This patch allows losetup and mount to do cryptoloop encryption with keys
of size other than 256 bits. For example, to use 128-bit AES-CBC encryption,
the syntax is:
losetup -e aes-cbc-128 /dev/loop/10 /home/sluskyb/testloop
or
mount -o loop,encryption=aes-cbc-128 /home/sluskyb/testloop /mnt/testloop
I figured that since we're now requiring the user to add the -cbc (or -ctr
etc.), -128 would fit in.
This is implemented using POSIX regular expressions. I'm not particularly
proud of that, but I think if we want to specify key size within the existing
encryption= option then that's the best way to go.
QCF?
--
Ben Slusky | You must be smarter than
sluskyb@xxxxxxxxxxxxxx | <= this stick to ride the
sluskyb@xxxxxxxxxx | internet.
PGP keyID ADA44B3B
--- lomount.c-fixed-key-size 2003-07-16 19:56:53.000000000 -0400
+++ lomount.c 2003-08-02 19:25:01.000000000 -0400
@@ -24,12 +24,15 @@
#include <ctype.h>
#include <fcntl.h>
#include <errno.h>
+#include <limits.h>
#include <stdlib.h>
#include <unistd.h>
+#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/sysmacros.h>
+#include <regex.h>
#include "loop.h"
#include "lomount.h"
@@ -249,8 +252,10 @@
set_loop(const char *device, const char *file, int offset,
const char *encryption, int pfd, int *loopro) {
struct loop_info64 loopinfo64;
- int fd, ffd, mode;
- char *pass;
+ int fd, ffd, mode, keysize = 0, rerror;
+ char *pass, *encryption_buf, rerror_buf[LINE_MAX+1];
+ regex_t keysize_re;
+ regmatch_t keysize_rm;
mode = (*loopro ? O_RDONLY : O_RDWR);
if ((ffd = open(file, mode)) < 0) {
@@ -276,8 +281,38 @@
loopinfo64.lo_encrypt_type = atoi(encryption);
} else {
loopinfo64.lo_encrypt_type = LO_CRYPT_CRYPTOAPI;
+
+ if((encryption_buf = strdup(encryption)) == NULL) {
+ perror("strdup");
+ fprintf(stderr,
+ _("Couldn't allocate memory, exiting.\n"));
+ exit(1);
+ }
+
+ if ((rerror = regcomp(&keysize_re,
+ "-[[:digit:]]+$",
+ REG_EXTENDED)) != 0) {
+ fprintf(stderr, _("regcomp: "));
+ regerror(rerror, &keysize_re, rerror_buf,
+ LINE_MAX);
+ fprintf(stderr, "%s\n", rerror_buf);
+ } else {
+ if (regexec(&keysize_re, encryption_buf,
+ 1, &keysize_rm, 0) == 0) {
+ keysize = atoi(encryption_buf +
+ keysize_rm.rm_so + 1);
+ /* convert #bits to #bytes */
+ keysize /= 8;
+ /* cut the keysize out now */
+ encryption_buf[keysize_rm.rm_so] = '\0';
+ }
+
+ regfree(&keysize_re);
+ }
+
snprintf(loopinfo64.lo_crypt_name, LO_NAME_SIZE,
- "%s", encryption);
+ "%s", encryption_buf);
+ free(encryption_buf);
}
}
@@ -307,9 +342,14 @@
strlen(loopinfo64.lo_encrypt_key);
break;
default:
+ if (keysize == 0) {
+ fprintf(stderr, _("You must specify a key size (in bits) for use with CryptoAPI encryption.\n"));
+ return -1;
+ }
+ /* FIXME we should be checking keysize against the min/max in /proc/crypto */
pass = xgetpass(pfd, _("Password: "));
xstrncpy(loopinfo64.lo_encrypt_key, pass, LO_KEY_SIZE);
- loopinfo64.lo_encrypt_key_size = LO_KEY_SIZE;
+ loopinfo64.lo_encrypt_key_size = keysize;
}
if (ioctl(fd, LOOP_SET_FD, ffd) < 0) {
