lkml.org 
[lkml]   [2014]   [May]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v2 3/3] selftests: add memfd_create() + sealing tests
From
Hi

On Tue, May 20, 2014 at 4:22 AM, Hugh Dickins <hughd@google.com> wrote:
> On Tue, 15 Apr 2014, David Herrmann wrote:
>
>> Some basic tests to verify sealing on memfds works as expected and
>> guarantees the advertised semantics.
>
> Thanks for providing these.
>
> A few remarks below, and I should note one oddity.
>
> Curious about leaks (probably none, I was merely curious), I tried to
> run memfd_test 4096 times in succession, and never succeeded. After
> many iterations, the 32-bit one tends to hang somewhere just before
> reaching the DONE, and the 64-bit one gave me some kind of assert
> error from a library.
>
> I expect there's some threading race around join_idle_thread():
> which I think you will sort out infinitely sooner than I would.
> No need to fix it right now: the test works well enough.

Ugh, I will look into that. Didn't see anything obvious so far.

>>
>> Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
>> ---
>> tools/testing/selftests/Makefile | 1 +
>> tools/testing/selftests/memfd/.gitignore | 2 +
>> tools/testing/selftests/memfd/Makefile | 29 +
>> tools/testing/selftests/memfd/memfd_test.c | 944 +++++++++++++++++++++++++++++
>> 4 files changed, 976 insertions(+)
>> create mode 100644 tools/testing/selftests/memfd/.gitignore
>> create mode 100644 tools/testing/selftests/memfd/Makefile
>> create mode 100644 tools/testing/selftests/memfd/memfd_test.c
>>
>> diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
>> index 32487ed..c57325a 100644
>> --- a/tools/testing/selftests/Makefile
>> +++ b/tools/testing/selftests/Makefile
>> @@ -2,6 +2,7 @@ TARGETS = breakpoints
>> TARGETS += cpu-hotplug
>> TARGETS += efivarfs
>> TARGETS += kcmp
>> +TARGETS += memfd
>> TARGETS += memory-hotplug
>> TARGETS += mqueue
>> TARGETS += net
>> diff --git a/tools/testing/selftests/memfd/.gitignore b/tools/testing/selftests/memfd/.gitignore
>> new file mode 100644
>> index 0000000..bcc8ee2
>> --- /dev/null
>> +++ b/tools/testing/selftests/memfd/.gitignore
>> @@ -0,0 +1,2 @@
>> +memfd_test
>> +memfd-test-file
>> diff --git a/tools/testing/selftests/memfd/Makefile b/tools/testing/selftests/memfd/Makefile
>> new file mode 100644
>> index 0000000..36653b9
>> --- /dev/null
>> +++ b/tools/testing/selftests/memfd/Makefile
>> @@ -0,0 +1,29 @@
>> +uname_M := $(shell uname -m 2>/dev/null || echo not)
>> +ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/i386/)
>> +ifeq ($(ARCH),i386)
>> + ARCH := X86
>> +endif
>> +ifeq ($(ARCH),x86_64)
>> + ARCH := X86
>> +endif
>> +
>> +CFLAGS += -I../../../../arch/x86/include/generated/uapi/
>> +CFLAGS += -I../../../../arch/x86/include/uapi/
>> +CFLAGS += -I../../../../include/uapi/
>> +CFLAGS += -I../../../../include/
>> +
>> +all:
>> +ifeq ($(ARCH),X86)
>> + gcc $(CFLAGS) memfd_test.c -o memfd_test
>> +else
>> + echo "Not an x86 target, can't build memfd selftest"
>> +endif
>> +
>> +run_tests: all
>> +ifeq ($(ARCH),X86)
>> + gcc $(CFLAGS) memfd_test.c -o memfd_test
>> +endif
>> + @./memfd_test || echo "memfd_test: [FAIL]"
>> +
>> +clean:
>> + $(RM) memfd_test
>> diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c
>> new file mode 100644
>> index 0000000..3e105ea
>> --- /dev/null
>> +++ b/tools/testing/selftests/memfd/memfd_test.c
>> @@ -0,0 +1,944 @@
>> +#define _GNU_SOURCE
>> +#define __EXPORTED_HEADERS__
>> +
>> +#include <errno.h>
>> +#include <inttypes.h>
>> +#include <limits.h>
>> +#include <linux/falloc.h>
>> +#include <linux/fcntl.h>
>> +#include <linux/memfd.h>
>> +#include <sched.h>
>> +#include <stdio.h>
>> +#include <stdlib.h>
>> +#include <signal.h>
>> +#include <string.h>
>> +#include <sys/mman.h>
>> +#include <sys/stat.h>
>> +#include <sys/syscall.h>
>> +#include <unistd.h>
>> +
>> +#define MFD_DEF_SIZE 8192
>> +#define STACK_SIZE 65535
>> +
>> +static int sys_memfd_create(const char *name,
>> + __u64 size,
>> + __u64 flags)
>> +{
>> + return syscall(__NR_memfd_create, name, size, flags);
>> +}
>> +
>> +static int mfd_assert_new(const char *name, __u64 sz, __u64 flags)
>> +{
>> + int r;
>> +
>> + r = sys_memfd_create(name, sz, flags);
>> + if (r < 0) {
>> + printf("memfd_create(\"%s\", %llu, %llu) failed: %m\n",
>> + name,
>> + (unsigned long long)sz,
>> + (unsigned long long)flags);
>> + abort();
>> + }
>> +
>> + return r;
>> +}
>> +
>> +static void mfd_fail_new(const char *name, __u64 size, __u64 flags)
>> +{
>> + int r;
>> +
>> + r = sys_memfd_create(name, size, flags);
>> + if (r >= 0) {
>> + printf("memfd_create(\"%s\", %llu, %llu) succeeded, but failure expected\n",
>
> scripts/checkpatch.pl complains about line-length: please ignore it on this.
>
>> + name,
>> + (unsigned long long)size,
>> + (unsigned long long)flags);
>> + close(r);
>> + abort();
>> + }
>> +}
>> +
>> +static __u64 mfd_assert_get_seals(int fd)
>> +{
>> + long r;
>> +
>> + r = fcntl(fd, F_GET_SEALS);
>> + if (r < 0) {
>> + printf("GET_SEALS(%d) failed: %m\n", fd);
>> + abort();
>> + }
>> +
>> + return r;
>> +}
>> +
>> +static void mfd_fail_get_seals(int fd)
>> +{
>> + long r;
>> +
>> + r = fcntl(fd, F_GET_SEALS);
>> + if (r >= 0) {
>> + printf("GET_SEALS(%d) succeeded, but failure expected\n");
>> + abort();
>> + }
>> +}
>> +
>> +static void mfd_assert_has_seals(int fd, __u64 seals)
>> +{
>> + __u64 s;
>> +
>> + s = mfd_assert_get_seals(fd);
>> + if (s != seals) {
>> + printf("%llu != %llu = GET_SEALS(%d)\n",
>> + (unsigned long long)seals, (unsigned long long)s, fd);
>> + abort();
>> + }
>> +}
>> +
>> +static void mfd_assert_add_seals(int fd, __u64 seals)
>> +{
>> + long r;
>> + __u64 s;
>> +
>> + s = mfd_assert_get_seals(fd);
>> + r = fcntl(fd, F_ADD_SEALS, seals);
>> + if (r < 0) {
>> + printf("ADD_SEALS(%d, %llu -> %llu) failed: %m\n",
>> + fd, (unsigned long long)s, (unsigned long long)seals);
>> + abort();
>> + }
>> +}
>> +
>> +static void mfd_fail_add_seals(int fd, __u64 seals)
>> +{
>> + long r;
>> + __u64 s;
>> +
>> + r = fcntl(fd, F_GET_SEALS);
>> + if (r < 0)
>> + s = 0;
>> + else
>> + s = r;
>> +
>> + r = fcntl(fd, F_ADD_SEALS, seals);
>> + if (r >= 0) {
>> + printf("ADD_SEALS(%d, %llu -> %llu) didn't fail as expected\n",
>> + fd, (unsigned long long)s, (unsigned long long)seals);
>> + abort();
>> + }
>> +}
>> +
>> +static void mfd_assert_size(int fd, size_t size)
>> +{
>> + struct stat st;
>> + int r;
>> +
>> + r = fstat(fd, &st);
>> + if (r < 0) {
>> + printf("fstat(%d) failed: %m\n", fd);
>> + abort();
>> + } else if (st.st_size != size) {
>> + printf("wrong file size %lld, but expected %lld\n",
>> + (long long)st.st_size, (long long)size);
>> + abort();
>> + }
>> +}
>> +
>> +static int mfd_assert_dup(int fd)
>> +{
>> + int r;
>> +
>> + r = dup(fd);
>> + if (r < 0) {
>> + printf("dup(%d) failed: %m\n", fd);
>> + abort();
>> + }
>> +
>> + return r;
>> +}
>> +
>> +static void *mfd_assert_mmap_shared(int fd)
>> +{
>> + void *p;
>> +
>> + p = mmap(NULL,
>> + MFD_DEF_SIZE,
>> + PROT_READ | PROT_WRITE,
>> + MAP_SHARED,
>> + fd,
>> + 0);
>> + if (p == MAP_FAILED) {
>> + printf("mmap() failed: %m\n");
>> + abort();
>> + }
>> +
>> + return p;
>> +}
>> +
>> +static void *mfd_assert_mmap_private(int fd)
>> +{
>> + void *p;
>> +
>> + p = mmap(NULL,
>> + MFD_DEF_SIZE,
>> + PROT_READ,
>> + MAP_PRIVATE,
>> + fd,
>> + 0);
>> + if (p == MAP_FAILED) {
>> + printf("mmap() failed: %m\n");
>> + abort();
>> + }
>> +
>> + return p;
>> +}
>> +
>> +static int mfd_assert_open(int fd, int flags, mode_t mode)
>> +{
>> + char buf[512];
>> + int r;
>> +
>> + sprintf(buf, "/proc/self/fd/%d", fd);
>> + r = open(buf, flags, mode);
>> + if (r < 0) {
>> + printf("open(%s) failed: %m\n", buf);
>> + abort();
>> + }
>> +
>> + return r;
>> +}
>> +
>> +static void mfd_fail_open(int fd, int flags, mode_t mode)
>> +{
>> + char buf[512];
>> + int r;
>> +
>> + sprintf(buf, "/proc/self/fd/%d", fd);
>> + r = open(buf, flags, mode);
>> + if (r >= 0) {
>> + printf("open(%s) didn't fail as expected\n");
>> + abort();
>> + }
>> +}
>> +
>> +static void mfd_assert_read(int fd)
>> +{
>> + char buf[16];
>> + void *p;
>> + ssize_t l;
>> +
>> + l = read(fd, buf, sizeof(buf));
>> + if (l != sizeof(buf)) {
>> + printf("read() failed: %m\n");
>> + abort();
>> + }
>> +
>> + /* verify PROT_READ *is* allowed */
>> + p = mmap(NULL,
>> + MFD_DEF_SIZE,
>> + PROT_READ,
>> + MAP_PRIVATE,
>> + fd,
>> + 0);
>> + if (p == MAP_FAILED) {
>> + printf("mmap() failed: %m\n");
>> + abort();
>> + }
>> + munmap(p, MFD_DEF_SIZE);
>> +
>> + /* verify MAP_PRIVATE is *always* allowed (even writable) */
>> + p = mmap(NULL,
>> + MFD_DEF_SIZE,
>> + PROT_READ | PROT_WRITE,
>> + MAP_PRIVATE,
>> + fd,
>> + 0);
>> + if (p == MAP_FAILED) {
>> + printf("mmap() failed: %m\n");
>> + abort();
>> + }
>> + munmap(p, MFD_DEF_SIZE);
>> +}
>> +
>> +static void mfd_assert_write(int fd)
>> +{
>> + ssize_t l;
>> + void *p;
>> + int r;
>> +
>> + /* verify write() succeeds */
>> + l = write(fd, "\0\0\0\0", 4);
>> + if (l != 4) {
>> + printf("write() failed: %m\n");
>> + abort();
>> + }
>> +
>> + /* verify PROT_READ | PROT_WRITE is allowed */
>> + p = mmap(NULL,
>> + MFD_DEF_SIZE,
>> + PROT_READ | PROT_WRITE,
>> + MAP_SHARED,
>> + fd,
>> + 0);
>> + if (p == MAP_FAILED) {
>> + printf("mmap() failed: %m\n");
>> + abort();
>> + }
>> + *(char*)p = 0;
>
> scripts/checkpatch.pl complains about (char*): better calm it with (char *).
> Same on two other lines below.
>
>> + munmap(p, MFD_DEF_SIZE);
>> +
>> + /* verify PROT_WRITE is allowed */
>> + p = mmap(NULL,
>> + MFD_DEF_SIZE,
>> + PROT_WRITE,
>> + MAP_SHARED,
>> + fd,
>> + 0);
>> + if (p == MAP_FAILED) {
>> + printf("mmap() failed: %m\n");
>> + abort();
>> + }
>> + *(char*)p = 0;
>> + munmap(p, MFD_DEF_SIZE);
>> +
>> + /* verify PROT_READ with MAP_SHARED is allowed and a following
>> + * mprotect(PROT_WRITE) allows writing */
>> + p = mmap(NULL,
>> + MFD_DEF_SIZE,
>> + PROT_READ,
>> + MAP_SHARED,
>> + fd,
>> + 0);
>> + if (p == MAP_FAILED) {
>> + printf("mmap() failed: %m\n");
>> + abort();
>> + }
>> +
>> + r = mprotect(p, MFD_DEF_SIZE, PROT_READ | PROT_WRITE);
>> + if (r < 0) {
>> + printf("mprotect() failed: %m\n");
>> + abort();
>> + }
>> +
>> + *(char*)p = 0;
>> + munmap(p, MFD_DEF_SIZE);
>> +
>> + /* verify PUNCH_HOLE works */
>> + r = fallocate(fd,
>> + FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
>> + 0,
>> + MFD_DEF_SIZE);
>> + if (r < 0) {
>> + printf("fallocate(PUNCH_HOLE) failed: %m\n");
>> + abort();
>> + }
>> +}
>> +
>> +static void mfd_fail_write(int fd)
>> +{
>> + ssize_t l;
>> + void *p;
>> + int r;
>> +
>> + /* verify write() fails */
>> + l = write(fd, "data", 4);
>> + if (l != -EPERM) {
>> + printf("expected EPERM on write(), but got %d: %m\n", (int)l);
>> + abort();
>> + }
>> +
>> + /* verify PROT_READ | PROT_WRITE is not allowed */
>> + p = mmap(NULL,
>> + MFD_DEF_SIZE,
>> + PROT_READ | PROT_WRITE,
>> + MAP_SHARED,
>> + fd,
>> + 0);
>> + if (p != MAP_FAILED) {
>> + printf("mmap() didn't fail as expected\n");
>> + abort();
>> + }
>> +
>> + /* verify PROT_WRITE is not allowed */
>> + p = mmap(NULL,
>> + MFD_DEF_SIZE,
>> + PROT_WRITE,
>> + MAP_SHARED,
>> + fd,
>> + 0);
>> + if (p != MAP_FAILED) {
>> + printf("mmap() didn't fail as expected\n");
>> + abort();
>> + }
>> +
>> + /* verify PROT_READ with MAP_SHARED is not allowed */
>
> This is a particularly interesting case, checking PROT_READ,MAP_SHARED
> not allowed in mfd_fail_write(). It feels invidious to ask for more
> of a comment, in a test which you have been generous to provide at all.
> But it stopped me short for a while: more comment might help others too.
>
> The reason being (right?) that this fd was opened O_RDWR, so a
> MAP_SHARED mapping would permit a subsequent mprotect(,,PROT_WRITE),
> which sealing the file against writes must prevent.
>
> Your kernel checks rely on VM_SHARED and i_mmap_writable for this
> protection: which is fine, but an implementation detail which could
> be modified in future, if this case were ever to pose a difficulty.

Yes indeed, this is meant to catch VM_MAYWRITE. Currently, every
mmap(MAP_SHARED) on a writable FD allows mprotect(PROT_WRITE) later
on. I thought that's hard-coded ABI so I rely on it here. But I can
definitely add a comment mentioning VM_MAYWRITE.

Given that this test-case fails if I run mfd_fail_write() on a
read-only FD, I might even want to change it to run mmap()+mprotect().
This should clear up all doubts.

Thanks!
David

>> + p = mmap(NULL,
>> + MFD_DEF_SIZE,
>> + PROT_READ,
>> + MAP_SHARED,
>> + fd,
>> + 0);
>> + if (p != MAP_FAILED) {
>> + printf("mmap() didn't fail as expected\n");
>> + abort();
>> + }
>> +
>> + /* verify PUNCH_HOLE fails */
>> + r = fallocate(fd,
>> + FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
>> + 0,
>> + MFD_DEF_SIZE);
>> + if (r >= 0) {
>> + printf("fallocate(PUNCH_HOLE) didn't fail as expected\n");
>> + abort();
>> + }
>> +}
>> +
>> +static void mfd_assert_shrink(int fd)
>> +{
>> + int r, fd2;
>> +
>> + r = ftruncate(fd, MFD_DEF_SIZE / 2);
>> + if (r < 0) {
>> + printf("ftruncate(SHRINK) failed: %m\n");
>> + abort();
>> + }
>> +
>> + mfd_assert_size(fd, MFD_DEF_SIZE / 2);
>> +
>> + fd2 = mfd_assert_open(fd,
>> + O_RDWR | O_CREAT | O_TRUNC,
>> + S_IRUSR | S_IWUSR);
>> + close(fd2);
>> +
>> + mfd_assert_size(fd, 0);
>> +}
>> +
>> +static void mfd_fail_shrink(int fd)
>> +{
>> + int r;
>> +
>> + r = ftruncate(fd, MFD_DEF_SIZE / 2);
>> + if (r >= 0) {
>> + printf("ftruncate(SHRINK) didn't fail as expected\n");
>> + abort();
>> + }
>> +
>> + mfd_fail_open(fd,
>> + O_RDWR | O_CREAT | O_TRUNC,
>> + S_IRUSR | S_IWUSR);
>> +}
>> +
>> +static void mfd_assert_grow(int fd)
>> +{
>> + int r;
>> +
>> + r = ftruncate(fd, MFD_DEF_SIZE * 2);
>> + if (r < 0) {
>> + printf("ftruncate(GROW) failed: %m\n");
>> + abort();
>> + }
>> +
>> + mfd_assert_size(fd, MFD_DEF_SIZE * 2);
>> +
>> + r = fallocate(fd,
>> + 0,
>> + 0,
>> + MFD_DEF_SIZE * 4);
>> + if (r < 0) {
>> + printf("fallocate(ALLOC) failed: %m\n");
>> + abort();
>> + }
>> +
>> + mfd_assert_size(fd, MFD_DEF_SIZE * 4);
>> +}
>> +
>> +static void mfd_fail_grow(int fd)
>> +{
>> + int r;
>> +
>> + r = ftruncate(fd, MFD_DEF_SIZE * 2);
>> + if (r >= 0) {
>> + printf("ftruncate(GROW) didn't fail as expected\n");
>> + abort();
>> + }
>> +
>> + r = fallocate(fd,
>> + 0,
>> + 0,
>> + MFD_DEF_SIZE * 4);
>> + if (r >= 0) {
>> + printf("fallocate(ALLOC) didn't fail as expected\n");
>> + abort();
>> + }
>> +}
>> +
>> +static void mfd_assert_grow_write(int fd)
>> +{
>> + static char buf[MFD_DEF_SIZE * 8];
>> + ssize_t l;
>> +
>> + l = pwrite(fd, buf, sizeof(buf), 0);
>> + if (l != sizeof(buf)) {
>> + printf("pwrite() failed: %m\n");
>> + abort();
>> + }
>> +
>> + mfd_assert_size(fd, MFD_DEF_SIZE * 8);
>> +}
>> +
>> +static void mfd_fail_grow_write(int fd)
>> +{
>> + static char buf[MFD_DEF_SIZE * 8];
>> + ssize_t l;
>> +
>> + l = pwrite(fd, buf, sizeof(buf), 0);
>> + if (l == sizeof(buf)) {
>> + printf("pwrite() didn't fail as expected\n");
>> + abort();
>> + }
>> +}
>> +
>> +static int idle_thread_fn(void *arg)
>> +{
>> + sigset_t set;
>> + int sig;
>> +
>> + /* dummy waiter; SIGTERM terminates us anyway */
>> + sigemptyset(&set);
>> + sigaddset(&set, SIGTERM);
>> + sigwait(&set, &sig);
>> +
>> + return 0;
>> +}
>> +
>> +static pid_t spawn_idle_thread(void)
>> +{
>> + uint8_t *stack;
>> + pid_t pid;
>> +
>> + stack = malloc(STACK_SIZE);
>> + if (!stack) {
>> + printf("malloc(STACK_SIZE) failed: %m\n");
>> + abort();
>> + }
>> +
>> + pid = clone(idle_thread_fn,
>> + stack + STACK_SIZE,
>> + CLONE_FILES | CLONE_FS | CLONE_VM | SIGCHLD,
>> + NULL);
>> + if (pid < 0) {
>> + printf("clone() failed: %m\n");
>> + abort();
>> + }
>> +
>> + return pid;
>> +}
>> +
>> +static void join_idle_thread(pid_t pid)
>> +{
>> + kill(pid, SIGTERM);
>> + waitpid(pid, NULL, 0);
>> +}
>> +
>> +static pid_t spawn_idle_proc(void)
>> +{
>> + pid_t pid;
>> + sigset_t set;
>> + int sig;
>> +
>> + pid = fork();
>> + if (pid < 0) {
>> + printf("fork() failed: %m\n");
>> + abort();
>> + } else if (!pid) {
>> + /* dummy waiter; SIGTERM terminates us anyway */
>> + sigemptyset(&set);
>> + sigaddset(&set, SIGTERM);
>> + sigwait(&set, &sig);
>> + exit(0);
>> + }
>> +
>> + return pid;
>> +}
>> +
>> +static void join_idle_proc(pid_t pid)
>> +{
>> + kill(pid, SIGTERM);
>> + waitpid(pid, NULL, 0);
>> +}
>> +
>> +/*
>> + * Test memfd_create() syscall
>> + * Verify syscall-argument validation, including name checks, flag validation
>> + * and more.
>> + */
>> +static void test_create(void)
>> +{
>> + char buf[2048];
>> + int fd;
>> +
>> + /* test NULL name */
>> + mfd_fail_new(NULL, 0, 0);
>> +
>> + /* test over-long name (not zero-terminated) */
>> + memset(buf, 0xff, sizeof(buf));
>> + mfd_fail_new(buf, 0, 0);
>> +
>> + /* test over-long zero-terminated name */
>> + memset(buf, 0xff, sizeof(buf));
>> + buf[sizeof(buf) - 1] = 0;
>> + mfd_fail_new(buf, 0, 0);
>> +
>> + /* verify "" is a valid name */
>> + fd = mfd_assert_new("", 0, 0);
>> + close(fd);
>> +
>> + /* verify invalid O_* open flags */
>> + mfd_fail_new("", 0, 0x0100);
>> + mfd_fail_new("", 0, ~MFD_CLOEXEC);
>> + mfd_fail_new("", 0, ~MFD_ALLOW_SEALING);
>> + mfd_fail_new("", 0, ~0);
>> + mfd_fail_new("", 0, 0x8000000000000000ULL);
>> +
>> + /* verify MFD_CLOEXEC is allowed */
>> + fd = mfd_assert_new("", 0, MFD_CLOEXEC);
>> + close(fd);
>> +
>> + /* verify MFD_ALLOW_SEALING is allowed */
>> + fd = mfd_assert_new("", 0, MFD_ALLOW_SEALING);
>> + close(fd);
>> +
>> + /* verify MFD_ALLOW_SEALING | MFD_CLOEXEC is allowed */
>> + fd = mfd_assert_new("", 0, MFD_ALLOW_SEALING | MFD_CLOEXEC);
>> + close(fd);
>> +}
>> +
>> +/*
>> + * Test basic sealing
>> + * A very basic sealing test to see whether setting/retrieving seals works.
>> + */
>> +static void test_basic(void)
>> +{
>> + int fd;
>> +
>> + fd = mfd_assert_new("kern_memfd_basic",
>> + MFD_DEF_SIZE,
>> + MFD_CLOEXEC | MFD_ALLOW_SEALING);
>> +
>> + /* add basic seals */
>> + mfd_assert_has_seals(fd, 0);
>> + mfd_assert_add_seals(fd, F_SEAL_SHRINK |
>> + F_SEAL_WRITE);
>> + mfd_assert_has_seals(fd, F_SEAL_SHRINK |
>> + F_SEAL_WRITE);
>> +
>> + /* add them again */
>> + mfd_assert_add_seals(fd, F_SEAL_SHRINK |
>> + F_SEAL_WRITE);
>> + mfd_assert_has_seals(fd, F_SEAL_SHRINK |
>> + F_SEAL_WRITE);
>> +
>> + /* add more seals and seal against sealing */
>> + mfd_assert_add_seals(fd, F_SEAL_GROW | F_SEAL_SEAL);
>> + mfd_assert_has_seals(fd, F_SEAL_SHRINK |
>> + F_SEAL_GROW |
>> + F_SEAL_WRITE |
>> + F_SEAL_SEAL);
>> +
>> + /* verify that sealing no longer works */
>> + mfd_fail_add_seals(fd, F_SEAL_GROW);
>> + mfd_fail_add_seals(fd, 0);
>> +
>> + close(fd);
>> +
>> + /* verify sealing does not work without MFD_ALLOW_SEALING */
>> + fd = mfd_assert_new("kern_memfd_basic",
>> + MFD_DEF_SIZE,
>> + MFD_CLOEXEC);
>> + mfd_fail_get_seals(fd);
>> + mfd_fail_add_seals(fd, F_SEAL_SHRINK |
>> + F_SEAL_GROW |
>> + F_SEAL_WRITE);
>> + mfd_fail_get_seals(fd);
>> + close(fd);
>> +}
>> +
>> +/*
>> + * Test SEAL_WRITE
>> + * Test whether SEAL_WRITE actually prevents modifications.
>> + */
>> +static void test_seal_write(void)
>> +{
>> + int fd;
>> +
>> + fd = mfd_assert_new("kern_memfd_seal_write",
>> + MFD_DEF_SIZE,
>> + MFD_CLOEXEC | MFD_ALLOW_SEALING);
>> + mfd_assert_has_seals(fd, 0);
>> + mfd_assert_add_seals(fd, F_SEAL_WRITE);
>> + mfd_assert_has_seals(fd, F_SEAL_WRITE);
>> +
>> + mfd_assert_read(fd);
>> + mfd_fail_write(fd);
>> + mfd_assert_shrink(fd);
>> + mfd_assert_grow(fd);
>> + mfd_fail_grow_write(fd);
>> +
>> + close(fd);
>> +}
>> +
>> +/*
>> + * Test SEAL_SHRINK
>> + * Test whether SEAL_SHRINK actually prevents shrinking
>> + */
>> +static void test_seal_shrink(void)
>> +{
>> + int fd;
>> +
>> + fd = mfd_assert_new("kern_memfd_seal_shrink",
>> + MFD_DEF_SIZE,
>> + MFD_CLOEXEC | MFD_ALLOW_SEALING);
>> + mfd_assert_has_seals(fd, 0);
>> + mfd_assert_add_seals(fd, F_SEAL_SHRINK);
>> + mfd_assert_has_seals(fd, F_SEAL_SHRINK);
>> +
>> + mfd_assert_read(fd);
>> + mfd_assert_write(fd);
>> + mfd_fail_shrink(fd);
>> + mfd_assert_grow(fd);
>> + mfd_assert_grow_write(fd);
>> +
>> + close(fd);
>> +}
>> +
>> +/*
>> + * Test SEAL_GROW
>> + * Test whether SEAL_GROW actually prevents growing
>> + */
>> +static void test_seal_grow(void)
>> +{
>> + int fd;
>> +
>> + fd = mfd_assert_new("kern_memfd_seal_grow",
>> + MFD_DEF_SIZE,
>> + MFD_CLOEXEC | MFD_ALLOW_SEALING);
>> + mfd_assert_has_seals(fd, 0);
>> + mfd_assert_add_seals(fd, F_SEAL_GROW);
>> + mfd_assert_has_seals(fd, F_SEAL_GROW);
>> +
>> + mfd_assert_read(fd);
>> + mfd_assert_write(fd);
>> + mfd_assert_shrink(fd);
>> + mfd_fail_grow(fd);
>> + mfd_fail_grow_write(fd);
>> +
>> + close(fd);
>> +}
>> +
>> +/*
>> + * Test SEAL_SHRINK | SEAL_GROW
>> + * Test whether SEAL_SHRINK | SEAL_GROW actually prevents resizing
>> + */
>> +static void test_seal_resize(void)
>> +{
>> + int fd;
>> +
>> + fd = mfd_assert_new("kern_memfd_seal_resize",
>> + MFD_DEF_SIZE,
>> + MFD_CLOEXEC | MFD_ALLOW_SEALING);
>> + mfd_assert_has_seals(fd, 0);
>> + mfd_assert_add_seals(fd, F_SEAL_SHRINK | F_SEAL_GROW);
>> + mfd_assert_has_seals(fd, F_SEAL_SHRINK | F_SEAL_GROW);
>> +
>> + mfd_assert_read(fd);
>> + mfd_assert_write(fd);
>> + mfd_fail_shrink(fd);
>> + mfd_fail_grow(fd);
>> + mfd_fail_grow_write(fd);
>> +
>> + close(fd);
>> +}
>> +
>> +/*
>> + * Test sharing via dup()
>> + * Test that seals are shared between dupped FDs and they're all equal.
>> + */
>> +static void test_share_dup(void)
>> +{
>> + int fd, fd2;
>> +
>> + fd = mfd_assert_new("kern_memfd_share_dup",
>> + MFD_DEF_SIZE,
>> + MFD_CLOEXEC | MFD_ALLOW_SEALING);
>> + mfd_assert_has_seals(fd, 0);
>> +
>> + fd2 = mfd_assert_dup(fd);
>> + mfd_assert_has_seals(fd2, 0);
>> +
>> + mfd_assert_add_seals(fd, F_SEAL_WRITE);
>> + mfd_assert_has_seals(fd, F_SEAL_WRITE);
>> + mfd_assert_has_seals(fd2, F_SEAL_WRITE);
>> +
>> + mfd_assert_add_seals(fd2, F_SEAL_SHRINK);
>> + mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK);
>> + mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK);
>> +
>> + mfd_assert_add_seals(fd, F_SEAL_SEAL);
>> + mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL);
>> + mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL);
>> +
>> + mfd_fail_add_seals(fd, F_SEAL_GROW);
>> + mfd_fail_add_seals(fd2, F_SEAL_GROW);
>> + mfd_fail_add_seals(fd, F_SEAL_SEAL);
>> + mfd_fail_add_seals(fd2, F_SEAL_SEAL);
>> +
>> + close(fd2);
>> +
>> + mfd_fail_add_seals(fd, F_SEAL_GROW);
>> + close(fd);
>> +}
>> +
>> +/*
>> + * Test sealing with active mmap()s
>> + * Modifying seals is only allowed if no other mmap() refs exist.
>> + */
>> +static void test_share_mmap(void)
>> +{
>> + int fd;
>> + void *p;
>> +
>> + fd = mfd_assert_new("kern_memfd_share_mmap",
>> + MFD_DEF_SIZE,
>> + MFD_CLOEXEC | MFD_ALLOW_SEALING);
>> + mfd_assert_has_seals(fd, 0);
>> +
>> + /* shared/writable ref prevents sealing */
>> + p = mfd_assert_mmap_shared(fd);
>> + mfd_fail_add_seals(fd, F_SEAL_SHRINK);
>> + mfd_assert_has_seals(fd, 0);
>> + munmap(p, MFD_DEF_SIZE);
>> +
>> + /* readable ref allows sealing */
>> + p = mfd_assert_mmap_private(fd);
>> + mfd_assert_add_seals(fd, F_SEAL_SHRINK);
>> + mfd_assert_has_seals(fd, F_SEAL_SHRINK);
>> + munmap(p, MFD_DEF_SIZE);
>> +
>> + close(fd);
>> +}
>> +
>> +/*
>> + * Test sealing with open(/proc/self/fd/%d)
>> + * Via /proc we can get access to a separate file-context for the same memfd.
>> + * This is *not* like dup(), but like a real separate open(). Make sure the
>> + * semantics are as expected and we correctly check for RDONLY / WRONLY / RDWR.
>> + */
>> +static void test_share_open(void)
>> +{
>> + int fd, fd2;
>> +
>> + fd = mfd_assert_new("kern_memfd_share_open",
>> + MFD_DEF_SIZE,
>> + MFD_CLOEXEC | MFD_ALLOW_SEALING);
>> + mfd_assert_has_seals(fd, 0);
>> +
>> + fd2 = mfd_assert_open(fd, O_RDWR, 0);
>> + mfd_assert_add_seals(fd, F_SEAL_WRITE);
>> + mfd_assert_has_seals(fd, F_SEAL_WRITE);
>> + mfd_assert_has_seals(fd2, F_SEAL_WRITE);
>> +
>> + mfd_assert_add_seals(fd2, F_SEAL_SHRINK);
>> + mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK);
>> + mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK);
>> +
>> + close(fd);
>> + fd = mfd_assert_open(fd2, O_RDONLY, 0);
>> +
>> + mfd_fail_add_seals(fd, F_SEAL_SEAL);
>> + mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK);
>> + mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK);
>> +
>> + close(fd2);
>> + fd2 = mfd_assert_open(fd, O_RDWR, 0);
>> +
>> + mfd_assert_add_seals(fd2, F_SEAL_SEAL);
>> + mfd_assert_has_seals(fd, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL);
>> + mfd_assert_has_seals(fd2, F_SEAL_WRITE | F_SEAL_SHRINK | F_SEAL_SEAL);
>> +
>> + close(fd2);
>> + close(fd);
>> +}
>> +
>> +/*
>> + * Test sharing via fork()
>> + * Test whether seal-modifications work as expected with forked childs.
>> + */
>> +static void test_share_fork(void)
>> +{
>> + int fd;
>> + pid_t pid;
>> +
>> + fd = mfd_assert_new("kern_memfd_share_fork",
>> + MFD_DEF_SIZE,
>> + MFD_CLOEXEC | MFD_ALLOW_SEALING);
>> + mfd_assert_has_seals(fd, 0);
>> +
>> + pid = spawn_idle_proc();
>> + mfd_assert_add_seals(fd, F_SEAL_SEAL);
>> + mfd_assert_has_seals(fd, F_SEAL_SEAL);
>> +
>> + mfd_fail_add_seals(fd, F_SEAL_WRITE);
>> + mfd_assert_has_seals(fd, F_SEAL_SEAL);
>> +
>> + join_idle_proc(pid);
>> +
>> + mfd_fail_add_seals(fd, F_SEAL_WRITE);
>> + mfd_assert_has_seals(fd, F_SEAL_SEAL);
>> +
>> + close(fd);
>> +}
>> +
>> +int main(int argc, char **argv)
>> +{
>> + pid_t pid;
>> +
>> + printf("memfd: CREATE\n");
>> + test_create();
>> + printf("memfd: BASIC\n");
>> + test_basic();
>> +
>> + printf("memfd: SEAL-WRITE\n");
>> + test_seal_write();
>> + printf("memfd: SEAL-SHRINK\n");
>> + test_seal_shrink();
>> + printf("memfd: SEAL-GROW\n");
>> + test_seal_grow();
>> + printf("memfd: SEAL-RESIZE\n");
>> + test_seal_resize();
>> +
>> + printf("memfd: SHARE-DUP\n");
>> + test_share_dup();
>> + printf("memfd: SHARE-MMAP\n");
>> + test_share_mmap();
>> + printf("memfd: SHARE-OPEN\n");
>> + test_share_open();
>> + printf("memfd: SHARE-FORK\n");
>> + test_share_fork();
>> +
>> + /* Run test-suite in a multi-threaded environment with a shared
>> + * file-table. */
>> + pid = spawn_idle_thread();
>> + printf("memfd: SHARE-DUP (shared file-table)\n");
>> + test_share_dup();
>> + printf("memfd: SHARE-MMAP (shared file-table)\n");
>> + test_share_mmap();
>> + printf("memfd: SHARE-OPEN (shared file-table)\n");
>> + test_share_open();
>> + printf("memfd: SHARE-FORK (shared file-table)\n");
>> + test_share_fork();
>> + join_idle_thread(pid);
>> +
>> + printf("memfd: DONE\n");
>> +
>> + return 0;
>> +}
>> --
>> 1.9.2


\
 
 \ /
  Last update: 2014-05-23 20:01    [W:0.240 / U:22.472 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site