Rewrite asn1_item_ex_d2i() using CBS.

This requires a few wrappers to call into some non-CBS functions, however
we can now remove the asn1_d2i_ex_primitive() wrapper as there are no
longer any non-CBS callers.

ok tb@

1 files changed, 125 insertions, 58 deletions

diff --git a/src/lib/libcrypto/asn1/tasn_dec.c b/src/lib/libcrypto/asn1/tasn_dec.c
index de0b819064..f3e032c1c1 100644
--- a/src/lib/libcrypto/asn1/tasn_dec.c
+++ b/src/lib/libcrypto/asn1/tasn_dec.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tasn_dec.c,v 1.62 2022/05/10 05:19:22 jsing Exp $ */
+/* $OpenBSD: tasn_dec.c,v 1.63 2022/05/10 18:40:06 jsing Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project 2000.
  */
@@ -83,13 +83,16 @@ static int asn1_collect(CBB *cbb, CBS *cbs, char indefinite, int expected_tag,
     int expected_class, int depth);
 
 static int asn1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in,
-    long len, const ASN1_ITEM *it, int tag, int aclass, char opt, int depth);
+    long len, const ASN1_ITEM *it, int tag_number, int tag_class, char optional,
+    int depth);
+static int asn1_template_ex_d2i_cbs(ASN1_VALUE **pval, CBS *cbs,
+    const ASN1_TEMPLATE *tt, char optional, int depth);
 static int asn1_template_ex_d2i(ASN1_VALUE **pval, const unsigned char **in,
     long len, const ASN1_TEMPLATE *tt, char opt, int depth);
 static int asn1_template_noexp_d2i(ASN1_VALUE **val, const unsigned char **in,
     long len, const ASN1_TEMPLATE *tt, char opt, int depth);
-static int asn1_d2i_ex_primitive(ASN1_VALUE **pval, const unsigned char **in,
-    long len, const ASN1_ITEM *it, int tag, int aclass, char opt);
+static int asn1_d2i_ex_primitive(ASN1_VALUE **pval, CBS *cbs,
+    const ASN1_ITEM *it, int tag_number, int tag_class, char optional);
 static int asn1_ex_c2i(ASN1_VALUE **pval, CBS *content, int utype,
     const ASN1_ITEM *it);
 
@@ -218,6 +221,26 @@ asn1_item_ex_d2i_choice(ASN1_VALUE **pval, const unsigned char **in, long len,
 }
 
 static int
+asn1_item_ex_d2i_choice_cbs(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it,
+    int tag_number, int tag_class, char optional, int depth)
+{
+        const unsigned char *p;
+        int ret;
+
+        if (CBS_len(cbs) > LONG_MAX)
+                return 0;
+
+        p = CBS_data(cbs);
+        ret = asn1_item_ex_d2i_choice(pval, &p, (long)CBS_len(cbs), it,
+            tag_number, tag_class, optional, depth);
+        if (ret == 1) {
+                if (!CBS_skip(cbs, p - CBS_data(cbs)))
+                        return 0;
+        }
+        return ret;
+}
+
+static int
 asn1_item_ex_d2i_sequence(ASN1_VALUE **pval, const unsigned char **in, long len,
     const ASN1_ITEM *it, int tag, int aclass, char opt, int depth)
 {
@@ -390,22 +413,43 @@ asn1_item_ex_d2i_sequence(ASN1_VALUE **pval, const unsigned char **in, long len,
         return 0;
 }
 
+static int
+asn1_item_ex_d2i_sequence_cbs(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it,
+    int tag_number, int tag_class, char optional, int depth)
+{
+        const unsigned char *p;
+        int ret;
+
+        if (CBS_len(cbs) > LONG_MAX)
+                return 0;
+
+        p = CBS_data(cbs);
+        ret = asn1_item_ex_d2i_sequence(pval, &p, (long)CBS_len(cbs), it,
+            tag_number, tag_class, optional, depth);
+        if (ret == 1) {
+                if (!CBS_skip(cbs, p - CBS_data(cbs)))
+                        return 0;
+        }
+        return ret;
+}
+
 /*
  * Decode an item, taking care of IMPLICIT tagging, if any.
  * If 'opt' set and tag mismatch return -1 to handle OPTIONAL
  */
 static int
-asn1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
-    const ASN1_ITEM *it, int tag, int aclass, char opt, int depth)
+asn1_item_ex_d2i_cbs(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it,
+    int tag_number, int tag_class, char optional, int depth)
 {
-        const ASN1_EXTERN_FUNCS *ef;
-        ASN1_TLC ctx = { 0 };
+        const ASN1_EXTERN_FUNCS *ef = it->funcs;
         const unsigned char *p = NULL;
+        ASN1_TLC ctx = { 0 };
+        CBS cbs_mstring;
         unsigned char oclass;
         int otag;
         int ret = 0;
 
-        if (!pval)
+        if (pval == NULL)
                 return 0;
 
         if (++depth > ASN1_MAX_CONSTRUCTED_NEST) {
@@ -415,23 +459,23 @@ asn1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
 
         switch (it->itype) {
         case ASN1_ITYPE_PRIMITIVE:
-                if (it->templates) {
-                        /* tagging or OPTIONAL is currently illegal on an item
+                if (it->templates != NULL) {
+                        /*
+                         * Tagging or OPTIONAL is currently illegal on an item
                          * template because the flags can't get passed down.
                          * In practice this isn't a problem: we include the
                          * relevant flags from the item template in the
                          * template itself.
                          */
-                        if ((tag != -1) || opt) {
+                        if (tag_number != -1 || optional) {
                                 ASN1error(ASN1_R_ILLEGAL_OPTIONS_ON_ITEM_TEMPLATE);
                                 goto err;
                         }
-                        return asn1_template_ex_d2i(pval, in, len,
-                            it->templates, opt, depth);
+                        return asn1_template_ex_d2i_cbs(pval, cbs,
+                            it->templates, optional, depth);
                 }
-                return asn1_d2i_ex_primitive(pval, in, len, it,
-                    tag, aclass, opt);
-                break;
+                return asn1_d2i_ex_primitive(pval, cbs, it, tag_number,
+                    tag_class, optional);
 
         case ASN1_ITYPE_MSTRING:
                 /*
@@ -439,52 +483,54 @@ asn1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
                  * tagging, so if tag != -1, then this looks like an error in
                  * the template.
                  */
-                if (tag != -1) {
+                if (tag_number != -1) {
                         ASN1error(ASN1_R_BAD_TEMPLATE);
                         goto err;
                 }
 
-                p = *in;
-                /* Just read in tag and class */
-                ret = asn1_check_tag(NULL, &otag, &oclass, NULL, NULL, &p, len,
-                    -1, 0, 1);
-                if (!ret) {
+                /* XXX - avoid reading the header twice for MSTRING. */
+                CBS_dup(cbs, &cbs_mstring);
+                if (asn1_check_tag_cbs(&cbs_mstring, NULL, &otag, &oclass,
+                    NULL, NULL, -1, 0, 1) != 1) {
                         ASN1error(ERR_R_NESTED_ASN1_ERROR);
                         goto err;
                 }
 
                 /* Must be UNIVERSAL class */
                 if (oclass != V_ASN1_UNIVERSAL) {
-                        /* If OPTIONAL, assume this is OK */
-                        if (opt)
+                        if (optional)
                                 return -1;
                         ASN1error(ASN1_R_MSTRING_NOT_UNIVERSAL);
                         goto err;
                 }
                 /* Check tag matches bit map */
                 if (!(ASN1_tag2bit(otag) & it->utype)) {
-                        /* If OPTIONAL, assume this is OK */
-                        if (opt)
+                        if (optional)
                                 return -1;
                         ASN1error(ASN1_R_MSTRING_WRONG_TAG);
                         goto err;
                 }
-                return asn1_d2i_ex_primitive(pval, in, len,
-                    it, otag, 0, 0);
+                return asn1_d2i_ex_primitive(pval, cbs, it, otag, 0, 0);
 
         case ASN1_ITYPE_EXTERN:
-                /* Use new style d2i */
-                ef = it->funcs;
-                return ef->asn1_ex_d2i(pval, in, len, it, tag, aclass, opt, &ctx);
+                if (CBS_len(cbs) > LONG_MAX)
+                        return 0;
+                p = CBS_data(cbs);
+                if ((ret = ef->asn1_ex_d2i(pval, &p, (long)CBS_len(cbs), it,
+                    tag_number, tag_class, optional, &ctx)) == 1) {
+                        if (!CBS_skip(cbs, p - CBS_data(cbs)))
+                                goto err;
+                }
+                return ret;
 
         case ASN1_ITYPE_CHOICE:
-                return asn1_item_ex_d2i_choice(pval, in, len, it, tag,
-                    aclass, opt, depth);
+                return asn1_item_ex_d2i_choice_cbs(pval, cbs, it, tag_number,
+                    tag_class, optional, depth);
 
         case ASN1_ITYPE_NDEF_SEQUENCE:
         case ASN1_ITYPE_SEQUENCE:
-                return asn1_item_ex_d2i_sequence(pval, in, len, it, tag,
-                    aclass, opt, depth);
+                return asn1_item_ex_d2i_sequence_cbs(pval, cbs, it, tag_number,
+                    tag_class, optional, depth);
 
         default:
                 return 0;
@@ -498,6 +544,28 @@ asn1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
         return 0;
 }
 
+static int
+asn1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long inlen,
+    const ASN1_ITEM *it, int tag_number, int tag_class, char optional,
+    int depth)
+{
+        CBS cbs;
+        int ret;
+
+        if (inlen < 0)
+                return 0;
+
+        CBS_init(&cbs, *in, inlen);
+
+        ret = asn1_item_ex_d2i_cbs(pval, &cbs, it, tag_number, tag_class,
+            optional, depth);
+
+        if (ret == 1)
+                *in = CBS_data(&cbs);
+
+        return ret;
+}
+
 int
 ASN1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
     const ASN1_ITEM *it, int tag, int aclass, char opt, ASN1_TLC *ctx)
@@ -579,6 +647,26 @@ asn1_template_ex_d2i(ASN1_VALUE **val, const unsigned char **in, long inlen,
 }
 
 static int
+asn1_template_ex_d2i_cbs(ASN1_VALUE **pval, CBS *cbs, const ASN1_TEMPLATE *tt,
+    char optional, int depth)
+{
+        const unsigned char *p;
+        int ret;
+
+        if (CBS_len(cbs) > LONG_MAX)
+                return 0;
+
+        p = CBS_data(cbs);
+        ret = asn1_template_ex_d2i(pval, &p, (long)CBS_len(cbs), tt,
+            optional, depth);
+        if (ret == 1) {
+                if (!CBS_skip(cbs, p - CBS_data(cbs)))
+                        return 0;
+        }
+        return ret;
+}
+
+static int
 asn1_template_noexp_d2i(ASN1_VALUE **val, const unsigned char **in, long len,
     const ASN1_TEMPLATE *tt, char opt, int depth)
 {
@@ -696,7 +784,7 @@ asn1_template_noexp_d2i(ASN1_VALUE **val, const unsigned char **in, long len,
 }
 
 static int
-asn1_d2i_ex_primitive_cbs(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it,
+asn1_d2i_ex_primitive(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it,
     int tag_number, int tag_class, char optional)
 {
         CBS cbs_any, cbs_content, cbs_object, cbs_initial;
@@ -816,27 +904,6 @@ asn1_d2i_ex_primitive_cbs(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it,
 }
 
 static int
-asn1_d2i_ex_primitive(ASN1_VALUE **pval, const unsigned char **in, long inlen,
-    const ASN1_ITEM *it, int tag_number, int tag_class, char optional)
-{
-        CBS cbs;
-        int ret;
-
-        if (inlen < 0)
-                return 0;
-
-        CBS_init(&cbs, *in, inlen);
-
-        ret = asn1_d2i_ex_primitive_cbs(pval, &cbs, it, tag_number, tag_class,
-            optional);
-
-        if (ret == 1)
-                *in = CBS_data(&cbs);
-
-        return ret;
-}
-
-static int
 asn1_ex_c2i_primitive(ASN1_VALUE **pval, CBS *content, int utype, const ASN1_ITEM *it)
 {
         ASN1_STRING *stmp;