From 37f1ba0909dfa12c75f8e8ea7a2f01355ebd60f1 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Sun, 5 Nov 2017 08:15:34 -0500 Subject: [PATCH] selftests/bpf: add a test for device cgroup controller Add a test for device cgroup controller. The test loads a simple bpf program which logs all device access attempts using trace_printk() and forbids all operations except operations with /dev/zero and /dev/urandom. Then the test creates and joins a test cgroup, and attaches the bpf program to it. Then it tries to perform some simple device operations and checks the result: create /dev/null (should fail) create /dev/zero (should pass) copy data from /dev/urandom to /dev/zero (should pass) copy data from /dev/urandom to /dev/full (should fail) copy data from /dev/random to /dev/zero (should fail) Signed-off-by: Roman Gushchin Acked-by: Alexei Starovoitov Acked-by: Tejun Heo Cc: Daniel Borkmann Signed-off-by: David S. Miller --- tools/testing/selftests/bpf/Makefile | 4 +- tools/testing/selftests/bpf/dev_cgroup.c | 60 ++++++++++++ tools/testing/selftests/bpf/test_dev_cgroup.c | 93 +++++++++++++++++++ 3 files changed, 155 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/bpf/dev_cgroup.c create mode 100644 tools/testing/selftests/bpf/test_dev_cgroup.c diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 9fbb02638198..333a48655ee0 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -13,11 +13,11 @@ CFLAGS += -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(GENDIR) $(GENFLAGS) -I../../../i LDLIBS += -lcap -lelf TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \ - test_align test_verifier_log + test_align test_verifier_log test_dev_cgroup TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test_obj_id.o \ test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o \ - sockmap_verdict_prog.o + sockmap_verdict_prog.o dev_cgroup.o TEST_PROGS := test_kmod.sh test_xdp_redirect.sh test_xdp_meta.sh diff --git a/tools/testing/selftests/bpf/dev_cgroup.c b/tools/testing/selftests/bpf/dev_cgroup.c new file mode 100644 index 000000000000..ce41a3475f27 --- /dev/null +++ b/tools/testing/selftests/bpf/dev_cgroup.c @@ -0,0 +1,60 @@ +/* Copyright (c) 2017 Facebook + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + */ + +#include +#include +#include "bpf_helpers.h" + +SEC("cgroup/dev") +int bpf_prog1(struct bpf_cgroup_dev_ctx *ctx) +{ + short type = ctx->access_type & 0xFFFF; +#ifdef DEBUG + short access = ctx->access_type >> 16; + char fmt[] = " %d:%d \n"; + + switch (type) { + case BPF_DEVCG_DEV_BLOCK: + fmt[0] = 'b'; + break; + case BPF_DEVCG_DEV_CHAR: + fmt[0] = 'c'; + break; + default: + fmt[0] = '?'; + break; + } + + if (access & BPF_DEVCG_ACC_READ) + fmt[8] = 'r'; + + if (access & BPF_DEVCG_ACC_WRITE) + fmt[9] = 'w'; + + if (access & BPF_DEVCG_ACC_MKNOD) + fmt[10] = 'm'; + + bpf_trace_printk(fmt, sizeof(fmt), ctx->major, ctx->minor); +#endif + + /* Allow access to /dev/zero and /dev/random. + * Forbid everything else. + */ + if (ctx->major != 1 || type != BPF_DEVCG_DEV_CHAR) + return 0; + + switch (ctx->minor) { + case 5: /* 1:5 /dev/zero */ + case 9: /* 1:9 /dev/urandom */ + return 1; + } + + return 0; +} + +char _license[] SEC("license") = "GPL"; +__u32 _version SEC("version") = LINUX_VERSION_CODE; diff --git a/tools/testing/selftests/bpf/test_dev_cgroup.c b/tools/testing/selftests/bpf/test_dev_cgroup.c new file mode 100644 index 000000000000..02c85d6c89b0 --- /dev/null +++ b/tools/testing/selftests/bpf/test_dev_cgroup.c @@ -0,0 +1,93 @@ +/* Copyright (c) 2017 Facebook + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + */ + +#include +#include +#include +#include +#include + +#include +#include +#include + +#include "cgroup_helpers.h" + +#define DEV_CGROUP_PROG "./dev_cgroup.o" + +#define TEST_CGROUP "test-bpf-based-device-cgroup/" + +int main(int argc, char **argv) +{ + struct bpf_object *obj; + int error = EXIT_FAILURE; + int prog_fd, cgroup_fd; + __u32 prog_cnt; + + if (bpf_prog_load(DEV_CGROUP_PROG, BPF_PROG_TYPE_CGROUP_DEVICE, + &obj, &prog_fd)) { + printf("Failed to load DEV_CGROUP program\n"); + goto err; + } + + if (setup_cgroup_environment()) { + printf("Failed to load DEV_CGROUP program\n"); + goto err; + } + + /* Create a cgroup, get fd, and join it */ + cgroup_fd = create_and_get_cgroup(TEST_CGROUP); + if (!cgroup_fd) { + printf("Failed to create test cgroup\n"); + goto err; + } + + if (join_cgroup(TEST_CGROUP)) { + printf("Failed to join cgroup\n"); + goto err; + } + + /* Attach bpf program */ + if (bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_DEVICE, 0)) { + printf("Failed to attach DEV_CGROUP program"); + goto err; + } + + if (bpf_prog_query(cgroup_fd, BPF_CGROUP_DEVICE, 0, NULL, NULL, + &prog_cnt)) { + printf("Failed to query attached programs"); + goto err; + } + + /* All operations with /dev/zero and and /dev/urandom are allowed, + * everything else is forbidden. + */ + assert(system("rm -f /tmp/test_dev_cgroup_null") == 0); + assert(system("mknod /tmp/test_dev_cgroup_null c 1 3")); + assert(system("rm -f /tmp/test_dev_cgroup_null") == 0); + + /* /dev/zero is whitelisted */ + assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0); + assert(system("mknod /tmp/test_dev_cgroup_zero c 1 5") == 0); + assert(system("rm -f /tmp/test_dev_cgroup_zero") == 0); + + assert(system("dd if=/dev/urandom of=/dev/zero count=64") == 0); + + /* src is allowed, target is forbidden */ + assert(system("dd if=/dev/urandom of=/dev/full count=64")); + + /* src is forbidden, target is allowed */ + assert(system("dd if=/dev/random of=/dev/zero count=64")); + + error = 0; + printf("test_dev_cgroup:PASS\n"); + +err: + cleanup_cgroup_environment(); + + return error; +}