Use the correct function types in X509V3_EXT_METHODs.
While C allows function pointer casts, it is UB to call a function with
a different type than its actual type signature. That is, even though
`void f(int *)` and `void g(void *)` have the same ABI, it is UB to
cast `f` to a `void(*)(void *)` and then call it through that pointer.
Clang CFI will try to enforce this rule.
The recent CL to call X509_print in tests revealed that all the i2? and
?2i callbacks in X509V3_EXT_METHODs were implemented with functions of
the wrong type, out of some combination of missing consts and void*
turned into T*.
This CL fixes this. Where the function wasn't exported, or had no
callers, I just fixed the function itself. Where it had extension
callers, I added a wrapper function with a void* type.
I'm not positive whether the wrappers are the right call. On the one
hand, keeping the exported functions as-is is more type-safe and more
OpenSSL-compatible. However, most (but not all) uses of these are in
other code defining X509V3_EXT_METHODs themselves, so the void*
signature is more correct for them too. And the functions have a type
signature meant for X509V3_EXT_METHOD, complete with method pointer.
I've gone with leaving the exported ones as-is for now. Probably the
right answer anyway is to migrate the external callers, of either type
signature.
Change-Id: Ib8f2995cbd890221eaa9ac864a7e553cb6711901
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/52686
Commit-Queue: Bob Beck <bbe@google.com>
Reviewed-by: Bob Beck <bbe@google.com>
diff --git a/crypto/x509v3/v3_bitst.c b/crypto/x509v3/v3_bitst.c
index 871b776..3420b12 100644
--- a/crypto/x509v3/v3_bitst.c
+++ b/crypto/x509v3/v3_bitst.c
@@ -91,15 +91,10 @@
{-1, NULL, NULL}
};
-const X509V3_EXT_METHOD v3_nscert =
-EXT_BITSTRING(NID_netscape_cert_type, ns_cert_type_table);
-const X509V3_EXT_METHOD v3_key_usage =
-EXT_BITSTRING(NID_key_usage, key_usage_type_table);
-
-STACK_OF(CONF_VALUE) *i2v_ASN1_BIT_STRING(X509V3_EXT_METHOD *method,
- ASN1_BIT_STRING *bits,
- STACK_OF(CONF_VALUE) *ret)
+static STACK_OF(CONF_VALUE) *i2v_ASN1_BIT_STRING(
+ const X509V3_EXT_METHOD *method, void *ext, STACK_OF(CONF_VALUE) *ret)
{
+ const ASN1_BIT_STRING *bits = ext;
const BIT_STRING_BITNAME *bnam;
for (bnam = method->usr_data; bnam->lname; bnam++) {
if (ASN1_BIT_STRING_get_bit(bits, bnam->bitnum))
@@ -108,9 +103,8 @@
return ret;
}
-ASN1_BIT_STRING *v2i_ASN1_BIT_STRING(X509V3_EXT_METHOD *method,
- X509V3_CTX *ctx,
- STACK_OF(CONF_VALUE) *nval)
+static void *v2i_ASN1_BIT_STRING(const X509V3_EXT_METHOD *method,
+ X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *nval)
{
CONF_VALUE *val;
ASN1_BIT_STRING *bs;
@@ -142,3 +136,14 @@
}
return bs;
}
+
+#define EXT_BITSTRING(nid, table) \
+ { \
+ nid, 0, ASN1_ITEM_ref(ASN1_BIT_STRING), 0, 0, 0, 0, 0, 0, \
+ i2v_ASN1_BIT_STRING, v2i_ASN1_BIT_STRING, NULL, NULL, (void *)(table) \
+ }
+
+const X509V3_EXT_METHOD v3_nscert =
+EXT_BITSTRING(NID_netscape_cert_type, ns_cert_type_table);
+const X509V3_EXT_METHOD v3_key_usage =
+EXT_BITSTRING(NID_key_usage, key_usage_type_table);
