From 01d7dd0e9f8c5f1888619d2649c7da389232b408 Mon Sep 17 00:00:00 2001 From: Ralf Baechle Date: Tue, 23 Aug 2005 10:11:45 -0700 Subject: [PATCH] [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 Signed-off-by: David S. Miller --- include/net/ax25.h | 18 ++++++++- net/ax25/af_ax25.c | 20 ++++++---- net/ax25/ax25_route.c | 12 +++--- net/ax25/ax25_uid.c | 83 ++++++++++++++++++------------------------ net/netrom/af_netrom.c | 24 ++++++++---- net/rose/af_rose.c | 20 ++++++---- 6 files changed, 100 insertions(+), 77 deletions(-) diff --git a/include/net/ax25.h b/include/net/ax25.h index 828a3a93dd..3696f988a9 100644 --- a/include/net/ax25.h +++ b/include/net/ax25.h @@ -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]; @@ -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); diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index 7d8ecadba6..a5c94f1154 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -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; @@ -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); @@ -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 diff --git a/net/ax25/ax25_route.c b/net/ax25/ax25_route.c index 44b99b1ff9..c288526da4 100644 --- a/net/ax25/ax25_route.c +++ b/net/ax25/ax25_route.c @@ -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) @@ -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; diff --git a/net/ax25/ax25_uid.c b/net/ax25/ax25_uid.c index cea6b7d197..a8b3822f3e 100644 --- a/net/ax25/ax25_uid.c +++ b/net/ax25/ax25_uid.c @@ -28,6 +28,7 @@ #include #include #include +#include #include #include #include @@ -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); } diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c index 5385835e92..162a85fed1 100644 --- a/net/netrom/af_netrom.c +++ b/net/netrom/af_netrom.c @@ -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)) { @@ -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; } @@ -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); @@ -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; diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c index 3fe7e56212..5480caf8cc 100644 --- a/net/rose/af_rose.c +++ b/net/rose/af_rose.c @@ -626,7 +626,8 @@ static int rose_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) 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 @@ static int rose_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len) 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 @@ static int rose_connect(struct socket *sock, struct sockaddr *uaddr, int addr_le 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 @@ static int rose_connect(struct socket *sock, struct sockaddr *uaddr, int addr_le 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 */ } -- 2.39.5