[v3,bpf-next,12/21] selftests/bpf: Test sysctl_get_current_value helper

Message ID	ea283f5ecf3f43e8b5fd0106d4dee3aeaff25ab0.1554485410.git.rdna@fb.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-fsdevel-owner@kernel.org> Smtp-Origin-Hostprefix: dev From: Andrey Ignatov <rdna@fb.com> Smtp-Origin-Hostname: dev082.prn2.facebook.com To: <netdev@vger.kernel.org> CC: Andrey Ignatov <rdna@fb.com>, <ast@kernel.org>, <daniel@iogearbox.net>, <guro@fb.com>, <kernel-team@fb.com>, Luis Chamberlain <mcgrof@kernel.org>, Kees Cook <keescook@chromium.org>, Alexey Dobriyan <adobriyan@gmail.com>, <linux-kernel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org> Smtp-Origin-Cluster: prn2c23 Subject: [PATCH v3 bpf-next 12/21] selftests/bpf: Test sysctl_get_current_value helper Date: Fri, 5 Apr 2019 12:35:34 -0700 Message-ID: <ea283f5ecf3f43e8b5fd0106d4dee3aeaff25ab0.1554485410.git.rdna@fb.com> In-Reply-To: <cover.1554485409.git.rdna@fb.com> References: <cover.1554485409.git.rdna@fb.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk
Series	bpf: Sysctl hook \| expand [v3,bpf-next,00/21] bpf: Sysctl hook [v3,bpf-next,01/21] bpf: Add base proto function for cgroup-bpf programs [v3,bpf-next,02/21] bpf: Sysctl hook [v3,bpf-next,03/21] bpf: Introduce bpf_sysctl_get_name helper [v3,bpf-next,04/21] bpf: Introduce bpf_sysctl_get_current_value helper [v3,bpf-next,05/21] bpf: Introduce bpf_sysctl_{get,set}_new_value helpers [v3,bpf-next,06/21] bpf: Add file_pos field to bpf_sysctl ctx [v3,bpf-next,07/21] bpf: Sync bpf.h to tools/ [v3,bpf-next,08/21] libbpf: Support sysctl hook [v3,bpf-next,09/21] selftests/bpf: Test sysctl section name [v3,bpf-next,10/21] selftests/bpf: Test BPF_CGROUP_SYSCTL [v3,bpf-next,11/21] selftests/bpf: Test bpf_sysctl_get_name helper [v3,bpf-next,12/21] selftests/bpf: Test sysctl_get_current_value helper [v3,bpf-next,13/21] selftests/bpf: Test bpf_sysctl_{get,set}_new_value helpers [v3,bpf-next,14/21] selftests/bpf: Test file_pos field in bpf_sysctl ctx [v3,bpf-next,15/21] bpf: Introduce ARG_PTR_TO_{INT,LONG} arg types [v3,bpf-next,16/21] bpf: Introduce bpf_strtol and bpf_strtoul helpers [v3,bpf-next,17/21] bpf: Sync bpf.h to tools/ [v3,bpf-next,18/21] selftests/bpf: Add sysctl and strtoX helpers to bpf_helpers.h [v3,bpf-next,19/21] selftests/bpf: Test ARG_PTR_TO_LONG arg type [v3,bpf-next,20/21] selftests/bpf: Test bpf_strtol and bpf_strtoul helpers [v3,bpf-next,21/21] selftests/bpf: C based test for sysctl and strtoX

diff --git a/tools/testing/selftests/bpf/test_sysctl.c b/tools/testing/selftests/bpf/test_sysctl.c index 2e7ef04503a8..9fb6560fa775 100644 --- a/tools/testing/selftests/bpf/test_sysctl.c +++ b/tools/testing/selftests/bpf/test_sysctl.c @@ -18,11 +18,13 @@ #define CG_PATH "/foo" #define MAX_INSNS 512 +#define FIXUP_SYSCTL_VALUE 0 char bpf_log_buf[BPF_LOG_BUF_SIZE]; struct sysctl_test { const char *descr; + size_t fixup_value_insn; struct bpf_insn insns[MAX_INSNS]; enum bpf_attach_type attach_type; const char *sysctl; @@ -350,6 +352,190 @@ static struct sysctl_test tests[] = { .open_flags = O_RDONLY, .result = SUCCESS, }, + { + .descr = "sysctl_get_current_value sysctl:read ok, gt", + .insns = { + /* sysctl_get_current_value arg2 (buf) */ + BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), + BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), + + /* sysctl_get_current_value arg3 (buf_len) */ + BPF_MOV64_IMM(BPF_REG_3, 8), + + /* sysctl_get_current_value(ctx, buf, buf_len) */ + BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), + + /* if (ret == expected && */ + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 6, 6), + + /* buf[0:6] == "Linux\n\0") */ + BPF_LD_IMM64(BPF_REG_8, 0x000a78756e694cULL), + BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), + BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), + + /* return ALLOW; */ + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_JMP_A(1), + + /* else return DENY; */ + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .attach_type = BPF_CGROUP_SYSCTL, + .sysctl = "kernel/ostype", + .open_flags = O_RDONLY, + .result = SUCCESS, + }, + { + .descr = "sysctl_get_current_value sysctl:read ok, eq", + .insns = { + /* sysctl_get_current_value arg2 (buf) */ + BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_STX_MEM(BPF_B, BPF_REG_7, BPF_REG_0, 7), + + BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), + + /* sysctl_get_current_value arg3 (buf_len) */ + BPF_MOV64_IMM(BPF_REG_3, 7), + + /* sysctl_get_current_value(ctx, buf, buf_len) */ + BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), + + /* if (ret == expected && */ + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 6, 6), + + /* buf[0:6] == "Linux\n\0") */ + BPF_LD_IMM64(BPF_REG_8, 0x000a78756e694cULL), + BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), + BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), + + /* return ALLOW; */ + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_JMP_A(1), + + /* else return DENY; */ + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .attach_type = BPF_CGROUP_SYSCTL, + .sysctl = "kernel/ostype", + .open_flags = O_RDONLY, + .result = SUCCESS, + }, + { + .descr = "sysctl_get_current_value sysctl:read E2BIG truncated", + .insns = { + /* sysctl_get_current_value arg2 (buf) */ + BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_STX_MEM(BPF_H, BPF_REG_7, BPF_REG_0, 6), + + BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), + + /* sysctl_get_current_value arg3 (buf_len) */ + BPF_MOV64_IMM(BPF_REG_3, 6), + + /* sysctl_get_current_value(ctx, buf, buf_len) */ + BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), + + /* if (ret == expected && */ + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -E2BIG, 6), + + /* buf[0:6] == "Linux\0") */ + BPF_LD_IMM64(BPF_REG_8, 0x000078756e694cULL), + BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), + BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), + + /* return ALLOW; */ + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_JMP_A(1), + + /* else return DENY; */ + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .attach_type = BPF_CGROUP_SYSCTL, + .sysctl = "kernel/ostype", + .open_flags = O_RDONLY, + .result = SUCCESS, + }, + { + .descr = "sysctl_get_current_value sysctl:read EINVAL", + .insns = { + /* sysctl_get_current_value arg2 (buf) */ + BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), + + BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), + + /* sysctl_get_current_value arg3 (buf_len) */ + BPF_MOV64_IMM(BPF_REG_3, 8), + + /* sysctl_get_current_value(ctx, buf, buf_len) */ + BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), + + /* if (ret == expected && */ + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, -EINVAL, 4), + + /* buf[0:8] is NUL-filled) */ + BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), + BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0, 2), + + /* return DENY; */ + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_JMP_A(1), + + /* else return ALLOW; */ + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_EXIT_INSN(), + }, + .attach_type = BPF_CGROUP_SYSCTL, + .sysctl = "net/ipv6/conf/lo/stable_secret", /* -EIO */ + .open_flags = O_RDONLY, + .result = OP_EPERM, + }, + { + .descr = "sysctl_get_current_value sysctl:write ok", + .fixup_value_insn = 6, + .insns = { + /* sysctl_get_current_value arg2 (buf) */ + BPF_MOV64_REG(BPF_REG_7, BPF_REG_10), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8), + + BPF_MOV64_REG(BPF_REG_2, BPF_REG_7), + + /* sysctl_get_current_value arg3 (buf_len) */ + BPF_MOV64_IMM(BPF_REG_3, 8), + + /* sysctl_get_current_value(ctx, buf, buf_len) */ + BPF_EMIT_CALL(BPF_FUNC_sysctl_get_current_value), + + /* if (ret == expected && */ + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 4, 6), + + /* buf[0:4] == expected) */ + BPF_LD_IMM64(BPF_REG_8, FIXUP_SYSCTL_VALUE), + BPF_LDX_MEM(BPF_DW, BPF_REG_9, BPF_REG_7, 0), + BPF_JMP_REG(BPF_JNE, BPF_REG_8, BPF_REG_9, 2), + + /* return DENY; */ + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_JMP_A(1), + + /* else return ALLOW; */ + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_EXIT_INSN(), + }, + .attach_type = BPF_CGROUP_SYSCTL, + .sysctl = "net/ipv4/route/mtu_expires", + .open_flags = O_WRONLY, + .newval = "600", /* same as default, should fail anyway */ + .result = OP_EPERM, + }, }; static size_t probe_prog_length(const struct bpf_insn *fp) @@ -362,6 +548,27 @@ static size_t probe_prog_length(const struct bpf_insn *fp) return len + 1; } +static int fixup_sysctl_value(const char *buf, size_t buf_len, + struct bpf_insn *prog, size_t insn_num) +{ + uint32_t value_num = 0; + uint8_t c, i; + + if (buf_len > sizeof(value_num)) { + log_err("Value is too big (%zd) to use in fixup", buf_len); + return -1; + } + + for (i = 0; i < buf_len; ++i) { + c = buf[i]; + value_num |= (c << i * 8); + } + + prog[insn_num].imm = value_num; + + return 0; +} + static int load_sysctl_prog(struct sysctl_test *test, const char *sysctl_path) { struct bpf_insn *prog = test->insns; @@ -374,6 +581,27 @@ static int load_sysctl_prog(struct sysctl_test *test, const char *sysctl_path) attr.insns_cnt = probe_prog_length(attr.insns); attr.license = "GPL"; + if (test->fixup_value_insn) { + char buf[128]; + ssize_t len; + int fd; + + fd = open(sysctl_path, O_RDONLY | O_CLOEXEC); + if (fd < 0) { + log_err("open(%s) failed", sysctl_path); + return -1; + } + len = read(fd, buf, sizeof(buf)); + if (len == -1) { + log_err("read(%s) failed", sysctl_path); + close(fd); + return -1; + } + close(fd); + if (fixup_sysctl_value(buf, len, prog, test->fixup_value_insn)) + return -1; + } + ret = bpf_load_program_xattr(&attr, bpf_log_buf, BPF_LOG_BUF_SIZE); if (ret < 0 && test->result != LOAD_REJECT) { log_err(">>> Loading program error.\n"

[v3,bpf-next,12/21] selftests/bpf: Test sysctl_get_current_value helper

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