diff options
Diffstat (limited to 'samples/bpf/test_cgrp2_sock.c')
| -rw-r--r-- | samples/bpf/test_cgrp2_sock.c | 294 |
1 files changed, 294 insertions, 0 deletions
diff --git a/samples/bpf/test_cgrp2_sock.c b/samples/bpf/test_cgrp2_sock.c new file mode 100644 index 000000000..a0811df88 --- /dev/null +++ b/samples/bpf/test_cgrp2_sock.c @@ -0,0 +1,294 @@ +/* eBPF example program: + * + * - Loads eBPF program + * + * The eBPF program sets the sk_bound_dev_if index in new AF_INET{6} + * sockets opened by processes in the cgroup. + * + * - Attaches the new program to a cgroup using BPF_PROG_ATTACH + */ + +#define _GNU_SOURCE + +#include <stdio.h> +#include <stdlib.h> +#include <stddef.h> +#include <string.h> +#include <unistd.h> +#include <assert.h> +#include <errno.h> +#include <fcntl.h> +#include <net/if.h> +#include <inttypes.h> +#include <linux/bpf.h> +#include <bpf/bpf.h> + +#include "bpf_insn.h" + +char bpf_log_buf[BPF_LOG_BUF_SIZE]; + +static int prog_load(__u32 idx, __u32 mark, __u32 prio) +{ + /* save pointer to context */ + struct bpf_insn prog_start[] = { + BPF_MOV64_REG(BPF_REG_6, BPF_REG_1), + }; + struct bpf_insn prog_end[] = { + BPF_MOV64_IMM(BPF_REG_0, 1), /* r0 = verdict */ + BPF_EXIT_INSN(), + }; + + /* set sk_bound_dev_if on socket */ + struct bpf_insn prog_dev[] = { + BPF_MOV64_IMM(BPF_REG_3, idx), + BPF_MOV64_IMM(BPF_REG_2, offsetof(struct bpf_sock, bound_dev_if)), + BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3, offsetof(struct bpf_sock, bound_dev_if)), + }; + + /* set mark on socket */ + struct bpf_insn prog_mark[] = { + /* get uid of process */ + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, + BPF_FUNC_get_current_uid_gid), + BPF_ALU64_IMM(BPF_AND, BPF_REG_0, 0xffffffff), + + /* if uid is 0, use given mark, else use the uid as the mark */ + BPF_MOV64_REG(BPF_REG_3, BPF_REG_0), + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1), + BPF_MOV64_IMM(BPF_REG_3, mark), + + /* set the mark on the new socket */ + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), + BPF_MOV64_IMM(BPF_REG_2, offsetof(struct bpf_sock, mark)), + BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3, offsetof(struct bpf_sock, mark)), + }; + + /* set priority on socket */ + struct bpf_insn prog_prio[] = { + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), + BPF_MOV64_IMM(BPF_REG_3, prio), + BPF_MOV64_IMM(BPF_REG_2, offsetof(struct bpf_sock, priority)), + BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3, offsetof(struct bpf_sock, priority)), + }; + LIBBPF_OPTS(bpf_prog_load_opts, opts, + .log_buf = bpf_log_buf, + .log_size = BPF_LOG_BUF_SIZE, + ); + + struct bpf_insn *prog; + size_t insns_cnt; + void *p; + int ret; + + insns_cnt = sizeof(prog_start) + sizeof(prog_end); + if (idx) + insns_cnt += sizeof(prog_dev); + + if (mark) + insns_cnt += sizeof(prog_mark); + + if (prio) + insns_cnt += sizeof(prog_prio); + + p = prog = malloc(insns_cnt); + if (!prog) { + fprintf(stderr, "Failed to allocate memory for instructions\n"); + return EXIT_FAILURE; + } + + memcpy(p, prog_start, sizeof(prog_start)); + p += sizeof(prog_start); + + if (idx) { + memcpy(p, prog_dev, sizeof(prog_dev)); + p += sizeof(prog_dev); + } + + if (mark) { + memcpy(p, prog_mark, sizeof(prog_mark)); + p += sizeof(prog_mark); + } + + if (prio) { + memcpy(p, prog_prio, sizeof(prog_prio)); + p += sizeof(prog_prio); + } + + memcpy(p, prog_end, sizeof(prog_end)); + p += sizeof(prog_end); + + insns_cnt /= sizeof(struct bpf_insn); + + ret = bpf_prog_load(BPF_PROG_TYPE_CGROUP_SOCK, NULL, "GPL", + prog, insns_cnt, &opts); + + free(prog); + + return ret; +} + +static int get_bind_to_device(int sd, char *name, size_t len) +{ + socklen_t optlen = len; + int rc; + + name[0] = '\0'; + rc = getsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, name, &optlen); + if (rc < 0) + perror("setsockopt(SO_BINDTODEVICE)"); + + return rc; +} + +static unsigned int get_somark(int sd) +{ + unsigned int mark = 0; + socklen_t optlen = sizeof(mark); + int rc; + + rc = getsockopt(sd, SOL_SOCKET, SO_MARK, &mark, &optlen); + if (rc < 0) + perror("getsockopt(SO_MARK)"); + + return mark; +} + +static unsigned int get_priority(int sd) +{ + unsigned int prio = 0; + socklen_t optlen = sizeof(prio); + int rc; + + rc = getsockopt(sd, SOL_SOCKET, SO_PRIORITY, &prio, &optlen); + if (rc < 0) + perror("getsockopt(SO_PRIORITY)"); + + return prio; +} + +static int show_sockopts(int family) +{ + unsigned int mark, prio; + char name[16]; + int sd; + + sd = socket(family, SOCK_DGRAM, 17); + if (sd < 0) { + perror("socket"); + return 1; + } + + if (get_bind_to_device(sd, name, sizeof(name)) < 0) + return 1; + + mark = get_somark(sd); + prio = get_priority(sd); + + close(sd); + + printf("sd %d: dev %s, mark %u, priority %u\n", sd, name, mark, prio); + + return 0; +} + +static int usage(const char *argv0) +{ + printf("Usage:\n"); + printf(" Attach a program\n"); + printf(" %s -b bind-to-dev -m mark -p prio cg-path\n", argv0); + printf("\n"); + printf(" Detach a program\n"); + printf(" %s -d cg-path\n", argv0); + printf("\n"); + printf(" Show inherited socket settings (mark, priority, and device)\n"); + printf(" %s [-6]\n", argv0); + return EXIT_FAILURE; +} + +int main(int argc, char **argv) +{ + __u32 idx = 0, mark = 0, prio = 0; + const char *cgrp_path = NULL; + int cg_fd, prog_fd, ret; + int family = PF_INET; + int do_attach = 1; + int rc; + + while ((rc = getopt(argc, argv, "db:m:p:6")) != -1) { + switch (rc) { + case 'd': + do_attach = 0; + break; + case 'b': + idx = if_nametoindex(optarg); + if (!idx) { + idx = strtoumax(optarg, NULL, 0); + if (!idx) { + printf("Invalid device name\n"); + return EXIT_FAILURE; + } + } + break; + case 'm': + mark = strtoumax(optarg, NULL, 0); + break; + case 'p': + prio = strtoumax(optarg, NULL, 0); + break; + case '6': + family = PF_INET6; + break; + default: + return usage(argv[0]); + } + } + + if (optind == argc) + return show_sockopts(family); + + cgrp_path = argv[optind]; + if (!cgrp_path) { + fprintf(stderr, "cgroup path not given\n"); + return EXIT_FAILURE; + } + + if (do_attach && !idx && !mark && !prio) { + fprintf(stderr, + "One of device, mark or priority must be given\n"); + return EXIT_FAILURE; + } + + cg_fd = open(cgrp_path, O_DIRECTORY | O_RDONLY); + if (cg_fd < 0) { + printf("Failed to open cgroup path: '%s'\n", strerror(errno)); + return EXIT_FAILURE; + } + + if (do_attach) { + prog_fd = prog_load(idx, mark, prio); + if (prog_fd < 0) { + printf("Failed to load prog: '%s'\n", strerror(errno)); + printf("Output from kernel verifier:\n%s\n-------\n", + bpf_log_buf); + return EXIT_FAILURE; + } + + ret = bpf_prog_attach(prog_fd, cg_fd, + BPF_CGROUP_INET_SOCK_CREATE, 0); + if (ret < 0) { + printf("Failed to attach prog to cgroup: '%s'\n", + strerror(errno)); + return EXIT_FAILURE; + } + } else { + ret = bpf_prog_detach(cg_fd, BPF_CGROUP_INET_SOCK_CREATE); + if (ret < 0) { + printf("Failed to detach prog from cgroup: '%s'\n", + strerror(errno)); + return EXIT_FAILURE; + } + } + + close(cg_fd); + return EXIT_SUCCESS; +} |