fix bugs and cleanup cryptsetup code

devfs:

- fix memory leak in devfs leaking the aes key
- allocate aes-xts cipher state in secure memory
- actually check if the hexkey got fully parsed

cryptsetup:

- get rid of stupid "type YES" prompt
- use genrandom() to generate salts and keys
- rewrite cryptsetup to use common pbkdf2 and readcons routines
- fix alot of error handling and simplify the code
- move cryptsetup command to disk/cryptsetup
- update cryptsetup(8) manual page

1 files changed, 212 insertions, 0 deletions

diff --git a/sys/src/cmd/disk/cryptsetup.c b/sys/src/cmd/disk/cryptsetup.c
new file mode 100644
index 000000000..7e537867d
--- /dev/null
+++ b/sys/src/cmd/disk/cryptsetup.c
@@ -0,0 +1,212 @@
+// Original Author Taru Karttunen <taruti@taruti.net>
+// This file can be used as both Public Domain or Creative Commons CC0.
+#include <u.h>
+#include <libc.h>
+#include <libsec.h>
+#include <authsrv.h>
+
+typedef struct {
+	uchar Salt[16];
+	uchar Key[32];
+} Slot;
+
+typedef struct {
+	uchar Master[32];
+	Slot Slots[8];
+	AESstate C1, C2;
+} XtsState;
+
+uchar zeros[16] = {0};
+uchar buf[64*1024];
+AESstate cbc;
+XtsState s;
+
+void 
+setupkey(char *pass, uchar salt[16], AESstate *aes)
+{
+	uchar tkey[32];
+
+	pbkdf2_x((uchar*)pass, strlen(pass), salt, 16, 9999, tkey, 32, hmac_sha1, SHA1dlen);
+	setupAESstate(aes, tkey, 16, zeros);
+	memset(tkey, 0, sizeof(tkey));
+}
+
+void
+freepass(char *pass)
+{
+	if(pass != nil){
+		memset(pass, 0, strlen(pass));
+		free(pass);
+	}
+}
+
+void
+cformat(char *files[])
+{
+	char *pass, *tmp;
+	int fd, i, j;
+
+	pass = nil;
+	do {
+		freepass(pass);
+		pass = readcons("Password", nil, 1);
+		if(pass == nil || pass[0] == 0)
+			sysfatal("input aborted");
+		tmp = readcons("Confirm", nil, 1);
+		if(tmp == nil || tmp[0] == 0)
+			sysfatal("input aborted");
+		i = strcmp(pass, tmp);
+		freepass(tmp);
+	} while(i != 0);
+
+	for(;*files != nil; files++) {
+		genrandom((uchar*)&s, sizeof(s));
+		setupkey(pass, s.Slots[0].Salt, &cbc);
+		memcpy(s.Slots[0].Key, s.Master, 32);
+		aesCBCencrypt(s.Slots[0].Key, 32, &cbc);
+
+		genrandom(buf, 16*4096);
+		for(i=0; i<16; i++)
+			for(j=0; j<8; j++) {
+				buf[(4096*i)+(4*j)+1] = s.Slots[j].Salt[i];
+				buf[(4096*i)+(4*j)+2] = s.Slots[j].Key[i];
+				buf[(4096*i)+(4*j)+3] = s.Slots[j].Key[i+16];
+			}
+
+		if((fd = open(*files, OWRITE)) < 0)
+			sysfatal("open disk: %r");
+	
+		/* make the pad for checking crypto */
+		for(i=0; i<8; i++)
+			buf[(64*1024)-8+i] = ~buf[(64*1024)-16+i];
+
+		setupAESstate(&cbc, s.Master, 16, zeros);
+		aes_encrypt(cbc.ekey, cbc.rounds, &buf[(64*1024)-16], &buf[(64*1024)-16]);
+
+		if(write(fd, buf, 64*1024) != 64*1024)
+			sysfatal("writing disk: %r");
+	}
+}
+
+void
+copen(char *files[], int ctl)
+{
+	char *pass, *name;
+	uchar cbuf[16];
+	int fd, i, j;
+
+	pass = nil;
+	for(;*files != nil; files++) {
+		memset(&s, 0, sizeof(s));
+		if((fd = open(*files, OREAD)) < 0)
+			sysfatal("open disk: %r");
+	
+		if(read(fd, buf, 1024*64) != 1024*64) 
+			sysfatal("read disk: %r");
+	
+	retrypass:
+		for(i=0; i<16; i++)
+			for(j=0; j<8; j++) {
+				s.Slots[j].Salt[i] = buf[(4096*i)+(4*j)+1];
+				s.Slots[j].Key[i] = buf[(4096*i)+(4*j)+2];
+				s.Slots[j].Key[i+16] = buf[(4096*i)+(4*j)+3];
+			}
+
+		if(pass == nil){
+			pass = readcons("Password", nil, 1);
+			if(pass == nil || pass[0] == 0)
+				sysfatal("input aborted");
+		}
+
+		setupkey(pass, s.Slots[0].Salt, &cbc);
+		memcpy(s.Master, s.Slots[0].Key, 32);
+		aesCBCdecrypt(s.Master, 32, &cbc);
+		setupAESstate(&cbc, s.Master, 16, zeros);
+
+		memcpy(cbuf, &buf[(64*1024)-16], 16);
+		aes_decrypt(cbc.dkey, cbc.rounds, cbuf, cbuf);
+
+		/* make the pad for checking crypto */
+		for(i=0; i<8; i++)
+			if((cbuf[i] ^ cbuf[i+8]) != 255) {
+				freepass(pass);
+				pass = nil;
+				fprint(2, "wrong key\n");
+				goto retrypass;
+			}
+
+		fd2path(fd, (char*)buf, sizeof(buf));
+		close(fd);
+
+		if((name = strrchr(*files, '/')) != nil)
+			name++;
+		else
+			name = *files;
+
+		if(fprint(ctl, "crypt %q %q %.32H\n", name, (char*)buf, s.Master) < 0)
+			sysfatal("write: %r");
+	}
+}
+
+void 
+usage(void)
+{
+	print("usage:\n"
+		"%s -f files\t\t# Format file or device\n"
+		"%s -o files\t\t# Print commandline for open\n"
+		"%s -i files\t\t# Install (open) files\n",
+		argv0, argv0, argv0);
+	exits("usage");
+}
+
+void
+main(int argc, char *argv[])
+{
+	enum {
+		NoMode,
+		Format,
+		Open,
+		Install,
+	};
+	int mode, ctl;
+
+	quotefmtinstall();
+	fmtinstall('H', encodefmt);
+
+	ctl = 1;
+	mode = NoMode;
+
+	ARGBEGIN {
+	default:
+		usage();
+	case 'f':
+		mode = Format;
+		break;
+	case 'o':
+		mode = Open;
+		break;
+	case 'i':
+		mode = Install;
+		break;
+	} ARGEND;
+
+	if(argc < 0)
+		usage();
+
+	switch(mode){
+	default:
+		usage();
+	case Format:
+		cformat(argv);
+		break;
+	case Install:
+		if((ctl = open("/dev/fs/ctl", OWRITE)) < 0)
+			sysfatal("open ctl: %r");
+		/* no break */
+	case Open:
+		copen(argv, ctl);
+		break;
+	}
+
+	exits(nil);
+}