Add better error logging if SCTP AUTH chunks are not enabled

In order to use SCTP over DTLS we need ACTP AUTH chunks to be enabled in
the kernel.
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3286)

crypto/bio/bio_err.c

@@ -36,6 +36,7 @@ static ERR_STRING_DATA BIO_str_functs[] = {
     {ERR_FUNC(BIO_F_BIO_LOOKUP_EX), "BIO_lookup_ex"},
     {ERR_FUNC(BIO_F_BIO_MAKE_PAIR), "bio_make_pair"},
     {ERR_FUNC(BIO_F_BIO_NEW), "BIO_new"},
+    {ERR_FUNC(BIO_F_BIO_NEW_DGRAM_SCTP), "BIO_new_dgram_sctp"},
     {ERR_FUNC(BIO_F_BIO_NEW_FILE), "BIO_new_file"},
     {ERR_FUNC(BIO_F_BIO_NEW_MEM_BUF), "BIO_new_mem_buf"},
     {ERR_FUNC(BIO_F_BIO_NREAD), "BIO_nread"},

crypto/bio/bss_dgram.c

@@ -842,6 +842,8 @@ BIO *BIO_new_dgram_sctp(int fd, int close_flag)
                    sizeof(struct sctp_authchunk));
     if (ret < 0) {
         BIO_vfree(bio);
+        BIOerr(BIO_F_BIO_NEW_DGRAM_SCTP, ERR_R_SYS_LIB);
+        ERR_add_error_data(1, "Ensure SCTP AUTH chunks are enabled in kernel");
         return (NULL);
     }
     auth.sauth_chunk = OPENSSL_SCTP_FORWARD_CUM_TSN_CHUNK_TYPE;
@@ -850,13 +852,16 @@ BIO *BIO_new_dgram_sctp(int fd, int close_flag)
                    sizeof(struct sctp_authchunk));
     if (ret < 0) {
         BIO_vfree(bio);
+        BIOerr(BIO_F_BIO_NEW_DGRAM_SCTP, ERR_R_SYS_LIB);
+        ERR_add_error_data(1, "Ensure SCTP AUTH chunks are enabled in kernel");
         return (NULL);
     }
 
     /*
      * Test if activation was successful. When using accept(), SCTP-AUTH has
      * to be activated for the listening socket already, otherwise the
-     * connected socket won't use it.
+     * connected socket won't use it. Similarly with connect(): the socket
+     * prior to connection must be activated for SCTP-AUTH
      */
     sockopt_len = (socklen_t) (sizeof(sctp_assoc_t) + 256 * sizeof(uint8_t));
     authchunks = OPENSSL_zalloc(sockopt_len);
@@ -883,8 +888,14 @@ BIO *BIO_new_dgram_sctp(int fd, int close_flag)
 
     OPENSSL_free(authchunks);
 
-    OPENSSL_assert(auth_data);
-    OPENSSL_assert(auth_forward);
+    if (!auth_data || !auth_forward) {
+        BIO_vfree(bio);
+        BIOerr(BIO_F_BIO_NEW_DGRAM_SCTP, ERR_R_SYS_LIB);
+        ERR_add_error_data(1,
+                           "Ensure SCTP AUTH chunks are enabled on the "
+                           "underlying socket");
+        return NULL;
+    }
 
 #  ifdef SCTP_AUTHENTICATION_EVENT
 #   ifdef SCTP_EVENT

include/openssl/bio.h

@@ -811,6 +811,7 @@ int ERR_load_BIO_strings(void);
 # define BIO_F_BIO_LOOKUP_EX                              143
 # define BIO_F_BIO_MAKE_PAIR                              121
 # define BIO_F_BIO_NEW                                    108
+# define BIO_F_BIO_NEW_DGRAM_SCTP                         145
 # define BIO_F_BIO_NEW_FILE                               109
 # define BIO_F_BIO_NEW_MEM_BUF                            126
 # define BIO_F_BIO_NREAD                                  123