asn1-parser: Fix CHOICE parsing

Fixes: CVE-2017-9023

3 files changed, 134 insertions, 75 deletions

diff --git a/src/libstrongswan/asn1/asn1_parser.c b/src/libstrongswan/asn1/asn1_parser.c
index e7b7a428d..4d5f799b7 100644
--- a/src/libstrongswan/asn1/asn1_parser.c
+++ b/src/libstrongswan/asn1/asn1_parser.c
@@ -1,8 +1,7 @@
 /*
  * Copyright (C) 2006 Martin Will
- * Copyright (C) 2000-2008 Andreas Steffen
- *
- * Hochschule fuer Technik Rapperswil
+ * Copyright (C) 2000-2017 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
@@ -76,12 +75,18 @@ struct private_asn1_parser_t {
 	 * Current parsing pointer for each level
 	 */
 	chunk_t blobs[ASN1_MAX_LEVEL + 2];
+
+	/**
+	 * Parsing a CHOICE on the current level ?
+	 */
+	bool choice[ASN1_MAX_LEVEL + 2];
+
 };
 
 METHOD(asn1_parser_t, iterate, bool,
 	private_asn1_parser_t *this, int *objectID, chunk_t *object)
 {
-	chunk_t *blob, *blob1;
+	chunk_t *blob, *blob1, blob_ori;
 	u_char *start_ptr;
 	u_int level;
 	asn1Object_t obj;
@@ -97,7 +102,7 @@ METHOD(asn1_parser_t, iterate, bool,
 		return FALSE;
 	}
 
-	if (obj.flags & ASN1_END)  /* end of loop or option found */
+	if (obj.flags & ASN1_END)  /* end of loop or choice or option found */
 	{
 		if (this->loopAddr[obj.level] && this->blobs[obj.level+1].len > 0)
 		{
@@ -106,13 +111,42 @@ METHOD(asn1_parser_t, iterate, bool,
 		}
 		else
 		{
-			this->loopAddr[obj.level] = 0;		 /* exit loop or option*/
+			this->loopAddr[obj.level] = 0;		 /* exit loop */
+
+			if (obj.flags & ASN1_CHOICE) /* end of choices */
+			{
+				if (this->choice[obj.level+1])
+				{
+					DBG1(DBG_ASN, "L%d - %s:  incorrect choice encoding",
+						this->level0 + obj.level, obj.name);
+					this->success = FALSE;
+					goto end;
+				}
+			}
+
+			if (obj.flags & ASN1_CH) /* end of choice */
+			{
+				/* parsed a valid choice */
+				this->choice[obj.level] = FALSE;
+
+				/* advance to end of choices */
+				do
+				{
+					this->line++;
+				}
+				while (!((this->objects[this->line].flags & ASN1_END) &&
+						 (this->objects[this->line].flags & ASN1_CHOICE) &&
+						 (this->objects[this->line].level == obj.level-1)));
+				this->line--;
+			}
+
 			goto end;
 		}
 	}
 
 	level = this->level0 + obj.level;
 	blob = this->blobs + obj.level;
+	blob_ori = *blob;
 	blob1 = blob + 1;
 	start_ptr = blob->ptr;
 
@@ -129,7 +163,6 @@ METHOD(asn1_parser_t, iterate, bool,
 	}
 
 	/* handle ASN.1 options */
-
 	if ((obj.flags & ASN1_OPT)
 			&& (blob->len == 0 || *start_ptr != obj.type))
 	{
@@ -144,7 +177,6 @@ METHOD(asn1_parser_t, iterate, bool,
 	}
 
 	/* an ASN.1 object must possess at least a tag and length field */
-
 	if (blob->len < 2)
 	{
 		DBG1(DBG_ASN, "L%d - %s:  ASN.1 object smaller than 2 octets",
@@ -167,8 +199,16 @@ METHOD(asn1_parser_t, iterate, bool,
 	blob->ptr += blob1->len;
 	blob->len -= blob1->len;
 
-	/* return raw ASN.1 object without prior type checking */
+	/* handle ASN.1 choice without explicit context encoding */
+	if ((obj.flags & ASN1_CHOICE) && obj.type == ASN1_EOC)
+	{
+		DBG2(DBG_ASN, "L%d - %s:", level, obj.name);
+		this->choice[obj.level+1] = TRUE;
+		*blob1 = blob_ori;
+		goto end;
+	}
 
+	/* return raw ASN.1 object without prior type checking */
 	if (obj.flags & ASN1_RAW)
 	{
 		DBG2(DBG_ASN, "L%d - %s:", level, obj.name);
@@ -209,6 +249,18 @@ METHOD(asn1_parser_t, iterate, bool,
 		}
 	}
 
+	/* In case of a "CHOICE" start to scan for exactly one valid choice */
+	if (obj.flags & ASN1_CHOICE)
+	{
+		if (blob1->len == 0)
+		{
+			DBG1(DBG_ASN, "L%d - %s:  contains no choice", level, obj.name);
+			this->success = FALSE;
+			goto end;
+		}
+		this->choice[obj.level+1] = TRUE;
+	}
+
 	if (obj.flags & ASN1_OBJ)
 	{
 		object->ptr = start_ptr;
diff --git a/src/libstrongswan/asn1/asn1_parser.h b/src/libstrongswan/asn1/asn1_parser.h
index 0edc22c23..2ee1e892f 100644
--- a/src/libstrongswan/asn1/asn1_parser.h
+++ b/src/libstrongswan/asn1/asn1_parser.h
@@ -1,8 +1,7 @@
 /*
  * Copyright (C) 2006 Martin Will
- * Copyright (C) 2000-2008 Andreas Steffen
- *
- * Hochschule fuer Technik Rapperswil
+ * Copyright (C) 2000-2017 Andreas Steffen
+ * HSR Hochschule fuer Technik Rapperswil
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
@@ -32,15 +31,17 @@
 /**
  * Definition of ASN.1 flags
  */
-#define ASN1_NONE	0x00
-#define ASN1_DEF	0x01
-#define ASN1_OPT	0x02
-#define ASN1_LOOP	0x04
-#define ASN1_END	0x08
-#define ASN1_OBJ	0x10
-#define ASN1_BODY	0x20
-#define ASN1_RAW	0x40
-#define ASN1_EXIT	0x80
+#define ASN1_NONE    0x0000
+#define ASN1_DEF     0x0001
+#define ASN1_OPT     0x0002
+#define ASN1_LOOP    0x0004
+#define ASN1_CHOICE  0x0008
+#define ASN1_CH      0x0010
+#define ASN1_END     0x0020
+#define ASN1_OBJ     0x0040
+#define ASN1_BODY    0x0080
+#define ASN1_RAW     0x0100
+#define ASN1_EXIT    0x0200
 
 typedef struct asn1Object_t asn1Object_t;
 
@@ -51,7 +52,7 @@ struct asn1Object_t{
 	u_int level;
 	const u_char *name;
 	asn1_t type;
-	u_char flags;
+	uint16_t flags;
 };
 
 typedef struct asn1_parser_t asn1_parser_t;
diff --git a/src/libstrongswan/plugins/x509/x509_cert.c b/src/libstrongswan/plugins/x509/x509_cert.c
index ee630eee0..8f1901da8 100644
--- a/src/libstrongswan/plugins/x509/x509_cert.c
+++ b/src/libstrongswan/plugins/x509/x509_cert.c
@@ -2,10 +2,10 @@
  * Copyright (C) 2000 Andreas Hess, Patric Lichtsteiner, Roger Wegmann
  * Copyright (C) 2001 Marco Bertossa, Andreas Schleiss
  * Copyright (C) 2002 Mario Strasser
- * Copyright (C) 2000-2006 Andreas Steffen
+ * Copyright (C) 2000-2017 Andreas Steffen
  * Copyright (C) 2006-2009 Martin Willi
  * Copyright (C) 2008 Tobias Brunner
- * Hochschule fuer Technik Rapperswil
+ * HSR Hochschule fuer Technik Rapperswil
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
@@ -812,20 +812,20 @@ static bool parse_extendedKeyUsage(chunk_t blob, int level0,
  * ASN.1 definition of crlDistributionPoints
  */
 static const asn1Object_t crlDistributionPointsObjects[] = {
-	{ 0, "crlDistributionPoints",	ASN1_SEQUENCE,		ASN1_LOOP			}, /*  0 */
-	{ 1,   "DistributionPoint",		ASN1_SEQUENCE,		ASN1_NONE			}, /*  1 */
-	{ 2,     "distributionPoint",	ASN1_CONTEXT_C_0,	ASN1_OPT|ASN1_LOOP	}, /*  2 */
-	{ 3,       "fullName",			ASN1_CONTEXT_C_0,	ASN1_OPT|ASN1_OBJ	}, /*  3 */
-	{ 3,       "end choice",		ASN1_EOC,			ASN1_END			}, /*  4 */
-	{ 3,       "nameRelToCRLIssuer",ASN1_CONTEXT_C_1,	ASN1_OPT|ASN1_BODY	}, /*  5 */
-	{ 3,       "end choice",		ASN1_EOC,			ASN1_END			}, /*  6 */
-	{ 2,     "end opt",				ASN1_EOC,			ASN1_END			}, /*  7 */
-	{ 2,     "reasons",				ASN1_CONTEXT_C_1,	ASN1_OPT|ASN1_BODY	}, /*  8 */
-	{ 2,     "end opt",				ASN1_EOC,			ASN1_END			}, /*  9 */
-	{ 2,     "crlIssuer",			ASN1_CONTEXT_C_2,	ASN1_OPT|ASN1_OBJ	}, /* 10 */
-	{ 2,     "end opt",				ASN1_EOC,			ASN1_END			}, /* 11 */
-	{ 0, "end loop",				ASN1_EOC,			ASN1_END			}, /* 12 */
-	{ 0, "exit",					ASN1_EOC,			ASN1_EXIT			}
+	{ 0, "crlDistributionPoints",   ASN1_SEQUENCE,    ASN1_LOOP            }, /*  0 */
+	{ 1,   "DistributionPoint",     ASN1_SEQUENCE,    ASN1_NONE            }, /*  1 */
+	{ 2,     "distributionPoint",   ASN1_CONTEXT_C_0, ASN1_OPT|ASN1_CHOICE }, /*  2 */
+	{ 3,       "fullName",          ASN1_CONTEXT_C_0, ASN1_OPT|ASN1_OBJ    }, /*  3 */
+	{ 3,       "end choice",        ASN1_EOC,         ASN1_END|ASN1_CH     }, /*  4 */
+	{ 3,       "nameRelToCRLIssuer",ASN1_CONTEXT_C_1, ASN1_OPT|ASN1_BODY   }, /*  5 */
+	{ 3,       "end choice",        ASN1_EOC,         ASN1_END|ASN1_CH     }, /*  6 */
+	{ 2,     "end opt/choices",     ASN1_EOC,         ASN1_END|ASN1_CHOICE }, /*  7 */
+	{ 2,     "reasons",             ASN1_CONTEXT_C_1, ASN1_OPT|ASN1_BODY   }, /*  8 */
+	{ 2,     "end opt",             ASN1_EOC,         ASN1_END             }, /*  9 */
+	{ 2,     "crlIssuer",           ASN1_CONTEXT_C_2, ASN1_OPT|ASN1_OBJ    }, /* 10 */
+	{ 2,     "end opt",             ASN1_EOC,         ASN1_END             }, /* 11 */
+	{ 0, "end loop",                ASN1_EOC,         ASN1_END             }, /* 12 */
+	{ 0, "exit",                    ASN1_EOC,         ASN1_EXIT            }
 };
 #define CRL_DIST_POINTS				 1
 #define CRL_DIST_POINTS_FULLNAME	 3
@@ -997,25 +997,27 @@ end:
  * ASN.1 definition of a certificatePolicies extension
  */
 static const asn1Object_t certificatePoliciesObject[] = {
-	{ 0, "certificatePolicies",		ASN1_SEQUENCE,	ASN1_LOOP			}, /*  0 */
-	{ 1,   "policyInformation",		ASN1_SEQUENCE,	ASN1_NONE			}, /*  1 */
-	{ 2,     "policyId",			ASN1_OID,		ASN1_BODY			}, /*  2 */
-	{ 2,     "qualifiers",			ASN1_SEQUENCE,	ASN1_OPT|ASN1_LOOP	}, /*  3 */
-	{ 3,       "qualifierInfo",		ASN1_SEQUENCE,	ASN1_NONE			}, /*  4 */
-	{ 4,         "qualifierId",		ASN1_OID,		ASN1_BODY			}, /*  5 */
-	{ 4,         "cPSuri",			ASN1_IA5STRING,	ASN1_OPT|ASN1_BODY	}, /*  6 */
-	{ 4,         "end choice",		ASN1_EOC,		ASN1_END			}, /*  7 */
-	{ 4,         "userNotice",		ASN1_SEQUENCE,	ASN1_OPT|ASN1_BODY	}, /*  8 */
-	{ 5,           "explicitText",	ASN1_EOC,		ASN1_RAW			}, /*  9 */
-	{ 4,         "end choice",		ASN1_EOC,		ASN1_END			}, /* 10 */
-	{ 2,      "end opt/loop",		ASN1_EOC,		ASN1_END			}, /* 12 */
-	{ 0, "end loop",				ASN1_EOC,		ASN1_END			}, /* 13 */
-	{ 0, "exit",					ASN1_EOC,		ASN1_EXIT			}
+	{ 0, "certificatePolicies",      ASN1_SEQUENCE,  ASN1_LOOP            }, /*  0 */
+	{ 1,   "policyInformation",      ASN1_SEQUENCE,  ASN1_NONE            }, /*  1 */
+	{ 2,     "policyId",             ASN1_OID,       ASN1_BODY            }, /*  2 */
+	{ 2,     "qualifiers",           ASN1_SEQUENCE,  ASN1_OPT|ASN1_LOOP   }, /*  3 */
+	{ 3,       "qualifierInfo",      ASN1_SEQUENCE,  ASN1_NONE            }, /*  4 */
+	{ 4,         "qualifierId",      ASN1_OID,       ASN1_BODY            }, /*  5 */
+	{ 4,         "qualifier",        ASN1_EOC,       ASN1_CHOICE          }, /*  6 */
+	{ 5,           "cPSuri",         ASN1_IA5STRING, ASN1_OPT|ASN1_BODY   }, /*  7 */
+	{ 5,           "end choice",     ASN1_EOC,       ASN1_END|ASN1_CH     }, /*  8 */
+	{ 5,           "userNotice",     ASN1_SEQUENCE,  ASN1_OPT|ASN1_BODY   }, /*  9 */
+	{ 6,             "explicitText", ASN1_EOC,       ASN1_RAW             }, /* 10 */
+	{ 5,           "end choice",     ASN1_EOC,       ASN1_END|ASN1_CH     }, /* 11 */
+	{ 4,         "end choices",      ASN1_EOC,       ASN1_END|ASN1_CHOICE }, /* 12 */
+	{ 2,     "end opt/loop",         ASN1_EOC,       ASN1_END             }, /* 13 */
+	{ 0, "end loop",                 ASN1_EOC,       ASN1_END             }, /* 14 */
+	{ 0, "exit",                     ASN1_EOC,       ASN1_EXIT            }
 };
-#define CERT_POLICY_ID				2
-#define CERT_POLICY_QUALIFIER_ID	5
-#define CERT_POLICY_CPS_URI			6
-#define CERT_POLICY_EXPLICIT_TEXT	9
+#define CERT_POLICY_ID              2
+#define CERT_POLICY_QUALIFIER_ID    5
+#define CERT_POLICY_CPS_URI         7
+#define CERT_POLICY_EXPLICIT_TEXT  10
 
 /**
  * Parse certificatePolicies
@@ -1180,27 +1182,31 @@ static bool parse_policyConstraints(chunk_t blob, int level0,
  * ASN.1 definition of ipAddrBlocks according to RFC 3779
  */
 static const asn1Object_t ipAddrBlocksObjects[] = {
-	{ 0, "ipAddrBlocks",			ASN1_SEQUENCE,		ASN1_LOOP			}, /*  0 */
-	{ 1,   "ipAddressFamily",		ASN1_SEQUENCE,		ASN1_NONE			}, /*  1 */
-	{ 2,     "addressFamily",		ASN1_OCTET_STRING,	ASN1_BODY			}, /*  2 */
-	{ 2,     "inherit",				ASN1_NULL,			ASN1_OPT|ASN1_NONE	}, /*  3 */
-	{ 2,     "end choice",			ASN1_EOC,			ASN1_END			}, /*  4 */
-	{ 2,     "addressesOrRanges",	ASN1_SEQUENCE,		ASN1_OPT|ASN1_LOOP	}, /*  5 */
-	{ 3,       "addressPrefix",		ASN1_BIT_STRING,	ASN1_OPT|ASN1_BODY  }, /*  6 */
-	{ 3,       "end choice",		ASN1_EOC,			ASN1_END			}, /*  7 */
-	{ 3,       "addressRange",		ASN1_SEQUENCE,		ASN1_OPT|ASN1_NONE	}, /*  8 */
-	{ 4,         "min",				ASN1_BIT_STRING,	ASN1_BODY			}, /*  9 */
-	{ 4,         "max",				ASN1_BIT_STRING,	ASN1_BODY			}, /* 10 */
-	{ 3,       "end choice",		ASN1_EOC,			ASN1_END			}, /* 11 */
-	{ 2,     "end opt/loop",		ASN1_EOC,			ASN1_END			}, /* 12 */
-	{ 0, "end loop",				ASN1_EOC,			ASN1_END			}, /* 13 */
-	{ 0, "exit",					ASN1_EOC,			ASN1_EXIT			}
+	{ 0, "ipAddrBlocks",            ASN1_SEQUENCE,     ASN1_LOOP            }, /*  0 */
+	{ 1,   "ipAddressFamily",       ASN1_SEQUENCE,     ASN1_NONE            }, /*  1 */
+	{ 2,     "addressFamily",       ASN1_OCTET_STRING, ASN1_BODY            }, /*  2 */
+	{ 2,     "ipAddressChoice",     ASN1_EOC,          ASN1_CHOICE          }, /*  3 */
+	{ 3,       "inherit",           ASN1_NULL,         ASN1_OPT             }, /*  4 */
+	{ 3,       "end choice",        ASN1_EOC,          ASN1_END|ASN1_CH     }, /*  5 */
+	{ 3,       "addressesOrRanges", ASN1_SEQUENCE,     ASN1_OPT|ASN1_LOOP   }, /*  6 */
+	{ 4,         "addressOrRange",  ASN1_EOC,          ASN1_CHOICE          }, /*  7 */
+	{ 5,           "addressPrefix", ASN1_BIT_STRING,   ASN1_OPT|ASN1_BODY   }, /*  8 */
+	{ 5,           "end choice",    ASN1_EOC,          ASN1_END|ASN1_CH     }, /*  9 */
+	{ 5,           "addressRange",  ASN1_SEQUENCE,     ASN1_OPT             }, /* 10 */
+	{ 6,             "min",         ASN1_BIT_STRING,   ASN1_BODY            }, /* 11 */
+	{ 6,             "max",         ASN1_BIT_STRING,   ASN1_BODY            }, /* 12 */
+	{ 5,           "end choice",    ASN1_EOC,          ASN1_END|ASN1_CH     }, /* 13 */
+	{ 4,         "end choices",     ASN1_EOC,          ASN1_END|ASN1_CHOICE }, /* 14 */
+	{ 3,       "end loop/choice",   ASN1_EOC,          ASN1_END|ASN1_CH     }, /* 15 */
+	{ 2,     "end choices",         ASN1_EOC,          ASN1_END|ASN1_CHOICE }, /* 16 */
+	{ 0, "end loop",                ASN1_EOC,          ASN1_END             }, /* 17 */
+	{ 0, "exit",                    ASN1_EOC,          ASN1_EXIT            }
 };
 #define IP_ADDR_BLOCKS_FAMILY       2
-#define IP_ADDR_BLOCKS_INHERIT      3
-#define IP_ADDR_BLOCKS_PREFIX       6
-#define IP_ADDR_BLOCKS_MIN          9
-#define IP_ADDR_BLOCKS_MAX         10
+#define IP_ADDR_BLOCKS_INHERIT      4
+#define IP_ADDR_BLOCKS_PREFIX       8
+#define IP_ADDR_BLOCKS_MIN         11
+#define IP_ADDR_BLOCKS_MAX         12
 
 static bool check_address_object(ts_type_t ts_type, chunk_t object)
 {