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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>
This commit is contained in:
Eric W. Biederman 2007-10-18 03:05:23 -07:00 committed by Linus Torvalds
parent d8217f076b
commit 49a0c45833
2 changed files with 47 additions and 20 deletions
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1
include/linux/sysctl.h
View File

@ -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;

66
kernel/sysctl.c
View File

@ -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 @@ out:
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);