]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - c_src/libbcachefs/checksum.c
move Rust sources to top level, C sources into c_src
[bcachefs-tools-debian] / c_src / libbcachefs / checksum.c
diff --git a/c_src/libbcachefs/checksum.c b/c_src/libbcachefs/checksum.c
new file mode 100644 (file)
index 0000000..3c761ad
--- /dev/null
@@ -0,0 +1,804 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "bcachefs.h"
+#include "checksum.h"
+#include "errcode.h"
+#include "super.h"
+#include "super-io.h"
+
+#include <linux/crc32c.h>
+#include <linux/crypto.h>
+#include <linux/xxhash.h>
+#include <linux/key.h>
+#include <linux/random.h>
+#include <linux/scatterlist.h>
+#include <crypto/algapi.h>
+#include <crypto/chacha.h>
+#include <crypto/hash.h>
+#include <crypto/poly1305.h>
+#include <crypto/skcipher.h>
+#include <keys/user-type.h>
+
+/*
+ * bch2_checksum state is an abstraction of the checksum state calculated over different pages.
+ * it features page merging without having the checksum algorithm lose its state.
+ * for native checksum aglorithms (like crc), a default seed value will do.
+ * for hash-like algorithms, a state needs to be stored
+ */
+
+struct bch2_checksum_state {
+       union {
+               u64 seed;
+               struct xxh64_state h64state;
+       };
+       unsigned int type;
+};
+
+static void bch2_checksum_init(struct bch2_checksum_state *state)
+{
+       switch (state->type) {
+       case BCH_CSUM_none:
+       case BCH_CSUM_crc32c:
+       case BCH_CSUM_crc64:
+               state->seed = 0;
+               break;
+       case BCH_CSUM_crc32c_nonzero:
+               state->seed = U32_MAX;
+               break;
+       case BCH_CSUM_crc64_nonzero:
+               state->seed = U64_MAX;
+               break;
+       case BCH_CSUM_xxhash:
+               xxh64_reset(&state->h64state, 0);
+               break;
+       default:
+               BUG();
+       }
+}
+
+static u64 bch2_checksum_final(const struct bch2_checksum_state *state)
+{
+       switch (state->type) {
+       case BCH_CSUM_none:
+       case BCH_CSUM_crc32c:
+       case BCH_CSUM_crc64:
+               return state->seed;
+       case BCH_CSUM_crc32c_nonzero:
+               return state->seed ^ U32_MAX;
+       case BCH_CSUM_crc64_nonzero:
+               return state->seed ^ U64_MAX;
+       case BCH_CSUM_xxhash:
+               return xxh64_digest(&state->h64state);
+       default:
+               BUG();
+       }
+}
+
+static void bch2_checksum_update(struct bch2_checksum_state *state, const void *data, size_t len)
+{
+       switch (state->type) {
+       case BCH_CSUM_none:
+               return;
+       case BCH_CSUM_crc32c_nonzero:
+       case BCH_CSUM_crc32c:
+               state->seed = crc32c(state->seed, data, len);
+               break;
+       case BCH_CSUM_crc64_nonzero:
+       case BCH_CSUM_crc64:
+               state->seed = crc64_be(state->seed, data, len);
+               break;
+       case BCH_CSUM_xxhash:
+               xxh64_update(&state->h64state, data, len);
+               break;
+       default:
+               BUG();
+       }
+}
+
+static inline int do_encrypt_sg(struct crypto_sync_skcipher *tfm,
+                               struct nonce nonce,
+                               struct scatterlist *sg, size_t len)
+{
+       SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
+       int ret;
+
+       skcipher_request_set_sync_tfm(req, tfm);
+       skcipher_request_set_crypt(req, sg, sg, len, nonce.d);
+
+       ret = crypto_skcipher_encrypt(req);
+       if (ret)
+               pr_err("got error %i from crypto_skcipher_encrypt()", ret);
+
+       return ret;
+}
+
+static inline int do_encrypt(struct crypto_sync_skcipher *tfm,
+                             struct nonce nonce,
+                             void *buf, size_t len)
+{
+       if (!is_vmalloc_addr(buf)) {
+               struct scatterlist sg;
+
+               sg_init_table(&sg, 1);
+               sg_set_page(&sg,
+                           is_vmalloc_addr(buf)
+                           ? vmalloc_to_page(buf)
+                           : virt_to_page(buf),
+                           len, offset_in_page(buf));
+               return do_encrypt_sg(tfm, nonce, &sg, len);
+       } else {
+               unsigned pages = buf_pages(buf, len);
+               struct scatterlist *sg;
+               size_t orig_len = len;
+               int ret, i;
+
+               sg = kmalloc_array(pages, sizeof(*sg), GFP_KERNEL);
+               if (!sg)
+                       return -BCH_ERR_ENOMEM_do_encrypt;
+
+               sg_init_table(sg, pages);
+
+               for (i = 0; i < pages; i++) {
+                       unsigned offset = offset_in_page(buf);
+                       unsigned pg_len = min_t(size_t, len, PAGE_SIZE - offset);
+
+                       sg_set_page(sg + i, vmalloc_to_page(buf), pg_len, offset);
+                       buf += pg_len;
+                       len -= pg_len;
+               }
+
+               ret = do_encrypt_sg(tfm, nonce, sg, orig_len);
+               kfree(sg);
+               return ret;
+       }
+}
+
+int bch2_chacha_encrypt_key(struct bch_key *key, struct nonce nonce,
+                           void *buf, size_t len)
+{
+       struct crypto_sync_skcipher *chacha20 =
+               crypto_alloc_sync_skcipher("chacha20", 0, 0);
+       int ret;
+
+       ret = PTR_ERR_OR_ZERO(chacha20);
+       if (ret) {
+               pr_err("error requesting chacha20 cipher: %s", bch2_err_str(ret));
+               return ret;
+       }
+
+       ret = crypto_skcipher_setkey(&chacha20->base,
+                                    (void *) key, sizeof(*key));
+       if (ret) {
+               pr_err("error from crypto_skcipher_setkey(): %s", bch2_err_str(ret));
+               goto err;
+       }
+
+       ret = do_encrypt(chacha20, nonce, buf, len);
+err:
+       crypto_free_sync_skcipher(chacha20);
+       return ret;
+}
+
+static int gen_poly_key(struct bch_fs *c, struct shash_desc *desc,
+                       struct nonce nonce)
+{
+       u8 key[POLY1305_KEY_SIZE];
+       int ret;
+
+       nonce.d[3] ^= BCH_NONCE_POLY;
+
+       memset(key, 0, sizeof(key));
+       ret = do_encrypt(c->chacha20, nonce, key, sizeof(key));
+       if (ret)
+               return ret;
+
+       desc->tfm = c->poly1305;
+       crypto_shash_init(desc);
+       crypto_shash_update(desc, key, sizeof(key));
+       return 0;
+}
+
+struct bch_csum bch2_checksum(struct bch_fs *c, unsigned type,
+                             struct nonce nonce, const void *data, size_t len)
+{
+       switch (type) {
+       case BCH_CSUM_none:
+       case BCH_CSUM_crc32c_nonzero:
+       case BCH_CSUM_crc64_nonzero:
+       case BCH_CSUM_crc32c:
+       case BCH_CSUM_xxhash:
+       case BCH_CSUM_crc64: {
+               struct bch2_checksum_state state;
+
+               state.type = type;
+
+               bch2_checksum_init(&state);
+               bch2_checksum_update(&state, data, len);
+
+               return (struct bch_csum) { .lo = cpu_to_le64(bch2_checksum_final(&state)) };
+       }
+
+       case BCH_CSUM_chacha20_poly1305_80:
+       case BCH_CSUM_chacha20_poly1305_128: {
+               SHASH_DESC_ON_STACK(desc, c->poly1305);
+               u8 digest[POLY1305_DIGEST_SIZE];
+               struct bch_csum ret = { 0 };
+
+               gen_poly_key(c, desc, nonce);
+
+               crypto_shash_update(desc, data, len);
+               crypto_shash_final(desc, digest);
+
+               memcpy(&ret, digest, bch_crc_bytes[type]);
+               return ret;
+       }
+       default:
+               BUG();
+       }
+}
+
+int bch2_encrypt(struct bch_fs *c, unsigned type,
+                 struct nonce nonce, void *data, size_t len)
+{
+       if (!bch2_csum_type_is_encryption(type))
+               return 0;
+
+       return do_encrypt(c->chacha20, nonce, data, len);
+}
+
+static struct bch_csum __bch2_checksum_bio(struct bch_fs *c, unsigned type,
+                                          struct nonce nonce, struct bio *bio,
+                                          struct bvec_iter *iter)
+{
+       struct bio_vec bv;
+
+       switch (type) {
+       case BCH_CSUM_none:
+               return (struct bch_csum) { 0 };
+       case BCH_CSUM_crc32c_nonzero:
+       case BCH_CSUM_crc64_nonzero:
+       case BCH_CSUM_crc32c:
+       case BCH_CSUM_xxhash:
+       case BCH_CSUM_crc64: {
+               struct bch2_checksum_state state;
+
+               state.type = type;
+               bch2_checksum_init(&state);
+
+#ifdef CONFIG_HIGHMEM
+               __bio_for_each_segment(bv, bio, *iter, *iter) {
+                       void *p = kmap_local_page(bv.bv_page) + bv.bv_offset;
+
+                       bch2_checksum_update(&state, p, bv.bv_len);
+                       kunmap_local(p);
+               }
+#else
+               __bio_for_each_bvec(bv, bio, *iter, *iter)
+                       bch2_checksum_update(&state, page_address(bv.bv_page) + bv.bv_offset,
+                               bv.bv_len);
+#endif
+               return (struct bch_csum) { .lo = cpu_to_le64(bch2_checksum_final(&state)) };
+       }
+
+       case BCH_CSUM_chacha20_poly1305_80:
+       case BCH_CSUM_chacha20_poly1305_128: {
+               SHASH_DESC_ON_STACK(desc, c->poly1305);
+               u8 digest[POLY1305_DIGEST_SIZE];
+               struct bch_csum ret = { 0 };
+
+               gen_poly_key(c, desc, nonce);
+
+#ifdef CONFIG_HIGHMEM
+               __bio_for_each_segment(bv, bio, *iter, *iter) {
+                       void *p = kmap_local_page(bv.bv_page) + bv.bv_offset;
+
+                       crypto_shash_update(desc, p, bv.bv_len);
+                       kunmap_local(p);
+               }
+#else
+               __bio_for_each_bvec(bv, bio, *iter, *iter)
+                       crypto_shash_update(desc,
+                               page_address(bv.bv_page) + bv.bv_offset,
+                               bv.bv_len);
+#endif
+               crypto_shash_final(desc, digest);
+
+               memcpy(&ret, digest, bch_crc_bytes[type]);
+               return ret;
+       }
+       default:
+               BUG();
+       }
+}
+
+struct bch_csum bch2_checksum_bio(struct bch_fs *c, unsigned type,
+                                 struct nonce nonce, struct bio *bio)
+{
+       struct bvec_iter iter = bio->bi_iter;
+
+       return __bch2_checksum_bio(c, type, nonce, bio, &iter);
+}
+
+int __bch2_encrypt_bio(struct bch_fs *c, unsigned type,
+                    struct nonce nonce, struct bio *bio)
+{
+       struct bio_vec bv;
+       struct bvec_iter iter;
+       struct scatterlist sgl[16], *sg = sgl;
+       size_t bytes = 0;
+       int ret = 0;
+
+       if (!bch2_csum_type_is_encryption(type))
+               return 0;
+
+       sg_init_table(sgl, ARRAY_SIZE(sgl));
+
+       bio_for_each_segment(bv, bio, iter) {
+               if (sg == sgl + ARRAY_SIZE(sgl)) {
+                       sg_mark_end(sg - 1);
+
+                       ret = do_encrypt_sg(c->chacha20, nonce, sgl, bytes);
+                       if (ret)
+                               return ret;
+
+                       nonce = nonce_add(nonce, bytes);
+                       bytes = 0;
+
+                       sg_init_table(sgl, ARRAY_SIZE(sgl));
+                       sg = sgl;
+               }
+
+               sg_set_page(sg++, bv.bv_page, bv.bv_len, bv.bv_offset);
+               bytes += bv.bv_len;
+       }
+
+       sg_mark_end(sg - 1);
+       return do_encrypt_sg(c->chacha20, nonce, sgl, bytes);
+}
+
+struct bch_csum bch2_checksum_merge(unsigned type, struct bch_csum a,
+                                   struct bch_csum b, size_t b_len)
+{
+       struct bch2_checksum_state state;
+
+       state.type = type;
+       bch2_checksum_init(&state);
+       state.seed = le64_to_cpu(a.lo);
+
+       BUG_ON(!bch2_checksum_mergeable(type));
+
+       while (b_len) {
+               unsigned page_len = min_t(unsigned, b_len, PAGE_SIZE);
+
+               bch2_checksum_update(&state,
+                               page_address(ZERO_PAGE(0)), page_len);
+               b_len -= page_len;
+       }
+       a.lo = cpu_to_le64(bch2_checksum_final(&state));
+       a.lo ^= b.lo;
+       a.hi ^= b.hi;
+       return a;
+}
+
+int bch2_rechecksum_bio(struct bch_fs *c, struct bio *bio,
+                       struct bversion version,
+                       struct bch_extent_crc_unpacked crc_old,
+                       struct bch_extent_crc_unpacked *crc_a,
+                       struct bch_extent_crc_unpacked *crc_b,
+                       unsigned len_a, unsigned len_b,
+                       unsigned new_csum_type)
+{
+       struct bvec_iter iter = bio->bi_iter;
+       struct nonce nonce = extent_nonce(version, crc_old);
+       struct bch_csum merged = { 0 };
+       struct crc_split {
+               struct bch_extent_crc_unpacked  *crc;
+               unsigned                        len;
+               unsigned                        csum_type;
+               struct bch_csum                 csum;
+       } splits[3] = {
+               { crc_a, len_a, new_csum_type, { 0 }},
+               { crc_b, len_b, new_csum_type, { 0 } },
+               { NULL,  bio_sectors(bio) - len_a - len_b, new_csum_type, { 0 } },
+       }, *i;
+       bool mergeable = crc_old.csum_type == new_csum_type &&
+               bch2_checksum_mergeable(new_csum_type);
+       unsigned crc_nonce = crc_old.nonce;
+
+       BUG_ON(len_a + len_b > bio_sectors(bio));
+       BUG_ON(crc_old.uncompressed_size != bio_sectors(bio));
+       BUG_ON(crc_is_compressed(crc_old));
+       BUG_ON(bch2_csum_type_is_encryption(crc_old.csum_type) !=
+              bch2_csum_type_is_encryption(new_csum_type));
+
+       for (i = splits; i < splits + ARRAY_SIZE(splits); i++) {
+               iter.bi_size = i->len << 9;
+               if (mergeable || i->crc)
+                       i->csum = __bch2_checksum_bio(c, i->csum_type,
+                                                     nonce, bio, &iter);
+               else
+                       bio_advance_iter(bio, &iter, i->len << 9);
+               nonce = nonce_add(nonce, i->len << 9);
+       }
+
+       if (mergeable)
+               for (i = splits; i < splits + ARRAY_SIZE(splits); i++)
+                       merged = bch2_checksum_merge(new_csum_type, merged,
+                                                    i->csum, i->len << 9);
+       else
+               merged = bch2_checksum_bio(c, crc_old.csum_type,
+                               extent_nonce(version, crc_old), bio);
+
+       if (bch2_crc_cmp(merged, crc_old.csum) && !c->opts.no_data_io) {
+               bch_err(c, "checksum error in %s() (memory corruption or bug?)\n"
+                       "expected %0llx:%0llx got %0llx:%0llx (old type %s new type %s)",
+                       __func__,
+                       crc_old.csum.hi,
+                       crc_old.csum.lo,
+                       merged.hi,
+                       merged.lo,
+                       bch2_csum_types[crc_old.csum_type],
+                       bch2_csum_types[new_csum_type]);
+               return -EIO;
+       }
+
+       for (i = splits; i < splits + ARRAY_SIZE(splits); i++) {
+               if (i->crc)
+                       *i->crc = (struct bch_extent_crc_unpacked) {
+                               .csum_type              = i->csum_type,
+                               .compression_type       = crc_old.compression_type,
+                               .compressed_size        = i->len,
+                               .uncompressed_size      = i->len,
+                               .offset                 = 0,
+                               .live_size              = i->len,
+                               .nonce                  = crc_nonce,
+                               .csum                   = i->csum,
+                       };
+
+               if (bch2_csum_type_is_encryption(new_csum_type))
+                       crc_nonce += i->len;
+       }
+
+       return 0;
+}
+
+/* BCH_SB_FIELD_crypt: */
+
+static int bch2_sb_crypt_validate(struct bch_sb *sb,
+                                 struct bch_sb_field *f,
+                                 struct printbuf *err)
+{
+       struct bch_sb_field_crypt *crypt = field_to_type(f, crypt);
+
+       if (vstruct_bytes(&crypt->field) < sizeof(*crypt)) {
+               prt_printf(err, "wrong size (got %zu should be %zu)",
+                      vstruct_bytes(&crypt->field), sizeof(*crypt));
+               return -BCH_ERR_invalid_sb_crypt;
+       }
+
+       if (BCH_CRYPT_KDF_TYPE(crypt)) {
+               prt_printf(err, "bad kdf type %llu", BCH_CRYPT_KDF_TYPE(crypt));
+               return -BCH_ERR_invalid_sb_crypt;
+       }
+
+       return 0;
+}
+
+static void bch2_sb_crypt_to_text(struct printbuf *out, struct bch_sb *sb,
+                                 struct bch_sb_field *f)
+{
+       struct bch_sb_field_crypt *crypt = field_to_type(f, crypt);
+
+       prt_printf(out, "KFD:               %llu", BCH_CRYPT_KDF_TYPE(crypt));
+       prt_newline(out);
+       prt_printf(out, "scrypt n:          %llu", BCH_KDF_SCRYPT_N(crypt));
+       prt_newline(out);
+       prt_printf(out, "scrypt r:          %llu", BCH_KDF_SCRYPT_R(crypt));
+       prt_newline(out);
+       prt_printf(out, "scrypt p:          %llu", BCH_KDF_SCRYPT_P(crypt));
+       prt_newline(out);
+}
+
+const struct bch_sb_field_ops bch_sb_field_ops_crypt = {
+       .validate       = bch2_sb_crypt_validate,
+       .to_text        = bch2_sb_crypt_to_text,
+};
+
+#ifdef __KERNEL__
+static int __bch2_request_key(char *key_description, struct bch_key *key)
+{
+       struct key *keyring_key;
+       const struct user_key_payload *ukp;
+       int ret;
+
+       keyring_key = request_key(&key_type_user, key_description, NULL);
+       if (IS_ERR(keyring_key))
+               return PTR_ERR(keyring_key);
+
+       down_read(&keyring_key->sem);
+       ukp = dereference_key_locked(keyring_key);
+       if (ukp->datalen == sizeof(*key)) {
+               memcpy(key, ukp->data, ukp->datalen);
+               ret = 0;
+       } else {
+               ret = -EINVAL;
+       }
+       up_read(&keyring_key->sem);
+       key_put(keyring_key);
+
+       return ret;
+}
+#else
+#include <keyutils.h>
+
+static int __bch2_request_key(char *key_description, struct bch_key *key)
+{
+       key_serial_t key_id;
+
+       key_id = request_key("user", key_description, NULL,
+                            KEY_SPEC_SESSION_KEYRING);
+       if (key_id >= 0)
+               goto got_key;
+
+       key_id = request_key("user", key_description, NULL,
+                            KEY_SPEC_USER_KEYRING);
+       if (key_id >= 0)
+               goto got_key;
+
+       key_id = request_key("user", key_description, NULL,
+                            KEY_SPEC_USER_SESSION_KEYRING);
+       if (key_id >= 0)
+               goto got_key;
+
+       return -errno;
+got_key:
+
+       if (keyctl_read(key_id, (void *) key, sizeof(*key)) != sizeof(*key))
+               return -1;
+
+       return 0;
+}
+
+#include "../crypto.h"
+#endif
+
+int bch2_request_key(struct bch_sb *sb, struct bch_key *key)
+{
+       struct printbuf key_description = PRINTBUF;
+       int ret;
+
+       prt_printf(&key_description, "bcachefs:");
+       pr_uuid(&key_description, sb->user_uuid.b);
+
+       ret = __bch2_request_key(key_description.buf, key);
+       printbuf_exit(&key_description);
+
+#ifndef __KERNEL__
+       if (ret) {
+               char *passphrase = read_passphrase("Enter passphrase: ");
+               struct bch_encrypted_key sb_key;
+
+               bch2_passphrase_check(sb, passphrase,
+                                     key, &sb_key);
+               ret = 0;
+       }
+#endif
+
+       /* stash with memfd, pass memfd fd to mount */
+
+       return ret;
+}
+
+#ifndef __KERNEL__
+int bch2_revoke_key(struct bch_sb *sb)
+{
+       key_serial_t key_id;
+       struct printbuf key_description = PRINTBUF;
+
+       prt_printf(&key_description, "bcachefs:");
+       pr_uuid(&key_description, sb->user_uuid.b);
+
+       key_id = request_key("user", key_description.buf, NULL, KEY_SPEC_USER_KEYRING);
+       printbuf_exit(&key_description);
+       if (key_id < 0)
+               return errno;
+
+       keyctl_revoke(key_id);
+
+       return 0;
+}
+#endif
+
+int bch2_decrypt_sb_key(struct bch_fs *c,
+                       struct bch_sb_field_crypt *crypt,
+                       struct bch_key *key)
+{
+       struct bch_encrypted_key sb_key = crypt->key;
+       struct bch_key user_key;
+       int ret = 0;
+
+       /* is key encrypted? */
+       if (!bch2_key_is_encrypted(&sb_key))
+               goto out;
+
+       ret = bch2_request_key(c->disk_sb.sb, &user_key);
+       if (ret) {
+               bch_err(c, "error requesting encryption key: %s", bch2_err_str(ret));
+               goto err;
+       }
+
+       /* decrypt real key: */
+       ret = bch2_chacha_encrypt_key(&user_key, bch2_sb_key_nonce(c),
+                                     &sb_key, sizeof(sb_key));
+       if (ret)
+               goto err;
+
+       if (bch2_key_is_encrypted(&sb_key)) {
+               bch_err(c, "incorrect encryption key");
+               ret = -EINVAL;
+               goto err;
+       }
+out:
+       *key = sb_key.key;
+err:
+       memzero_explicit(&sb_key, sizeof(sb_key));
+       memzero_explicit(&user_key, sizeof(user_key));
+       return ret;
+}
+
+static int bch2_alloc_ciphers(struct bch_fs *c)
+{
+       int ret;
+
+       if (!c->chacha20)
+               c->chacha20 = crypto_alloc_sync_skcipher("chacha20", 0, 0);
+       ret = PTR_ERR_OR_ZERO(c->chacha20);
+
+       if (ret) {
+               bch_err(c, "error requesting chacha20 module: %s", bch2_err_str(ret));
+               return ret;
+       }
+
+       if (!c->poly1305)
+               c->poly1305 = crypto_alloc_shash("poly1305", 0, 0);
+       ret = PTR_ERR_OR_ZERO(c->poly1305);
+
+       if (ret) {
+               bch_err(c, "error requesting poly1305 module: %s", bch2_err_str(ret));
+               return ret;
+       }
+
+       return 0;
+}
+
+int bch2_disable_encryption(struct bch_fs *c)
+{
+       struct bch_sb_field_crypt *crypt;
+       struct bch_key key;
+       int ret = -EINVAL;
+
+       mutex_lock(&c->sb_lock);
+
+       crypt = bch2_sb_field_get(c->disk_sb.sb, crypt);
+       if (!crypt)
+               goto out;
+
+       /* is key encrypted? */
+       ret = 0;
+       if (bch2_key_is_encrypted(&crypt->key))
+               goto out;
+
+       ret = bch2_decrypt_sb_key(c, crypt, &key);
+       if (ret)
+               goto out;
+
+       crypt->key.magic        = cpu_to_le64(BCH_KEY_MAGIC);
+       crypt->key.key          = key;
+
+       SET_BCH_SB_ENCRYPTION_TYPE(c->disk_sb.sb, 0);
+       bch2_write_super(c);
+out:
+       mutex_unlock(&c->sb_lock);
+
+       return ret;
+}
+
+int bch2_enable_encryption(struct bch_fs *c, bool keyed)
+{
+       struct bch_encrypted_key key;
+       struct bch_key user_key;
+       struct bch_sb_field_crypt *crypt;
+       int ret = -EINVAL;
+
+       mutex_lock(&c->sb_lock);
+
+       /* Do we already have an encryption key? */
+       if (bch2_sb_field_get(c->disk_sb.sb, crypt))
+               goto err;
+
+       ret = bch2_alloc_ciphers(c);
+       if (ret)
+               goto err;
+
+       key.magic = cpu_to_le64(BCH_KEY_MAGIC);
+       get_random_bytes(&key.key, sizeof(key.key));
+
+       if (keyed) {
+               ret = bch2_request_key(c->disk_sb.sb, &user_key);
+               if (ret) {
+                       bch_err(c, "error requesting encryption key: %s", bch2_err_str(ret));
+                       goto err;
+               }
+
+               ret = bch2_chacha_encrypt_key(&user_key, bch2_sb_key_nonce(c),
+                                             &key, sizeof(key));
+               if (ret)
+                       goto err;
+       }
+
+       ret = crypto_skcipher_setkey(&c->chacha20->base,
+                       (void *) &key.key, sizeof(key.key));
+       if (ret)
+               goto err;
+
+       crypt = bch2_sb_field_resize(&c->disk_sb, crypt,
+                                    sizeof(*crypt) / sizeof(u64));
+       if (!crypt) {
+               ret = -BCH_ERR_ENOSPC_sb_crypt;
+               goto err;
+       }
+
+       crypt->key = key;
+
+       /* write superblock */
+       SET_BCH_SB_ENCRYPTION_TYPE(c->disk_sb.sb, 1);
+       bch2_write_super(c);
+err:
+       mutex_unlock(&c->sb_lock);
+       memzero_explicit(&user_key, sizeof(user_key));
+       memzero_explicit(&key, sizeof(key));
+       return ret;
+}
+
+void bch2_fs_encryption_exit(struct bch_fs *c)
+{
+       if (!IS_ERR_OR_NULL(c->poly1305))
+               crypto_free_shash(c->poly1305);
+       if (!IS_ERR_OR_NULL(c->chacha20))
+               crypto_free_sync_skcipher(c->chacha20);
+       if (!IS_ERR_OR_NULL(c->sha256))
+               crypto_free_shash(c->sha256);
+}
+
+int bch2_fs_encryption_init(struct bch_fs *c)
+{
+       struct bch_sb_field_crypt *crypt;
+       struct bch_key key;
+       int ret = 0;
+
+       c->sha256 = crypto_alloc_shash("sha256", 0, 0);
+       ret = PTR_ERR_OR_ZERO(c->sha256);
+       if (ret) {
+               bch_err(c, "error requesting sha256 module: %s", bch2_err_str(ret));
+               goto out;
+       }
+
+       crypt = bch2_sb_field_get(c->disk_sb.sb, crypt);
+       if (!crypt)
+               goto out;
+
+       ret = bch2_alloc_ciphers(c);
+       if (ret)
+               goto out;
+
+       ret = bch2_decrypt_sb_key(c, crypt, &key);
+       if (ret)
+               goto out;
+
+       ret = crypto_skcipher_setkey(&c->chacha20->base,
+                       (void *) &key.key, sizeof(key.key));
+       if (ret)
+               goto out;
+out:
+       memzero_explicit(&key, sizeof(key));
+       return ret;
+}