTURE_SETUP(test_standard_target) +{ + logger_set_file(stderr); + ASSERT_EQ(0, create_context(&self->ctx)); + + memset(&self->ipt_target, 0, sizeof(self->ipt_target)); + init_standard_target(&self->ipt_target, 0, variant->verdict); +} + +FIXTURE_TEARDOWN(test_standard_target) +{ + free_context(&self->ctx); +} + +TEST_F(test_standard_target, init) +{ + ASSERT_EQ(0, init_target(&self->ctx, (const struct bpfilter_ipt_target *)&self->ipt_target, + &self->target)); +} + +FIXTURE(test_error_target) +{ + struct context ctx; + struct xt_error_target ipt_target; + struct target target; +}; + +FIXTURE_SETUP(test_error_target) +{ + logger_set_file(stderr); + ASSERT_EQ(0, create_context(&self->ctx)); + + memset(&self->ipt_target, 0, sizeof(self->ipt_target)); + init_error_target(&self->ipt_target, 0, "x"); +} + +FIXTURE_TEARDOWN(test_error_target) +{ + free_context(&self->ctx); +} + +TEST_F(test_error_target, init) +{ + ASSERT_EQ(0, init_target(&self->ctx, (const struct bpfilter_ipt_target *)&self->ipt_target, + &self->target)); +} + +TEST_HARNESS_MAIN