[edk2-devel] [PATCH v1] NetworkPkg/Ip6Dxe: Improve Neightbor Discovery message validation (CVE-2019-14559)
Maciej Rabeda
maciej.rabeda at linux.intel.com
Mon Mar 2 12:38:52 UTC 2020
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2174
Problem has been identified with Ip6ProcessRouterAdvertise() when
Router Advertise packet contains options with malicious/invalid
'Length' field. This can lead to platform entering infinite loop
when processing options from that packet.
Cc: Jiaxin Wu <jiaxin.wu at intel.com>
Cc: Siyuan Fu <siyuan.fu at intel.com>
Signed-off-by: Maciej Rabeda <maciej.rabeda at linux.intel.com>
---
NetworkPkg/Ip6Dxe/Ip6Nd.c | 44 +++++++++------
NetworkPkg/Ip6Dxe/Ip6Nd.h | 13 +++++
NetworkPkg/Ip6Dxe/Ip6Option.c | 57 +++++++++++++++-----
3 files changed, 83 insertions(+), 31 deletions(-)
diff --git a/NetworkPkg/Ip6Dxe/Ip6Nd.c b/NetworkPkg/Ip6Dxe/Ip6Nd.c
index 4288ef02dd46..fd7f60b2f92c 100644
--- a/NetworkPkg/Ip6Dxe/Ip6Nd.c
+++ b/NetworkPkg/Ip6Dxe/Ip6Nd.c
@@ -1927,7 +1927,7 @@ Ip6ProcessRouterAdvertise (
UINT32 ReachableTime;
UINT32 RetransTimer;
UINT16 RouterLifetime;
- UINT16 Offset;
+ UINT32 Offset;
UINT8 Type;
UINT8 Length;
IP6_ETHER_ADDR_OPTION LinkLayerOption;
@@ -2094,10 +2094,11 @@ Ip6ProcessRouterAdvertise (
//
// The only defined options that may appear are the Source
// Link-Layer Address, Prefix information and MTU options.
- // All included options have a length that is greater than zero.
+ // All included options have a length that is greater than zero and
+ // fit within the input packet.
//
Offset = 16;
- while (Offset < Head->PayloadLength) {
+ while (Offset < (UINT32) Head->PayloadLength) {
NetbufCopy (Packet, Offset, sizeof (UINT8), &Type);
switch (Type) {
case Ip6OptionEtherSource:
@@ -2105,9 +2106,12 @@ Ip6ProcessRouterAdvertise (
// Update the neighbor cache
//
NetbufCopy (Packet, Offset, sizeof (IP6_ETHER_ADDR_OPTION), (UINT8 *) &LinkLayerOption);
- if (LinkLayerOption.Length <= 0) {
- goto Exit;
- }
+
+ //
+ // Option size validity ensured by Ip6IsNDOptionValid().
+ //
+ ASSERT (LinkLayerOption.Length != 0);
+ ASSERT (Offset + (UINT32) LinkLayerOption.Length * 8 >= (UINT32) Head->PayloadLength);
ZeroMem (&LinkLayerAddress, sizeof (EFI_MAC_ADDRESS));
CopyMem (&LinkLayerAddress, LinkLayerOption.EtherAddr, 6);
@@ -2151,13 +2155,17 @@ Ip6ProcessRouterAdvertise (
}
}
- Offset = (UINT16) (Offset + (UINT16) LinkLayerOption.Length * 8);
+ Offset += (UINT32) LinkLayerOption.Length * 8;
break;
case Ip6OptionPrefixInfo:
NetbufCopy (Packet, Offset, sizeof (IP6_PREFIX_INFO_OPTION), (UINT8 *) &PrefixOption);
- if (PrefixOption.Length != 4) {
- goto Exit;
- }
+
+ //
+ // Option size validity ensured by Ip6IsNDOptionValid().
+ //
+ ASSERT (PrefixOption.Length == 4);
+ ASSERT (Offset + (UINT32) PrefixOption.Length * 8 >= (UINT32) Head->PayloadLength);
+
PrefixOption.ValidLifetime = NTOHL (PrefixOption.ValidLifetime);
PrefixOption.PreferredLifetime = NTOHL (PrefixOption.PreferredLifetime);
@@ -2321,9 +2329,12 @@ Ip6ProcessRouterAdvertise (
break;
case Ip6OptionMtu:
NetbufCopy (Packet, Offset, sizeof (IP6_MTU_OPTION), (UINT8 *) &MTUOption);
- if (MTUOption.Length != 1) {
- goto Exit;
- }
+
+ //
+ // Option size validity ensured by Ip6IsNDOptionValid().
+ //
+ ASSERT (MTUOption.Length == 1);
+ ASSERT (Offset + (UINT32) MTUOption.Length * 8 >= (UINT32) Head->PayloadLength);
//
// Use IPv6 minimum link MTU 1280 bytes as the maximum packet size in order
@@ -2338,11 +2349,10 @@ Ip6ProcessRouterAdvertise (
// Silently ignore unrecognized options
//
NetbufCopy (Packet, Offset + sizeof (UINT8), sizeof (UINT8), &Length);
- if (Length <= 0) {
- goto Exit;
- }
- Offset = (UINT16) (Offset + (UINT16) Length * 8);
+ ASSERT (Length != 0);
+
+ Offset += (UINT32) Length * 8;
break;
}
}
diff --git a/NetworkPkg/Ip6Dxe/Ip6Nd.h b/NetworkPkg/Ip6Dxe/Ip6Nd.h
index 560dfa343782..5f1bd6fb922a 100644
--- a/NetworkPkg/Ip6Dxe/Ip6Nd.h
+++ b/NetworkPkg/Ip6Dxe/Ip6Nd.h
@@ -56,12 +56,21 @@ VOID
VOID *Context
);
+typedef struct _IP6_OPTION_HEADER {
+ UINT8 Type;
+ UINT8 Length;
+} IP6_OPTION_HEADER;
+
+STATIC_ASSERT (sizeof (IP6_OPTION_HEADER) == 2, "IP6_OPTION_HEADER is expected to be exactly 2 bytes long.");
+
typedef struct _IP6_ETHE_ADDR_OPTION {
UINT8 Type;
UINT8 Length;
UINT8 EtherAddr[6];
} IP6_ETHER_ADDR_OPTION;
+STATIC_ASSERT (sizeof (IP6_ETHER_ADDR_OPTION) == 8, "IP6_ETHER_ADDR_OPTION is expected to be exactly 8 bytes long.");
+
typedef struct _IP6_MTU_OPTION {
UINT8 Type;
UINT8 Length;
@@ -69,6 +78,8 @@ typedef struct _IP6_MTU_OPTION {
UINT32 Mtu;
} IP6_MTU_OPTION;
+STATIC_ASSERT (sizeof (IP6_MTU_OPTION) == 8, "IP6_MTU_OPTION is expected to be exactly 8 bytes long.");
+
typedef struct _IP6_PREFIX_INFO_OPTION {
UINT8 Type;
UINT8 Length;
@@ -80,6 +91,8 @@ typedef struct _IP6_PREFIX_INFO_OPTION {
EFI_IPv6_ADDRESS Prefix;
} IP6_PREFIX_INFO_OPTION;
+STATIC_ASSERT (sizeof (IP6_PREFIX_INFO_OPTION) == 32, "IP6_PREFIX_INFO_OPTION is expected to be exactly 32 bytes long.");
+
typedef
VOID
(*IP6_DAD_CALLBACK) (
diff --git a/NetworkPkg/Ip6Dxe/Ip6Option.c b/NetworkPkg/Ip6Dxe/Ip6Option.c
index 4d92a852dc86..6b4b029d1479 100644
--- a/NetworkPkg/Ip6Dxe/Ip6Option.c
+++ b/NetworkPkg/Ip6Dxe/Ip6Option.c
@@ -129,45 +129,74 @@ Ip6IsNDOptionValid (
IN UINT16 OptionLen
)
{
- UINT16 Offset;
- UINT8 OptionType;
+ UINT32 Offset;
UINT16 Length;
+ IP6_OPTION_HEADER *OptionHeader;
+
+ if (Option == NULL) {
+ ASSERT (Option != NULL);
+ return FALSE;
+ }
Offset = 0;
- while (Offset < OptionLen) {
- OptionType = *(Option + Offset);
- Length = (UINT16) (*(Option + Offset + 1) * 8);
+ //
+ // RFC 4861 states that Neighbor Discovery packet can contain zero or more
+ // options. Start processing the options if at least Type + Length fields
+ // fit within the input buffer.
+ //
+ while (Offset + sizeof (IP6_OPTION_HEADER) - 1 < OptionLen) {
+ OptionHeader = (IP6_OPTION_HEADER*) (Option + Offset);
+ Length = (UINT16) OptionHeader->Length * 8;
- switch (OptionType) {
+ switch (OptionHeader->Type) {
case Ip6OptionPrefixInfo:
if (Length != 32) {
return FALSE;
}
-
break;
case Ip6OptionMtu:
if (Length != 8) {
return FALSE;
}
-
break;
default:
- //
- // Check the length of Ip6OptionEtherSource, Ip6OptionEtherTarget, and
- // Ip6OptionRedirected here. For unrecognized options, silently ignore
- // and continue processing the message.
- //
+ // RFC 4861 states that Length field cannot be 0.
if (Length == 0) {
return FALSE;
}
+ break;
+ }
+
+ //
+ // Check whether recognized options are within the input buffer's scope.
+ //
+ switch (OptionHeader->Type) {
+ case Ip6OptionEtherSource:
+ case Ip6OptionEtherTarget:
+ case Ip6OptionPrefixInfo:
+ case Ip6OptionRedirected:
+ case Ip6OptionMtu:
+ if (Offset + Length > (UINT32) OptionLen) {
+ return FALSE;
+ }
+ break;
+ default:
+ //
+ // Unrecognized options can be either valid (but unused) or invalid
+ // (garbage in between or right after valid options). Silently ignore.
+ //
break;
}
- Offset = (UINT16) (Offset + Length);
+ //
+ // Advance to the next option.
+ // Length already considers option header's Type + Length.
+ //
+ Offset += Length;
}
return TRUE;
--
2.24.0.windows.2
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