linux/net/sunrpc/sysctl.c
Cyrill Gorcunov 27df6f25ff sunrpc: fix possible overrun on read of /proc/sys/sunrpc/transports
Vegard Nossum reported
----------------------
> I noticed that something weird is going on with /proc/sys/sunrpc/transports.
> This file is generated in net/sunrpc/sysctl.c, function proc_do_xprt(). When
> I "cat" this file, I get the expected output:
>    $ cat /proc/sys/sunrpc/transports
>    tcp 1048576
>    udp 32768

> But I think that it does not check the length of the buffer supplied by
> userspace to read(). With my original program, I found that the stack was
> being overwritten by the characters above, even when the length given to
> read() was just 1.

David Wagner added (among other things) that copy_to_user could be
probably used here.

Ingo Oeser suggested to use simple_read_from_buffer() here.

The conclusion is that proc_do_xprt doesn't check for userside buffer
size indeed so fix this by using Ingo's suggestion.

Reported-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
CC: Ingo Oeser <ioe-lkml@rameria.de>
Cc: Neil Brown <neilb@suse.de>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Greg Banks <gnb@sgi.com>
Cc: Tom Tucker <tom@opengridcomputing.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
2008-09-01 14:24:24 -04:00

184 lines
3.6 KiB
C

/*
* linux/net/sunrpc/sysctl.c
*
* Sysctl interface to sunrpc module.
*
* I would prefer to register the sunrpc table below sys/net, but that's
* impossible at the moment.
*/
#include <linux/types.h>
#include <linux/linkage.h>
#include <linux/ctype.h>
#include <linux/fs.h>
#include <linux/sysctl.h>
#include <linux/module.h>
#include <asm/uaccess.h>
#include <linux/sunrpc/types.h>
#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/svc_xprt.h>
/*
* Declare the debug flags here
*/
unsigned int rpc_debug;
EXPORT_SYMBOL_GPL(rpc_debug);
unsigned int nfs_debug;
EXPORT_SYMBOL_GPL(nfs_debug);
unsigned int nfsd_debug;
EXPORT_SYMBOL_GPL(nfsd_debug);
unsigned int nlm_debug;
EXPORT_SYMBOL_GPL(nlm_debug);
#ifdef RPC_DEBUG
static struct ctl_table_header *sunrpc_table_header;
static ctl_table sunrpc_table[];
void
rpc_register_sysctl(void)
{
if (!sunrpc_table_header)
sunrpc_table_header = register_sysctl_table(sunrpc_table);
}
void
rpc_unregister_sysctl(void)
{
if (sunrpc_table_header) {
unregister_sysctl_table(sunrpc_table_header);
sunrpc_table_header = NULL;
}
}
static int proc_do_xprt(ctl_table *table, int write, struct file *file,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
char tmpbuf[256];
size_t len;
if ((*ppos && !write) || !*lenp) {
*lenp = 0;
return 0;
}
len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
return simple_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
}
static int
proc_dodebug(ctl_table *table, int write, struct file *file,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
char tmpbuf[20], c, *s;
char __user *p;
unsigned int value;
size_t left, len;
if ((*ppos && !write) || !*lenp) {
*lenp = 0;
return 0;
}
left = *lenp;
if (write) {
if (!access_ok(VERIFY_READ, buffer, left))
return -EFAULT;
p = buffer;
while (left && __get_user(c, p) >= 0 && isspace(c))
left--, p++;
if (!left)
goto done;
if (left > sizeof(tmpbuf) - 1)
return -EINVAL;
if (copy_from_user(tmpbuf, p, left))
return -EFAULT;
tmpbuf[left] = '\0';
for (s = tmpbuf, value = 0; '0' <= *s && *s <= '9'; s++, left--)
value = 10 * value + (*s - '0');
if (*s && !isspace(*s))
return -EINVAL;
while (left && isspace(*s))
left--, s++;
*(unsigned int *) table->data = value;
/* Display the RPC tasks on writing to rpc_debug */
if (strcmp(table->procname, "rpc_debug") == 0)
rpc_show_tasks();
} else {
if (!access_ok(VERIFY_WRITE, buffer, left))
return -EFAULT;
len = sprintf(tmpbuf, "%d", *(unsigned int *) table->data);
if (len > left)
len = left;
if (__copy_to_user(buffer, tmpbuf, len))
return -EFAULT;
if ((left -= len) > 0) {
if (put_user('\n', (char __user *)buffer + len))
return -EFAULT;
left--;
}
}
done:
*lenp -= left;
*ppos += *lenp;
return 0;
}
static ctl_table debug_table[] = {
{
.procname = "rpc_debug",
.data = &rpc_debug,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dodebug
},
{
.procname = "nfs_debug",
.data = &nfs_debug,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dodebug
},
{
.procname = "nfsd_debug",
.data = &nfsd_debug,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dodebug
},
{
.procname = "nlm_debug",
.data = &nlm_debug,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dodebug
},
{
.procname = "transports",
.maxlen = 256,
.mode = 0444,
.proc_handler = &proc_do_xprt,
},
{ .ctl_name = 0 }
};
static ctl_table sunrpc_table[] = {
{
.ctl_name = CTL_SUNRPC,
.procname = "sunrpc",
.mode = 0555,
.child = debug_table
},
{ .ctl_name = 0 }
};
#endif