2023-05-26 06:37:28

by Thomas Weißschuh

Subject: [PATCH 0/2] tools/nolibc: avoid coredumps and speed up tests

Small optimization to avoid coredump writing during the stack protector
tests.
Adds prctl() as prerequisite.

This series is based on nolibc/20230524-nolibc-rv32+stkp4

Signed-off-by: Thomas Weißschuh <[email protected]>
---
Thomas Weißschuh (2):
tools/nolibc: add support for prctl()
selftests/nolibc: prevent coredumps during test execution

tools/include/nolibc/sys.h | 27 +++++++++++++++++++++++++++
tools/testing/selftests/nolibc/nolibc-test.c | 3 +++
2 files changed, 30 insertions(+)
---
base-commit: 1974a2b5fd434812b32952b09df7b79fdee8104d
change-id: 20230526-nolibc-test-no-dump-a1b1d9557df8

Best regards,
--
Thomas Weißschuh <[email protected]>

2023-05-26 06:38:44

by Thomas Weißschuh

Subject: [PATCH 2/2] selftests/nolibc: prevent coredumps during test execution

The child process forked during stackprotector tests intentionally gets
killed with SIGABRT. By default this will trigger writing a coredump.
The writing of the coredump can spam the systems coredump machinery and
take some time.

Timings for the full run of nolibc-test:
Before: 200ms
After: 20ms

This is on a desktop x86 system with systemd-coredumpd enabled.

Signed-off-by: Thomas Weißschuh <[email protected]>
---
tools/testing/selftests/nolibc/nolibc-test.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 76a9a0f362b1..40fb684eaac9 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -831,6 +831,7 @@ static int run_protection(int min, int max)
close(STDOUT_FILENO);
close(STDERR_FILENO);

+ prctl(PR_SET_DUMPABLE, 0, 0, 0, 0);
smash_stack();
return 1;


--
2.40.1

2023-05-26 07:03:10

by Thomas Weißschuh

Subject: [PATCH 1/2] tools/nolibc: add support for prctl()

It will be used to disable core dumps from the child spawned to validate
the stack protector functionality.

Signed-off-by: Thomas Weißschuh <[email protected]>
---
tools/include/nolibc/sys.h | 27 +++++++++++++++++++++++++++
tools/testing/selftests/nolibc/nolibc-test.c | 2 ++
2 files changed, 29 insertions(+)

diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
index 7874062bea95..3d521feffad6 100644
--- a/tools/include/nolibc/sys.h
+++ b/tools/include/nolibc/sys.h
@@ -22,6 +22,7 @@
#include <linux/fcntl.h> /* for O_* and AT_* */
#include <linux/stat.h> /* for statx() */
#include <linux/reboot.h> /* for LINUX_REBOOT_* */
+#include <linux/prctl.h>

#include "arch.h"
#include "errno.h"
@@ -894,6 +895,32 @@ int open(const char *path, int flags, ...)
}


+/*
+ * int prctl(int option, unsigned long arg2, unsigned long arg3,
+ * unsigned long arg4, unsigned long arg5);
+ */
+
+static __attribute__((unused))
+int sys_prctl(int option, unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5)
+{
+ return my_syscall5(__NR_prctl, option, arg2, arg3, arg4, arg5);
+}
+
+static __attribute__((unused))
+int prctl(int option, unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5)
+{
+ int ret = sys_prctl(option, arg2, arg3, arg4, arg5);
+
+ if (ret < 0) {
+ SET_ERRNO(-ret);
+ ret = -1;
+ }
+ return ret;
+}
+
+
/*
* int pivot_root(const char *new, const char *old);
*/
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 6e0a4dbe321e..76a9a0f362b1 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -22,6 +22,7 @@
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/mount.h>
+#include <sys/prctl.h>
#include <sys/reboot.h>
#include <sys/stat.h>
#include <sys/syscall.h>
@@ -580,6 +581,7 @@ int run_syscall(int min, int max)
CASE_TEST(poll_null); EXPECT_SYSZR(1, poll(NULL, 0, 0)); break;
CASE_TEST(poll_stdout); EXPECT_SYSNE(1, ({ struct pollfd fds = { 1, POLLOUT, 0}; poll(&fds, 1, 0); }), -1); break;
CASE_TEST(poll_fault); EXPECT_SYSER(1, poll((void *)1, 1, 0), -1, EFAULT); break;
+ CASE_TEST(prctl); EXPECT_SYSER(1, prctl(PR_SET_NAME, NULL, 0, 0, 0), -1, EFAULT); break;
CASE_TEST(read_badf); EXPECT_SYSER(1, read(-1, &tmp, 1), -1, EBADF); break;
CASE_TEST(sched_yield); EXPECT_SYSZR(1, sched_yield()); break;
CASE_TEST(select_null); EXPECT_SYSZR(1, ({ struct timeval tv = { 0 }; select(0, NULL, NULL, NULL, &tv); })); break;

--
2.40.1

2023-05-28 07:35:49

by Willy Tarreau

Subject: Re: [PATCH 0/2] tools/nolibc: avoid coredumps and speed up tests

On Fri, May 26, 2023 at 08:30:34AM +0200, Thomas Wei?schuh wrote:
> Small optimization to avoid coredump writing during the stack protector
> tests.
> Adds prctl() as prerequisite.
>
> This series is based on nolibc/20230524-nolibc-rv32+stkp4

Looks good and now queued, thank you Thomas,
Willy