From 49a0c45833c9aa9852ba02c9df0f18029509d0a9 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Thu, 18 Oct 2007 03:05:23 -0700
Subject: [PATCH] sysctl: Factor out sysctl_data.
There as been no easy way to wrap the default sysctl strategy routine except
for returning 0. Which is not always what we want. The few instances I have
seen that want different behaviour have written their own version of
sysctl_data. While not too hard it is unnecessary code and has the potential
for extra bugs.
So to make these situations easier and make that part of sysctl more symetric
I have factord sysctl_data out of do_sysctl_strategy and exported as a
function everyone can use.
Further having sysctl_data be an explicit function makes checking for badly
formed sysctl tables much easier.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/sysctl.h | 1 +
kernel/sysctl.c | 66 +++++++++++++++++++++++++++++-------------
2 files changed, 47 insertions(+), 20 deletions(-)
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index f73be4cd662ed..5ca510b3cbe20 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -972,6 +972,7 @@ extern int do_sysctl_strategy (struct ctl_table *table,
void __user *oldval, size_t __user *oldlenp,
void __user *newval, size_t newlen);
+extern ctl_handler sysctl_data;
extern ctl_handler sysctl_string;
extern ctl_handler sysctl_intvec;
extern ctl_handler sysctl_jiffies;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 73c84b6e7a354..88c8ea8f5e8cd 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1443,7 +1443,6 @@ int do_sysctl_strategy (struct ctl_table *table,
void __user *newval, size_t newlen)
{
int op = 0, rc;
- size_t len;
if (oldval)
op |= 004;
@@ -1464,25 +1463,10 @@ int do_sysctl_strategy (struct ctl_table *table,
/* If there is no strategy routine, or if the strategy returns
* zero, proceed with automatic r/w */
if (table->data && table->maxlen) {
- if (oldval && oldlenp) {
- if (get_user(len, oldlenp))
- return -EFAULT;
- if (len) {
- if (len > table->maxlen)
- len = table->maxlen;
- if(copy_to_user(oldval, table->data, len))
- return -EFAULT;
- if(put_user(len, oldlenp))
- return -EFAULT;
- }
- }
- if (newval && newlen) {
- len = newlen;
- if (len > table->maxlen)
- len = table->maxlen;
- if(copy_from_user(table->data, newval, len))
- return -EFAULT;
- }
+ rc = sysctl_data(table, name, nlen, oldval, oldlenp,
+ newval, newlen);
+ if (rc < 0)
+ return rc;
}
return 0;
}
@@ -2381,6 +2365,40 @@ int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int write,
* General sysctl support routines
*/
+/* The generic sysctl data routine (used if no strategy routine supplied) */
+int sysctl_data(struct ctl_table *table, int __user *name, int nlen,
+ void __user *oldval, size_t __user *oldlenp,
+ void __user *newval, size_t newlen)
+{
+ size_t len;
+
+ /* Get out of I don't have a variable */
+ if (!table->data || !table->maxlen)
+ return -ENOTDIR;
+
+ if (oldval && oldlenp) {
+ if (get_user(len, oldlenp))
+ return -EFAULT;
+ if (len) {
+ if (len > table->maxlen)
+ len = table->maxlen;
+ if (copy_to_user(oldval, table->data, len))
+ return -EFAULT;
+ if (put_user(len, oldlenp))
+ return -EFAULT;
+ }
+ }
+
+ if (newval && newlen) {
+ if (newlen > table->maxlen)
+ newlen = table->maxlen;
+
+ if (copy_from_user(table->data, newval, newlen))
+ return -EFAULT;
+ }
+ return 1;
+}
+
/* The generic string strategy routine: */
int sysctl_string(struct ctl_table *table, int __user *name, int nlen,
void __user *oldval, size_t __user *oldlenp,
@@ -2569,6 +2587,13 @@ asmlinkage long sys_sysctl(struct __sysctl_args __user *args)
return -ENOSYS;
}
+int sysctl_data(struct ctl_table *table, int __user *name, int nlen,
+ void __user *oldval, size_t __user *oldlenp,
+ void __user *newval, size_t newlen)
+{
+ return -ENOSYS;
+}
+
int sysctl_string(struct ctl_table *table, int __user *name, int nlen,
void __user *oldval, size_t __user *oldlenp,
void __user *newval, size_t newlen)
@@ -2616,4 +2641,5 @@ EXPORT_SYMBOL(sysctl_intvec);
EXPORT_SYMBOL(sysctl_jiffies);
EXPORT_SYMBOL(sysctl_ms_jiffies);
EXPORT_SYMBOL(sysctl_string);
+EXPORT_SYMBOL(sysctl_data);
EXPORT_SYMBOL(unregister_sysctl_table);
--
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