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[AX25]: UID fixes

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o Brown paperbag bug - ax25_findbyuid() was always returning a NULL pointer
   as the result.  Breaks ROSE completly and AX.25 if UID policy set to deny.

 o While the list structure of AX.25's UID to callsign mapping table was
   properly protected by a spinlock, it's elements were not refcounted
   resulting in a race between removal and usage of an element.

Signed-off-by: Ralf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ralf Baechle
2005-08-23 10:11:45 -07:00
committed by David S. Miller
parent 53b924b31f
commit 01d7dd0e9f
6 changed files with 100 additions and 77 deletions
Download Patch File Download Diff File Expand all files Collapse all files

83
net/ax25/ax25_uid.c
View File

@@ -28,6 +28,7 @@
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/notifier.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
@@ -41,38 +42,41 @@
* Callsign/UID mapper. This is in kernel space for security on multi-amateur machines.
*/
static ax25_uid_assoc *ax25_uid_list;
HLIST_HEAD(ax25_uid_list);
static DEFINE_RWLOCK(ax25_uid_lock);
int ax25_uid_policy = 0;
ax25_address *ax25_findbyuid(uid_t uid)
ax25_uid_assoc *ax25_findbyuid(uid_t uid)
{
ax25_uid_assoc *ax25_uid;
ax25_address *res = NULL;
ax25_uid_assoc *ax25_uid, *res = NULL;
struct hlist_node *node;
read_lock(&ax25_uid_lock);
for (ax25_uid = ax25_uid_list; ax25_uid != NULL; ax25_uid = ax25_uid->next) {
ax25_uid_for_each(ax25_uid, node, &ax25_uid_list) {
if (ax25_uid->uid == uid) {
res = &ax25_uid->call;
ax25_uid_hold(ax25_uid);
res = ax25_uid;
break;
}
}
read_unlock(&ax25_uid_lock);
return NULL;
return res;
}
int ax25_uid_ioctl(int cmd, struct sockaddr_ax25 *sax)
{
ax25_uid_assoc *s, *ax25_uid;
ax25_uid_assoc *ax25_uid;
struct hlist_node *node;
ax25_uid_assoc *user;
unsigned long res;
switch (cmd) {
case SIOCAX25GETUID:
res = -ENOENT;
read_lock(&ax25_uid_lock);
for (ax25_uid = ax25_uid_list; ax25_uid != NULL; ax25_uid = ax25_uid->next) {
ax25_uid_for_each(ax25_uid, node, &ax25_uid_list) {
if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0) {
res = ax25_uid->uid;
break;
@@ -85,19 +89,22 @@ int ax25_uid_ioctl(int cmd, struct sockaddr_ax25 *sax)
case SIOCAX25ADDUID:
if (!capable(CAP_NET_ADMIN))
return -EPERM;
if (ax25_findbyuid(sax->sax25_uid))
user = ax25_findbyuid(sax->sax25_uid);
if (user) {
ax25_uid_put(user);
return -EEXIST;
}
if (sax->sax25_uid == 0)
return -EINVAL;
if ((ax25_uid = kmalloc(sizeof(*ax25_uid), GFP_KERNEL)) == NULL)
return -ENOMEM;
atomic_set(&ax25_uid->refcount, 1);
ax25_uid->uid = sax->sax25_uid;
ax25_uid->call = sax->sax25_call;
write_lock(&ax25_uid_lock);
ax25_uid->next = ax25_uid_list;
ax25_uid_list = ax25_uid;
hlist_add_head(&ax25_uid->uid_node, &ax25_uid_list);
write_unlock(&ax25_uid_lock);
return 0;
@@ -106,34 +113,21 @@ int ax25_uid_ioctl(int cmd, struct sockaddr_ax25 *sax)
if (!capable(CAP_NET_ADMIN))
return -EPERM;
ax25_uid = NULL;
write_lock(&ax25_uid_lock);
for (ax25_uid = ax25_uid_list; ax25_uid != NULL; ax25_uid = ax25_uid->next) {
if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0) {
ax25_uid_for_each(ax25_uid, node, &ax25_uid_list) {
if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0)
break;
}
}
if (ax25_uid == NULL) {
write_unlock(&ax25_uid_lock);
return -ENOENT;
}
if ((s = ax25_uid_list) == ax25_uid) {
ax25_uid_list = s->next;
write_unlock(&ax25_uid_lock);
kfree(ax25_uid);
return 0;
}
while (s != NULL && s->next != NULL) {
if (s->next == ax25_uid) {
s->next = ax25_uid->next;
write_unlock(&ax25_uid_lock);
kfree(ax25_uid);
return 0;
}
s = s->next;
}
hlist_del_init(&ax25_uid->uid_node);
ax25_uid_put(ax25_uid);
write_unlock(&ax25_uid_lock);
return -ENOENT;
return 0;
default:
return -EINVAL;
@@ -147,13 +141,11 @@ int ax25_uid_ioctl(int cmd, struct sockaddr_ax25 *sax)
static void *ax25_uid_seq_start(struct seq_file *seq, loff_t *pos)
{
struct ax25_uid_assoc *pt;
int i = 1;
struct hlist_node *node;
int i = 0;
read_lock(&ax25_uid_lock);
if (*pos == 0)
return SEQ_START_TOKEN;
for (pt = ax25_uid_list; pt != NULL; pt = pt->next) {
ax25_uid_for_each(pt, node, &ax25_uid_list) {
if (i == *pos)
return pt;
++i;
@@ -164,8 +156,9 @@ static void *ax25_uid_seq_start(struct seq_file *seq, loff_t *pos)
static void *ax25_uid_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
++*pos;
return (v == SEQ_START_TOKEN) ? ax25_uid_list :
((struct ax25_uid_assoc *) v)->next;
return hlist_entry(((ax25_uid_assoc *)v)->uid_node.next,
ax25_uid_assoc, uid_node);
}
static void ax25_uid_seq_stop(struct seq_file *seq, void *v)
@@ -179,7 +172,6 @@ static int ax25_uid_seq_show(struct seq_file *seq, void *v)
seq_printf(seq, "Policy: %d\n", ax25_uid_policy);
else {
struct ax25_uid_assoc *pt = v;
seq_printf(seq, "%6d %s\n", pt->uid, ax2asc(&pt->call));
}
@@ -213,16 +205,13 @@ struct file_operations ax25_uid_fops = {
*/
void __exit ax25_uid_free(void)
{
ax25_uid_assoc *s, *ax25_uid;
ax25_uid_assoc *ax25_uid;
struct hlist_node *node;
write_lock(&ax25_uid_lock);
ax25_uid = ax25_uid_list;
while (ax25_uid != NULL) {
s = ax25_uid;
ax25_uid = ax25_uid->next;
kfree(s);
ax25_uid_for_each(ax25_uid, node, &ax25_uid_list) {
hlist_del_init(&ax25_uid->uid_node);
ax25_uid_put(ax25_uid);
}
ax25_uid_list = NULL;
write_unlock(&ax25_uid_lock);
}