Handle kernel crypto api init failure better.

lib/crypto_backend/crypto_cipher_kernel.c

@@ -24,6 +24,7 @@
 #include <errno.h>
 #include <unistd.h>
 #include <sys/socket.h>
+#include <sys/stat.h>
 #include <linux/if_alg.h>
 #include "crypto_backend.h"
 
@@ -43,29 +44,40 @@ int crypt_kernel_socket_init(struct sockaddr_alg *sa, int *tfmfd, int *opfd)
 {
 	*tfmfd = socket(AF_ALG, SOCK_SEQPACKET, 0);
 	if (*tfmfd == -1)
-		goto bad;
+		return -ENOENT;
 
-	if (bind(*tfmfd, (struct sockaddr *)sa, sizeof(*sa)) == -1)
-		goto bad;
-
-	*opfd = accept(*tfmfd, NULL, 0);
-	if (*opfd == -1)
-		goto bad;
-
-	return 0;
-bad:
-	if (*tfmfd != -1) {
+	if (bind(*tfmfd, (struct sockaddr *)sa, sizeof(*sa)) == -1) {
 		close(*tfmfd);
 		*tfmfd = -1;
+		return -ENOENT;
 	}
-	if (*opfd != -1) {
-		close(*opfd);
-		*opfd = -1;
-	}
+
+	*opfd = accept(*tfmfd, NULL, 0);
+	if (*opfd == -1) {
+		close(*tfmfd);
+		*tfmfd = -1;
 		return -EINVAL;
+	}
+
+	return 0;
 }
 
-/* ciphers */
+static int crypt_kernel_cipher_available(void)
+{
+	struct stat st;
+
+	if(stat("/sys/module/algif_skcipher", &st) < 0)
+		return -ENOENT;
+
+	return -ENOTSUP;
+}
+
+/*
+ *ciphers
+ *
+ * ENOENT - no API available
+ * ENOTSUP - algorithm not available
+ */
 int crypt_cipher_init(struct crypt_cipher **ctx, const char *name,
 		    const char *mode, const void *buffer, size_t length)
 {
@@ -74,6 +86,7 @@ int crypt_cipher_init(struct crypt_cipher **ctx, const char *name,
 		.salg_family = AF_ALG,
 		.salg_type = "skcipher",
 	};
+	int r;
 
 	h = malloc(sizeof(*h));
 	if (!h)
@@ -82,9 +95,12 @@ int crypt_cipher_init(struct crypt_cipher **ctx, const char *name,
 	snprintf((char *)sa.salg_name, sizeof(sa.salg_name),
 		 "%s(%s)", mode, name);
 
-	if (crypt_kernel_socket_init(&sa, &h->tfmfd, &h->opfd) < 0) {
+	r = crypt_kernel_socket_init(&sa, &h->tfmfd, &h->opfd);
+	if (r < 0) {
 		free(h);
-		return -ENOTSUP;
+		if (r == -ENOENT)
+			return crypt_kernel_cipher_available();
+		return r;
 	}
 
 	if (setsockopt(h->tfmfd, SOL_ALG, ALG_SET_KEY, buffer, length) == -1) {

lib/tcrypt/tcrypt.c

@@ -244,7 +244,7 @@ static int decrypt_blowfish_le_cbc(struct tcrypt_alg *alg,
 	r = crypt_cipher_init(&cipher, "blowfish", "ecb",
 			      &key[alg->key_offset], alg->key_size);
 	if (r < 0)
-		goto out;
+		return r;
 
 	memcpy(iv, &key[alg->iv_offset], alg->iv_size);
 	for (i = 0; i < TCRYPT_HDR_LEN; i += bs) {
@@ -254,12 +254,12 @@ static int decrypt_blowfish_le_cbc(struct tcrypt_alg *alg,
 					  bs, NULL, 0);
 		blowfish_le(&buf[i]);
 		if (r < 0)
-			goto out;
+			break;
 		for (j = 0; j < bs; j++)
 			buf[i + j] ^= iv[j];
 		memcpy(iv, iv_old, bs);
 	}
-out:
+
 	crypt_cipher_destroy(cipher);
 	return r;
 }
@@ -394,10 +394,18 @@ static int decrypt_hdr(struct crypt_device *cd, struct tcrypt_phdr *hdr,
 				continue;
 			r = decrypt_hdr_one(&tcrypt_cipher[i].cipher[j],
 					    tcrypt_cipher[i].mode, key, &hdr2);
-			if (r < 0) {
-				log_dbg("Error %s.", tcrypt_cipher[i].cipher[j].name);
+			if (r < 0)
 				break;
 		}
+
+		if (r == -ENOENT) {
+			log_err(cd, _("Required kernel crypto interface is not available.\n"
+				      "Ensure you have af_skcipher kernel module loaded.\n"));
+			return -ENOTSUP;
+		}
+		if (r < 0) {
+			log_dbg("TCRYPT:   returned error %d, skipped.", r);
+			continue;
 		}
 
 		if (!strncmp(hdr2.d.magic, TCRYPT_HDR_MAGIC, TCRYPT_HDR_MAGIC_LEN)) {

src/cryptsetup.c

@@ -489,14 +489,18 @@ static int action_benchmark(int arg __attribute__((unused)))
 			strncat(cipher, cipher_mode, MAX_CIPHER_LEN);
 			log_std("%11s  %4db  %5.1f MiB/s  %5.1f MiB/s\n",
 				cipher, key_size, enc_mbr, dec_mbr);
-		} else
-			log_err(_("Cannot benchmark %s.\n"), cipher);
+		} else if (r == -ENOTSUP)
+			log_err(_("Cipher %s is not available.\n"), opt_cipher);
 	} else {
-		log_std("%s", header);
 		for (i = 0; bciphers[i].cipher; i++) {
 			r = crypt_benchmark(NULL, bciphers[i].cipher, bciphers[i].mode,
 					    bciphers[i].key_size, bciphers[i].iv_size,
 					    buffer_size, &enc_mbr, &dec_mbr);
+			if (r == -ENOENT)
+				break;
+			if (i == 0)
+				log_std("%s", header);
+
 			snprintf(cipher, MAX_CIPHER_LEN, "%s-%s",
 				 bciphers[i].cipher, bciphers[i].mode);
 			if (!r)
@@ -508,6 +512,9 @@ static int action_benchmark(int arg __attribute__((unused)))
 		}
 	}
 
+	if (r == -ENOENT)
+		log_err( _("Required kernel crypto interface is not available.\n"
+			   "Ensure you have af_skcipher kernel module loaded.\n"));
 	return r;
 }