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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>
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@ralfbaechle @davem330
ralfbaechle authored and davem330 committed Aug 23, 2005
1 parent 53b924b commit 01d7dd0
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Showing 6 changed files with 100 additions and 77 deletions.
18 changes: 16 additions & 2 deletions include/net/ax25.h
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Original file line number Diff line number Diff line change
Expand Up @@ -139,11 +139,25 @@ enum {
#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];
Expand Down Expand Up @@ -376,7 +390,7 @@ extern unsigned long ax25_display_timer(struct timer_list *);

/* 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);
Expand Down
20 changes: 12 additions & 8 deletions net/ax25/af_ax25.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1002,7 +1002,8 @@ static int ax25_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
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;

Expand All @@ -1021,9 +1022,15 @@ static int ax25_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
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);
Expand All @@ -1034,10 +1041,7 @@ static int ax25_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
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
Expand Down
12 changes: 7 additions & 5 deletions net/ax25/ax25_route.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -422,8 +422,8 @@ static inline void ax25_adjust_path(ax25_address *addr, ax25_digi *digipeat)
*/
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)
Expand All @@ -434,16 +434,18 @@ int ax25_rt_autobind(ax25_cb *ax25, ax25_address *addr)
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;
Expand Down
83 changes: 36 additions & 47 deletions net/ax25/ax25_uid.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand All @@ -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;
Expand All @@ -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;
Expand All @@ -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;
Expand All @@ -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;
Expand All @@ -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)
Expand All @@ -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));
}
Expand Down Expand Up @@ -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);
}
24 changes: 16 additions & 8 deletions net/netrom/af_netrom.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -536,7 +536,8 @@ static int nr_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
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)) {
Expand Down Expand Up @@ -575,16 +576,19 @@ static int nr_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
} 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;
}

Expand All @@ -604,7 +608,8 @@ static int nr_connect(struct socket *sock, struct sockaddr *uaddr,
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);
Expand Down Expand Up @@ -645,16 +650,19 @@ static int nr_connect(struct socket *sock, struct sockaddr *uaddr,
}
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;

Expand Down
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