Add --enable-discards option to allow discards/TRIM requests.

git-svn-id: https://cryptsetup.googlecode.com/svn/trunk@572 36d66b0a-2a48-0410-832c-cd162a569da5

ChangeLog

@@ -1,5 +1,6 @@
 2011-07-07  Milan Broz  <mbroz@redhat.com>
 	* Remove old API functions (all functions using crypt_options).
+	* Add --enable-discards option to allow discards/TRIM requests.
 
 2011-07-01  Milan Broz  <mbroz@redhat.com>
 	* Add --shared option for creating non-overlapping crypt segments.

TODO

@@ -1,5 +1,4 @@
 Version 1.4.0:
-- Remove old API (all calls using crypt_options)
 - Support separation of metadata device
 - Wipe device flag
 - Support K/M suffixes for align payload (new switch?).

lib/libcryptsetup.h

@@ -377,6 +377,7 @@ int crypt_keyslot_destroy(struct crypt_device *cd, int keyslot);
 #define CRYPT_ACTIVATE_READONLY (1 << 0)
 #define CRYPT_ACTIVATE_NO_UUID  (1 << 1) /* ignored */
 #define CRYPT_ACTIVATE_SHARED   (1 << 2)
+#define CRYPT_ACTIVATE_ALLOW_DISCARDS (1 << 3) /* enable discards aka TRIM */
 
 /**
  * Active device runtime attributes

lib/libdevmapper.c

@@ -119,6 +119,9 @@ static void _dm_set_crypt_compat(const char *dm_version, unsigned crypt_maj,
 	if (crypt_maj >= 1 && crypt_min >= 8)
 		_dm_crypt_flags |= DM_PLAIN64_SUPPORTED;
 
+	if (crypt_maj >= 1 && crypt_min >= 11)
+		_dm_crypt_flags |= DM_DISCARDS_SUPPORTED;
+
 	/* Repeat test if dm-crypt is not present */
 	if (crypt_maj > 0)
 		_dm_crypt_checked = 1;
@@ -238,25 +241,38 @@ static void hex_key(char *hexkey, size_t key_size, const char *key)
 		sprintf(&hexkey[i * 2], "%02x", (unsigned char)key[i]);
 }
 
-static char *get_params(const char *device, uint64_t skip, uint64_t offset,
+static char *get_params(struct crypt_dm_active_device *dmd)
-			const char *cipher, struct volume_key *vk)
 {
-	char *params;
+	int r, max_size;
-	char *hexkey;
+	char *params, *hexkey, *features = "";
 
-	hexkey = crypt_safe_alloc(vk->keylength * 2 + 1);
+	if (dmd->flags & CRYPT_ACTIVATE_ALLOW_DISCARDS) {
+		if (dm_flags() & DM_DISCARDS_SUPPORTED) {
+			features =" 1 allow_discards";
+			log_dbg("Discard/TRIM is allowed.");
+		} else
+			log_dbg("Discard/TRIM is not supported by the kernel.");
+	}
+
+	hexkey = crypt_safe_alloc(dmd->vk->keylength * 2 + 1);
 	if (!hexkey)
 		return NULL;
 
-	hex_key(hexkey, vk->keylength, vk->key);
+	hex_key(hexkey, dmd->vk->keylength, dmd->vk->key);
 
-	params = crypt_safe_alloc(strlen(hexkey) + strlen(cipher) + strlen(device) + 64);
+	max_size = strlen(hexkey) + strlen(dmd->cipher) +
+		   strlen(dmd->device) + strlen(features) + 64;
+	params = crypt_safe_alloc(max_size);
 	if (!params)
 		goto out;
 
-	sprintf(params, "%s %s %" PRIu64 " %s %" PRIu64,
+	r = snprintf(params, max_size, "%s %s %" PRIu64 " %s %" PRIu64 "%s",
-	        cipher, hexkey, skip, device, offset);
+		     dmd->cipher, hexkey, dmd->iv_offset, dmd->device,
-
+		     dmd->offset, features);
+	if (r < 0 || r >= max_size) {
+		crypt_safe_free(params);
+		params = NULL;
+	}
 out:
 	crypt_safe_free(hexkey);
 	return params;
@@ -410,8 +426,7 @@ int dm_create_device(const char *name,
 	uint32_t cookie = 0;
 	uint16_t udev_flags = 0;
 
-	params = get_params(dmd->device, dmd->iv_offset, dmd->offset,
+	params = get_params(dmd);
-			    dmd->cipher, dmd->vk);
 	if (!params)
 		goto out_no_removal;
 
@@ -575,7 +590,7 @@ int dm_query_device(const char *name, uint32_t get_flags,
 	struct dm_task *dmt;
 	struct dm_info dmi;
 	uint64_t start, length, val64;
-	char *target_type, *params, *rcipher, *key_, *rdevice, *endp, buffer[3];
+	char *target_type, *params, *rcipher, *key_, *rdevice, *endp, buffer[3], *arg;
 	const char *tmp_uuid;
 	void *next = NULL;
 	unsigned int i;
@@ -637,10 +652,35 @@ int dm_query_device(const char *name, uint32_t get_flags,
 	if (!params)
 		goto out;
 	val64 = strtoull(params, &params, 10);
-	if (*params)
-		goto out;
 	dmd->offset = val64;
 
+	/* Features section, available since crypt target version 1.11 */
+	if (*params) {
+		if (*params != ' ')
+			goto out;
+		params++;
+
+		/* Number of arguments */
+		val64 = strtoull(params, &params, 10);
+		if (*params != ' ')
+			goto out;
+		params++;
+
+		for (i = 0; i < val64; i++) {
+			if (!params)
+				goto out;
+			arg = strsep(&params, " ");
+			if (!strcasecmp(arg, "allow_discards"))
+				dmd->flags |= CRYPT_ACTIVATE_ALLOW_DISCARDS;
+			else /* unknown option */
+				goto out;
+		}
+
+		/* All parameters shold be processed */
+		if (params)
+			goto out;
+	}
+
 	if (get_flags & DM_ACTIVE_KEY) {
 		dmd->vk = crypt_alloc_volume_key(strlen(key_) / 2, NULL);
 		if (!dmd->vk) {

lib/utils_dm.h

@@ -12,6 +12,7 @@ struct volume_key;
 #define DM_LMK_SUPPORTED      (1 << 1)	/* lmk mode */
 #define DM_SECURE_SUPPORTED   (1 << 2)	/* wipe (secure) buffer flag */
 #define DM_PLAIN64_SUPPORTED  (1 << 3)	/* plain64 IV */
+#define DM_DISCARDS_SUPPORTED (1 << 4)	/* discards/TRIM option is supported */
 uint32_t dm_flags(void);
 
 #define DM_ACTIVE_DEVICE	(1 << 0)

man/cryptsetup.8

@@ -14,7 +14,8 @@ For basic (plain) dm-crypt mappings, there are four operations.
 creates a mapping with <name> backed by device <device>.
 
 \fB<options>\fR can be [\-\-hash, \-\-cipher, \-\-verify-passphrase,
-\-\-key-file, \-\-key-size, \-\-offset, \-\-skip, \-\-size, \-\-readonly, \-\-shared]
+\-\-key-file, \-\-key-size, \-\-offset, \-\-skip, \-\-size, \-\-readonly, \-\-shared,
+\-\-allow-discards]
 .PP
 \fIremove\fR <name>
 .IP
@@ -51,7 +52,7 @@ opens the LUKS partition <device> and sets up a mapping <name> after
 successful verification of the supplied key material
 (either via key file by \-\-key-file, or via prompting).
 
-\fB<options>\fR can be [\-\-key-file, \-\-keyfile-size, \-\-readonly].
+\fB<options>\fR can be [\-\-key-file, \-\-keyfile-size, \-\-readonly, \-\-allow-discards].
 .PP
 \fIluksClose\fR <name>
 .IP
@@ -186,8 +187,8 @@ and not used it in IV sector calculations, you have to explicitly use
 Use \fB\-\-hash\fR to override hash function for password hashing
 (otherwise it is detected according to key size).
 
-\fB<options>\fR can be [\-\-key-file, \-\-key-size, \-\-offset, \-\-skip, 
+\fB<options>\fR can be [\-\-key-file, \-\-key-size, \-\-offset, \-\-skip,
-\-\-hash, \-\-readonly].
+\-\-hash, \-\-readonly, \-\-allow-discards].
 .PP
 \fIloopaesClose\fR <name>
 .IP
@@ -361,6 +362,18 @@ new one or change existing UUID in \fIluksUUID\fR command.
 The UUID must be provided in standard UUID format
 (e.g. 12345678-1234-1234-1234-123456789abc).
 .TP
+.B "\-\-allow-discards\fR"
+Allow using of discards (TRIM) requests for device.
+This option is only relevant for \fIcreate\fR, \fIluksOpen\fR or \fIloopaesOpen\fR.
+
+\fBWARNING:\fR Assess the specific security risks carefully before enabling this
+option.  For example, allowing discards on encrypted devices may lead to the leak
+of information about the ciphertext device (filesystem type, used space etc.)
+if the discarded blocks can be located easily on the device later.
+
+Kernel version 3.1 or more recent is required.
+For older versions is the option ignored.
+.TP
 .B "\-\-version"
 Show the version.
 .SH RETURN CODES

src/cryptsetup.c

@@ -62,6 +62,7 @@ static int opt_random = 0;
 static int opt_urandom = 0;
 static int opt_dump_master_key = 0;
 static int opt_shared = 0;
+static int opt_allow_discards = 0;
 
 static const char **action_argv;
 static int action_argc;
@@ -271,6 +272,9 @@ static int action_create(int arg __attribute__((unused)))
 	if (opt_shared)
 		activate_flags |= CRYPT_ACTIVATE_SHARED;
 
+	if (opt_allow_discards)
+		activate_flags |= CRYPT_ACTIVATE_ALLOW_DISCARDS;
+
 	if (opt_key_file)
 		/* With hashing, read the whole keyfile */
 		r = crypt_activate_by_keyfile(cd, action_argv[0],
@@ -304,6 +308,7 @@ static int action_loopaesOpen(int arg __attribute__((unused)))
 		.skip = opt_skip_valid ? opt_skip : opt_offset,
 	};
 	unsigned int key_size = (opt_key_size ?: DEFAULT_LOOPAES_KEYBITS) / 8;
+	uint32_t activate_flags = 0;
 	int r;
 
 	if (!opt_key_file) {
@@ -311,6 +316,12 @@ static int action_loopaesOpen(int arg __attribute__((unused)))
 		return -EINVAL;
 	}
 
+	if (opt_readonly)
+		activate_flags |= CRYPT_ACTIVATE_READONLY;
+
+	if (opt_allow_discards)
+		activate_flags |= CRYPT_ACTIVATE_ALLOW_DISCARDS;
+
 	if ((r = crypt_init(&cd, action_argv[0])))
 		goto out;
 
@@ -319,9 +330,8 @@ static int action_loopaesOpen(int arg __attribute__((unused)))
 	if (r < 0)
 		goto out;
 
-	r = crypt_activate_by_keyfile(cd, action_argv[1],
+	r = crypt_activate_by_keyfile(cd, action_argv[1], CRYPT_ANY_SLOT,
-		CRYPT_ANY_SLOT, opt_key_file, opt_keyfile_size,
+				      opt_key_file, opt_keyfile_size, activate_flags);
-		opt_readonly ?  CRYPT_ACTIVATE_READONLY : 0);
 out:
 	crypt_free(cd);
 
@@ -401,6 +411,8 @@ static int action_status(int arg __attribute__((unused)))
 			log_std("  skipped: %" PRIu64 " sectors\n", cad.iv_offset);
 		log_std("  mode:    %s\n", cad.flags & CRYPT_ACTIVATE_READONLY ?
 					   "readonly" : "read/write");
+		if (cad.flags & CRYPT_ACTIVATE_ALLOW_DISCARDS)
+			log_std("  flags:   discards\n");
 	}
 out:
 	crypt_free(cd);
@@ -522,9 +534,13 @@ static int action_luksOpen(int arg __attribute__((unused)))
 
 	if (opt_iteration_time)
 		crypt_set_iterarion_time(cd, opt_iteration_time);
+
 	if (opt_readonly)
 		flags |= CRYPT_ACTIVATE_READONLY;
 
+	if (opt_allow_discards)
+		flags |= CRYPT_ACTIVATE_ALLOW_DISCARDS;
+
 	if (opt_key_file) {
 		crypt_set_password_retry(cd, 1);
 		r = crypt_activate_by_keyfile(cd, action_argv[1],
@@ -1138,7 +1154,8 @@ int main(int argc, const char **argv)
 		{ "use-random",        '\0', POPT_ARG_NONE, &opt_random,                0, N_("Use /dev/random for generating volume key."), NULL },
 		{ "use-urandom",       '\0', POPT_ARG_NONE, &opt_urandom,               0, N_("Use /dev/urandom for generating volume key."), NULL },
 		{ "shared",            '\0', POPT_ARG_NONE, &opt_shared,                0, N_("Share device with another non-overlapping crypt segment."), NULL },
-		{ "uuid",              '\0',  POPT_ARG_STRING, &opt_uuid,               0, N_("UUID for device to use."), NULL },
+		{ "uuid",              '\0', POPT_ARG_STRING, &opt_uuid,                0, N_("UUID for device to use."), NULL },
+		{ "allow-discards",    '\0', POPT_ARG_NONE, &opt_allow_discards,        0, N_("Allow discards (aka TRIM) requests for device."), NULL },
 		POPT_TABLEEND
 	};
 	poptContext popt_context;
@@ -1225,6 +1242,15 @@ int main(int argc, const char **argv)
 		      poptGetInvocationName(popt_context));
 	}
 
+	if (opt_allow_discards &&
+	    strcmp(aname, "luksOpen") &&
+	    strcmp(aname, "create") &&
+	    strcmp(aname, "loopaesOpen")) {
+		usage(popt_context, EXIT_FAILURE,
+		      _("Option --allow-discards is allowed only for luksOpen, loopaesOpen and create operation.\n"),
+		      poptGetInvocationName(popt_context));
+	}
+
 	if (opt_key_size &&
 	   strcmp(aname, "luksFormat") &&
 	   strcmp(aname, "create") &&

tests/Makefile.am

@@ -1,7 +1,7 @@
-TESTS = api-test compat-test loopaes-test align-test mode-test password-hash-test
+TESTS = api-test compat-test loopaes-test align-test discards-test mode-test password-hash-test
 
 EXTRA_DIST = compatimage.img.bz2 \
-	     compat-test loopaes-test align-test mode-test password-hash-test
+	     compat-test loopaes-test align-test discards-test mode-test password-hash-test
 
 differ_SOURCES = differ.c
 differ_CFLAGS = -Wall -O2

tests/discards-test

@@ -0,0 +1,81 @@
+#!/bin/bash
+
+CRYPTSETUP="../src/cryptsetup"
+DEV_NAME="discard-t3st"
+DEV=""
+
+cleanup() {
+	[ -b /dev/mapper/$DEV_NAME ] && dmsetup remove $DEV_NAME
+	udevadm settle >/dev/null 2>&1
+	rmmod scsi_debug 2>/dev/null
+	sleep 2
+}
+
+fail()
+{
+	echo "FAILED"
+	cleanup
+	exit 100
+}
+
+add_device() {
+	modprobe scsi_debug $@
+	if [ $? -ne 0 ] ; then
+		echo "This kernel seems to not support proper scsi_debug module, test skipped."
+		exit 0
+	fi
+
+	sleep 2
+	DEV=$(grep scsi_debug /sys/block/*/device/model | cut -f4 -d /)
+
+	DEV="/dev/$DEV"
+	[ -b $DEV ] || fail "Cannot find $DEV."
+}
+
+function check_version()
+{
+        VER_STR=$(dmsetup targets | grep crypt | cut -f 2 -dv)
+        VER_MAJ=$(echo $VER_STR | cut -f 1 -d.)
+        VER_MIN=$(echo $VER_STR | cut -f 2 -d.)
+
+	# option supported in 1.11
+        test $VER_MAJ -gt 1 && return 0
+        test $VER_MIN -ge 11 && return 0
+        return 1
+}
+
+if [ $(id -u) != 0 ]; then
+	echo "WARNING: You must be root to run this test, test skipped."
+	exit 0
+fi
+
+modprobe --dry-run scsi_debug || exit 0
+modprobe dm-crypt >/dev/null 2>&1
+if ! check_version ; then
+	echo "Probably old kernel, test skipped."
+	exit 0
+fi
+
+add_device dev_size_mb=16 sector_size=512 num_tgts=1 lbpu=1
+
+# FIXME test hash of device (unmap -> zero)
+# for now just check that flag is enabled
+
+echo "[1] Allowing discards for LUKS device"
+echo xxx | $CRYPTSETUP luksFormat $DEV -q -i1 || fail
+echo xxx | $CRYPTSETUP luksOpen $DEV $DEV_NAME --allow-discards || fail
+$CRYPTSETUP status $DEV_NAME | grep flags | grep discards >/dev/null || fail
+$CRYPTSETUP resize $DEV_NAME --size 100 || fail
+$CRYPTSETUP status $DEV_NAME | grep flags | grep discards >/dev/null || fail
+dmsetup table $DEV_NAME | grep allow_discards >/dev/null || fail
+$CRYPTSETUP luksClose $DEV_NAME || fail
+
+echo "[2] Allowing discards for plain device"
+echo xxx | $CRYPTSETUP create $DEV_NAME $DEV --allow-discards || fail
+$CRYPTSETUP status $DEV_NAME | grep flags | grep discards >/dev/null || fail
+$CRYPTSETUP resize $DEV_NAME --size 100 || fail
+$CRYPTSETUP status $DEV_NAME | grep flags | grep discards >/dev/null || fail
+dmsetup table $DEV_NAME | grep allow_discards >/dev/null || fail
+$CRYPTSETUP remove $DEV_NAME || fail
+
+cleanup