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Commit 49a0c458 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Linus Torvalds
Browse files

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: default avatarEric W. Biederman <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d8217f07

include/linux/sysctl.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

kernel/sysctl.c

+46 −20
Original line number Diff line number Diff line
@@ -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);