1 files changed, 130 insertions, 0 deletions
diff --git a/crypto.c b/crypto.c
new file mode 100644
index 0000000..3f68835
--- /dev/null
+++ b/crypto.c
@@ -0,0 +1,130 @@
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <termios.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <linux/random.h>
+#include <libscrypt.h>
+#include <sodium/crypto_stream_chacha20.h>
+
+#include "crypto.h"
+
+char *read_passphrase(const char *prompt)
+{
+	struct termios old, new;
+	char *buf = NULL;
+	size_t buflen = 0;
+	ssize_t ret;
+
+	fprintf(stderr, "%s", prompt);
+	fflush(stderr);
+
+	if (tcgetattr(fileno(stdin), &old))
+		die("error getting terminal attrs");
+
+	new = old;
+	new.c_lflag &= ~ECHO;
+	if (tcsetattr(fileno(stdin), TCSAFLUSH, &new))
+		die("error setting terminal attrs");
+
+	ret = getline(&buf, &buflen, stdin);
+	if (ret <= 0)
+		die("error reading passphrase");
+
+	tcsetattr(fileno(stdin), TCSAFLUSH, &old);
+	fprintf(stderr, "\n");
+	return buf;
+}
+
+void derive_passphrase(struct bcache_key *key, const char *passphrase)
+{
+	const unsigned char salt[] = "bcache";
+	int ret;
+
+	ret = libscrypt_scrypt((void *) passphrase, strlen(passphrase),
+			       salt, sizeof(salt),
+			       SCRYPT_N, SCRYPT_r, SCRYPT_p,
+			       (void *) key, sizeof(*key));
+	if (ret)
+		die("scrypt error: %i", ret);
+}
+
+void disk_key_encrypt(struct bcache_disk_key *disk_key,
+		      struct bcache_key *key)
+{
+	int ret;
+
+	ret = crypto_stream_chacha20_xor((void *) disk_key,
+					 (void *) disk_key, sizeof(*disk_key),
+					 (void *) &bch_master_key_nonce,
+					 (void *) key);
+	if (ret)
+		die("chacha20 error: %i", ret);
+}
+
+void disk_key_init(struct bcache_disk_key *disk_key)
+{
+	ssize_t ret;
+
+	memcpy(&disk_key->header, bch_key_header, sizeof(bch_key_header));
+#if 0
+	ret = getrandom(disk_key->key, sizeof(disk_key->key), GRND_RANDOM);
+	if (ret != sizeof(disk_key->key))
+		die("error getting random bytes for key");
+#else
+	int fd = open("/dev/random", O_RDONLY|O_NONBLOCK);
+	if (fd < 0)
+		die("error opening /dev/random");
+
+	size_t n = 0;
+	struct timespec start;
+	bool printed = false;
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+
+	while (n < sizeof(disk_key->key)) {
+		struct timeval timeout = { 1, 0 };
+		fd_set set;
+
+		FD_ZERO(&set);
+		FD_SET(fd, &set);
+
+		if (select(fd + 1, &set, NULL, NULL, &timeout) < 0)
+			die("select error");
+
+		ret = read(fd,
+			   (void *) disk_key->key + n,
+			   sizeof(disk_key->key) - n);
+		if (ret == -1 && errno != EINTR && errno != EAGAIN)
+			die("error reading from /dev/random");
+		if (ret > 0)
+			n += ret;
+
+		struct timespec now;
+		clock_gettime(CLOCK_MONOTONIC, &now);
+
+		now.tv_sec	-= start.tv_sec;
+		now.tv_nsec	-= start.tv_nsec;
+
+		while (now.tv_nsec < 0) {
+			long nsec_per_sec = 1000 * 1000 * 1000;
+			long sec = now.tv_nsec / nsec_per_sec - 1;
+			now.tv_nsec	-= sec * nsec_per_sec;
+			now.tv_sec	+= sec;
+		}
+
+		if (!printed && now.tv_sec >= 3) {
+			printf("Reading from /dev/random is taking a long time...\n)");
+			printed = true;
+		}
+	}
+	close(fd);
+#endif
+}