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Message-Id: <1208288637-15304-8-git-send-email-allan.stephens@windriver.com>
Date: Tue, 15 Apr 2008 15:43:57 -0400
From: Allan Stephens <allan.stephens@...driver.com>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org, allan.stephens@...driver.com
Subject: [PATCH 7/7 net-2.6.26] [TIPC]: Enhance validation of format on incoming messages
This patch ensures that TIPC properly handles incoming messages
that have incorrect or unexpected formats. Most significantly,
it now ensures that each sl_buff has at least as much data as
the message header indicates it should, and that the entire
message header is stored contiguously; this prevents TIPC from
accidentally accessing memory that is not part of the sk_buff.
Signed-off-by: Allan Stephens <allan.stephens@...driver.com>
---
net/tipc/link.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++-------
1 files changed, 77 insertions(+), 12 deletions(-)
diff --git a/net/tipc/link.c b/net/tipc/link.c
index 0873793..2a26a16 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -1785,6 +1785,56 @@ static struct sk_buff *link_insert_deferred_queue(struct link *l_ptr,
return buf;
}
+/**
+ * link_recv_buf_validate - validate basic format of received message
+ *
+ * This routine ensures a TIPC message has an acceptable header, and at least
+ * as much data as the header indicates it should. The routine also ensures
+ * that the entire message header is stored in the main fragment of the message
+ * buffer, to simplify future access to message header fields.
+ *
+ * Note: Having extra info present in the message header or data areas is OK.
+ * TIPC will ignore the excess, under the assumption that it is optional info
+ * introduced by a later release of the protocol.
+ */
+
+static int link_recv_buf_validate(struct sk_buff *buf)
+{
+ static u32 min_data_hdr_size[8] = {
+ SHORT_H_SIZE, MCAST_H_SIZE, LONG_H_SIZE, DIR_MSG_H_SIZE,
+ MAX_H_SIZE, MAX_H_SIZE, MAX_H_SIZE, MAX_H_SIZE
+ };
+
+ struct tipc_msg *msg;
+ u32 tipc_hdr[2];
+ u32 size;
+ u32 hdr_size;
+ u32 min_hdr_size;
+
+ if (unlikely(buf->len < MIN_H_SIZE))
+ return 0;
+
+ msg = skb_header_pointer(buf, 0, sizeof(tipc_hdr), tipc_hdr);
+ if (msg == NULL)
+ return 0;
+
+ if (unlikely(msg_version(msg) != TIPC_VERSION))
+ return 0;
+
+ size = msg_size(msg);
+ hdr_size = msg_hdr_sz(msg);
+ min_hdr_size = msg_isdata(msg) ?
+ min_data_hdr_size[msg_type(msg)] : INT_H_SIZE;
+
+ if (unlikely((hdr_size < min_hdr_size) ||
+ (size < hdr_size) ||
+ (buf->len < size) ||
+ (size - hdr_size > TIPC_MAX_USER_MSG_SIZE)))
+ return 0;
+
+ return pskb_may_pull(buf, hdr_size);
+}
+
void tipc_recv_msg(struct sk_buff *head, struct tipc_bearer *tb_ptr)
{
read_lock_bh(&tipc_net_lock);
@@ -1794,9 +1844,9 @@ void tipc_recv_msg(struct sk_buff *head, struct tipc_bearer *tb_ptr)
struct link *l_ptr;
struct sk_buff *crs;
struct sk_buff *buf = head;
- struct tipc_msg *msg = buf_msg(buf);
- u32 seq_no = msg_seqno(msg);
- u32 ackd = msg_ack(msg);
+ struct tipc_msg *msg;
+ u32 seq_no;
+ u32 ackd;
u32 released = 0;
int type;
@@ -1804,12 +1854,11 @@ void tipc_recv_msg(struct sk_buff *head, struct tipc_bearer *tb_ptr)
TIPC_SKB_CB(buf)->handle = b_ptr;
head = head->next;
- if (unlikely(msg_version(msg) != TIPC_VERSION))
+
+ /* Ensure message is well-formed */
+
+ if (unlikely(!link_recv_buf_validate(buf)))
goto cont;
-#if 0
- if (msg_user(msg) != LINK_PROTOCOL)
-#endif
- msg_dbg(msg,"<REC<");
/* Ensure message data is a single contiguous unit */
@@ -1817,6 +1866,10 @@ void tipc_recv_msg(struct sk_buff *head, struct tipc_bearer *tb_ptr)
goto cont;
}
+ /* Handle arrival of a non-unicast link message */
+
+ msg = buf_msg(buf);
+
if (unlikely(msg_non_seq(msg))) {
link_recv_non_seq(buf);
continue;
@@ -1826,19 +1879,26 @@ void tipc_recv_msg(struct sk_buff *head, struct tipc_bearer *tb_ptr)
(msg_destnode(msg) != tipc_own_addr)))
goto cont;
+ /* Locate unicast link endpoint that should handle message */
+
n_ptr = tipc_node_find(msg_prevnode(msg));
if (unlikely(!n_ptr))
goto cont;
-
tipc_node_lock(n_ptr);
+
l_ptr = n_ptr->links[b_ptr->identity];
if (unlikely(!l_ptr)) {
tipc_node_unlock(n_ptr);
goto cont;
}
- /*
- * Release acked messages
- */
+
+ /* Validate message sequence number info */
+
+ seq_no = msg_seqno(msg);
+ ackd = msg_ack(msg);
+
+ /* Release acked messages */
+
if (less(n_ptr->bclink.acked, msg_bcast_ack(msg))) {
if (tipc_node_is_up(n_ptr) && n_ptr->bclink.supported)
tipc_bclink_acknowledge(n_ptr, msg_bcast_ack(msg));
@@ -1857,6 +1917,9 @@ void tipc_recv_msg(struct sk_buff *head, struct tipc_bearer *tb_ptr)
l_ptr->first_out = crs;
l_ptr->out_queue_size -= released;
}
+
+ /* Try sending any messages link endpoint has pending */
+
if (unlikely(l_ptr->next_out))
tipc_link_push_queue(l_ptr);
if (unlikely(!list_empty(&l_ptr->waiting_ports)))
@@ -1866,6 +1929,8 @@ void tipc_recv_msg(struct sk_buff *head, struct tipc_bearer *tb_ptr)
tipc_link_send_proto_msg(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
}
+ /* Now (finally!) process the incoming message */
+
protocol_check:
if (likely(link_working_working(l_ptr))) {
if (likely(seq_no == mod(l_ptr->next_in_no))) {
--
1.5.3.2
--
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