v4.19.13 snapshot.
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
new file mode 100644
index 0000000..0f46cf5
--- /dev/null
+++ b/fs/crypto/crypto.c
@@ -0,0 +1,501 @@
+/*
+ * This contains encryption functions for per-file encryption.
+ *
+ * Copyright (C) 2015, Google, Inc.
+ * Copyright (C) 2015, Motorola Mobility
+ *
+ * Written by Michael Halcrow, 2014.
+ *
+ * Filename encryption additions
+ * Uday Savagaonkar, 2014
+ * Encryption policy handling additions
+ * Ildar Muslukhov, 2014
+ * Add fscrypt_pullback_bio_page()
+ * Jaegeuk Kim, 2015.
+ *
+ * This has not yet undergone a rigorous security audit.
+ *
+ * The usage of AES-XTS should conform to recommendations in NIST
+ * Special Publication 800-38E and IEEE P1619/D16.
+ */
+
+#include <linux/pagemap.h>
+#include <linux/mempool.h>
+#include <linux/module.h>
+#include <linux/scatterlist.h>
+#include <linux/ratelimit.h>
+#include <linux/dcache.h>
+#include <linux/namei.h>
+#include <crypto/aes.h>
+#include <crypto/skcipher.h>
+#include "fscrypt_private.h"
+
+static unsigned int num_prealloc_crypto_pages = 32;
+static unsigned int num_prealloc_crypto_ctxs = 128;
+
+module_param(num_prealloc_crypto_pages, uint, 0444);
+MODULE_PARM_DESC(num_prealloc_crypto_pages,
+ "Number of crypto pages to preallocate");
+module_param(num_prealloc_crypto_ctxs, uint, 0444);
+MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
+ "Number of crypto contexts to preallocate");
+
+static mempool_t *fscrypt_bounce_page_pool = NULL;
+
+static LIST_HEAD(fscrypt_free_ctxs);
+static DEFINE_SPINLOCK(fscrypt_ctx_lock);
+
+static struct workqueue_struct *fscrypt_read_workqueue;
+static DEFINE_MUTEX(fscrypt_init_mutex);
+
+static struct kmem_cache *fscrypt_ctx_cachep;
+struct kmem_cache *fscrypt_info_cachep;
+
+void fscrypt_enqueue_decrypt_work(struct work_struct *work)
+{
+ queue_work(fscrypt_read_workqueue, work);
+}
+EXPORT_SYMBOL(fscrypt_enqueue_decrypt_work);
+
+/**
+ * fscrypt_release_ctx() - Releases an encryption context
+ * @ctx: The encryption context to release.
+ *
+ * If the encryption context was allocated from the pre-allocated pool, returns
+ * it to that pool. Else, frees it.
+ *
+ * If there's a bounce page in the context, this frees that.
+ */
+void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
+{
+ unsigned long flags;
+
+ if (ctx->flags & FS_CTX_HAS_BOUNCE_BUFFER_FL && ctx->w.bounce_page) {
+ mempool_free(ctx->w.bounce_page, fscrypt_bounce_page_pool);
+ ctx->w.bounce_page = NULL;
+ }
+ ctx->w.control_page = NULL;
+ if (ctx->flags & FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
+ kmem_cache_free(fscrypt_ctx_cachep, ctx);
+ } else {
+ spin_lock_irqsave(&fscrypt_ctx_lock, flags);
+ list_add(&ctx->free_list, &fscrypt_free_ctxs);
+ spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
+ }
+}
+EXPORT_SYMBOL(fscrypt_release_ctx);
+
+/**
+ * fscrypt_get_ctx() - Gets an encryption context
+ * @inode: The inode for which we are doing the crypto
+ * @gfp_flags: The gfp flag for memory allocation
+ *
+ * Allocates and initializes an encryption context.
+ *
+ * Return: An allocated and initialized encryption context on success; error
+ * value or NULL otherwise.
+ */
+struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *inode, gfp_t gfp_flags)
+{
+ struct fscrypt_ctx *ctx = NULL;
+ struct fscrypt_info *ci = inode->i_crypt_info;
+ unsigned long flags;
+
+ if (ci == NULL)
+ return ERR_PTR(-ENOKEY);
+
+ /*
+ * We first try getting the ctx from a free list because in
+ * the common case the ctx will have an allocated and
+ * initialized crypto tfm, so it's probably a worthwhile
+ * optimization. For the bounce page, we first try getting it
+ * from the kernel allocator because that's just about as fast
+ * as getting it from a list and because a cache of free pages
+ * should generally be a "last resort" option for a filesystem
+ * to be able to do its job.
+ */
+ spin_lock_irqsave(&fscrypt_ctx_lock, flags);
+ ctx = list_first_entry_or_null(&fscrypt_free_ctxs,
+ struct fscrypt_ctx, free_list);
+ if (ctx)
+ list_del(&ctx->free_list);
+ spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
+ if (!ctx) {
+ ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, gfp_flags);
+ if (!ctx)
+ return ERR_PTR(-ENOMEM);
+ ctx->flags |= FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
+ } else {
+ ctx->flags &= ~FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
+ }
+ ctx->flags &= ~FS_CTX_HAS_BOUNCE_BUFFER_FL;
+ return ctx;
+}
+EXPORT_SYMBOL(fscrypt_get_ctx);
+
+int fscrypt_do_page_crypto(const struct inode *inode, fscrypt_direction_t rw,
+ u64 lblk_num, struct page *src_page,
+ struct page *dest_page, unsigned int len,
+ unsigned int offs, gfp_t gfp_flags)
+{
+ struct {
+ __le64 index;
+ u8 padding[FS_IV_SIZE - sizeof(__le64)];
+ } iv;
+ struct skcipher_request *req = NULL;
+ DECLARE_CRYPTO_WAIT(wait);
+ struct scatterlist dst, src;
+ struct fscrypt_info *ci = inode->i_crypt_info;
+ struct crypto_skcipher *tfm = ci->ci_ctfm;
+ int res = 0;
+
+ BUG_ON(len == 0);
+
+ BUILD_BUG_ON(sizeof(iv) != FS_IV_SIZE);
+ BUILD_BUG_ON(AES_BLOCK_SIZE != FS_IV_SIZE);
+ iv.index = cpu_to_le64(lblk_num);
+ memset(iv.padding, 0, sizeof(iv.padding));
+
+ if (ci->ci_essiv_tfm != NULL) {
+ crypto_cipher_encrypt_one(ci->ci_essiv_tfm, (u8 *)&iv,
+ (u8 *)&iv);
+ }
+
+ req = skcipher_request_alloc(tfm, gfp_flags);
+ if (!req)
+ return -ENOMEM;
+
+ skcipher_request_set_callback(
+ req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+ crypto_req_done, &wait);
+
+ sg_init_table(&dst, 1);
+ sg_set_page(&dst, dest_page, len, offs);
+ sg_init_table(&src, 1);
+ sg_set_page(&src, src_page, len, offs);
+ skcipher_request_set_crypt(req, &src, &dst, len, &iv);
+ if (rw == FS_DECRYPT)
+ res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait);
+ else
+ res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
+ skcipher_request_free(req);
+ if (res) {
+ fscrypt_err(inode->i_sb,
+ "%scryption failed for inode %lu, block %llu: %d",
+ (rw == FS_DECRYPT ? "de" : "en"),
+ inode->i_ino, lblk_num, res);
+ return res;
+ }
+ return 0;
+}
+
+struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
+ gfp_t gfp_flags)
+{
+ ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);
+ if (ctx->w.bounce_page == NULL)
+ return ERR_PTR(-ENOMEM);
+ ctx->flags |= FS_CTX_HAS_BOUNCE_BUFFER_FL;
+ return ctx->w.bounce_page;
+}
+
+/**
+ * fscypt_encrypt_page() - Encrypts a page
+ * @inode: The inode for which the encryption should take place
+ * @page: The page to encrypt. Must be locked for bounce-page
+ * encryption.
+ * @len: Length of data to encrypt in @page and encrypted
+ * data in returned page.
+ * @offs: Offset of data within @page and returned
+ * page holding encrypted data.
+ * @lblk_num: Logical block number. This must be unique for multiple
+ * calls with same inode, except when overwriting
+ * previously written data.
+ * @gfp_flags: The gfp flag for memory allocation
+ *
+ * Encrypts @page using the ctx encryption context. Performs encryption
+ * either in-place or into a newly allocated bounce page.
+ * Called on the page write path.
+ *
+ * Bounce page allocation is the default.
+ * In this case, the contents of @page are encrypted and stored in an
+ * allocated bounce page. @page has to be locked and the caller must call
+ * fscrypt_restore_control_page() on the returned ciphertext page to
+ * release the bounce buffer and the encryption context.
+ *
+ * In-place encryption is used by setting the FS_CFLG_OWN_PAGES flag in
+ * fscrypt_operations. Here, the input-page is returned with its content
+ * encrypted.
+ *
+ * Return: A page with the encrypted content on success. Else, an
+ * error value or NULL.
+ */
+struct page *fscrypt_encrypt_page(const struct inode *inode,
+ struct page *page,
+ unsigned int len,
+ unsigned int offs,
+ u64 lblk_num, gfp_t gfp_flags)
+
+{
+ struct fscrypt_ctx *ctx;
+ struct page *ciphertext_page = page;
+ int err;
+
+ BUG_ON(len % FS_CRYPTO_BLOCK_SIZE != 0);
+
+ if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) {
+ /* with inplace-encryption we just encrypt the page */
+ err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num, page,
+ ciphertext_page, len, offs,
+ gfp_flags);
+ if (err)
+ return ERR_PTR(err);
+
+ return ciphertext_page;
+ }
+
+ BUG_ON(!PageLocked(page));
+
+ ctx = fscrypt_get_ctx(inode, gfp_flags);
+ if (IS_ERR(ctx))
+ return (struct page *)ctx;
+
+ /* The encryption operation will require a bounce page. */
+ ciphertext_page = fscrypt_alloc_bounce_page(ctx, gfp_flags);
+ if (IS_ERR(ciphertext_page))
+ goto errout;
+
+ ctx->w.control_page = page;
+ err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num,
+ page, ciphertext_page, len, offs,
+ gfp_flags);
+ if (err) {
+ ciphertext_page = ERR_PTR(err);
+ goto errout;
+ }
+ SetPagePrivate(ciphertext_page);
+ set_page_private(ciphertext_page, (unsigned long)ctx);
+ lock_page(ciphertext_page);
+ return ciphertext_page;
+
+errout:
+ fscrypt_release_ctx(ctx);
+ return ciphertext_page;
+}
+EXPORT_SYMBOL(fscrypt_encrypt_page);
+
+/**
+ * fscrypt_decrypt_page() - Decrypts a page in-place
+ * @inode: The corresponding inode for the page to decrypt.
+ * @page: The page to decrypt. Must be locked in case
+ * it is a writeback page (FS_CFLG_OWN_PAGES unset).
+ * @len: Number of bytes in @page to be decrypted.
+ * @offs: Start of data in @page.
+ * @lblk_num: Logical block number.
+ *
+ * Decrypts page in-place using the ctx encryption context.
+ *
+ * Called from the read completion callback.
+ *
+ * Return: Zero on success, non-zero otherwise.
+ */
+int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
+ unsigned int len, unsigned int offs, u64 lblk_num)
+{
+ if (!(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES))
+ BUG_ON(!PageLocked(page));
+
+ return fscrypt_do_page_crypto(inode, FS_DECRYPT, lblk_num, page, page,
+ len, offs, GFP_NOFS);
+}
+EXPORT_SYMBOL(fscrypt_decrypt_page);
+
+/*
+ * Validate dentries for encrypted directories to make sure we aren't
+ * potentially caching stale data after a key has been added or
+ * removed.
+ */
+static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ struct dentry *dir;
+ int dir_has_key, cached_with_key;
+
+ if (flags & LOOKUP_RCU)
+ return -ECHILD;
+
+ dir = dget_parent(dentry);
+ if (!IS_ENCRYPTED(d_inode(dir))) {
+ dput(dir);
+ return 0;
+ }
+
+ spin_lock(&dentry->d_lock);
+ cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY;
+ spin_unlock(&dentry->d_lock);
+ dir_has_key = (d_inode(dir)->i_crypt_info != NULL);
+ dput(dir);
+
+ /*
+ * If the dentry was cached without the key, and it is a
+ * negative dentry, it might be a valid name. We can't check
+ * if the key has since been made available due to locking
+ * reasons, so we fail the validation so ext4_lookup() can do
+ * this check.
+ *
+ * We also fail the validation if the dentry was created with
+ * the key present, but we no longer have the key, or vice versa.
+ */
+ if ((!cached_with_key && d_is_negative(dentry)) ||
+ (!cached_with_key && dir_has_key) ||
+ (cached_with_key && !dir_has_key))
+ return 0;
+ return 1;
+}
+
+const struct dentry_operations fscrypt_d_ops = {
+ .d_revalidate = fscrypt_d_revalidate,
+};
+
+void fscrypt_restore_control_page(struct page *page)
+{
+ struct fscrypt_ctx *ctx;
+
+ ctx = (struct fscrypt_ctx *)page_private(page);
+ set_page_private(page, (unsigned long)NULL);
+ ClearPagePrivate(page);
+ unlock_page(page);
+ fscrypt_release_ctx(ctx);
+}
+EXPORT_SYMBOL(fscrypt_restore_control_page);
+
+static void fscrypt_destroy(void)
+{
+ struct fscrypt_ctx *pos, *n;
+
+ list_for_each_entry_safe(pos, n, &fscrypt_free_ctxs, free_list)
+ kmem_cache_free(fscrypt_ctx_cachep, pos);
+ INIT_LIST_HEAD(&fscrypt_free_ctxs);
+ mempool_destroy(fscrypt_bounce_page_pool);
+ fscrypt_bounce_page_pool = NULL;
+}
+
+/**
+ * fscrypt_initialize() - allocate major buffers for fs encryption.
+ * @cop_flags: fscrypt operations flags
+ *
+ * We only call this when we start accessing encrypted files, since it
+ * results in memory getting allocated that wouldn't otherwise be used.
+ *
+ * Return: Zero on success, non-zero otherwise.
+ */
+int fscrypt_initialize(unsigned int cop_flags)
+{
+ int i, res = -ENOMEM;
+
+ /* No need to allocate a bounce page pool if this FS won't use it. */
+ if (cop_flags & FS_CFLG_OWN_PAGES)
+ return 0;
+
+ mutex_lock(&fscrypt_init_mutex);
+ if (fscrypt_bounce_page_pool)
+ goto already_initialized;
+
+ for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
+ struct fscrypt_ctx *ctx;
+
+ ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS);
+ if (!ctx)
+ goto fail;
+ list_add(&ctx->free_list, &fscrypt_free_ctxs);
+ }
+
+ fscrypt_bounce_page_pool =
+ mempool_create_page_pool(num_prealloc_crypto_pages, 0);
+ if (!fscrypt_bounce_page_pool)
+ goto fail;
+
+already_initialized:
+ mutex_unlock(&fscrypt_init_mutex);
+ return 0;
+fail:
+ fscrypt_destroy();
+ mutex_unlock(&fscrypt_init_mutex);
+ return res;
+}
+
+void fscrypt_msg(struct super_block *sb, const char *level,
+ const char *fmt, ...)
+{
+ static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
+ DEFAULT_RATELIMIT_BURST);
+ struct va_format vaf;
+ va_list args;
+
+ if (!__ratelimit(&rs))
+ return;
+
+ va_start(args, fmt);
+ vaf.fmt = fmt;
+ vaf.va = &args;
+ if (sb)
+ printk("%sfscrypt (%s): %pV\n", level, sb->s_id, &vaf);
+ else
+ printk("%sfscrypt: %pV\n", level, &vaf);
+ va_end(args);
+}
+
+/**
+ * fscrypt_init() - Set up for fs encryption.
+ */
+static int __init fscrypt_init(void)
+{
+ /*
+ * Use an unbound workqueue to allow bios to be decrypted in parallel
+ * even when they happen to complete on the same CPU. This sacrifices
+ * locality, but it's worthwhile since decryption is CPU-intensive.
+ *
+ * Also use a high-priority workqueue to prioritize decryption work,
+ * which blocks reads from completing, over regular application tasks.
+ */
+ fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue",
+ WQ_UNBOUND | WQ_HIGHPRI,
+ num_online_cpus());
+ if (!fscrypt_read_workqueue)
+ goto fail;
+
+ fscrypt_ctx_cachep = KMEM_CACHE(fscrypt_ctx, SLAB_RECLAIM_ACCOUNT);
+ if (!fscrypt_ctx_cachep)
+ goto fail_free_queue;
+
+ fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT);
+ if (!fscrypt_info_cachep)
+ goto fail_free_ctx;
+
+ return 0;
+
+fail_free_ctx:
+ kmem_cache_destroy(fscrypt_ctx_cachep);
+fail_free_queue:
+ destroy_workqueue(fscrypt_read_workqueue);
+fail:
+ return -ENOMEM;
+}
+module_init(fscrypt_init)
+
+/**
+ * fscrypt_exit() - Shutdown the fs encryption system
+ */
+static void __exit fscrypt_exit(void)
+{
+ fscrypt_destroy();
+
+ if (fscrypt_read_workqueue)
+ destroy_workqueue(fscrypt_read_workqueue);
+ kmem_cache_destroy(fscrypt_ctx_cachep);
+ kmem_cache_destroy(fscrypt_info_cachep);
+
+ fscrypt_essiv_cleanup();
+}
+module_exit(fscrypt_exit);
+
+MODULE_LICENSE("GPL");