* [PATCH 1/3] firewire: net: guard against rx buffer overflows
2016-11-02 20:05 [PATCH 0/3] firewire: net: IP-over-1394 link fragmentation fixes Stefan Richter
@ 2016-11-02 20:07 ` Stefan Richter
2016-11-02 20:08 ` [PATCH 2/3] firewire: net: fix fragmented datagram_size off-by-one Stefan Richter
2016-11-02 20:09 ` [PATCH 3/3] firewire: net: max MTU off by one Stefan Richter
2 siblings, 0 replies; 4+ messages in thread
From: Stefan Richter @ 2016-11-02 20:07 UTC (permalink / raw)
To: linux1394-devel; +Cc: linux-kernel, Eyal Itkin
Date: Sat, 29 Oct 2016 21:28:18 +0200
The IP-over-1394 driver firewire-net lacked input validation when
handling incoming fragmented datagrams. A maliciously formed fragment
with a respectively large datagram_offset would cause a memcpy past the
datagram buffer.
So, drop any packets carrying a fragment with offset + length larger
than datagram_size.
In addition, ensure that
- GASP header, unfragmented encapsulation header, or fragment
encapsulation header actually exists before we access it,
- the encapsulated datagram or fragment is of nonzero size.
Reported-by: Eyal Itkin <eyal.itkin@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
drivers/firewire/net.c | 51 ++++++++++++++++++++++++++++-------------
1 file changed, 35 insertions(+), 16 deletions(-)
--- a/drivers/firewire/net.c
+++ b/drivers/firewire/net.c
@@ -578,6 +578,9 @@ static int fwnet_incoming_packet(struct
int retval;
u16 ether_type;
+ if (len <= RFC2374_UNFRAG_HDR_SIZE)
+ return 0;
+
hdr.w0 = be32_to_cpu(buf[0]);
lf = fwnet_get_hdr_lf(&hdr);
if (lf == RFC2374_HDR_UNFRAG) {
@@ -602,7 +605,12 @@ static int fwnet_incoming_packet(struct
return fwnet_finish_incoming_packet(net, skb, source_node_id,
is_broadcast, ether_type);
}
+
/* A datagram fragment has been received, now the fun begins. */
+
+ if (len <= RFC2374_FRAG_HDR_SIZE)
+ return 0;
+
hdr.w1 = ntohl(buf[1]);
buf += 2;
len -= RFC2374_FRAG_HDR_SIZE;
@@ -616,6 +624,9 @@ static int fwnet_incoming_packet(struct
datagram_label = fwnet_get_hdr_dgl(&hdr);
dg_size = fwnet_get_hdr_dg_size(&hdr); /* ??? + 1 */
+ if (fg_off + len > dg_size)
+ return 0;
+
spin_lock_irqsave(&dev->lock, flags);
peer = fwnet_peer_find_by_node_id(dev, source_node_id, generation);
@@ -722,6 +733,22 @@ static void fwnet_receive_packet(struct
fw_send_response(card, r, rcode);
}
+static int gasp_source_id(__be32 *p)
+{
+ return be32_to_cpu(p[0]) >> 16;
+}
+
+static u32 gasp_specifier_id(__be32 *p)
+{
+ return (be32_to_cpu(p[0]) & 0xffff) << 8 |
+ (be32_to_cpu(p[1]) & 0xff000000) >> 24;
+}
+
+static u32 gasp_version(__be32 *p)
+{
+ return be32_to_cpu(p[1]) & 0xffffff;
+}
+
static void fwnet_receive_broadcast(struct fw_iso_context *context,
u32 cycle, size_t header_length, void *header, void *data)
{
@@ -731,9 +758,6 @@ static void fwnet_receive_broadcast(stru
__be32 *buf_ptr;
int retval;
u32 length;
- u16 source_node_id;
- u32 specifier_id;
- u32 ver;
unsigned long offset;
unsigned long flags;
@@ -750,22 +774,17 @@ static void fwnet_receive_broadcast(stru
spin_unlock_irqrestore(&dev->lock, flags);
- specifier_id = (be32_to_cpu(buf_ptr[0]) & 0xffff) << 8
- | (be32_to_cpu(buf_ptr[1]) & 0xff000000) >> 24;
- ver = be32_to_cpu(buf_ptr[1]) & 0xffffff;
- source_node_id = be32_to_cpu(buf_ptr[0]) >> 16;
-
- if (specifier_id == IANA_SPECIFIER_ID &&
- (ver == RFC2734_SW_VERSION
+ if (length > IEEE1394_GASP_HDR_SIZE &&
+ gasp_specifier_id(buf_ptr) == IANA_SPECIFIER_ID &&
+ (gasp_version(buf_ptr) == RFC2734_SW_VERSION
#if IS_ENABLED(CONFIG_IPV6)
- || ver == RFC3146_SW_VERSION
+ || gasp_version(buf_ptr) == RFC3146_SW_VERSION
#endif
- )) {
- buf_ptr += 2;
- length -= IEEE1394_GASP_HDR_SIZE;
- fwnet_incoming_packet(dev, buf_ptr, length, source_node_id,
+ ))
+ fwnet_incoming_packet(dev, buf_ptr + 2,
+ length - IEEE1394_GASP_HDR_SIZE,
+ gasp_source_id(buf_ptr),
context->card->generation, true);
- }
packet.payload_length = dev->rcv_buffer_size;
packet.interrupt = 1;
--
Stefan Richter
-======----- =-== ---=-
http://arcgraph.de/sr/
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH 2/3] firewire: net: fix fragmented datagram_size off-by-one
2016-11-02 20:05 [PATCH 0/3] firewire: net: IP-over-1394 link fragmentation fixes Stefan Richter
2016-11-02 20:07 ` [PATCH 1/3] firewire: net: guard against rx buffer overflows Stefan Richter
@ 2016-11-02 20:08 ` Stefan Richter
2016-11-02 20:09 ` [PATCH 3/3] firewire: net: max MTU off by one Stefan Richter
2 siblings, 0 replies; 4+ messages in thread
From: Stefan Richter @ 2016-11-02 20:08 UTC (permalink / raw)
To: linux1394-devel; +Cc: linux-kernel, Eyal Itkin
Date: Sun, 30 Oct 2016 17:32:01 +0100
RFC 2734 defines the datagram_size field in fragment encapsulation
headers thus:
datagram_size: The encoded size of the entire IP datagram. The
value of datagram_size [...] SHALL be one less than the value of
Total Length in the datagram's IP header (see STD 5, RFC 791).
Accordingly, the eth1394 driver of Linux 2.6.36 and older set and got
this field with a -/+1 offset:
ether1394_tx() /* transmit */
ether1394_encapsulate_prep()
hdr->ff.dg_size = dg_size - 1;
ether1394_data_handler() /* receive */
if (hdr->common.lf == ETH1394_HDR_LF_FF)
dg_size = hdr->ff.dg_size + 1;
else
dg_size = hdr->sf.dg_size + 1;
Likewise, I observe OS X 10.4 and Windows XP Pro SP3 to transmit 1500
byte sized datagrams in fragments with datagram_size=1499 if link
fragmentation is required.
Only firewire-net sets and gets datagram_size without this offset. The
result is lacking interoperability of firewire-net with OS X, Windows
XP, and presumably Linux' eth1394. (I did not test with the latter.)
For example, FTP data transfers to a Linux firewire-net box with max_rec
smaller than the 1500 bytes MTU
- from OS X fail entirely,
- from Win XP start out with a bunch of fragmented datagrams which
time out, then continue with unfragmented datagrams because Win XP
temporarily reduces the MTU to 576 bytes.
So let's fix firewire-net's datagram_size accessors.
Note that firewire-net thereby loses interoperability with unpatched
firewire-net, but only if link fragmentation is employed. (This happens
with large broadcast datagrams, and with large datagrams on several
FireWire CardBus cards with smaller max_rec than equivalent PCI cards,
and it can be worked around by setting a small enough MTU.)
Cc: stable@vger.kernel.org
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
drivers/firewire/net.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/drivers/firewire/net.c
+++ b/drivers/firewire/net.c
@@ -73,13 +73,13 @@ struct rfc2734_header {
#define fwnet_get_hdr_lf(h) (((h)->w0 & 0xc0000000) >> 30)
#define fwnet_get_hdr_ether_type(h) (((h)->w0 & 0x0000ffff))
-#define fwnet_get_hdr_dg_size(h) (((h)->w0 & 0x0fff0000) >> 16)
+#define fwnet_get_hdr_dg_size(h) ((((h)->w0 & 0x0fff0000) >> 16) + 1)
#define fwnet_get_hdr_fg_off(h) (((h)->w0 & 0x00000fff))
#define fwnet_get_hdr_dgl(h) (((h)->w1 & 0xffff0000) >> 16)
-#define fwnet_set_hdr_lf(lf) ((lf) << 30)
+#define fwnet_set_hdr_lf(lf) ((lf) << 30)
#define fwnet_set_hdr_ether_type(et) (et)
-#define fwnet_set_hdr_dg_size(dgs) ((dgs) << 16)
+#define fwnet_set_hdr_dg_size(dgs) (((dgs) - 1) << 16)
#define fwnet_set_hdr_fg_off(fgo) (fgo)
#define fwnet_set_hdr_dgl(dgl) ((dgl) << 16)
@@ -622,7 +622,7 @@ static int fwnet_incoming_packet(struct
fg_off = fwnet_get_hdr_fg_off(&hdr);
}
datagram_label = fwnet_get_hdr_dgl(&hdr);
- dg_size = fwnet_get_hdr_dg_size(&hdr); /* ??? + 1 */
+ dg_size = fwnet_get_hdr_dg_size(&hdr);
if (fg_off + len > dg_size)
return 0;
--
Stefan Richter
-======----- =-== ---=-
http://arcgraph.de/sr/
^ permalink raw reply [flat|nested] 4+ messages in thread