selftests/bpf: add sockopt test that exercises sk helpers

socktop test that introduces new SOL_CUSTOM sockopt level and
stores whatever users sets in sk storage. Whenever getsockopt
is called, the original value is retrieved.

v9:
* SO_SNDBUF example to override user-supplied buffer

v7:
* use retval=0 and optlen-1

v6:
* test 'ret=1' use-case as well (Alexei Starovoitov)

v4:
* don't call bpf_sk_fullsock helper

v3:
* drop (__u8 *)(long) casts for optval{,_end}

v2:
* new test

Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Martin Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
index 3fe9260..8ac076c 100644 (file)
--- a/tools/testing/selftests/bpf/.gitignore
+++ b/tools/testing/selftests/bpf/.gitignore
@@ -40,3 +40,4 @@ test_hashmap
 test_btf_dump
 xdping
 test_sockopt
+test_sockopt_sk

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 7f22104..57ae4e1 100644 (file)
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -26,7 +26,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
        test_sock test_btf test_sockmap get_cgroup_id_user test_socket_cookie \
        test_cgroup_storage test_select_reuseport test_section_names \
        test_netcnt test_tcpnotify_user test_sock_fields test_sysctl test_hashmap \
-       test_btf_dump test_cgroup_attach xdping test_sockopt
+       test_btf_dump test_cgroup_attach xdping test_sockopt test_sockopt_sk
 
 BPF_OBJ_FILES = $(patsubst %.c,%.o, $(notdir $(wildcard progs/*.c)))
 TEST_GEN_FILES = $(BPF_OBJ_FILES)
@@ -104,6 +104,7 @@ $(OUTPUT)/test_sock_fields: cgroup_helpers.c
 $(OUTPUT)/test_sysctl: cgroup_helpers.c
 $(OUTPUT)/test_cgroup_attach: cgroup_helpers.c
 $(OUTPUT)/test_sockopt: cgroup_helpers.c
+$(OUTPUT)/test_sockopt_sk: cgroup_helpers.c
 
 .PHONY: force
 

diff --git a/tools/testing/selftests/bpf/progs/sockopt_sk.c b/tools/testing/selftests/bpf/progs/sockopt_sk.c
new file mode 100644 (file)
index 0000000..076122c
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/sockopt_sk.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <netinet/in.h>
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+__u32 _version SEC("version") = 1;
+
+#define SOL_CUSTOM                     0xdeadbeef
+
+struct sockopt_sk {
+       __u8 val;
+};
+
+struct bpf_map_def SEC("maps") socket_storage_map = {
+       .type = BPF_MAP_TYPE_SK_STORAGE,
+       .key_size = sizeof(int),
+       .value_size = sizeof(struct sockopt_sk),
+       .map_flags = BPF_F_NO_PREALLOC,
+};
+BPF_ANNOTATE_KV_PAIR(socket_storage_map, int, struct sockopt_sk);
+
+SEC("cgroup/getsockopt")
+int _getsockopt(struct bpf_sockopt *ctx)
+{
+       __u8 *optval_end = ctx->optval_end;
+       __u8 *optval = ctx->optval;
+       struct sockopt_sk *storage;
+
+       if (ctx->level == SOL_IP && ctx->optname == IP_TOS)
+               /* Not interested in SOL_IP:IP_TOS;
+                * let next BPF program in the cgroup chain or kernel
+                * handle it.
+                */
+               return 1;
+
+       if (ctx->level == SOL_SOCKET && ctx->optname == SO_SNDBUF) {
+               /* Not interested in SOL_SOCKET:SO_SNDBUF;
+                * let next BPF program in the cgroup chain or kernel
+                * handle it.
+                */
+               return 1;
+       }
+
+       if (ctx->level != SOL_CUSTOM)
+               return 0; /* EPERM, deny everything except custom level */
+
+       if (optval + 1 > optval_end)
+               return 0; /* EPERM, bounds check */
+
+       storage = bpf_sk_storage_get(&socket_storage_map, ctx->sk, 0,
+                                    BPF_SK_STORAGE_GET_F_CREATE);
+       if (!storage)
+               return 0; /* EPERM, couldn't get sk storage */
+
+       if (!ctx->retval)
+               return 0; /* EPERM, kernel should not have handled
+                          * SOL_CUSTOM, something is wrong!
+                          */
+       ctx->retval = 0; /* Reset system call return value to zero */
+
+       optval[0] = storage->val;
+       ctx->optlen = 1;
+
+       return 1;
+}
+
+SEC("cgroup/setsockopt")
+int _setsockopt(struct bpf_sockopt *ctx)
+{
+       __u8 *optval_end = ctx->optval_end;
+       __u8 *optval = ctx->optval;
+       struct sockopt_sk *storage;
+
+       if (ctx->level == SOL_IP && ctx->optname == IP_TOS)
+               /* Not interested in SOL_IP:IP_TOS;
+                * let next BPF program in the cgroup chain or kernel
+                * handle it.
+                */
+               return 1;
+
+       if (ctx->level == SOL_SOCKET && ctx->optname == SO_SNDBUF) {
+               /* Overwrite SO_SNDBUF value */
+
+               if (optval + sizeof(__u32) > optval_end)
+                       return 0; /* EPERM, bounds check */
+
+               *(__u32 *)optval = 0x55AA;
+               ctx->optlen = 4;
+
+               return 1;
+       }
+
+       if (ctx->level != SOL_CUSTOM)
+               return 0; /* EPERM, deny everything except custom level */
+
+       if (optval + 1 > optval_end)
+               return 0; /* EPERM, bounds check */
+
+       storage = bpf_sk_storage_get(&socket_storage_map, ctx->sk, 0,
+                                    BPF_SK_STORAGE_GET_F_CREATE);
+       if (!storage)
+               return 0; /* EPERM, couldn't get sk storage */
+
+       storage->val = optval[0];
+       ctx->optlen = -1; /* BPF has consumed this option, don't call kernel
+                          * setsockopt handler.
+                          */
+
+       return 1;
+}

diff --git a/tools/testing/selftests/bpf/test_sockopt_sk.c b/tools/testing/selftests/bpf/test_sockopt_sk.c
new file mode 100644 (file)
index 0000000..12e79ed
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_sockopt_sk.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+#include <linux/filter.h>
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include "bpf_rlimit.h"
+#include "bpf_util.h"
+#include "cgroup_helpers.h"
+
+#define CG_PATH                                "/sockopt"
+
+#define SOL_CUSTOM                     0xdeadbeef
+
+static int getsetsockopt(void)
+{
+       int fd, err;
+       char buf[4] = {};
+       socklen_t optlen;
+
+       fd = socket(AF_INET, SOCK_STREAM, 0);
+       if (fd < 0) {
+               log_err("Failed to create socket");
+               return -1;
+       }
+
+       /* IP_TOS - BPF bypass */
+
+       buf[0] = 0x08;
+       err = setsockopt(fd, SOL_IP, IP_TOS, buf, 1);
+       if (err) {
+               log_err("Failed to call setsockopt(IP_TOS)");
+               goto err;
+       }
+
+       buf[0] = 0x00;
+       optlen = 1;
+       err = getsockopt(fd, SOL_IP, IP_TOS, buf, &optlen);
+       if (err) {
+               log_err("Failed to call getsockopt(IP_TOS)");
+               goto err;
+       }
+
+       if (buf[0] != 0x08) {
+               log_err("Unexpected getsockopt(IP_TOS) buf[0] 0x%02x != 0x08",
+                       buf[0]);
+               goto err;
+       }
+
+       /* IP_TTL - EPERM */
+
+       buf[0] = 1;
+       err = setsockopt(fd, SOL_IP, IP_TTL, buf, 1);
+       if (!err || errno != EPERM) {
+               log_err("Unexpected success from setsockopt(IP_TTL)");
+               goto err;
+       }
+
+       /* SOL_CUSTOM - handled by BPF */
+
+       buf[0] = 0x01;
+       err = setsockopt(fd, SOL_CUSTOM, 0, buf, 1);
+       if (err) {
+               log_err("Failed to call setsockopt");
+               goto err;
+       }
+
+       buf[0] = 0x00;
+       optlen = 4;
+       err = getsockopt(fd, SOL_CUSTOM, 0, buf, &optlen);
+       if (err) {
+               log_err("Failed to call getsockopt");
+               goto err;
+       }
+
+       if (optlen != 1) {
+               log_err("Unexpected optlen %d != 1", optlen);
+               goto err;
+       }
+       if (buf[0] != 0x01) {
+               log_err("Unexpected buf[0] 0x%02x != 0x01", buf[0]);
+               goto err;
+       }
+
+       /* SO_SNDBUF is overwritten */
+
+       buf[0] = 0x01;
+       buf[1] = 0x01;
+       buf[2] = 0x01;
+       buf[3] = 0x01;
+       err = setsockopt(fd, SOL_SOCKET, SO_SNDBUF, buf, 4);
+       if (err) {
+               log_err("Failed to call setsockopt(SO_SNDBUF)");
+               goto err;
+       }
+
+       buf[0] = 0x00;
+       buf[1] = 0x00;
+       buf[2] = 0x00;
+       buf[3] = 0x00;
+       optlen = 4;
+       err = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, buf, &optlen);
+       if (err) {
+               log_err("Failed to call getsockopt(SO_SNDBUF)");
+               goto err;
+       }
+
+       if (*(__u32 *)buf != 0x55AA*2) {
+               log_err("Unexpected getsockopt(SO_SNDBUF) 0x%x != 0x55AA*2",
+                       *(__u32 *)buf);
+               goto err;
+       }
+
+       close(fd);
+       return 0;
+err:
+       close(fd);
+       return -1;
+}
+
+static int prog_attach(struct bpf_object *obj, int cgroup_fd, const char *title)
+{
+       enum bpf_attach_type attach_type;
+       enum bpf_prog_type prog_type;
+       struct bpf_program *prog;
+       int err;
+
+       err = libbpf_prog_type_by_name(title, &prog_type, &attach_type);
+       if (err) {
+               log_err("Failed to deduct types for %s BPF program", title);
+               return -1;
+       }
+
+       prog = bpf_object__find_program_by_title(obj, title);
+       if (!prog) {
+               log_err("Failed to find %s BPF program", title);
+               return -1;
+       }
+
+       err = bpf_prog_attach(bpf_program__fd(prog), cgroup_fd,
+                             attach_type, 0);
+       if (err) {
+               log_err("Failed to attach %s BPF program", title);
+               return -1;
+       }
+
+       return 0;
+}
+
+static int run_test(int cgroup_fd)
+{
+       struct bpf_prog_load_attr attr = {
+               .file = "./sockopt_sk.o",
+       };
+       struct bpf_object *obj;
+       int ignored;
+       int err;
+
+       err = bpf_prog_load_xattr(&attr, &obj, &ignored);
+       if (err) {
+               log_err("Failed to load BPF object");
+               return -1;
+       }
+
+       err = prog_attach(obj, cgroup_fd, "cgroup/getsockopt");
+       if (err)
+               goto close_bpf_object;
+
+       err = prog_attach(obj, cgroup_fd, "cgroup/setsockopt");
+       if (err)
+               goto close_bpf_object;
+
+       err = getsetsockopt();
+
+close_bpf_object:
+       bpf_object__close(obj);
+       return err;
+}
+
+int main(int args, char **argv)
+{
+       int cgroup_fd;
+       int err = EXIT_SUCCESS;
+
+       if (setup_cgroup_environment())
+               goto cleanup_obj;
+
+       cgroup_fd = create_and_get_cgroup(CG_PATH);
+       if (cgroup_fd < 0)
+               goto cleanup_cgroup_env;
+
+       if (join_cgroup(CG_PATH))
+               goto cleanup_cgroup;
+
+       if (run_test(cgroup_fd))
+               err = EXIT_FAILURE;
+
+       printf("test_sockopt_sk: %s\n",
+              err == EXIT_SUCCESS ? "PASSED" : "FAILED");
+
+cleanup_cgroup:
+       close(cgroup_fd);
+cleanup_cgroup_env:
+       cleanup_cgroup_environment();
+cleanup_obj:
+       return err;
+}