[Drbd-dev] drbd-svn can't handle modular hmac, and crashes if hash can't be found

[Mark Glines <mark@glines.org>]

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Hi,

A few minor issues.

1.  CONFIG_CRYPTO_HMAC can be defined as a module; the drbd code 
currently requires it to be built into the kernel, apparently for no 
good reason.

2.  If the hash algorithm itself isn't available (like sha1.ko wasn't 
loaded yet), crypto_alloc_hash() returns -ENOENT.  It does not return 
NULL, which is what the drbd code currently checks for.  This leads to 
crashes later.

3.  Once #2 is fixed, the user tools try to report the error, and the 
error message contains a typo, an extra ")".  "Failure: (120) The 
'cram-hmac-alg' you specified is not known in )the kernel."  It also 
doesn't tell the user what to do to fix it.

The attached patch fixes the above issues, and applies cleanly to your 
current svn.  Please review and apply.

Mark

P.S.  Since drbd no longer requires any exported symbols from the 
hmac/hash module, is there any reason to check CONFIG_CRYPTO_HMAC at 
all?  A simpler check on CONFIG_CRYPTO to make sure the basic API exists 
should be all you need...

[-- Attachment #2: drbd-hmac-fixes.diff --]
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Index: drbd/drbd_receiver.c
===================================================================
--- drbd/drbd_receiver.c	(revision 2687)
+++ drbd/drbd_receiver.c	(working copy)
@@ -2894,7 +2894,7 @@
 	return 0;
 }
 
-#ifndef CONFIG_CRYPTO_HMAC
+#if !defined(CONFIG_CRYPTO_HMAC) && !defined(CONFIG_CRYPTO_HMAC_MODULE)
 STATIC int drbd_do_auth(drbd_dev *mdev)
 {
 	ERR( "This kernel was build without CONFIG_CRYPTO_HMAC.\n");
Index: drbd/drbd_nl.c
===================================================================
--- drbd/drbd_nl.c	(revision 2687)
+++ drbd/drbd_nl.c	(working copy)
@@ -1052,7 +1052,8 @@
 	if( new_conf->cram_hmac_alg[0] != 0) {
 		snprintf(hmac_name,HMAC_NAME_L,"hmac(%s)",new_conf->cram_hmac_alg);
 		tfm = crypto_alloc_hash(hmac_name, 0, CRYPTO_ALG_ASYNC);
-		if (tfm == NULL) {
+		if (IS_ERR(tfm)) {
+			tfm = NULL;
 			retcode=CRAMAlgNotAvail;
 			goto fail;
 		}
Index: user/drbdsetup.c
===================================================================
--- user/drbdsetup.c	(revision 2687)
+++ user/drbdsetup.c	(working copy)
@@ -359,8 +359,8 @@
 	EM(MDIOError) = "IO error(s) orruced during initial access to meta-data.\n",
 	EM(MDInvalid) = "No valid meta-data signature found.\n)"
 	"Use 'drbdadm create-md res' to initialize meta-data area.\n",
-	EM(CRAMAlgNotAvail) = "The 'cram-hmac-alg' you specified is not known in )"
-	"the kernel.\n",
+	EM(CRAMAlgNotAvail) = "The 'cram-hmac-alg' you specified is not known in "
+	"the kernel. (maybe you need to modprobe it, or modprobe hmac?)\n",
 	EM(CRAMAlgNotDigest) = "The 'cram-hmac-alg' you specified is not a digest.",
 	EM(KMallocFailed) = "kmalloc() failed. Out of memory?",
 	EM(DiscardNotAllowed) = "--discard-my-data not allowed when primary.",