net/third_party/nss/patches/aesgcmchromium.patch

diff --git a/lib/ssl/ssl3con.c b/lib/ssl/ssl3con.c
index c5cb1eb..299e414 100644
--- a/lib/ssl/ssl3con.c
+++ b/lib/ssl/ssl3con.c
@@ -8,6 +8,7 @@
 
 /* TODO(ekr): Implement HelloVerifyRequest on server side. OK for now. */
 
+#define _GNU_SOURCE 1
 #include "cert.h"
 #include "ssl.h"
 #include "cryptohi.h"	/* for DSAU_ stuff */
@@ -46,6 +47,9 @@
 #ifdef NSS_ENABLE_ZLIB
 #include "zlib.h"
 #endif
+#ifdef LINUX
+#include <dlfcn.h>
+#endif
 
 #ifndef PK11_SETATTRS
 #define PK11_SETATTRS(x,id,v,l) (x)->type = (id); \
@@ -1897,6 +1901,63 @@ ssl3_BuildRecordPseudoHeader(unsigned char *out,
     return 13;
 }
 
+typedef SECStatus (*PK11CryptFcn)(
+    PK11SymKey *symKey, CK_MECHANISM_TYPE mechanism, SECItem *param,
+    unsigned char *out, unsigned int *outLen, unsigned int maxLen,
+    const unsigned char *in, unsigned int inLen);
+
+static PK11CryptFcn pk11_encrypt = NULL;
+static PK11CryptFcn pk11_decrypt = NULL;
+
+static PRCallOnceType resolvePK11CryptOnce;
+
+static PRStatus
+ssl3_ResolvePK11CryptFunctions(void)
+{
+#ifdef LINUX
+    /* On Linux we use the system NSS libraries. Look up the PK11_Encrypt and
+     * PK11_Decrypt functions at run time. */
+    pk11_encrypt = (PK11CryptFcn)dlsym(RTLD_DEFAULT, "PK11_Encrypt");
+    pk11_decrypt = (PK11CryptFcn)dlsym(RTLD_DEFAULT, "PK11_Decrypt");
+    return PR_SUCCESS;
+#else
+    /* On other platforms we use our own copy of NSS. PK11_Encrypt and
+     * PK11_Decrypt are known to be available. */
+    pk11_encrypt = PK11_Encrypt;
+    pk11_decrypt = PK11_Decrypt;
+    return PR_SUCCESS;
+#endif
+}
+
+/* 
+ * In NSS 3.15, PK11_Encrypt and PK11_Decrypt were added to provide access
+ * to the AES GCM implementation in the NSS softoken. So the presence of
+ * these two functions implies the NSS version supports AES GCM.
+ */
+static PRBool
+ssl3_HasGCMSupport(void)
+{
+    (void)PR_CallOnce(&resolvePK11CryptOnce, ssl3_ResolvePK11CryptFunctions);
+    return pk11_encrypt != NULL;
+}
+
+/* On this socket, disable the GCM cipher suites */
+SECStatus
+ssl3_DisableGCMSuites(sslSocket * ss)
+{
+    unsigned int i;
+
+    for (i = 0; i < PR_ARRAY_SIZE(cipher_suite_defs); i++) {
+	const ssl3CipherSuiteDef *cipher_def = &cipher_suite_defs[i];
+	if (cipher_def->bulk_cipher_alg == cipher_aes_128_gcm) {
+	    SECStatus rv = ssl3_CipherPrefSet(ss, cipher_def->cipher_suite,
+					      PR_FALSE);
+	    PORT_Assert(rv == SECSuccess); /* else is coding error */
+	}
+    }
+    return SECSuccess;
+}
+
 static SECStatus
 ssl3_AESGCM(ssl3KeyMaterial *keys,
 	    PRBool doDecrypt,
@@ -1948,10 +2009,10 @@ ssl3_AESGCM(ssl3KeyMaterial *keys,
     gcmParams.ulTagBits = tagSize * 8;
 
     if (doDecrypt) {
-	rv = PK11_Decrypt(keys->write_key, CKM_AES_GCM, &param, out, &uOutLen,
+	rv = pk11_decrypt(keys->write_key, CKM_AES_GCM, &param, out, &uOutLen,
 			  maxout, in, inlen);
     } else {
-	rv = PK11_Encrypt(keys->write_key, CKM_AES_GCM, &param, out, &uOutLen,
+	rv = pk11_encrypt(keys->write_key, CKM_AES_GCM, &param, out, &uOutLen,
 			  maxout, in, inlen);
     }
     *outlen += (int) uOutLen;
@@ -5337,6 +5398,10 @@ ssl3_SendClientHello(sslSocket *ss, PRBool resending)
 	ssl3_DisableNonDTLSSuites(ss);
     }
 
+    if (!ssl3_HasGCMSupport()) {
+	ssl3_DisableGCMSuites(ss);
+    }
+
     /* how many suites are permitted by policy and user preference? */
     num_suites = count_cipher_suites(ss, ss->ssl3.policy, PR_TRUE);
     if (!num_suites) {
@@ -8400,6 +8465,10 @@ ssl3_HandleClientHello(sslSocket *ss, SSL3Opaque *b, PRUint32 length)
 	ssl3_DisableNonDTLSSuites(ss);
     }
 
+    if (!ssl3_HasGCMSupport()) {
+	ssl3_DisableGCMSuites(ss);
+    }
+
 #ifdef PARANOID
     /* Look for a matching cipher suite. */
     j = ssl3_config_match_init(ss);