[PATCH 1/2 v2] futex: adjust a futex timeout with a per-timens offset

[PATCH 1/2 v2] futex: adjust a futex timeout with a per-timens offset

[Andrei Vagin]

For all commands except FUTEX_WAIT, timeout is interpreted as an
absolute value. This absolute value is inside the task's time namespace
and has to be converted to the host's time.

Cc: <stable@vger.kernel.org>
Fixes: 5a590f35add9 ("posix-clocks: Wire up clock_gettime() with timens offsets")
Reported-by: Hans van der Laan <j.h.vanderlaan@student.utwente.nl>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
---

v2:
* check FUTEX_CLOCK_REALTIME properly
* fix futex_time32 too

 kernel/futex.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/futex.c b/kernel/futex.c
index a5876694a60e..32056d2d4171 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -39,6 +39,7 @@
 #include <linux/freezer.h>
 #include <linux/memblock.h>
 #include <linux/fault-inject.h>
+#include <linux/time_namespace.h>
 
 #include <asm/futex.h>
 
@@ -3797,6 +3798,8 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
 		t = timespec64_to_ktime(ts);
 		if (cmd == FUTEX_WAIT)
 			t = ktime_add_safe(ktime_get(), t);
+		else if (!(op & FUTEX_CLOCK_REALTIME))
+			t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
 		tp = &t;
 	}
 	/*
@@ -3989,6 +3992,8 @@ SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
 		t = timespec64_to_ktime(ts);
 		if (cmd == FUTEX_WAIT)
 			t = ktime_add_safe(ktime_get(), t);
+		else if (!(op & FUTEX_CLOCK_REALTIME))
+			t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
 		tp = &t;
 	}
 	if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
-- 
2.26.2

[PATCH 2/2 v2] selftests/timens: Add a test for futex()

[Andrei Vagin]

Output on success:
 1..2
 ok 1 futex with the 0 clockid
 ok 2 futex with the 1 clockid
 # Totals: pass:2 fail:0 xfail:0 xpass:0 skip:0 error:0

Signed-off-by: Andrei Vagin <avagin@gmail.com>
---
v2: extend the test to check FUTEX_CLOCK_REALTIME

 tools/testing/selftests/timens/Makefile |   2 +-
 tools/testing/selftests/timens/futex.c  | 110 ++++++++++++++++++++++++
 2 files changed, 111 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/timens/futex.c

diff --git a/tools/testing/selftests/timens/Makefile b/tools/testing/selftests/timens/Makefile
index b4fd9a934654..3a5936cc10ab 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,4 +1,4 @@
-TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec
+TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec futex
 TEST_GEN_PROGS_EXTENDED := gettime_perf
 
 CFLAGS := -Wall -Werror -pthread
diff --git a/tools/testing/selftests/timens/futex.c b/tools/testing/selftests/timens/futex.c
new file mode 100644
index 000000000000..6b2b9264e851
--- /dev/null
+++ b/tools/testing/selftests/timens/futex.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sched.h>
+
+#include <linux/unistd.h>
+#include <linux/futex.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "log.h"
+#include "timens.h"
+
+#define NSEC_PER_SEC 1000000000ULL
+
+static int run_test(int clockid)
+{
+	int futex_op = FUTEX_WAIT_BITSET;
+	struct timespec timeout, end;
+	int val = 0;
+
+	if (clockid == CLOCK_REALTIME)
+		futex_op |= FUTEX_CLOCK_REALTIME;
+
+	clock_gettime(clockid, &timeout);
+	timeout.tv_nsec += NSEC_PER_SEC / 10; // 100ms
+	if (timeout.tv_nsec > NSEC_PER_SEC) {
+		timeout.tv_sec++;
+		timeout.tv_nsec -= NSEC_PER_SEC;
+	}
+
+	if (syscall(__NR_futex, &val, futex_op, 0,
+		    &timeout, 0, FUTEX_BITSET_MATCH_ANY) >= 0) {
+		ksft_test_result_fail("futex didn't return ETIMEDOUT\n");
+		return 1;
+	}
+
+	if (errno != ETIMEDOUT) {
+		ksft_test_result_fail("futex didn't return ETIMEDOUT: %s\n",
+							strerror(errno));
+		return 1;
+	}
+
+	clock_gettime(clockid, &end);
+
+	if (end.tv_sec < timeout.tv_sec ||
+	    (end.tv_sec == timeout.tv_sec && end.tv_nsec < timeout.tv_nsec)) {
+		ksft_test_result_fail("futex slept less than 100ms\n");
+		return 1;
+	}
+
+
+	ksft_test_result_pass("futex with the %d clockid\n", clockid);
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int status, len, fd;
+	char buf[4096];
+	pid_t pid;
+	struct timespec mtime_now;
+
+	nscheck();
+
+	ksft_set_plan(2);
+
+	clock_gettime(CLOCK_MONOTONIC, &mtime_now);
+
+	if (unshare_timens())
+		return 1;
+
+	len = snprintf(buf, sizeof(buf), "%d %d 0",
+			CLOCK_MONOTONIC, 70 * 24 * 3600);
+	fd = open("/proc/self/timens_offsets", O_WRONLY);
+	if (fd < 0)
+		return pr_perror("/proc/self/timens_offsets");
+
+	if (write(fd, buf, len) != len)
+		return pr_perror("/proc/self/timens_offsets");
+
+	close(fd);
+
+	pid = fork();
+	if (pid < 0)
+		return pr_perror("Unable to fork");
+	if (pid == 0) {
+		int ret = 0;
+
+		ret |= run_test(CLOCK_REALTIME);
+		ret |= run_test(CLOCK_MONOTONIC);
+		if (ret)
+			ksft_exit_fail();
+		ksft_exit_pass();
+		return 0;
+	}
+
+	if (waitpid(pid, &status, 0) != pid)
+		return pr_perror("Unable to wait the child process");
+
+	if (WIFEXITED(status))
+		return WEXITSTATUS(status);
+
+	return 1;
+}
-- 
2.26.2

Re: [PATCH 1/2 v2] futex: adjust a futex timeout with a per-timens offset

[Dmitry Safonov]

On 10/15/20 5:00 PM, Andrei Vagin wrote:
> For all commands except FUTEX_WAIT, timeout is interpreted as an
> absolute value. This absolute value is inside the task's time namespace
> and has to be converted to the host's time.
> 
> Cc: <stable@vger.kernel.org>
> Fixes: 5a590f35add9 ("posix-clocks: Wire up clock_gettime() with timens offsets")
> Reported-by: Hans van der Laan <j.h.vanderlaan@student.utwente.nl>
> Signed-off-by: Andrei Vagin <avagin@gmail.com>

Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>

> ---
> 
> v2:
> * check FUTEX_CLOCK_REALTIME properly
> * fix futex_time32 too
> 
>  kernel/futex.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/kernel/futex.c b/kernel/futex.c
> index a5876694a60e..32056d2d4171 100644
> --- a/kernel/futex.c
> +++ b/kernel/futex.c
> @@ -39,6 +39,7 @@
>  #include <linux/freezer.h>
>  #include <linux/memblock.h>
>  #include <linux/fault-inject.h>
> +#include <linux/time_namespace.h>
>  
>  #include <asm/futex.h>
>  
> @@ -3797,6 +3798,8 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
>  		t = timespec64_to_ktime(ts);
>  		if (cmd == FUTEX_WAIT)
>  			t = ktime_add_safe(ktime_get(), t);
> +		else if (!(op & FUTEX_CLOCK_REALTIME))
> +			t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
>  		tp = &t;
>  	}
>  	/*
> @@ -3989,6 +3992,8 @@ SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
>  		t = timespec64_to_ktime(ts);
>  		if (cmd == FUTEX_WAIT)
>  			t = ktime_add_safe(ktime_get(), t);
> +		else if (!(op & FUTEX_CLOCK_REALTIME))
> +			t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
>  		tp = &t;
>  	}
>  	if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
>

Thanks,
         Dmitry

[tip: timers/urgent] selftests/timens: Add a test for futex()

[tip-bot2 for Andrei Vagin]

The following commit has been merged into the timers/urgent branch of tip:

Commit-ID:     a4fd8414659bf470e2146b352574bbd274e54b7a
Gitweb:        https://git.kernel.org/tip/a4fd8414659bf470e2146b352574bbd274e54b7a
Author:        Andrei Vagin <avagin@gmail.com>
AuthorDate:    Thu, 15 Oct 2020 09:00:20 -07:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 20 Oct 2020 17:02:57 +02:00

selftests/timens: Add a test for futex()

Output on success:
 1..2
 ok 1 futex with the 0 clockid
 ok 2 futex with the 1 clockid
 # Totals: pass:2 fail:0 xfail:0 xpass:0 skip:0 error:0

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201015160020.293748-2-avagin@gmail.com

---
 tools/testing/selftests/timens/Makefile |   2 +-
 tools/testing/selftests/timens/futex.c  | 110 +++++++++++++++++++++++-
 2 files changed, 111 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/timens/futex.c

diff --git a/tools/testing/selftests/timens/Makefile b/tools/testing/selftests/timens/Makefile
index b4fd9a9..3a5936c 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,4 +1,4 @@
-TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec
+TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec futex
 TEST_GEN_PROGS_EXTENDED := gettime_perf
 
 CFLAGS := -Wall -Werror -pthread
diff --git a/tools/testing/selftests/timens/futex.c b/tools/testing/selftests/timens/futex.c
new file mode 100644
index 0000000..6b2b926
--- /dev/null
+++ b/tools/testing/selftests/timens/futex.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sched.h>
+
+#include <linux/unistd.h>
+#include <linux/futex.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "log.h"
+#include "timens.h"
+
+#define NSEC_PER_SEC 1000000000ULL
+
+static int run_test(int clockid)
+{
+	int futex_op = FUTEX_WAIT_BITSET;
+	struct timespec timeout, end;
+	int val = 0;
+
+	if (clockid == CLOCK_REALTIME)
+		futex_op |= FUTEX_CLOCK_REALTIME;
+
+	clock_gettime(clockid, &timeout);
+	timeout.tv_nsec += NSEC_PER_SEC / 10; // 100ms
+	if (timeout.tv_nsec > NSEC_PER_SEC) {
+		timeout.tv_sec++;
+		timeout.tv_nsec -= NSEC_PER_SEC;
+	}
+
+	if (syscall(__NR_futex, &val, futex_op, 0,
+		    &timeout, 0, FUTEX_BITSET_MATCH_ANY) >= 0) {
+		ksft_test_result_fail("futex didn't return ETIMEDOUT\n");
+		return 1;
+	}
+
+	if (errno != ETIMEDOUT) {
+		ksft_test_result_fail("futex didn't return ETIMEDOUT: %s\n",
+							strerror(errno));
+		return 1;
+	}
+
+	clock_gettime(clockid, &end);
+
+	if (end.tv_sec < timeout.tv_sec ||
+	    (end.tv_sec == timeout.tv_sec && end.tv_nsec < timeout.tv_nsec)) {
+		ksft_test_result_fail("futex slept less than 100ms\n");
+		return 1;
+	}
+
+
+	ksft_test_result_pass("futex with the %d clockid\n", clockid);
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int status, len, fd;
+	char buf[4096];
+	pid_t pid;
+	struct timespec mtime_now;
+
+	nscheck();
+
+	ksft_set_plan(2);
+
+	clock_gettime(CLOCK_MONOTONIC, &mtime_now);
+
+	if (unshare_timens())
+		return 1;
+
+	len = snprintf(buf, sizeof(buf), "%d %d 0",
+			CLOCK_MONOTONIC, 70 * 24 * 3600);
+	fd = open("/proc/self/timens_offsets", O_WRONLY);
+	if (fd < 0)
+		return pr_perror("/proc/self/timens_offsets");
+
+	if (write(fd, buf, len) != len)
+		return pr_perror("/proc/self/timens_offsets");
+
+	close(fd);
+
+	pid = fork();
+	if (pid < 0)
+		return pr_perror("Unable to fork");
+	if (pid == 0) {
+		int ret = 0;
+
+		ret |= run_test(CLOCK_REALTIME);
+		ret |= run_test(CLOCK_MONOTONIC);
+		if (ret)
+			ksft_exit_fail();
+		ksft_exit_pass();
+		return 0;
+	}
+
+	if (waitpid(pid, &status, 0) != pid)
+		return pr_perror("Unable to wait the child process");
+
+	if (WIFEXITED(status))
+		return WEXITSTATUS(status);
+
+	return 1;
+}

[tip: timers/urgent] futex: Adjust absolute futex timeouts with per time namespace offset

[tip-bot2 for Andrei Vagin]

The following commit has been merged into the timers/urgent branch of tip:

Commit-ID:     c2f7d08cccf4af2ce6992feaabb9e68e4ae0bff3
Gitweb:        https://git.kernel.org/tip/c2f7d08cccf4af2ce6992feaabb9e68e4ae0bff3
Author:        Andrei Vagin <avagin@gmail.com>
AuthorDate:    Thu, 15 Oct 2020 09:00:19 -07:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 20 Oct 2020 17:02:57 +02:00

futex: Adjust absolute futex timeouts with per time namespace offset

For all commands except FUTEX_WAIT, the timeout is interpreted as an
absolute value. This absolute value is inside the task's time namespace and
has to be converted to the host's time.

Fixes: 5a590f35add9 ("posix-clocks: Wire up clock_gettime() with timens offsets")
Reported-by: Hans van der Laan <j.h.vanderlaan@student.utwente.nl>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201015160020.293748-1-avagin@gmail.com
---
 kernel/futex.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/futex.c b/kernel/futex.c
index 680854d..be68ac0 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -39,6 +39,7 @@
 #include <linux/freezer.h>
 #include <linux/memblock.h>
 #include <linux/fault-inject.h>
+#include <linux/time_namespace.h>
 
 #include <asm/futex.h>
 
@@ -3797,6 +3798,8 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
 		t = timespec64_to_ktime(ts);
 		if (cmd == FUTEX_WAIT)
 			t = ktime_add_safe(ktime_get(), t);
+		else if (!(op & FUTEX_CLOCK_REALTIME))
+			t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
 		tp = &t;
 	}
 	/*
@@ -3989,6 +3992,8 @@ SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
 		t = timespec64_to_ktime(ts);
 		if (cmd == FUTEX_WAIT)
 			t = ktime_add_safe(ktime_get(), t);
+		else if (!(op & FUTEX_CLOCK_REALTIME))
+			t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
 		tp = &t;
 	}
 	if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||