lkml.org 
[lkml]   [2019]   [Apr]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCHv3 19/27] timens/fs/proc: Introduce /proc/pid/timens_offsets
Date
From: Andrei Vagin <avagin@gmail.com>

API to set time namespace offsets for children processes, i.e.:
echo "clockid off_ses off_nsec" > /proc/self/timens_offsets

Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
fs/proc/base.c | 101 +++++++++++++++++++++++++++++++++
include/linux/time_namespace.h | 10 ++++
kernel/time_namespace.c | 82 ++++++++++++++++++++++++++
3 files changed, 193 insertions(+)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 6a803a0b75df..76d58e9b5178 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -94,6 +94,7 @@
#include <linux/sched/debug.h>
#include <linux/sched/stat.h>
#include <linux/posix-timers.h>
+#include <linux/time_namespace.h>
#include <trace/events/oom.h>
#include "internal.h"
#include "fd.h"
@@ -1521,6 +1522,103 @@ static const struct file_operations proc_pid_sched_autogroup_operations = {

#endif /* CONFIG_SCHED_AUTOGROUP */

+#ifdef CONFIG_TIME_NS
+static int timens_offsets_show(struct seq_file *m, void *v)
+{
+ struct inode *inode = m->private;
+ struct task_struct *p;
+
+ p = get_proc_task(inode);
+ if (!p)
+ return -ESRCH;
+ proc_timens_show_offsets(p, m);
+
+ put_task_struct(p);
+
+ return 0;
+}
+
+static ssize_t
+timens_offsets_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct inode *inode = file_inode(file);
+ struct proc_timens_offset offsets[2];
+ char *kbuf = NULL, *pos, *next_line;
+ struct task_struct *p;
+ int ret, noffsets;
+
+ /* Only allow < page size writes at the beginning of the file */
+ if ((*ppos != 0) || (count >= PAGE_SIZE))
+ return -EINVAL;
+
+ /* Slurp in the user data */
+ kbuf = memdup_user_nul(buf, count);
+ if (IS_ERR(kbuf))
+ return PTR_ERR(kbuf);
+
+ /* Parse the user data */
+ ret = -EINVAL;
+ noffsets = 0;
+ pos = kbuf;
+ for (; pos; pos = next_line) {
+ struct proc_timens_offset *off = &offsets[noffsets];
+ int err;
+
+ /* Find the end of line and ensure I don't look past it */
+ next_line = strchr(pos, '\n');
+ if (next_line) {
+ *next_line = '\0';
+ next_line++;
+ if (*next_line == '\0')
+ next_line = NULL;
+ }
+
+ err = sscanf(pos, "%u %lld %lu", &off->clockid,
+ &off->val.tv_sec, &off->val.tv_nsec);
+ if (err != 3 || off->val.tv_nsec >= NSEC_PER_SEC)
+ goto out;
+ if (noffsets++ == ARRAY_SIZE(offsets))
+ break;
+ }
+
+ ret = -ESRCH;
+ p = get_proc_task(inode);
+ if (!p)
+ goto out;
+ ret = proc_timens_set_offset(p, offsets, noffsets);
+ put_task_struct(p);
+ if (ret)
+ goto out;
+
+ ret = count;
+out:
+ kfree(kbuf);
+ return ret;
+}
+
+static int timens_offsets_open(struct inode *inode, struct file *filp)
+{
+ int ret;
+
+ ret = single_open(filp, timens_offsets_show, NULL);
+ if (!ret) {
+ struct seq_file *m = filp->private_data;
+
+ m->private = inode;
+ }
+ return ret;
+}
+
+static const struct file_operations proc_timens_offsets_operations = {
+ .open = timens_offsets_open,
+ .read = seq_read,
+ .write = timens_offsets_write,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+#endif /* CONFIG_TIME_NS */
+
static ssize_t comm_write(struct file *file, const char __user *buf,
size_t count, loff_t *offset)
{
@@ -2982,6 +3080,9 @@ static const struct pid_entry tgid_base_stuff[] = {
#endif
#ifdef CONFIG_SCHED_AUTOGROUP
REG("autogroup", S_IRUGO|S_IWUSR, proc_pid_sched_autogroup_operations),
+#endif
+#ifdef CONFIG_TIME_NS
+ REG("timens_offsets", S_IRUGO|S_IWUSR, proc_timens_offsets_operations),
#endif
REG("comm", S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 988414f7f791..1434b5664673 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -40,6 +40,16 @@ static inline void put_time_ns(struct time_namespace *ns)
kref_put(&ns->kref, free_time_ns);
}

+extern void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m);
+
+struct proc_timens_offset {
+ int clockid;
+ struct timespec64 val;
+};
+
+extern int proc_timens_set_offset(struct task_struct *p,
+ struct proc_timens_offset *offsets, int n);
+
static inline void timens_add_monotonic(struct timespec64 *ts)
{
struct timens_offsets *ns_offsets = current->nsproxy->time_ns->offsets;
diff --git a/kernel/time_namespace.c b/kernel/time_namespace.c
index e806accc4eaf..9ad4b63c4ed2 100644
--- a/kernel/time_namespace.c
+++ b/kernel/time_namespace.c
@@ -13,6 +13,7 @@
#include <linux/user_namespace.h>
#include <linux/proc_ns.h>
#include <linux/sched/task.h>
+#include <linux/seq_file.h>
#include <linux/mm.h>
#include <asm/vdso.h>

@@ -202,6 +203,87 @@ static struct user_namespace *timens_owner(struct ns_common *ns)
return to_time_ns(ns)->user_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);
+}
+
+void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m)
+{
+ struct ns_common *ns;
+ struct time_namespace *time_ns;
+ struct timens_offsets *ns_offsets;
+
+ ns = timens_for_children_get(p);
+ if (!ns)
+ return;
+ time_ns = to_time_ns(ns);
+
+ if (!time_ns->offsets) {
+ put_time_ns(time_ns);
+ return;
+ }
+ ns_offsets = time_ns->offsets;
+
+ show_offset(m, CLOCK_MONOTONIC, &ns_offsets->monotonic_time_offset);
+ show_offset(m, CLOCK_BOOTTIME, &ns_offsets->monotonic_boottime_offset);
+ put_time_ns(time_ns);
+}
+
+int proc_timens_set_offset(struct task_struct *p,
+ struct proc_timens_offset *offsets, int noffsets)
+{
+ struct ns_common *ns;
+ struct time_namespace *time_ns;
+ struct timens_offsets *ns_offsets;
+ struct timespec64 *offset;
+ struct timespec64 tp;
+ int i, err;
+
+ ns = timens_for_children_get(p);
+ if (!ns)
+ return -ESRCH;
+ time_ns = to_time_ns(ns);
+
+ if (!time_ns->offsets || time_ns->initialized ||
+ !ns_capable(time_ns->user_ns, CAP_SYS_TIME)) {
+ put_time_ns(time_ns);
+ return -EPERM;
+ }
+ ns_offsets = time_ns->offsets;
+
+ err = -EINVAL;
+ for (i = 0; i < noffsets; i++) {
+ struct proc_timens_offset *off = &offsets[i];
+
+ switch (off->clockid) {
+ case CLOCK_MONOTONIC:
+ ktime_get_ts64(&tp);
+ offset = &ns_offsets->monotonic_time_offset;
+ break;
+ case CLOCK_BOOTTIME:
+ ktime_get_boottime_ts64(&tp);
+ offset = &ns_offsets->monotonic_boottime_offset;
+ break;
+ default:
+ goto out;
+ }
+
+ err = -ERANGE;
+ tp = timespec64_add(tp, off->val);
+ if (tp.tv_sec < 0 || tp.tv_sec > KTIME_SEC_MAX / 2)
+ goto out;
+ *offset = off->val;
+
+ }
+
+ err = 0;
+out:
+ put_time_ns(time_ns);
+
+ return err;
+}
+
const struct proc_ns_operations timens_operations = {
.name = "time",
.type = CLONE_NEWTIME,
--
2.21.0
\
 
 \ /
  Last update: 2019-04-25 18:16    [W:0.162 / U:7.628 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site