0001-fs-proc-uptime.s-allow-setting-uptime-from-userspace.patch

0001-fs-proc-uptime.s-allow-setting-uptime-from-userspace.patch.diff

From a0c891cc8c48d2105f8972f372e4619535151a25 Mon Sep 17 00:00:00 2001
From: Alexey Ignatov <lexszero@gmail.com>
Date: Fri, 7 Nov 2014 04:38:50 +0300
Subject: [PATCH] fs/proc/uptime.s: allow setting uptime from userspace

Use `echo 100500 > /proc/uptime' to add 100500 seconds to displayed uptime
value.

Signed-off-by: Alexey Ignatov <lexszero@gmail.com>
---
 fs/proc/uptime.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
index 33de567..302bdb7 100644
--- a/fs/proc/uptime.c
+++ b/fs/proc/uptime.c
@@ -7,6 +7,8 @@
 #include <linux/kernel_stat.h>
 #include <linux/cputime.h>
 
+static struct timespec uptime_offset = {0, 0};
+
 static int uptime_proc_show(struct seq_file *m, void *v)
 {
 	struct timespec uptime;
@@ -21,6 +23,7 @@ static int uptime_proc_show(struct seq_file *m, void *v)
 		idletime += (__force u64) kcpustat_cpu(i).cpustat[CPUTIME_IDLE];
 
 	get_monotonic_boottime(&uptime);
+	uptime = timespec_add_safe(uptime, uptime_offset);
 	nsec = cputime64_to_jiffies64(idletime) * TICK_NSEC;
 	idle.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
 	idle.tv_nsec = rem;
@@ -32,6 +35,21 @@ static int uptime_proc_show(struct seq_file *m, void *v)
 	return 0;
 }
 
+static ssize_t uptime_proc_write(struct file *file, const char __user *buf,
+		size_t size, loff_t *off)
+{
+	int ret;
+	unsigned long val;
+	char tmp[20];
+	ret = copy_from_user(tmp, buf, min(size, sizeof(tmp)));
+	tmp[min(size, sizeof(tmp)-1)] = 0;
+	ret = kstrtoul(tmp, 10, &val);
+	if (ret < 0)
+		return ret;
+	uptime_offset.tv_sec = val;
+	return size;
+}
+
 static int uptime_proc_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, uptime_proc_show, NULL);
@@ -40,13 +58,16 @@ static int uptime_proc_open(struct inode *inode, struct file *file)
 static const struct file_operations uptime_proc_fops = {
 	.open		= uptime_proc_open,
 	.read		= seq_read,
-	.llseek		= seq_lseek,
+	.write		= uptime_proc_write,
+	/* This shit fucks something up on writes, to lazy to kludge it
+	 * the right way */
+	//.llseek		= seq_lseek,
 	.release	= single_release,
 };
 
 static int __init proc_uptime_init(void)
 {
-	proc_create("uptime", 0, NULL, &uptime_proc_fops);
+	proc_create("uptime", 0644, NULL, &uptime_proc_fops);
 	return 0;
 }
 fs_initcall(proc_uptime_init);
-- 
1.8.5.3