proc, time/namespace: Show clock symbolic names in /proc/pid/timens_offsets (94d440d6) · Commits · 戴 / test

Michael Kerrisk suggested to replace numeric clock IDs with symbolic names. Now the content of these files looks like this: $ cat /proc/774/timens_offsets monotonic 864000 0 boottime 1728000 0 For setting offsets, both representations of clocks (numeric and symbolic) can be used. As for compatibility, it is acceptable to change things as long as userspace doesn't care. The format of timens_offsets files is very new and there are no userspace tools yet which rely on this format. But three projects crun, util-linux and criu rely on the interface of setting time offsets and this is why it's required to continue supporting the numeric clock IDs on write. Fixes: ("fs/proc: Introduce /proc/pid/timens_offsets") Suggested-by:

Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by:

Andrei Vagin <avagin@gmail.com> Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Tested-by:

Michael Kerrisk <mtk.manpages@gmail.com> Acked-by:

Michael Kerrisk <mtk.manpages@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20200411154031.642557-1-avagin@gmail.com

fs/proc/base.c

+13 −1

Original line number	Diff line number	Diff line
		@@ -1573,6 +1573,7 @@ static ssize_t timens_offsets_write(struct file file, const char __user buf,
		noffsets = 0;
		for (pos = kbuf; pos; pos = next_line) {
		struct proc_timens_offset *off = &offsets[noffsets];
		char clock[10];
		int err;

		/* Find the end of line and ensure we don't look past it */
		@@ -1584,10 +1585,21 @@ static ssize_t timens_offsets_write(struct file file, const char __user buf,
		next_line = NULL;
		}

		err = sscanf(pos, "%u %lld %lu", &off->clockid,
		err = sscanf(pos, "%9s %lld %lu", clock,
		&off->val.tv_sec, &off->val.tv_nsec);
		if (err != 3 \|\| off->val.tv_nsec >= NSEC_PER_SEC)
		goto out;

		clock[sizeof(clock) - 1] = 0;
		if (strcmp(clock, "monotonic") == 0 \|\|
		strcmp(clock, __stringify(CLOCK_MONOTONIC)) == 0)
		off->clockid = CLOCK_MONOTONIC;
		else if (strcmp(clock, "boottime") == 0 \|\|
		strcmp(clock, __stringify(CLOCK_BOOTTIME)) == 0)
		off->clockid = CLOCK_BOOTTIME;
		else
		goto out;

		noffsets++;
		if (noffsets == ARRAY_SIZE(offsets)) {
		if (next_line)

kernel/time/namespace.c

+14 −1

Original line number	Diff line number	Diff line
		@@ -338,7 +338,20 @@ static struct user_namespace timens_owner(struct ns_common ns)

		static void show_offset(struct seq_file m, int clockid, struct timespec64 ts)
		{
		seq_printf(m, "%d %lld %ld\n", clockid, ts->tv_sec, ts->tv_nsec);
		char *clock;

		switch (clockid) {
		case CLOCK_BOOTTIME:
		clock = "boottime";
		break;
		case CLOCK_MONOTONIC:
		clock = "monotonic";
		break;
		default:
		clock = "unknown";
		break;
		}
		seq_printf(m, "%-10s %10lld %9ld\n", clock, ts->tv_sec, ts->tv_nsec);
		}

		void proc_timens_show_offsets(struct task_struct p, struct seq_file m)

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