Add --device-size option for reencryption tool.

ChangeLog

@@ -1,3 +1,6 @@
+2012-06-25  Milan Broz  <gmazyland@gmail.com>
+	* Add --device-size option for reencryption tool.
+
 2012-06-20  Milan Broz  <gmazyland@gmail.com>
 	* Version 1.5.0-rc2.
 

lib/utils_crypt.c

@@ -23,6 +23,8 @@
 #include <stdio.h>
 #include <string.h>
 #include <errno.h>
+#include <ctype.h>
+#include <limits.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ -423,3 +425,65 @@ ssize_t crypt_hex_to_bytes(const char *hex, char **result, int safe_alloc)
 	*result = bytes;
 	return i;
 }
+
+/*
+ * Device size string parsing, suffixes:
+ * s|S - 512 bytes sectors
+ * k  |K  |m  |M  |g  |G  |t  |T   - 1024 base
+ * kiB|KiB|miB|MiB|giB|GiB|tiB|TiB - 1024 base
+ * kb |KB |mM |MB |gB |GB |tB |TB  - 1000 base
+ */
+int crypt_string_to_size(struct crypt_device *cd, const char *s, uint64_t *size)
+{
+	char *endp = NULL;
+	size_t len;
+	uint64_t mult_base, mult, tmp;
+
+	*size = strtoull(s, &endp, 10);
+	if (!isdigit(s[0]) ||
+	    (errno == ERANGE && *size == ULLONG_MAX) ||
+	    (errno != 0 && *size == 0))
+		return -EINVAL;
+
+	if (!endp)
+		return 0;
+
+	len = strlen(endp);
+	/* Allow "B" and "iB" suffixes */
+	if (len > 3 ||
+	   (len == 3 && (endp[1] != 'i' || endp[2] != 'B')) ||
+	   (len == 2 && endp[1] != 'B'))
+		return -EINVAL;
+
+	if (len == 1 || len == 3)
+		mult_base = 1024;
+	else
+		mult_base = 1000;
+
+	mult = 1;
+	switch (endp[0]) {
+	case 's':
+	case 'S': mult = 512;
+		break;
+	case 't':
+	case 'T': mult *= mult_base;
+	case 'g':
+	case 'G': mult *= mult_base;
+	case 'm':
+	case 'M': mult *= mult_base;
+	case 'k':
+	case 'K': mult *= mult_base;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	tmp = *size * mult;
+	if ((tmp / *size) != mult) {
+		log_dbg("Device size overflow.");
+		return -EINVAL;
+	}
+
+	*size = tmp;
+	return 0;
+}

lib/utils_crypt.h

@@ -44,5 +44,6 @@ void crypt_safe_free(void *data);
 void *crypt_safe_realloc(void *data, size_t size);
 
 ssize_t crypt_hex_to_bytes(const char *hex, char **result, int safe_alloc);
+int crypt_string_to_size(struct crypt_device *cd, const char *s, uint64_t *size);
 
 #endif /* _UTILS_CRYPT_H */

man/cryptsetup-reencrypt.8

@@ -122,6 +122,23 @@ partition (so last sectors contains no data).
 WARNING: This is destructive operation and cannot be reverted.
 Use with extreme care - shrinked filesystems are usually unrecoverable.
 
+You cannot shrink device more than by 64 MiB (131072 sectors).
+.TP
+.B "\-\-device-size \fIsize[units]\fR"
+Instead of real device size, use specified value.
+
+It means that only specified area (from the start of the device
+to the specified size) will be reencrypted.
+
+WARNING: This is destructive operation.
+
+If no unit suffix is specified, the size is in bytes.
+
+Unit suffix can be S for 512 byte sectors, K/M/G/T (or KiB,MiB,GiB,TiB)
+for units with 1024 base or KB/MB/GB/TB for 1000 base (SI scale).
+
+WARNING: This is destructive operation.
+
 You cannot shrink device more than by 64 MiB (131072 sectors).
 .TP
 .B "\-\-new, N"

src/cryptsetup_reencrypt.c

@@ -67,6 +67,9 @@ static int opt_key_slot = CRYPT_ANY_SLOT;
 static int opt_key_size = 0;
 static int opt_new = 0;
 
+static const char *opt_device_size_str = NULL;
+static uint64_t opt_device_size = 0;
+
 static const char **action_argv;
 
 static volatile int quit = 0;
@@ -75,7 +78,8 @@ static volatile int quit = 0;
 struct reenc_ctx {
 	char *device;
 	char *device_uuid;
-	uint64_t device_size;
+	uint64_t device_size; /* overrided by parameter */
+	uint64_t device_size_real;
 	uint64_t device_offset;
 	uint64_t device_shift;
 
@@ -750,6 +754,10 @@ static int copy_data_forward(struct reenc_ctx *rc, int fd_old, int fd_new,
 			return -EIO;
 		}
 
+		/* If device_size is forced, never write more than limit */
+		if ((s1 + rc->device_offset) > rc->device_size)
+			s1 = rc->device_size - rc->device_offset;
+
 		s2 = write(fd_new, buf, s1);
 		if (s2 < 0) {
 			log_dbg("Write error, expecting %d, got %d.",
@@ -861,11 +869,13 @@ static int copy_data(struct reenc_ctx *rc)
 	}
 
 	/* Check size */
-	if (ioctl(fd_new, BLKGETSIZE64, &rc->device_size) < 0) {
+	if (ioctl(fd_new, BLKGETSIZE64, &rc->device_size_real) < 0) {
 		log_err(_("Cannot get device size.\n"));
 		goto out;
 	}
 
+	rc->device_size = opt_device_size ?: rc->device_size_real;
+
 	if (posix_memalign((void *)&buf, alignment(fd_new), block_size)) {
 		log_err(_("Allocation of aligned memory failed.\n"));
 		r = -ENOMEM;
@@ -1230,6 +1240,7 @@ int main(int argc, const char **argv)
 		{ "keyfile-offset",   '\0',  POPT_ARG_LONG, &opt_keyfile_offset,        0, N_("Number of bytes to skip in keyfile"), N_("bytes") },
 		{ "keyfile-size",      'l',  POPT_ARG_LONG, &opt_keyfile_size,          0, N_("Limits the read from keyfile"), N_("bytes") },
 		{ "reduce-device-size",'\0', POPT_ARG_INT, &opt_reduce_device_size,     0, N_("Reduce data device size (move data offset). DANGEROUS!"), N_("SECTORS") },
+		{ "device-size",       '\0', POPT_ARG_STRING, &opt_device_size_str,     0, N_("Use only specified device size (ignore rest of device). DANGEROUS!"), N_("bytes") },
 		{ "new",               'N',  POPT_ARG_NONE,&opt_new,                    0, N_("Create new header on not encrypted device."), NULL },
 		POPT_TABLEEND
 	};
@@ -1311,6 +1322,11 @@ int main(int argc, const char **argv)
 		usage(popt_context, EXIT_FAILURE, _("Option --new must be used together with --reduce_device_size."),
 		      poptGetInvocationName(popt_context));
 
+	if (opt_device_size_str &&
+	    crypt_string_to_size(NULL, opt_device_size_str, &opt_device_size))
+		usage(popt_context, EXIT_FAILURE, _("Invalid device size specification."),
+		      poptGetInvocationName(popt_context));
+
 	if (opt_debug) {
 		opt_verbose = 1;
 		crypt_set_debug_level(-1);