Re: [PATCH net-next v6 10/11] bpf,landlock: Add tests for Landlock

From: Kees Cook
Date: Tue Apr 18 2017 - 19:17:02 EST

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On Tue, Mar 28, 2017 at 4:46 PM, MickaÃl SalaÃn <mic@xxxxxxxxxxx> wrote:
> Test basic context access, ptrace protection and filesystem event with
> multiple cases.
>
> Changes since v5:
> * add subtype test
> * add ptrace tests
> * split and rename files
> * cleanup and rebase
>
> Signed-off-by: MickaÃl SalaÃn <mic@xxxxxxxxxxx>
> Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> Cc: David S. Miller <davem@xxxxxxxxxxxxx>
> Cc: James Morris <james.l.morris@xxxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Cc: Serge E. Hallyn <serge@xxxxxxxxxx>
> Cc: Shuah Khan <shuah@xxxxxxxxxx>
> Cc: Will Drewry <wad@xxxxxxxxxxxx>
> ---
> tools/testing/selftests/Makefile | 1 +
> tools/testing/selftests/bpf/test_verifier.c | 64 +++++
> tools/testing/selftests/landlock/.gitignore | 4 +
> tools/testing/selftests/landlock/Makefile | 47 ++++
> tools/testing/selftests/landlock/rules/Makefile | 52 ++++
> tools/testing/selftests/landlock/rules/README.rst | 1 +
> .../testing/selftests/landlock/rules/bpf_helpers.h | 1 +
> .../testing/selftests/landlock/rules/fs_no_open.c | 31 +++
> .../selftests/landlock/rules/fs_read_only.c | 31 +++
> tools/testing/selftests/landlock/test.h | 35 +++
> tools/testing/selftests/landlock/test_base.c | 31 +++
> tools/testing/selftests/landlock/test_fs.c | 305 +++++++++++++++++++++
> tools/testing/selftests/landlock/test_ptrace.c | 161 +++++++++++
> 13 files changed, 764 insertions(+)
> create mode 100644 tools/testing/selftests/landlock/.gitignore
> create mode 100644 tools/testing/selftests/landlock/Makefile
> create mode 100644 tools/testing/selftests/landlock/rules/Makefile
> create mode 120000 tools/testing/selftests/landlock/rules/README.rst
> create mode 120000 tools/testing/selftests/landlock/rules/bpf_helpers.h
> create mode 100644 tools/testing/selftests/landlock/rules/fs_no_open.c
> create mode 100644 tools/testing/selftests/landlock/rules/fs_read_only.c
> create mode 100644 tools/testing/selftests/landlock/test.h
> create mode 100644 tools/testing/selftests/landlock/test_base.c
> create mode 100644 tools/testing/selftests/landlock/test_fs.c
> create mode 100644 tools/testing/selftests/landlock/test_ptrace.c
>
> diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
> index d8593f1251ec..b584ad456428 100644
> --- a/tools/testing/selftests/Makefile
> +++ b/tools/testing/selftests/Makefile
> @@ -12,6 +12,7 @@ TARGETS += gpio
> TARGETS += intel_pstate
> TARGETS += ipc
> TARGETS += kcmp
> +TARGETS += landlock
> TARGETS += lib
> TARGETS += membarrier
> TARGETS += memfd
> diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
> index daa87dd7c80e..77255b14871e 100644
> --- a/tools/testing/selftests/bpf/test_verifier.c
> +++ b/tools/testing/selftests/bpf/test_verifier.c
> @@ -4536,6 +4536,70 @@ static struct bpf_test tests[] = {
> .result = REJECT,
> .has_prog_subtype = true,
> },
> + {
> + "missing subtype",
> + .insns = {
> + BPF_MOV32_IMM(BPF_REG_0, 0),
> + BPF_EXIT_INSN(),
> + },
> + .errstr = "",
> + .result = REJECT,
> + .prog_type = BPF_PROG_TYPE_LANDLOCK,
> + },
> + {
> + "landlock/fs: always accept",
> + .insns = {
> + BPF_MOV32_IMM(BPF_REG_0, 0),
> + BPF_EXIT_INSN(),
> + },
> + .result = ACCEPT,
> + .prog_type = BPF_PROG_TYPE_LANDLOCK,
> + .has_prog_subtype = true,
> + .prog_subtype = {
> + .landlock_rule = {
> + .version = 1,
> + .event = LANDLOCK_SUBTYPE_EVENT_FS,
> + }
> + },
> + },
> + {
> + "landlock/fs: read context",
> + .insns = {
> + BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
> + BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_6,
> + offsetof(struct landlock_context, status)),
> + /* test operations on raw values */
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, 1),
> + BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
> + offsetof(struct landlock_context, arch)),
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, 1),
> + BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
> + offsetof(struct landlock_context, syscall_nr)),
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, 1),
> + BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
> + offsetof(struct landlock_context, syscall_cmd)),
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, 1),
> + BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
> + offsetof(struct landlock_context, event)),
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, 1),
> + BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_6,
> + offsetof(struct landlock_context, arg1)),
> + BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_6,
> + offsetof(struct landlock_context, arg2)),
> + BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, 1),
> + BPF_MOV32_IMM(BPF_REG_0, 0),
> + BPF_EXIT_INSN(),
> + },
> + .result = ACCEPT,
> + .prog_type = BPF_PROG_TYPE_LANDLOCK,
> + .has_prog_subtype = true,
> + .prog_subtype = {
> + .landlock_rule = {
> + .version = 1,
> + .event = LANDLOCK_SUBTYPE_EVENT_FS,
> + }
> + },
> + },
> };
>
> static int probe_filter_length(const struct bpf_insn *fp)
> diff --git a/tools/testing/selftests/landlock/.gitignore b/tools/testing/selftests/landlock/.gitignore
> new file mode 100644
> index 000000000000..25b9cd834c3c
> --- /dev/null
> +++ b/tools/testing/selftests/landlock/.gitignore
> @@ -0,0 +1,4 @@
> +/test_base
> +/test_fs
> +/test_ptrace
> +/tmp_*
> diff --git a/tools/testing/selftests/landlock/Makefile b/tools/testing/selftests/landlock/Makefile
> new file mode 100644
> index 000000000000..9a52c82d64fa
> --- /dev/null
> +++ b/tools/testing/selftests/landlock/Makefile
> @@ -0,0 +1,47 @@
> +LIBDIR := ../../../lib
> +BPFOBJ := $(LIBDIR)/bpf/bpf.o
> +LOADOBJ := ../../../../samples/bpf/bpf_load.o

Is the selftest tarball creation tool okay with this? IIRC, it should
be fine since it'll be a built object already, but it's a random
thought I had while looking at this.

> +
> +CFLAGS += -Wl,-no-as-needed -Wall -O2 -I../../../include/uapi -I$(LIBDIR)
> +LDFLAGS += -lelf
> +
> +test_src = $(wildcard test_*.c)
> +rule_src = $(wildcard rules/*.c)
> +
> +test_objs := $(test_src:.c=)
> +rule_objs := $(rule_src:.c=.o)
> +
> +TEST_PROGS := $(test_objs)
> +
> +.PHONY: all clean clean_tmp force
> +
> +all: $(test_objs) $(rule_objs)
> +
> +# force a rebuild of BPFOBJ when its dependencies are updated
> +force:
> +
> +$(BPFOBJ): force
> + $(MAKE) -C $(dir $(BPFOBJ))
> +
> +$(LOADOBJ):
> + $(MAKE) -C $(dir $(LOADOBJ))
> +
> +# minimize builds
> +rules/modules.order: $(rule_src)
> + $(MAKE) -C rules
> + @touch $@
> +
> +$(rule_objs): rules/modules.order
> + @
> +
> +$(test_objs): $(BPFOBJ) $(LOADOBJ)
> +
> +include ../lib.mk
> +
> +clean_tmp:
> + $(RM) -r tmp_*
> +
> +clean: clean_tmp
> + $(MAKE) -C rules clean
> + $(RM) $(test_objs)
> +
> diff --git a/tools/testing/selftests/landlock/rules/Makefile b/tools/testing/selftests/landlock/rules/Makefile
> new file mode 100644
> index 000000000000..8d6ff960ff7c
> --- /dev/null
> +++ b/tools/testing/selftests/landlock/rules/Makefile
> @@ -0,0 +1,52 @@
> +# kbuild trick to avoid linker error. Can be omitted if a module is built.
> +obj- := dummy.o
> +
> +# Tell kbuild to always build the programs
> +always := fs_read_only.o
> +always += fs_no_open.o
> +
> +EXTRA_CFLAGS = -Wall -Wextra
> +
> +# Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
> +# make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
> +LLC ?= llc
> +CLANG ?= clang
> +
> +# Verify LLVM compiler tools are available and bpf target is supported by llc
> +.PHONY: all clean verify_cmds verify_target_bpf $(CLANG) $(LLC)
> +
> +# Trick to allow make to be run from this directory
> +all:
> + $(MAKE) -C ../../../../../ $(CURDIR)/
> +
> +clean:
> + $(MAKE) -C ../../../../../ M=$(CURDIR) clean

Is this really needed? Others don't have it, I think.

> +verify_cmds: $(CLANG) $(LLC)
> + @for TOOL in $^ ; do \
> + if ! (which -- "$${TOOL}" > /dev/null 2>&1); then \
> + echo "*** ERROR: Cannot find LLVM tool $${TOOL}" ;\
> + exit 1; \
> + else true; fi; \
> + done
> +
> +verify_target_bpf: verify_cmds
> + @if ! (${LLC} -march=bpf -mattr=help > /dev/null 2>&1); then \
> + echo "*** ERROR: LLVM (${LLC}) does not support 'bpf' target" ;\
> + echo " NOTICE: LLVM version >= 3.7.1 required" ;\
> + exit 2; \
> + else true; fi
> +
> +%_kern.c: verify_target_bpf
> +
> +# asm/sysreg.h - inline assembly used by it is incompatible with llvm.
> +# But, there is no easy way to fix it, so just exclude it since it is
> +# useless for BPF samples.
> +$(obj)/%.o: $(src)/%.c
> + $(CLANG) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \
> + -D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \
> + -Wno-compare-distinct-pointer-types \
> + -Wno-gnu-variable-sized-type-not-at-end \
> + -Wno-tautological-compare \
> + -O2 -emit-llvm -c $< -o -| $(LLC) -march=bpf -filetype=obj -o $@

Is clang required for the samples and the selftests? That needs to be
avoided... there needs to be a way to show people how to build a
landlock rule without requiring clang.

> +
> diff --git a/tools/testing/selftests/landlock/rules/README.rst b/tools/testing/selftests/landlock/rules/README.rst
> new file mode 120000
> index 000000000000..605f48aa6f72
> --- /dev/null
> +++ b/tools/testing/selftests/landlock/rules/README.rst
> @@ -0,0 +1 @@
> +../../../../../samples/bpf/README.rst
> \ No newline at end of file
> diff --git a/tools/testing/selftests/landlock/rules/bpf_helpers.h b/tools/testing/selftests/landlock/rules/bpf_helpers.h
> new file mode 120000
> index 000000000000..0aa1a521b39a
> --- /dev/null
> +++ b/tools/testing/selftests/landlock/rules/bpf_helpers.h
> @@ -0,0 +1 @@
> +../../../../../samples/bpf/bpf_helpers.h
> \ No newline at end of file
> diff --git a/tools/testing/selftests/landlock/rules/fs_no_open.c b/tools/testing/selftests/landlock/rules/fs_no_open.c
> new file mode 100644
> index 000000000000..c6ea305e58a7
> --- /dev/null
> +++ b/tools/testing/selftests/landlock/rules/fs_no_open.c
> @@ -0,0 +1,31 @@
> +/*
> + * Landlock rule - no-open filesystem
> + *
> + * Copyright Â 2017 MickaÃl SalaÃn <mic@xxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2, as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <uapi/linux/bpf.h>
> +#include "bpf_helpers.h"
> +
> +SEC("landlock1")
> +static int landlock_fs_prog1(struct landlock_context *ctx)
> +{
> + if (!(ctx->arg2 & LANDLOCK_ACTION_FS_GET))
> + return 0;
> + return 1;
> +}
> +
> +SEC("subtype")
> +static union bpf_prog_subtype _subtype = {
> + .landlock_rule = {
> + .version = 1,
> + .event = LANDLOCK_SUBTYPE_EVENT_FS,
> + }
> +};
> +
> +SEC("license")
> +static const char _license[] = "GPL";
> diff --git a/tools/testing/selftests/landlock/rules/fs_read_only.c b/tools/testing/selftests/landlock/rules/fs_read_only.c
> new file mode 100644
> index 000000000000..212dda7c0c27
> --- /dev/null
> +++ b/tools/testing/selftests/landlock/rules/fs_read_only.c
> @@ -0,0 +1,31 @@
> +/*
> + * Landlock rule - read-only filesystem
> + *
> + * Copyright Â 2017 MickaÃl SalaÃn <mic@xxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2, as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <uapi/linux/bpf.h>
> +#include "bpf_helpers.h"
> +
> +SEC("landlock1")
> +static int landlock_fs_prog1(struct landlock_context *ctx)
> +{
> + if (!(ctx->arg2 & LANDLOCK_ACTION_FS_WRITE))
> + return 0;
> + return 1;
> +}
> +
> +SEC("subtype")
> +static union bpf_prog_subtype _subtype = {
> + .landlock_rule = {
> + .version = 1,
> + .event = LANDLOCK_SUBTYPE_EVENT_FS,
> + }
> +};
> +
> +SEC("license")
> +static const char _license[] = "GPL";
> diff --git a/tools/testing/selftests/landlock/test.h b/tools/testing/selftests/landlock/test.h
> new file mode 100644
> index 000000000000..7a194815391b
> --- /dev/null
> +++ b/tools/testing/selftests/landlock/test.h
> @@ -0,0 +1,35 @@
> +/*
> + * Landlock helpers
> + *
> + * Copyright Â 2017 MickaÃl SalaÃn <mic@xxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2, as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <errno.h>
> +#include <sys/prctl.h>
> +#include <sys/syscall.h>
> +
> +#include "../seccomp/test_harness.h"
> +#include "../../../../samples/bpf/bpf_load.h"
> +
> +#ifndef SECCOMP_APPEND_LANDLOCK_RULE
> +#define SECCOMP_APPEND_LANDLOCK_RULE 2
> +#endif
> +
> +#ifndef seccomp
> +static int seccomp(unsigned int op, unsigned int flags, void *args)
> +{
> + errno = 0;
> + return syscall(__NR_seccomp, op, flags, args);
> +}
> +#endif
> +
> +#define ASSERT_STEP(cond) \
> + { \
> + step--; \
> + if (!(cond)) \
> + _exit(step); \
> + }

Can you explain this in more detail? I'm assuming there is a problem
with writing to the TH_LOG_STREAM fd or something?

> diff --git a/tools/testing/selftests/landlock/test_base.c b/tools/testing/selftests/landlock/test_base.c
> new file mode 100644
> index 000000000000..bdf056edee03
> --- /dev/null
> +++ b/tools/testing/selftests/landlock/test_base.c
> @@ -0,0 +1,31 @@
> +/*
> + * Landlock tests - base
> + *
> + * Copyright Â 2017 MickaÃl SalaÃn <mic@xxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2, as
> + * published by the Free Software Foundation.
> + */
> +
> +#define _GNU_SOURCE
> +#include <errno.h>
> +
> +#include "test.h"
> +
> +TEST(seccomp_landlock)
> +{
> + int ret;
> +
> + ret = prctl(PR_SET_NO_NEW_PRIVS, 1, NULL, 0, 0);
> + ASSERT_EQ(0, ret) {
> + TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS");
> + }
> + ret = seccomp(SECCOMP_APPEND_LANDLOCK_RULE, 0, NULL);
> + EXPECT_EQ(-1, ret);
> + EXPECT_EQ(EFAULT, errno) {
> + TH_LOG("Kernel does not support CONFIG_SECURITY_LANDLOCK");
> + }
> +}
> +
> +TEST_HARNESS_MAIN
> diff --git a/tools/testing/selftests/landlock/test_fs.c b/tools/testing/selftests/landlock/test_fs.c
> new file mode 100644
> index 000000000000..e69eda433716
> --- /dev/null
> +++ b/tools/testing/selftests/landlock/test_fs.c
> @@ -0,0 +1,305 @@
> +/*
> + * Landlock tests - filesystem
> + *
> + * Copyright Â 2017 MickaÃl SalaÃn <mic@xxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2, as
> + * published by the Free Software Foundation.
> + */
> +
> +#define _GNU_SOURCE
> +#include <errno.h>
> +#include <linux/bpf.h>
> +#include <linux/filter.h>
> +#include <linux/seccomp.h>
> +#include <stddef.h>
> +#include <string.h>
> +#include <sys/prctl.h>
> +#include <sys/syscall.h>
> +
> +#include <fcntl.h> /* open() */
> +#include <sys/mount.h>
> +#include <sys/stat.h> /* mkdir() */
> +#include <sys/mman.h> /* mmap() */
> +
> +#include "test.h"
> +
> +#define TMP_PREFIX "tmp_"
> +
> +struct layout1 {
> + int file_ro;
> + int file_rw;
> + int file_wo;
> +};
> +
> +static void setup_layout1(struct __test_metadata *_metadata,
> + struct layout1 *l1)
> +{
> + int fd;
> + char buf[] = "fs_read_only";
> +
> + l1->file_ro = -1;
> + l1->file_rw = -1;
> + l1->file_wo = -1;
> +
> + fd = open(TMP_PREFIX "file_created",
> + O_CREAT | O_EXCL | O_WRONLY | O_CLOEXEC, 0600);
> + ASSERT_GE(fd, 0);
> + ASSERT_EQ(sizeof(buf), write(fd, buf, sizeof(buf)));
> + ASSERT_EQ(0, close(fd));
> +
> + fd = mkdir(TMP_PREFIX "dir_created", 0600);
> + ASSERT_GE(fd, 0);
> + ASSERT_EQ(0, close(fd));
> +
> + l1->file_ro = open(TMP_PREFIX "file_ro",
> + O_CREAT | O_EXCL | O_WRONLY | O_CLOEXEC, 0600);
> + ASSERT_LE(0, l1->file_ro);
> + ASSERT_EQ(sizeof(buf), write(l1->file_ro, buf, sizeof(buf)));
> + ASSERT_EQ(0, close(l1->file_ro));
> + l1->file_ro = open(TMP_PREFIX "file_ro",
> + O_RDONLY | O_CLOEXEC, 0600);
> + ASSERT_LE(0, l1->file_ro);
> +
> + l1->file_rw = open(TMP_PREFIX "file_rw",
> + O_CREAT | O_EXCL | O_RDWR | O_CLOEXEC, 0600);
> + ASSERT_LE(0, l1->file_rw);
> + ASSERT_EQ(sizeof(buf), write(l1->file_rw, buf, sizeof(buf)));
> + ASSERT_EQ(0, lseek(l1->file_rw, 0, SEEK_SET));
> +
> + l1->file_wo = open(TMP_PREFIX "file_wo",
> + O_CREAT | O_EXCL | O_WRONLY | O_CLOEXEC, 0600);
> + ASSERT_LE(0, l1->file_wo);
> + ASSERT_EQ(sizeof(buf), write(l1->file_wo, buf, sizeof(buf)));
> + ASSERT_EQ(0, lseek(l1->file_wo, 0, SEEK_SET));
> +}
> +
> +static void cleanup_layout1(void)
> +{
> + unlink(TMP_PREFIX "file_created");
> + unlink(TMP_PREFIX "file_ro");
> + unlink(TMP_PREFIX "file_rw");
> + unlink(TMP_PREFIX "file_wo");
> + unlink(TMP_PREFIX "should_not_exist");
> + rmdir(TMP_PREFIX "dir_created");
> +}
> +
> +FIXTURE(fs_read_only) {
> + struct layout1 l1;
> + int prog;
> +};
> +
> +FIXTURE_SETUP(fs_read_only)
> +{
> + cleanup_layout1();
> + setup_layout1(_metadata, &self->l1);
> +
> + ASSERT_EQ(0, load_bpf_file("rules/fs_read_only.o")) {
> + TH_LOG("%s", bpf_log_buf);
> + }
> + self->prog = prog_fd[0];
> + ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, NULL, 0, 0)) {
> + TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS");
> + }
> +}
> +
> +FIXTURE_TEARDOWN(fs_read_only)
> +{
> + EXPECT_EQ(0, close(self->prog));
> + /* cleanup_layout1() would be denied here */
> +}
> +
> +TEST_F(fs_read_only, load_prog) {}
> +
> +TEST_F(fs_read_only, read_only_file)
> +{
> + int fd;
> + int step = 0;
> + char buf_write[] = "should not be written";
> + char buf_read[2];
> +
> + ASSERT_EQ(-1, write(self->l1.file_ro, buf_write, sizeof(buf_write)));
> + ASSERT_EQ(EBADF, errno);
> +
> + ASSERT_EQ(-1, read(self->l1.file_wo, buf_read, sizeof(buf_read)));
> + ASSERT_EQ(EBADF, errno);
> +
> + ASSERT_EQ(0, seccomp(SECCOMP_APPEND_LANDLOCK_RULE, 0, &self->prog)) {
> + TH_LOG("Failed to apply rule fs_read_only: %s",
> + strerror(errno));
> + }
> +
> + fd = open(".", O_TMPFILE | O_EXCL | O_RDWR | O_CLOEXEC, 0600);
> + ASSERT_STEP(fd == -1);
> + ASSERT_STEP(errno != EOPNOTSUPP)
> + ASSERT_STEP(errno == EPERM);
> +
> + fd = open(TMP_PREFIX "file_created",
> + O_RDONLY | O_CLOEXEC);
> + ASSERT_STEP(fd >= 0);
> + ASSERT_STEP(!close(fd));
> +
> + fd = open(TMP_PREFIX "file_created",
> + O_RDWR | O_CLOEXEC);
> + ASSERT_STEP(fd == -1);
> + ASSERT_STEP(errno == EPERM);
> +
> + fd = open(TMP_PREFIX "file_created",
> + O_WRONLY | O_CLOEXEC);
> + ASSERT_STEP(fd == -1);
> + ASSERT_STEP(errno == EPERM);
> +
> + fd = open(TMP_PREFIX "should_not_exist",
> + O_CREAT | O_EXCL | O_CLOEXEC, 0600);
> + ASSERT_STEP(fd == -1);
> + ASSERT_STEP(errno == EPERM);
> +
> + ASSERT_STEP(-1 ==
> + write(self->l1.file_ro, buf_write, sizeof(buf_write)));
> + ASSERT_STEP(errno == EBADF);
> + ASSERT_STEP(sizeof(buf_read) ==
> + read(self->l1.file_ro, buf_read, sizeof(buf_read)));
> +
> + ASSERT_STEP(-1 ==
> + write(self->l1.file_rw, buf_write, sizeof(buf_write)));
> + ASSERT_STEP(errno == EPERM);
> + ASSERT_STEP(sizeof(buf_read) ==
> + read(self->l1.file_rw, buf_read, sizeof(buf_read)));
> +
> + ASSERT_STEP(-1 == write(self->l1.file_wo, buf_write, sizeof(buf_write)));
> + ASSERT_STEP(errno == EPERM);
> + ASSERT_STEP(-1 == read(self->l1.file_wo, buf_read, sizeof(buf_read)));
> + ASSERT_STEP(errno == EBADF);
> +
> + ASSERT_STEP(-1 == unlink(TMP_PREFIX "file_created"));
> + ASSERT_STEP(errno == EPERM);
> + ASSERT_STEP(-1 == rmdir(TMP_PREFIX "dir_created"));
> + ASSERT_STEP(errno == EPERM);
> +
> + ASSERT_STEP(0 == close(self->l1.file_ro));
> + ASSERT_STEP(0 == close(self->l1.file_rw));
> + ASSERT_STEP(0 == close(self->l1.file_wo));
> +}
> +
> +TEST_F(fs_read_only, read_only_mount)
> +{
> + int step = 0;
> +
> + ASSERT_EQ(0, mount(".", TMP_PREFIX "dir_created",
> + NULL, MS_BIND, NULL));
> + ASSERT_EQ(0, umount2(TMP_PREFIX "dir_created", MNT_FORCE));
> +
> + ASSERT_EQ(0, seccomp(SECCOMP_APPEND_LANDLOCK_RULE, 0, &self->prog)) {
> + TH_LOG("Failed to apply rule fs_read_only: %s",
> + strerror(errno));
> + }
> +
> + ASSERT_STEP(-1 == mount(".", TMP_PREFIX "dir_created",
> + NULL, MS_BIND, NULL));
> + ASSERT_STEP(errno == EPERM);
> + ASSERT_STEP(-1 == umount("/"));
> + ASSERT_STEP(errno == EPERM);
> +}
> +
> +TEST_F(fs_read_only, read_only_mem)
> +{
> + int step = 0;
> + void *addr;
> +
> + addr = mmap(NULL, 1, PROT_READ | PROT_WRITE,
> + MAP_SHARED, self->l1.file_rw, 0);
> + ASSERT_NE(NULL, addr);
> + ASSERT_EQ(0, munmap(addr, 1));
> +
> + ASSERT_EQ(0, seccomp(SECCOMP_APPEND_LANDLOCK_RULE, 0, &self->prog)) {
> + TH_LOG("Failed to apply rule fs_read_only: %s",
> + strerror(errno));
> + }
> +
> + addr = mmap(NULL, 1, PROT_READ, MAP_SHARED,
> + self->l1.file_rw, 0);
> + ASSERT_STEP(addr != NULL);
> + ASSERT_STEP(-1 == mprotect(addr, 1, PROT_WRITE));
> + ASSERT_STEP(errno == EPERM);
> + ASSERT_STEP(0 == munmap(addr, 1));
> +
> + addr = mmap(NULL, 1, PROT_READ | PROT_WRITE, MAP_SHARED,
> + self->l1.file_rw, 0);
> + ASSERT_STEP(addr != NULL);
> + ASSERT_STEP(errno == EPERM);
> +
> + addr = mmap(NULL, 1, PROT_READ | PROT_WRITE, MAP_PRIVATE,
> + self->l1.file_rw, 0);
> + ASSERT_STEP(addr != NULL);
> + ASSERT_STEP(0 == munmap(addr, 1));
> +}
> +
> +FIXTURE(fs_no_open) {
> + struct layout1 l1;
> + int prog;
> +};
> +
> +FIXTURE_SETUP(fs_no_open)
> +{
> + cleanup_layout1();
> + setup_layout1(_metadata, &self->l1);
> +
> + ASSERT_EQ(0, load_bpf_file("rules/fs_no_open.o")) {
> + TH_LOG("%s", bpf_log_buf);
> + }
> + self->prog = prog_fd[0];
> + ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, NULL, 0, 0)) {
> + TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS");
> + }
> +}
> +
> +FIXTURE_TEARDOWN(fs_no_open)
> +{
> + EXPECT_EQ(0, close(self->prog));
> + cleanup_layout1();
> +}
> +
> +static void landlocked_deny_open(struct __test_metadata *_metadata,
> + struct layout1 *l1)
> +{
> + int fd;
> + void *addr;
> +
> + fd = open(".", O_DIRECTORY | O_CLOEXEC);
> + ASSERT_EQ(-1, fd);
> + ASSERT_EQ(EPERM, errno);
> +
> + addr = mmap(NULL, 1, PROT_READ | PROT_WRITE,
> + MAP_SHARED, l1->file_rw, 0);
> + ASSERT_NE(NULL, addr);
> + ASSERT_EQ(0, munmap(addr, 1));
> +}
> +
> +TEST_F(fs_no_open, deny_open_for_hierarchy) {
> + int fd;
> + int status;
> + pid_t child;
> +
> + fd = open(".", O_DIRECTORY | O_CLOEXEC);
> + ASSERT_LE(0, fd);
> + ASSERT_EQ(0, close(fd));
> +
> + ASSERT_EQ(0, seccomp(SECCOMP_APPEND_LANDLOCK_RULE, 0, &self->prog)) {
> + TH_LOG("Failed to apply rule fs_no_open: %s", strerror(errno));
> + }
> +
> + landlocked_deny_open(_metadata, &self->l1);
> +
> + child = fork();
> + ASSERT_LE(0, child);
> + if (!child) {
> + landlocked_deny_open(_metadata, &self->l1);
> + _exit(1);
> + }
> + ASSERT_EQ(child, waitpid(child, &status, 0));
> + ASSERT_TRUE(WIFEXITED(status));
> + _exit(WEXITSTATUS(status));
> +}
> +
> +TEST_HARNESS_MAIN
> diff --git a/tools/testing/selftests/landlock/test_ptrace.c b/tools/testing/selftests/landlock/test_ptrace.c
> new file mode 100644
> index 000000000000..0c940a7fd3d0
> --- /dev/null
> +++ b/tools/testing/selftests/landlock/test_ptrace.c
> @@ -0,0 +1,161 @@
> +/*
> + * Landlock tests - ptrace
> + *
> + * Copyright Â 2017 MickaÃl SalaÃn <mic@xxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2, as
> + * published by the Free Software Foundation.
> + */
> +
> +#define _GNU_SOURCE
> +#include <signal.h> /* raise */
> +#include <sys/ptrace.h>
> +#include <sys/types.h> /* waitpid */
> +#include <sys/wait.h> /* waitpid */
> +#include <unistd.h> /* fork, pipe */
> +
> +#include "test.h"
> +
> +static void apply_null_sandbox(struct __test_metadata *_metadata)
> +{
> + const struct bpf_insn prog_accept[] = {
> + BPF_MOV32_IMM(BPF_REG_0, 0),
> + BPF_EXIT_INSN(),
> + };
> + const union bpf_prog_subtype subtype = {
> + .landlock_rule = {
> + .version = 1,
> + .event = LANDLOCK_SUBTYPE_EVENT_FS,
> + }
> + };
> + int prog;
> + char log[256] = "";
> +
> + prog = bpf_load_program(BPF_PROG_TYPE_LANDLOCK,
> + (const struct bpf_insn *)&prog_accept,
> + sizeof(prog_accept) / sizeof(struct bpf_insn), "GPL",
> + 0, log, sizeof(log), &subtype);
> + ASSERT_NE(-1, prog) {
> + TH_LOG("Failed to load minimal rule: %s\n%s",
> + strerror(errno), log);
> + }
> + ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, NULL, 0, 0)) {
> + TH_LOG("Kernel does not support PR_SET_NO_NEW_PRIVS");
> + }
> + ASSERT_EQ(0, seccomp(SECCOMP_APPEND_LANDLOCK_RULE, 0, &prog)) {
> + TH_LOG("Failed to apply minimal rule: %s", strerror(errno));
> + }
> + EXPECT_EQ(0, close(prog));
> +}
> +
> +/* PTRACE_TRACEME and PTRACE_ATTACH without Landlock rules effect */
> +static void check_ptrace(struct __test_metadata *_metadata,
> + int sandbox_both, int sandbox_parent, int sandbox_child,
> + int expect_ptrace)
> +{
> + pid_t child;
> + int status;
> + int pipefd[2];
> +
> + ASSERT_EQ(0, pipe(pipefd));
> + if (sandbox_both)
> + apply_null_sandbox(_metadata);
> +
> + child = fork();
> + ASSERT_LE(0, child);
> + if (child == 0) {
> + char buf;
> +
> + EXPECT_EQ(0, close(pipefd[1]));
> + if (sandbox_child)
> + apply_null_sandbox(_metadata);
> +
> + /* test traceme */
> + ASSERT_EQ(expect_ptrace, ptrace(PTRACE_TRACEME));
> + if (expect_ptrace) {
> + ASSERT_EQ(EPERM, errno);
> + } else {
> + ASSERT_EQ(0, raise(SIGSTOP));
> + }
> +
> + /* sync */
> + ASSERT_EQ(1, read(pipefd[0], &buf, 1)) {
> + TH_LOG("Failed to read() sync from parent");
> + }
> + ASSERT_EQ('.', buf);
> + _exit(_metadata->passed ? EXIT_SUCCESS : EXIT_FAILURE);
> + }
> +
> + EXPECT_EQ(0, close(pipefd[0]));
> + if (sandbox_parent)
> + apply_null_sandbox(_metadata);
> +
> + /* test traceme */
> + if (!expect_ptrace) {
> + ASSERT_EQ(child, waitpid(child, &status, 0));
> + ASSERT_EQ(1, WIFSTOPPED(status));
> + ASSERT_EQ(0, ptrace(PTRACE_DETACH, child, NULL, 0));
> + }
> + /* test attach */
> + ASSERT_EQ(expect_ptrace, ptrace(PTRACE_ATTACH, child, NULL, 0));
> + if (expect_ptrace) {
> + ASSERT_EQ(EPERM, errno);
> + } else {
> + ASSERT_EQ(child, waitpid(child, &status, 0));
> + ASSERT_EQ(1, WIFSTOPPED(status));
> + ASSERT_EQ(0, ptrace(PTRACE_CONT, child, NULL, 0));
> + }
> +
> + /* sync */
> + ASSERT_EQ(1, write(pipefd[1], ".", 1)) {
> + TH_LOG("Failed to write() sync to child");
> + }
> + ASSERT_EQ(child, waitpid(child, &status, 0));
> + if (WIFSIGNALED(status) || WEXITSTATUS(status))
> + _metadata->passed = 0;
> +}
> +
> +TEST(ptrace_allow_without_sandbox)
> +{
> + /* no sandbox */
> + check_ptrace(_metadata, 0, 0, 0, 0);
> +}
> +
> +TEST(ptrace_allow_with_one_sandbox)
> +{
> + /* child sandbox */
> + check_ptrace(_metadata, 0, 0, 1, 0);
> +}
> +
> +TEST(ptrace_allow_with_nested_sandbox)
> +{
> + /* inherited and child sandbox */
> + check_ptrace(_metadata, 1, 0, 1, 0);
> +}
> +
> +TEST(ptrace_deny_with_parent_sandbox)
> +{
> + /* parent sandbox */
> + check_ptrace(_metadata, 0, 1, 0, -1);
> +}
> +
> +TEST(ptrace_deny_with_nested_and_parent_sandbox)
> +{
> + /* inherited and parent sandbox */
> + check_ptrace(_metadata, 1, 1, 0, -1);
> +}
> +
> +TEST(ptrace_deny_with_forked_sandbox)
> +{
> + /* inherited, parent and child sandbox */
> + check_ptrace(_metadata, 1, 1, 1, -1);
> +}
> +
> +TEST(ptrace_deny_with_sibling_sandbox)
> +{
> + /* parent and child sandbox */
> + check_ptrace(_metadata, 0, 1, 1, -1);
> +}
> +
> +TEST_HARNESS_MAIN
> --
> 2.11.0
>

Awesome. I love to see all these tests, with both positive and
negative checks. Nice!

-Kees

--
Kees Cook
Pixel Security

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