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Message-ID: <ygfiq0bsjry.fsf@janus.isnogud.escape.de>
Date: 05 Nov 2010 19:33:05 +0100
From: Urs Thuermann <urs@...ogud.escape.de>
To: netdev@...r.kernel.org
Cc: socketcan@...tkopp.net, oliver.hartkopp@...kswagen.de,
Dan Rosenberg <drosenberg@...curity.com>, security@...nel.org,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH] Fix CAN info leak/minor heap overflow
This patch removes the leakage of kernel space addresses to userspace.
Instead, socket inode numbers are used to create unique proc file
names for CAN_BCM sockets and for referring to sockets in filter
lists. In addition, this makes debugging easier, since inode numbers
are also shown in ls -l /proc/<pid>/fd/<fd> and lsof(8) output.
BTW, if kernel space addresses are considered security critical
information one should also take a look and possibly change
/proc/net/{tcp,tcp6,udp,udp6,raw,raw6,unix}
and maybe some others.
The change of the procfs content leads to a new version string
20101105.
Signed-off-by: Urs Thuermann <urs@...ogud.escape.de>
Signed-off-by: Oliver Hartkopp <socketcan@...tkopp.net>
CC: Dan Rosenberg <drosenberg@...curity.com>
CC: Linus Torvalds <torvalds@...ux-foundation.org>
---
diff --git a/include/linux/can/core.h b/include/linux/can/core.h
index 6c507be..e20a841 100644
--- a/include/linux/can/core.h
+++ b/include/linux/can/core.h
@@ -19,7 +19,7 @@
#include <linux/skbuff.h>
#include <linux/netdevice.h>
-#define CAN_VERSION "20090105"
+#define CAN_VERSION "20101105"
/* increment this number each time you change some user-space interface */
#define CAN_ABI_VERSION "8"
diff --git a/net/can/bcm.c b/net/can/bcm.c
index 08ffe9e..0e81e04 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -86,6 +86,12 @@ MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Oliver Hartkopp <oliver.hartkopp@...kswagen.de>");
MODULE_ALIAS("can-proto-2");
+/*
+ * Point to the sockets inode number inside the bcm ident string.
+ * We skip the string length of "bcm " (== 4) created in bcm_init().
+ */
+#define INODENUM(bo) (bo->ident + 4)
+
/* easy access to can_frame payload */
static inline u64 GET_U64(const struct can_frame *cp)
{
@@ -125,7 +131,7 @@ struct bcm_sock {
struct list_head tx_ops;
unsigned long dropped_usr_msgs;
struct proc_dir_entry *bcm_proc_read;
- char procname [9]; /* pointer printed in ASCII with \0 */
+ char ident[32];
};
static inline struct bcm_sock *bcm_sk(const struct sock *sk)
@@ -165,9 +171,7 @@ static int bcm_proc_show(struct seq_file *m, void *v)
struct bcm_sock *bo = bcm_sk(sk);
struct bcm_op *op;
- seq_printf(m, ">>> socket %p", sk->sk_socket);
- seq_printf(m, " / sk %p", sk);
- seq_printf(m, " / bo %p", bo);
+ seq_printf(m, ">>> socket inode %s", INODENUM(bo));
seq_printf(m, " / dropped %lu", bo->dropped_usr_msgs);
seq_printf(m, " / bound %s", bcm_proc_getifname(ifname, bo->ifindex));
seq_printf(m, " <<<\n");
@@ -1168,7 +1172,7 @@ static int bcm_rx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
err = can_rx_register(dev, op->can_id,
REGMASK(op->can_id),
bcm_rx_handler, op,
- "bcm");
+ bo->ident);
op->rx_reg_dev = dev;
dev_put(dev);
@@ -1177,7 +1181,7 @@ static int bcm_rx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
} else
err = can_rx_register(NULL, op->can_id,
REGMASK(op->can_id),
- bcm_rx_handler, op, "bcm");
+ bcm_rx_handler, op, bo->ident);
if (err) {
/* this bcm rx op is broken -> remove it */
list_del(&op->list);
@@ -1402,6 +1406,8 @@ static int bcm_init(struct sock *sk)
{
struct bcm_sock *bo = bcm_sk(sk);
+ snprintf(bo->ident, sizeof(bo->ident), "bcm %lu", sock_i_ino(sk));
+
bo->bound = 0;
bo->ifindex = 0;
bo->dropped_usr_msgs = 0;
@@ -1466,7 +1472,7 @@ static int bcm_release(struct socket *sock)
/* remove procfs entry */
if (proc_dir && bo->bcm_proc_read)
- remove_proc_entry(bo->procname, proc_dir);
+ remove_proc_entry(INODENUM(bo), proc_dir);
/* remove device reference */
if (bo->bound) {
@@ -1519,13 +1525,11 @@ static int bcm_connect(struct socket *sock, struct sockaddr *uaddr, int len,
bo->bound = 1;
- if (proc_dir) {
- /* unique socket address as filename */
- sprintf(bo->procname, "%p", sock);
- bo->bcm_proc_read = proc_create_data(bo->procname, 0644,
+ /* use unique socket inode number as filename */
+ if (proc_dir)
+ bo->bcm_proc_read = proc_create_data(INODENUM(bo), 0644,
proc_dir,
&bcm_proc_fops, sk);
- }
return 0;
}
diff --git a/net/can/proc.c b/net/can/proc.c
index f4265cc..15bed1c 100644
--- a/net/can/proc.c
+++ b/net/can/proc.c
@@ -204,23 +204,17 @@ static void can_print_rcvlist(struct seq_file *m, struct hlist_head *rx_list,
hlist_for_each_entry_rcu(r, n, rx_list, list) {
char *fmt = (r->can_id & CAN_EFF_FLAG)?
- " %-5s %08X %08x %08x %08x %8ld %s\n" :
- " %-5s %03X %08x %08lx %08lx %8ld %s\n";
+ " %-5s %08X %08x %8ld %s\n" :
+ " %-5s %03X %08x %8ld %s\n";
seq_printf(m, fmt, DNAME(dev), r->can_id, r->mask,
- (unsigned long)r->func, (unsigned long)r->data,
r->matches, r->ident);
}
}
static void can_print_recv_banner(struct seq_file *m)
{
- /*
- * can1. 00000000 00000000 00000000
- * ....... 0 tp20
- */
- seq_puts(m, " device can_id can_mask function"
- " userdata matches ident\n");
+ seq_puts(m, " device can_id can_mask matches ident\n");
}
static int can_stats_proc_show(struct seq_file *m, void *v)
diff --git a/net/can/raw.c b/net/can/raw.c
index e88f610..e057f0d 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -88,6 +88,7 @@ struct raw_sock {
struct can_filter dfilter; /* default/single filter */
struct can_filter *filter; /* pointer to filter(s) */
can_err_mask_t err_mask;
+ char ident[32];
};
/*
@@ -154,13 +155,14 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
static int raw_enable_filters(struct net_device *dev, struct sock *sk,
struct can_filter *filter, int count)
{
+ struct raw_sock *ro = raw_sk(sk);
int err = 0;
int i;
for (i = 0; i < count; i++) {
err = can_rx_register(dev, filter[i].can_id,
filter[i].can_mask,
- raw_rcv, sk, "raw");
+ raw_rcv, sk, ro->ident);
if (err) {
/* clean up successfully registered filters */
while (--i >= 0)
@@ -177,11 +179,12 @@ static int raw_enable_filters(struct net_device *dev, struct sock *sk,
static int raw_enable_errfilter(struct net_device *dev, struct sock *sk,
can_err_mask_t err_mask)
{
+ struct raw_sock *ro = raw_sk(sk);
int err = 0;
if (err_mask)
err = can_rx_register(dev, 0, err_mask | CAN_ERR_FLAG,
- raw_rcv, sk, "raw");
+ raw_rcv, sk, ro->ident);
return err;
}
@@ -281,6 +284,8 @@ static int raw_init(struct sock *sk)
{
struct raw_sock *ro = raw_sk(sk);
+ snprintf(ro->ident, sizeof(ro->ident), "raw %lu", sock_i_ino(sk));
+
ro->bound = 0;
ro->ifindex = 0;
--
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