From: Doug Flick <dougfl...@microsoft.com>
REF:https://bugzilla.tianocore.org/show_bug.cgi?id=4537
REF:https://bugzilla.tianocore.org/show_bug.cgi?id=4538
Bug Details:
PixieFail Bug #4
CVE-2023-45232
CVSS 7.5 : CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')
Infinite loop when parsing unknown options in the Destination Options
header
PixieFail Bug #5
CVE-2023-45233
CVSS 7.5 : CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')
Infinite loop when parsing a PadN option in the Destination Options
header
Change Overview:
Most importantly this change corrects the following incorrect math
and cleans up the code.
> // It is a PadN option
> //
> - Offset = (UINT8)(Offset + *(Option + Offset + 1) + 2);
> + OptDataLen = ((EFI_IP6_OPTION *)(Option + Offset))->Length;
> + Offset = IP6_NEXT_OPTION_OFFSET (Offset, OptDataLen);
> case Ip6OptionSkip:
> - Offset = (UINT8)(Offset + *(Option + Offset + 1));
> OptDataLen = ((EFI_IP6_OPTION *)(Option + Offset))->Length;
> Offset = IP6_NEXT_OPTION_OFFSET (Offset, OptDataLen);
Additionally, this change also corrects incorrect math where the calling
function was calculating the HDR EXT optionLen as a uint8 instead of a
uint16
> - OptionLen = (UINT8)((*Option + 1) * 8 - 2);
> + OptionLen = IP6_HDR_EXT_LEN (*Option) -
IP6_COMBINED_SIZE_OF_NEXT_HDR_AND_LEN;
Additionally this check adds additional logic to santize the incoming
data
Cc: Saloni Kasbekar <saloni.kasbe...@intel.com>
Cc: Zachary Clark-williams <zachary.clark-willi...@intel.com>
Signed-off-by: Doug Flick [MSFT] <doug.e...@gmail.com>
---
NetworkPkg/Ip6Dxe/Ip6Nd.h | 35 ++++++++++++++++
NetworkPkg/Ip6Dxe/Ip6Option.h | 71 ++++++++++++++++++++++++++++++++
NetworkPkg/Ip6Dxe/Ip6Option.c | 76 ++++++++++++++++++++++++++++++-----
3 files changed, 171 insertions(+), 11 deletions(-)
diff --git a/NetworkPkg/Ip6Dxe/Ip6Nd.h b/NetworkPkg/Ip6Dxe/Ip6Nd.h
index 860934a167eb..bf64e9114e13 100644
--- a/NetworkPkg/Ip6Dxe/Ip6Nd.h
+++ b/NetworkPkg/Ip6Dxe/Ip6Nd.h
@@ -56,13 +56,48 @@ VOID
VOID *Context
);
+//
+// Per RFC8200 Section 4.2
+//
+// Two of the currently-defined extension headers -- the Hop-by-Hop
+// Options header and the Destination Options header -- carry a variable
+// number of type-length-value (TLV) encoded "options", of the following
+// format:
+//
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
+// | Option Type | Opt Data Len | Option Data
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
+//
+// Option Type 8-bit identifier of the type of option.
+//
+// Opt Data Len 8-bit unsigned integer. Length of the Option
+// Data field of this option, in octets.
+//
+// Option Data Variable-length field. Option-Type-specific
+// data.
+//
typedef struct _IP6_OPTION_HEADER {
+ ///
+ /// identifier of the type of option.
+ ///
UINT8 Type;
+ ///
+ /// Length of the Option Data field of this option, in octets.
+ ///
UINT8 Length;
+ ///
+ /// Option-Type-specific data.
+ ///
} IP6_OPTION_HEADER;
STATIC_ASSERT (sizeof (IP6_OPTION_HEADER) == 2, "IP6_OPTION_HEADER is expected
to be exactly 2 bytes long.");
+#define IP6_NEXT_OPTION_OFFSET(offset, length) (offset +
sizeof(IP6_OPTION_HEADER) + length)
+STATIC_ASSERT (
+ IP6_NEXT_OPTION_OFFSET (0, 0) == 2,
+ "The next option is minimally the combined size of the option tag and length"
+ );
+
typedef struct _IP6_ETHE_ADDR_OPTION {
UINT8 Type;
UINT8 Length;
diff --git a/NetworkPkg/Ip6Dxe/Ip6Option.h b/NetworkPkg/Ip6Dxe/Ip6Option.h
index bd8e223c8a67..fb07c28f5ad7 100644
--- a/NetworkPkg/Ip6Dxe/Ip6Option.h
+++ b/NetworkPkg/Ip6Dxe/Ip6Option.h
@@ -12,6 +12,77 @@
#define IP6_FRAGMENT_OFFSET_MASK (~0x3)
+//
+// For more information see RFC 8200, Section 4.3, 4.4, and 4.6
+//
+// This example format is from section 4.6
+// This does not apply to fragment headers
+//
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// | Next Header | Hdr Ext Len | |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+// | |
+// . .
+// . Header-Specific Data .
+// . .
+// | |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//
+// Next Header 8-bit selector. Identifies the type of
+// header immediately following the extension
+// header. Uses the same values as the IPv4
+// Protocol field [IANA-PN].
+//
+// Hdr Ext Len 8-bit unsigned integer. Length of the
+// Destination Options header in 8-octet units,
+// not including the first 8 octets.
+
+//
+// These defines apply to the following:
+// 1. Hop by Hop
+// 2. Routing
+// 3. Destination
+//
+typedef struct _IP6_EXT_HDR {
+ ///
+ /// The Next Header field identifies the type of header immediately
+ ///
+ UINT8 NextHeader;
+ ///
+ /// The Hdr Ext Len field specifies the length of the Hop-by-Hop Options
+ ///
+ UINT8 HdrExtLen;
+ ///
+ /// Header-Specific Data
+ ///
+} IP6_EXT_HDR;
+
+STATIC_ASSERT (
+ sizeof (IP6_EXT_HDR) == 2,
+ "The combined size of Next Header and Len is two 8 bit fields"
+ );
+
+//
+// IPv6 extension headers contain an 8-bit length field which describes the
size of
+// the header. However, the length field only includes the size of the
extension
+// header options, not the size of the first 8 bytes of the header. Therefore,
in
+// order to calculate the full size of the extension header, we add 1 (to
account
+// for the first 8 bytes omitted by the length field reporting) and then
multiply
+// by 8 (since the size is represented in 8-byte units).
+//
+// a is the length field of the extension header (UINT8)
+// The result may be up to 2046 octets (UINT16)
+//
+#define IP6_HDR_EXT_LEN(a) (((UINT16)((UINT8)(a)) + 1) * 8)
+
+// This is the maxmimum length permissible by a extension header
+// Length is UINT8 of 8 octets not including the first 8 octets
+#define IP6_MAX_EXT_DATA_LENGTH (IP6_HDR_EXT_LEN (MAX_UINT8) -
sizeof(IP6_EXT_HDR))
+STATIC_ASSERT (
+ IP6_MAX_EXT_DATA_LENGTH == 2046,
+ "Maximum data length is ((MAX_UINT8 + 1) * 8) - 2"
+ );
+
typedef struct _IP6_FRAGMENT_HEADER {
UINT8 NextHeader;
UINT8 Reserved;
diff --git a/NetworkPkg/Ip6Dxe/Ip6Option.c b/NetworkPkg/Ip6Dxe/Ip6Option.c
index 8718d5d8756a..fd97ce116f98 100644
--- a/NetworkPkg/Ip6Dxe/Ip6Option.c
+++ b/NetworkPkg/Ip6Dxe/Ip6Option.c
@@ -17,7 +17,8 @@
@param[in] IpSb The IP6 service data.
@param[in] Packet The to be validated packet.
@param[in] Option The first byte of the option.
- @param[in] OptionLen The length of the whole option.
+ @param[in] OptionLen The length of all options, expressed in byte
length of octets.
+ Maximum length is 2046 bytes or ((n + 1) * 8)
- 2 where n is 255.
@param[in] Pointer Identifies the octet offset within
the invoking packet where the error was
detected.
@@ -31,12 +32,33 @@ Ip6IsOptionValid (
IN IP6_SERVICE *IpSb,
IN NET_BUF *Packet,
IN UINT8 *Option,
- IN UINT8 OptionLen,
+ IN UINT16 OptionLen,
IN UINT32 Pointer
)
{
- UINT8 Offset;
- UINT8 OptionType;
+ UINT16 Offset;
+ UINT8 OptionType;
+ UINT8 OptDataLen;
+
+ if (Option == NULL) {
+ ASSERT (Option != NULL);
+ return FALSE;
+ }
+
+ if ((OptionLen <= 0) || (OptionLen > IP6_MAX_EXT_DATA_LENGTH)) {
+ ASSERT (OptionLen > 0 && OptionLen <= IP6_MAX_EXT_DATA_LENGTH);
+ return FALSE;
+ }
+
+ if (Packet == NULL) {
+ ASSERT (Packet != NULL);
+ return FALSE;
+ }
+
+ if (IpSb == NULL) {
+ ASSERT (IpSb != NULL);
+ return FALSE;
+ }
Offset = 0;
@@ -54,7 +76,8 @@ Ip6IsOptionValid (
//
// It is a PadN option
//
- Offset = (UINT8)(Offset + *(Option + Offset + 1) + 2);
+ OptDataLen = ((IP6_OPTION_HEADER *)(Option + Offset))->Length;
+ Offset = IP6_NEXT_OPTION_OFFSET (Offset, OptDataLen);
break;
case Ip6OptionRouterAlert:
//
@@ -69,7 +92,8 @@ Ip6IsOptionValid (
//
switch (OptionType & Ip6OptionMask) {
case Ip6OptionSkip:
- Offset = (UINT8)(Offset + *(Option + Offset + 1));
+ OptDataLen = ((IP6_OPTION_HEADER *)(Option + Offset))->Length;
+ Offset = IP6_NEXT_OPTION_OFFSET (Offset, OptDataLen);
break;
case Ip6OptionDiscard:
return FALSE;
@@ -308,7 +332,7 @@ Ip6IsExtsValid (
UINT32 Pointer;
UINT32 Offset;
UINT8 *Option;
- UINT8 OptionLen;
+ UINT16 OptionLen;
BOOLEAN Flag;
UINT8 CountD;
UINT8 CountA;
@@ -385,6 +409,36 @@ Ip6IsExtsValid (
// Fall through
//
case IP6_DESTINATION:
+ //
+ // See https://www.rfc-editor.org/rfc/rfc2460#section-4.2 page 23
+ //
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ // | Next Header | Hdr Ext Len | |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
+ // | |
+ // . .
+ // . Options .
+ // . .
+ // | |
+ // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ //
+ //
+ // Next Header 8-bit selector. Identifies the type of header
+ // immediately following the Destination Options
+ // header. Uses the same values as the IPv4
+ // Protocol field [RFC-1700 et seq.].
+ //
+ // Hdr Ext Len 8-bit unsigned integer. Length of the
+ // Destination Options header in 8-octet units, not
+ // including the first 8 octets.
+ //
+ // Options Variable-length field, of length such that the
+ // complete Destination Options header is an
+ // integer multiple of 8 octets long. Contains one
+ // or more TLV-encoded options, as described in
+ // section 4.2.
+ //
+
if (*NextHeader == IP6_DESTINATION) {
CountD++;
}
@@ -398,7 +452,7 @@ Ip6IsExtsValid (
Offset++;
Option = ExtHdrs + Offset;
- OptionLen = (UINT8)((*Option + 1) * 8 - 2);
+ OptionLen = IP6_HDR_EXT_LEN (*Option) - sizeof (IP6_EXT_HDR);
Option++;
Offset++;
@@ -430,7 +484,7 @@ Ip6IsExtsValid (
//
// Ignore the routing header and proceed to process the next header.
//
- Offset = Offset + (RoutingHead->HeaderLen + 1) * 8;
+ Offset = Offset + IP6_HDR_EXT_LEN (RoutingHead->HeaderLen);
if (UnFragmentLen != NULL) {
*UnFragmentLen = Offset;
@@ -441,7 +495,7 @@ Ip6IsExtsValid (
// to the packet's source address, pointing to the unrecognized
routing
// type.
//
- Pointer = Offset + 2 + sizeof (EFI_IP6_HEADER);
+ Pointer = Offset + sizeof (IP6_EXT_HDR) + sizeof (EFI_IP6_HEADER);
if ((IpSb != NULL) && (Packet != NULL) &&
!IP6_IS_MULTICAST (&Packet->Ip.Ip6->DestinationAddress))
{
@@ -527,7 +581,7 @@ Ip6IsExtsValid (
//
// RFC2402, Payload length is specified in 32-bit words, minus "2".
//
- OptionLen = (UINT8)((*Option + 2) * 4);
+ OptionLen = ((UINT16)(*Option + 2) * 4);
Offset = Offset + OptionLen;
break;
--
2.43.0
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