[AX25]: UID fixes
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>
diff --git a/include/net/ax25.h b/include/net/ax25.h
index 828a3a9..3696f98 100644
--- a/include/net/ax25.h
+++ b/include/net/ax25.h
@@ -139,11 +139,25 @@
#define AX25_DEF_DS_TIMEOUT (3 * 60 * HZ) /* DAMA timeout 3 minutes */
typedef struct ax25_uid_assoc {
- struct ax25_uid_assoc *next;
+ struct hlist_node uid_node;
+ atomic_t refcount;
uid_t uid;
ax25_address call;
} ax25_uid_assoc;
+#define ax25_uid_for_each(__ax25, node, list) \
+ hlist_for_each_entry(__ax25, node, list, uid_node)
+
+#define ax25_uid_hold(ax25) \
+ atomic_inc(&((ax25)->refcount))
+
+static inline void ax25_uid_put(ax25_uid_assoc *assoc)
+{
+ if (atomic_dec_and_test(&assoc->refcount)) {
+ kfree(assoc);
+ }
+}
+
typedef struct {
ax25_address calls[AX25_MAX_DIGIS];
unsigned char repeated[AX25_MAX_DIGIS];
@@ -376,7 +390,7 @@
/* ax25_uid.c */
extern int ax25_uid_policy;
-extern ax25_address *ax25_findbyuid(uid_t);
+extern ax25_uid_assoc *ax25_findbyuid(uid_t);
extern int ax25_uid_ioctl(int, struct sockaddr_ax25 *);
extern struct file_operations ax25_uid_fops;
extern void ax25_uid_free(void);
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index 7d8ecad..a5c94f1 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1002,7 +1002,8 @@
struct sock *sk = sock->sk;
struct full_sockaddr_ax25 *addr = (struct full_sockaddr_ax25 *)uaddr;
ax25_dev *ax25_dev = NULL;
- ax25_address *call;
+ ax25_uid_assoc *user;
+ ax25_address call;
ax25_cb *ax25;
int err = 0;
@@ -1021,9 +1022,15 @@
if (addr->fsa_ax25.sax25_family != AF_AX25)
return -EINVAL;
- call = ax25_findbyuid(current->euid);
- if (call == NULL && ax25_uid_policy && !capable(CAP_NET_ADMIN)) {
- return -EACCES;
+ user = ax25_findbyuid(current->euid);
+ if (user) {
+ call = user->call;
+ ax25_uid_put(user);
+ } else {
+ if (ax25_uid_policy && !capable(CAP_NET_ADMIN))
+ return -EACCES;
+
+ call = addr->fsa_ax25.sax25_call;
}
lock_sock(sk);
@@ -1034,10 +1041,7 @@
goto out;
}
- if (call == NULL)
- ax25->source_addr = addr->fsa_ax25.sax25_call;
- else
- ax25->source_addr = *call;
+ ax25->source_addr = call;
/*
* User already set interface with SO_BINDTODEVICE
diff --git a/net/ax25/ax25_route.c b/net/ax25/ax25_route.c
index 44b99b1..c288526 100644
--- a/net/ax25/ax25_route.c
+++ b/net/ax25/ax25_route.c
@@ -422,8 +422,8 @@
*/
int ax25_rt_autobind(ax25_cb *ax25, ax25_address *addr)
{
+ ax25_uid_assoc *user;
ax25_route *ax25_rt;
- ax25_address *call;
int err;
if ((ax25_rt = ax25_get_route(addr, NULL)) == NULL)
@@ -434,16 +434,18 @@
goto put;
}
- if ((call = ax25_findbyuid(current->euid)) == NULL) {
+ user = ax25_findbyuid(current->euid);
+ if (user) {
+ ax25->source_addr = user->call;
+ ax25_uid_put(user);
+ } else {
if (ax25_uid_policy && !capable(CAP_NET_BIND_SERVICE)) {
err = -EPERM;
goto put;
}
- call = (ax25_address *)ax25->ax25_dev->dev->dev_addr;
+ ax25->source_addr = *(ax25_address *)ax25->ax25_dev->dev->dev_addr;
}
- ax25->source_addr = *call;
-
if (ax25_rt->digipeat != NULL) {
if ((ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
err = -ENOMEM;
diff --git a/net/ax25/ax25_uid.c b/net/ax25/ax25_uid.c
index cea6b7d..a8b3822 100644
--- a/net/ax25/ax25_uid.c
+++ b/net/ax25/ax25_uid.c
@@ -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 @@
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 @@
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 @@
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_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 @@
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 @@
*/
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);
}
diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c
index 5385835..162a85f 100644
--- a/net/netrom/af_netrom.c
+++ b/net/netrom/af_netrom.c
@@ -536,7 +536,8 @@
struct nr_sock *nr = nr_sk(sk);
struct full_sockaddr_ax25 *addr = (struct full_sockaddr_ax25 *)uaddr;
struct net_device *dev;
- ax25_address *user, *source;
+ ax25_uid_assoc *user;
+ ax25_address *source;
lock_sock(sk);
if (!sock_flag(sk, SOCK_ZAPPED)) {
@@ -575,16 +576,19 @@
} else {
source = &addr->fsa_ax25.sax25_call;
- if ((user = ax25_findbyuid(current->euid)) == NULL) {
+ user = ax25_findbyuid(current->euid);
+ if (user) {
+ nr->user_addr = user->call;
+ ax25_uid_put(user);
+ } else {
if (ax25_uid_policy && !capable(CAP_NET_BIND_SERVICE)) {
release_sock(sk);
dev_put(dev);
return -EPERM;
}
- user = source;
+ nr->user_addr = *source;
}
- nr->user_addr = *user;
nr->source_addr = *source;
}
@@ -604,7 +608,8 @@
struct sock *sk = sock->sk;
struct nr_sock *nr = nr_sk(sk);
struct sockaddr_ax25 *addr = (struct sockaddr_ax25 *)uaddr;
- ax25_address *user, *source = NULL;
+ ax25_address *source = NULL;
+ ax25_uid_assoc *user;
struct net_device *dev;
lock_sock(sk);
@@ -645,16 +650,19 @@
}
source = (ax25_address *)dev->dev_addr;
- if ((user = ax25_findbyuid(current->euid)) == NULL) {
+ user = ax25_findbyuid(current->euid);
+ if (user) {
+ nr->user_addr = user->call;
+ ax25_uid_put(user);
+ } else {
if (ax25_uid_policy && !capable(CAP_NET_ADMIN)) {
dev_put(dev);
release_sock(sk);
return -EPERM;
}
- user = source;
+ nr->user_addr = *source;
}
- nr->user_addr = *user;
nr->source_addr = *source;
nr->device = dev;
diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c
index 3fe7e56..5480caf 100644
--- a/net/rose/af_rose.c
+++ b/net/rose/af_rose.c
@@ -626,7 +626,8 @@
struct rose_sock *rose = rose_sk(sk);
struct sockaddr_rose *addr = (struct sockaddr_rose *)uaddr;
struct net_device *dev;
- ax25_address *user, *source;
+ ax25_address *source;
+ ax25_uid_assoc *user;
int n;
if (!sock_flag(sk, SOCK_ZAPPED))
@@ -651,14 +652,17 @@
source = &addr->srose_call;
- if ((user = ax25_findbyuid(current->euid)) == NULL) {
+ user = ax25_findbyuid(current->euid);
+ if (user) {
+ rose->source_call = user->call;
+ ax25_uid_put(user);
+ } else {
if (ax25_uid_policy && !capable(CAP_NET_BIND_SERVICE))
return -EACCES;
- user = source;
+ rose->source_call = *source;
}
rose->source_addr = addr->srose_addr;
- rose->source_call = *user;
rose->device = dev;
rose->source_ndigis = addr->srose_ndigis;
@@ -685,8 +689,8 @@
struct rose_sock *rose = rose_sk(sk);
struct sockaddr_rose *addr = (struct sockaddr_rose *)uaddr;
unsigned char cause, diagnostic;
- ax25_address *user;
struct net_device *dev;
+ ax25_uid_assoc *user;
int n;
if (sk->sk_state == TCP_ESTABLISHED && sock->state == SS_CONNECTING) {
@@ -736,12 +740,14 @@
if ((dev = rose_dev_first()) == NULL)
return -ENETUNREACH;
- if ((user = ax25_findbyuid(current->euid)) == NULL)
+ user = ax25_findbyuid(current->euid);
+ if (!user)
return -EINVAL;
memcpy(&rose->source_addr, dev->dev_addr, ROSE_ADDR_LEN);
- rose->source_call = *user;
+ rose->source_call = user->call;
rose->device = dev;
+ ax25_uid_put(user);
rose_insert_socket(sk); /* Finish the bind */
}