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fs/proc: Introduce /proc/pid/timens_offsets
API to set time namespace offsets for children processes, i.e.: echo "$clockid $offset_sec $offset_nsec" > /proc/self/timens_offsets Co-developed-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Andrei Vagin <avagin@gmail.com> Signed-off-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20191112012724.250792-28-dima@arista.com
This commit is contained in:
Andrei Vagin
Thomas Gleixner
parent
70ddf65184
commit
04a8682a71
3 changed files with 205 additions and 0 deletions
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@ -94,6 +94,7 @@
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#include <linux/sched/debug.h>
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#include <linux/sched/stat.h>
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#include <linux/posix-timers.h>
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#include <linux/time_namespace.h>
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#include <trace/events/oom.h>
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#include "internal.h"
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#include "fd.h"
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@ -1533,6 +1534,96 @@ static const struct file_operations proc_pid_sched_autogroup_operations = {
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#endif /* CONFIG_SCHED_AUTOGROUP */
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#ifdef CONFIG_TIME_NS
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static int timens_offsets_show(struct seq_file *m, void *v)
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{
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struct task_struct *p;
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p = get_proc_task(file_inode(m->file));
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if (!p)
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return -ESRCH;
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proc_timens_show_offsets(p, m);
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put_task_struct(p);
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return 0;
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}
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static ssize_t timens_offsets_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct inode *inode = file_inode(file);
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struct proc_timens_offset offsets[2];
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char *kbuf = NULL, *pos, *next_line;
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struct task_struct *p;
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int ret, noffsets;
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/* Only allow < page size writes at the beginning of the file */
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if ((*ppos != 0) || (count >= PAGE_SIZE))
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return -EINVAL;
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/* Slurp in the user data */
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kbuf = memdup_user_nul(buf, count);
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if (IS_ERR(kbuf))
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return PTR_ERR(kbuf);
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/* Parse the user data */
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ret = -EINVAL;
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noffsets = 0;
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for (pos = kbuf; pos; pos = next_line) {
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struct proc_timens_offset *off = &offsets[noffsets];
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int err;
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/* Find the end of line and ensure we don't look past it */
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next_line = strchr(pos, '\n');
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if (next_line) {
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*next_line = '\0';
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next_line++;
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if (*next_line == '\0')
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next_line = NULL;
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}
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err = sscanf(pos, "%u %lld %lu", &off->clockid,
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&off->val.tv_sec, &off->val.tv_nsec);
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if (err != 3 || off->val.tv_nsec >= NSEC_PER_SEC)
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goto out;
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noffsets++;
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if (noffsets == ARRAY_SIZE(offsets)) {
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if (next_line)
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count = next_line - kbuf;
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break;
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}
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}
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ret = -ESRCH;
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p = get_proc_task(inode);
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if (!p)
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goto out;
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ret = proc_timens_set_offset(file, p, offsets, noffsets);
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put_task_struct(p);
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if (ret)
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goto out;
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ret = count;
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out:
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kfree(kbuf);
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return ret;
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}
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static int timens_offsets_open(struct inode *inode, struct file *filp)
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{
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return single_open(filp, timens_offsets_show, inode);
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}
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static const struct file_operations proc_timens_offsets_operations = {
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.open = timens_offsets_open,
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.read = seq_read,
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.write = timens_offsets_write,
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.llseek = seq_lseek,
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.release = single_release,
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};
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#endif /* CONFIG_TIME_NS */
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static ssize_t comm_write(struct file *file, const char __user *buf,
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size_t count, loff_t *offset)
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{
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@ -3015,6 +3106,9 @@ static const struct pid_entry tgid_base_stuff[] = {
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#endif
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#ifdef CONFIG_SCHED_AUTOGROUP
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REG("autogroup", S_IRUGO|S_IWUSR, proc_pid_sched_autogroup_operations),
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#endif
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#ifdef CONFIG_TIME_NS
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REG("timens_offsets", S_IRUGO|S_IWUSR, proc_timens_offsets_operations),
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#endif
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REG("comm", S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
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#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
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@ -52,6 +52,16 @@ static inline void put_time_ns(struct time_namespace *ns)
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kref_put(&ns->kref, free_time_ns);
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}
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void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m);
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struct proc_timens_offset {
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int clockid;
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struct timespec64 val;
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};
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int proc_timens_set_offset(struct file *file, struct task_struct *p,
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struct proc_timens_offset *offsets, int n);
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static inline void timens_add_monotonic(struct timespec64 *ts)
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{
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struct timens_offsets *ns_offsets = ¤t->nsproxy->time_ns->offsets;
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@ -8,6 +8,7 @@
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#include <linux/user_namespace.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/task.h>
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#include <linux/seq_file.h>
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#include <linux/proc_ns.h>
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#include <linux/export.h>
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#include <linux/time.h>
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@ -334,6 +335,106 @@ static struct user_namespace *timens_owner(struct ns_common *ns)
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return to_time_ns(ns)->user_ns;
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}
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static void show_offset(struct seq_file *m, int clockid, struct timespec64 *ts)
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{
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seq_printf(m, "%d %lld %ld\n", clockid, ts->tv_sec, ts->tv_nsec);
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}
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void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m)
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{
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struct ns_common *ns;
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struct time_namespace *time_ns;
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ns = timens_for_children_get(p);
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if (!ns)
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return;
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time_ns = to_time_ns(ns);
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show_offset(m, CLOCK_MONOTONIC, &time_ns->offsets.monotonic);
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show_offset(m, CLOCK_BOOTTIME, &time_ns->offsets.boottime);
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put_time_ns(time_ns);
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}
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int proc_timens_set_offset(struct file *file, struct task_struct *p,
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struct proc_timens_offset *offsets, int noffsets)
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{
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struct ns_common *ns;
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struct time_namespace *time_ns;
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struct timespec64 tp;
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int i, err;
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ns = timens_for_children_get(p);
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if (!ns)
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return -ESRCH;
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time_ns = to_time_ns(ns);
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if (!file_ns_capable(file, time_ns->user_ns, CAP_SYS_TIME)) {
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put_time_ns(time_ns);
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return -EPERM;
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}
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for (i = 0; i < noffsets; i++) {
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struct proc_timens_offset *off = &offsets[i];
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switch (off->clockid) {
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case CLOCK_MONOTONIC:
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ktime_get_ts64(&tp);
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break;
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case CLOCK_BOOTTIME:
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ktime_get_boottime_ts64(&tp);
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break;
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default:
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err = -EINVAL;
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goto out;
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}
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err = -ERANGE;
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if (off->val.tv_sec > KTIME_SEC_MAX ||
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off->val.tv_sec < -KTIME_SEC_MAX)
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goto out;
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tp = timespec64_add(tp, off->val);
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/*
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* KTIME_SEC_MAX is divided by 2 to be sure that KTIME_MAX is
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* still unreachable.
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*/
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if (tp.tv_sec < 0 || tp.tv_sec > KTIME_SEC_MAX / 2)
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goto out;
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}
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mutex_lock(&offset_lock);
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if (time_ns->frozen_offsets) {
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err = -EACCES;
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goto out_unlock;
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}
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err = 0;
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/* Don't report errors after this line */
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for (i = 0; i < noffsets; i++) {
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struct proc_timens_offset *off = &offsets[i];
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struct timespec64 *offset = NULL;
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switch (off->clockid) {
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case CLOCK_MONOTONIC:
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offset = &time_ns->offsets.monotonic;
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break;
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case CLOCK_BOOTTIME:
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offset = &time_ns->offsets.boottime;
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break;
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}
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*offset = off->val;
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}
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out_unlock:
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mutex_unlock(&offset_lock);
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out:
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put_time_ns(time_ns);
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return err;
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}
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const struct proc_ns_operations timens_operations = {
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.name = "time",
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.type = CLONE_NEWTIME,
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