Eric Biggers | 57d8e33 | 2017-04-12 11:09:25 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2017 Google, Inc. |
| 3 | * |
| 4 | * This software is licensed under the terms of the GNU General Public |
| 5 | * License version 2, as published by the Free Software Foundation, and |
| 6 | * may be copied, distributed, and modified under those terms. |
| 7 | * |
| 8 | * This program is distributed in the hope that it will be useful, |
| 9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 11 | * GNU General Public License for more details. |
| 12 | */ |
| 13 | |
| 14 | #include <linux/device-mapper.h> |
| 15 | #include <linux/module.h> |
| 16 | #include <linux/pfk.h> |
| 17 | |
| 18 | #define DM_MSG_PREFIX "default-key" |
| 19 | |
| 20 | struct default_key_c { |
| 21 | struct dm_dev *dev; |
| 22 | sector_t start; |
| 23 | struct blk_encryption_key key; |
| 24 | }; |
| 25 | |
| 26 | static void default_key_dtr(struct dm_target *ti) |
| 27 | { |
| 28 | struct default_key_c *dkc = ti->private; |
| 29 | |
| 30 | if (dkc->dev) |
| 31 | dm_put_device(ti, dkc->dev); |
| 32 | kzfree(dkc); |
| 33 | } |
| 34 | |
| 35 | /* |
| 36 | * Construct a default-key mapping: <mode> <key> <dev_path> <start> |
| 37 | */ |
| 38 | static int default_key_ctr(struct dm_target *ti, unsigned int argc, char **argv) |
| 39 | { |
| 40 | struct default_key_c *dkc; |
| 41 | size_t key_size; |
| 42 | unsigned long long tmp; |
| 43 | char dummy; |
| 44 | int err; |
| 45 | |
| 46 | if (argc != 4) { |
| 47 | ti->error = "Invalid argument count"; |
| 48 | return -EINVAL; |
| 49 | } |
| 50 | |
| 51 | dkc = kzalloc(sizeof(*dkc), GFP_KERNEL); |
| 52 | if (!dkc) { |
| 53 | ti->error = "Out of memory"; |
| 54 | return -ENOMEM; |
| 55 | } |
| 56 | ti->private = dkc; |
| 57 | |
| 58 | if (strcmp(argv[0], "AES-256-XTS") != 0) { |
| 59 | ti->error = "Unsupported encryption mode"; |
| 60 | err = -EINVAL; |
| 61 | goto bad; |
| 62 | } |
| 63 | |
| 64 | key_size = strlen(argv[1]); |
| 65 | if (key_size != 2 * BLK_ENCRYPTION_KEY_SIZE_AES_256_XTS) { |
| 66 | ti->error = "Unsupported key size"; |
| 67 | err = -EINVAL; |
| 68 | goto bad; |
| 69 | } |
| 70 | key_size /= 2; |
| 71 | |
| 72 | if (hex2bin(dkc->key.raw, argv[1], key_size) != 0) { |
| 73 | ti->error = "Malformed key string"; |
| 74 | err = -EINVAL; |
| 75 | goto bad; |
| 76 | } |
| 77 | |
| 78 | err = dm_get_device(ti, argv[2], dm_table_get_mode(ti->table), |
| 79 | &dkc->dev); |
| 80 | if (err) { |
| 81 | ti->error = "Device lookup failed"; |
| 82 | goto bad; |
| 83 | } |
| 84 | |
| 85 | if (sscanf(argv[3], "%llu%c", &tmp, &dummy) != 1) { |
| 86 | ti->error = "Invalid start sector"; |
| 87 | err = -EINVAL; |
| 88 | goto bad; |
| 89 | } |
| 90 | dkc->start = tmp; |
| 91 | |
| 92 | if (!blk_queue_inlinecrypt(bdev_get_queue(dkc->dev->bdev))) { |
| 93 | ti->error = "Device does not support inline encryption"; |
| 94 | err = -EINVAL; |
| 95 | goto bad; |
| 96 | } |
| 97 | |
| 98 | /* Pass flush requests through to the underlying device. */ |
| 99 | ti->num_flush_bios = 1; |
| 100 | |
| 101 | /* |
| 102 | * We pass discard requests through to the underlying device, although |
| 103 | * the discarded blocks will be zeroed, which leaks information about |
| 104 | * unused blocks. It's also impossible for dm-default-key to know not |
| 105 | * to decrypt discarded blocks, so they will not be read back as zeroes |
| 106 | * and we must set discard_zeroes_data_unsupported. |
| 107 | */ |
| 108 | ti->num_discard_bios = 1; |
| 109 | |
| 110 | /* |
| 111 | * It's unclear whether WRITE_SAME would work with inline encryption; it |
| 112 | * would depend on whether the hardware duplicates the data before or |
| 113 | * after encryption. But since the internal storage in some devices |
| 114 | * (MSM8998-based) doesn't claim to support WRITE_SAME anyway, we don't |
| 115 | * currently have a way to test it. Leave it disabled it for now. |
| 116 | */ |
| 117 | /*ti->num_write_same_bios = 1;*/ |
| 118 | |
| 119 | return 0; |
| 120 | |
| 121 | bad: |
| 122 | default_key_dtr(ti); |
| 123 | return err; |
| 124 | } |
| 125 | |
| 126 | static int default_key_map(struct dm_target *ti, struct bio *bio) |
| 127 | { |
| 128 | const struct default_key_c *dkc = ti->private; |
| 129 | |
| 130 | bio->bi_bdev = dkc->dev->bdev; |
| 131 | if (bio_sectors(bio)) { |
| 132 | bio->bi_iter.bi_sector = dkc->start + |
| 133 | dm_target_offset(ti, bio->bi_iter.bi_sector); |
| 134 | } |
| 135 | |
Jaegeuk Kim | 20bd93b | 2018-04-20 19:26:09 -0700 | [diff] [blame] | 136 | if (!bio->bi_crypt_key && !bio->bi_crypt_skip) |
Eric Biggers | 57d8e33 | 2017-04-12 11:09:25 -0700 | [diff] [blame] | 137 | bio->bi_crypt_key = &dkc->key; |
| 138 | |
| 139 | return DM_MAPIO_REMAPPED; |
| 140 | } |
| 141 | |
| 142 | static void default_key_status(struct dm_target *ti, status_type_t type, |
| 143 | unsigned int status_flags, char *result, |
| 144 | unsigned int maxlen) |
| 145 | { |
| 146 | const struct default_key_c *dkc = ti->private; |
| 147 | unsigned int sz = 0; |
| 148 | |
| 149 | switch (type) { |
| 150 | case STATUSTYPE_INFO: |
| 151 | result[0] = '\0'; |
| 152 | break; |
| 153 | |
| 154 | case STATUSTYPE_TABLE: |
| 155 | |
| 156 | /* encryption mode */ |
| 157 | DMEMIT("AES-256-XTS"); |
| 158 | |
| 159 | /* reserved for key; dm-crypt shows it, but we don't for now */ |
| 160 | DMEMIT(" -"); |
| 161 | |
| 162 | /* name of underlying device, and the start sector in it */ |
| 163 | DMEMIT(" %s %llu", dkc->dev->name, |
| 164 | (unsigned long long)dkc->start); |
| 165 | break; |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | static int default_key_prepare_ioctl(struct dm_target *ti, |
| 170 | struct block_device **bdev, fmode_t *mode) |
| 171 | { |
| 172 | struct default_key_c *dkc = ti->private; |
| 173 | struct dm_dev *dev = dkc->dev; |
| 174 | |
| 175 | *bdev = dev->bdev; |
| 176 | |
| 177 | /* |
| 178 | * Only pass ioctls through if the device sizes match exactly. |
| 179 | */ |
| 180 | if (dkc->start || |
| 181 | ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT) |
| 182 | return 1; |
| 183 | return 0; |
| 184 | } |
| 185 | |
| 186 | static int default_key_iterate_devices(struct dm_target *ti, |
| 187 | iterate_devices_callout_fn fn, |
| 188 | void *data) |
| 189 | { |
| 190 | struct default_key_c *dkc = ti->private; |
| 191 | |
| 192 | return fn(ti, dkc->dev, dkc->start, ti->len, data); |
| 193 | } |
| 194 | |
| 195 | static struct target_type default_key_target = { |
| 196 | .name = "default-key", |
| 197 | .version = {1, 0, 0}, |
| 198 | .module = THIS_MODULE, |
| 199 | .ctr = default_key_ctr, |
| 200 | .dtr = default_key_dtr, |
| 201 | .map = default_key_map, |
| 202 | .status = default_key_status, |
| 203 | .prepare_ioctl = default_key_prepare_ioctl, |
| 204 | .iterate_devices = default_key_iterate_devices, |
| 205 | }; |
| 206 | |
| 207 | static int __init dm_default_key_init(void) |
| 208 | { |
| 209 | return dm_register_target(&default_key_target); |
| 210 | } |
| 211 | |
| 212 | static void __exit dm_default_key_exit(void) |
| 213 | { |
| 214 | dm_unregister_target(&default_key_target); |
| 215 | } |
| 216 | |
| 217 | module_init(dm_default_key_init); |
| 218 | module_exit(dm_default_key_exit); |
| 219 | |
| 220 | MODULE_AUTHOR("Paul Lawrence <paullawrence@google.com>"); |
| 221 | MODULE_AUTHOR("Paul Crowley <paulcrowley@google.com>"); |
| 222 | MODULE_AUTHOR("Eric Biggers <ebiggers@google.com>"); |
| 223 | MODULE_DESCRIPTION(DM_NAME " target for encrypting filesystem metadata"); |
| 224 | MODULE_LICENSE("GPL v2"); |