fscrypt: factor out bio specific functions

That way we can get rid of the direct dependency on CONFIG_BLOCK.

Fixes: d475a507457b ("ubifs: Add skeleton for fscrypto")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Gstir <david@sigma-star.at>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

5 files changed, 177 insertions, 143 deletions

diff --git a/fs/crypto/Kconfig b/fs/crypto/Kconfig
index f514978f6688..08b46e6e3995 100644
--- a/fs/crypto/Kconfig
+++ b/fs/crypto/Kconfig
@@ -1,6 +1,5 @@
 config FS_ENCRYPTION
         tristate "FS Encryption (Per-file encryption)"
-        depends on BLOCK
         select CRYPTO
         select CRYPTO_AES
         select CRYPTO_CBC
diff --git a/fs/crypto/Makefile b/fs/crypto/Makefile
index f17684c48739..9f6607f17b53 100644
--- a/fs/crypto/Makefile
+++ b/fs/crypto/Makefile
@@ -1,3 +1,4 @@
 obj-$(CONFIG_FS_ENCRYPTION)     += fscrypto.o
 
 fscrypto-y := crypto.o fname.o policy.o keyinfo.o
+fscrypto-$(CONFIG_BLOCK) += bio.o
diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
new file mode 100644
index 000000000000..a409a84f1bca
--- /dev/null
+++ b/fs/crypto/bio.c
@@ -0,0 +1,145 @@
+/*
+ * 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/module.h>
+#include <linux/bio.h>
+#include <linux/namei.h>
+#include "fscrypt_private.h"
+
+/*
+ * Call fscrypt_decrypt_page on every single page, reusing the encryption
+ * context.
+ */
+static void completion_pages(struct work_struct *work)
+{
+        struct fscrypt_ctx *ctx =
+                container_of(work, struct fscrypt_ctx, r.work);
+        struct bio *bio = ctx->r.bio;
+        struct bio_vec *bv;
+        int i;
+
+        bio_for_each_segment_all(bv, bio, i) {
+                struct page *page = bv->bv_page;
+                int ret = fscrypt_decrypt_page(page->mapping->host, page,
+                                PAGE_SIZE, 0, page->index);
+
+                if (ret) {
+                        WARN_ON_ONCE(1);
+                        SetPageError(page);
+                } else {
+                        SetPageUptodate(page);
+                }
+                unlock_page(page);
+        }
+        fscrypt_release_ctx(ctx);
+        bio_put(bio);
+}
+
+void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio)
+{
+        INIT_WORK(&ctx->r.work, completion_pages);
+        ctx->r.bio = bio;
+        queue_work(fscrypt_read_workqueue, &ctx->r.work);
+}
+EXPORT_SYMBOL(fscrypt_decrypt_bio_pages);
+
+void fscrypt_pullback_bio_page(struct page **page, bool restore)
+{
+        struct fscrypt_ctx *ctx;
+        struct page *bounce_page;
+
+        /* The bounce data pages are unmapped. */
+        if ((*page)->mapping)
+                return;
+
+        /* The bounce data page is unmapped. */
+        bounce_page = *page;
+        ctx = (struct fscrypt_ctx *)page_private(bounce_page);
+
+        /* restore control page */
+        *page = ctx->w.control_page;
+
+        if (restore)
+                fscrypt_restore_control_page(bounce_page);
+}
+EXPORT_SYMBOL(fscrypt_pullback_bio_page);
+
+int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
+                                sector_t pblk, unsigned int len)
+{
+        struct fscrypt_ctx *ctx;
+        struct page *ciphertext_page = NULL;
+        struct bio *bio;
+        int ret, err = 0;
+
+        BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
+
+        ctx = fscrypt_get_ctx(inode, GFP_NOFS);
+        if (IS_ERR(ctx))
+                return PTR_ERR(ctx);
+
+        ciphertext_page = fscrypt_alloc_bounce_page(ctx, GFP_NOWAIT);
+        if (IS_ERR(ciphertext_page)) {
+                err = PTR_ERR(ciphertext_page);
+                goto errout;
+        }
+
+        while (len--) {
+                err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk,
+                                             ZERO_PAGE(0), ciphertext_page,
+                                             PAGE_SIZE, 0, GFP_NOFS);
+                if (err)
+                        goto errout;
+
+                bio = bio_alloc(GFP_NOWAIT, 1);
+                if (!bio) {
+                        err = -ENOMEM;
+                        goto errout;
+                }
+                bio->bi_bdev = inode->i_sb->s_bdev;
+                bio->bi_iter.bi_sector =
+                        pblk << (inode->i_sb->s_blocksize_bits - 9);
+                bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
+                ret = bio_add_page(bio, ciphertext_page,
+                                        inode->i_sb->s_blocksize, 0);
+                if (ret != inode->i_sb->s_blocksize) {
+                        /* should never happen! */
+                        WARN_ON(1);
+                        bio_put(bio);
+                        err = -EIO;
+                        goto errout;
+                }
+                err = submit_bio_wait(bio);
+                if ((err == 0) && bio->bi_error)
+                        err = -EIO;
+                bio_put(bio);
+                if (err)
+                        goto errout;
+                lblk++;
+                pblk++;
+        }
+        err = 0;
+errout:
+        fscrypt_release_ctx(ctx);
+        return err;
+}
+EXPORT_SYMBOL(fscrypt_zeroout_range);
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index ac8e4f6a3773..02a7a9286449 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -24,7 +24,6 @@
 #include <linux/module.h>
 #include <linux/scatterlist.h>
 #include <linux/ratelimit.h>
-#include <linux/bio.h>
 #include <linux/dcache.h>
 #include <linux/namei.h>
 #include "fscrypt_private.h"
@@ -44,7 +43,7 @@ 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;
+struct workqueue_struct *fscrypt_read_workqueue;
 static DEFINE_MUTEX(fscrypt_init_mutex);
 
 static struct kmem_cache *fscrypt_ctx_cachep;
@@ -141,16 +140,10 @@ static void page_crypt_complete(struct crypto_async_request *req, int res)
         complete(&ecr->completion);
 }
 
-typedef enum {
-        FS_DECRYPT = 0,
-        FS_ENCRYPT,
-} fscrypt_direction_t;
-
-static int 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)
+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;
@@ -205,7 +198,8 @@ static int do_page_crypto(const struct inode *inode,
         return 0;
 }
 
-static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags)
+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)
@@ -260,9 +254,9 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
 
         if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) {
                 /* with inplace-encryption we just encrypt the page */
-                err = do_page_crypto(inode, FS_ENCRYPT, lblk_num,
-                                        page, ciphertext_page,
-                                        len, offs, gfp_flags);
+                err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num, page,
+                                             ciphertext_page, len, offs,
+                                             gfp_flags);
                 if (err)
                         return ERR_PTR(err);
 
@@ -276,14 +270,14 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
                 return (struct page *)ctx;
 
         /* The encryption operation will require a bounce page. */
-        ciphertext_page = alloc_bounce_page(ctx, gfp_flags);
+        ciphertext_page = fscrypt_alloc_bounce_page(ctx, gfp_flags);
         if (IS_ERR(ciphertext_page))
                 goto errout;
 
         ctx->w.control_page = page;
-        err = do_page_crypto(inode, FS_ENCRYPT, lblk_num,
-                                        page, ciphertext_page,
-                                        len, offs, gfp_flags);
+        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;
@@ -320,72 +314,11 @@ int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
         if (!(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES))
                 BUG_ON(!PageLocked(page));
 
-        return do_page_crypto(inode, FS_DECRYPT, lblk_num, page, page, len,
-                        offs, GFP_NOFS);
+        return fscrypt_do_page_crypto(inode, FS_DECRYPT, lblk_num, page, page,
+                                      len, offs, GFP_NOFS);
 }
 EXPORT_SYMBOL(fscrypt_decrypt_page);
 
-int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
-                                sector_t pblk, unsigned int len)
-{
-        struct fscrypt_ctx *ctx;
-        struct page *ciphertext_page = NULL;
-        struct bio *bio;
-        int ret, err = 0;
-
-        BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
-
-        ctx = fscrypt_get_ctx(inode, GFP_NOFS);
-        if (IS_ERR(ctx))
-                return PTR_ERR(ctx);
-
-        ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT);
-        if (IS_ERR(ciphertext_page)) {
-                err = PTR_ERR(ciphertext_page);
-                goto errout;
-        }
-
-        while (len--) {
-                err = do_page_crypto(inode, FS_ENCRYPT, lblk,
-                                        ZERO_PAGE(0), ciphertext_page,
-                                        PAGE_SIZE, 0, GFP_NOFS);
-                if (err)
-                        goto errout;
-
-                bio = bio_alloc(GFP_NOWAIT, 1);
-                if (!bio) {
-                        err = -ENOMEM;
-                        goto errout;
-                }
-                bio->bi_bdev = inode->i_sb->s_bdev;
-                bio->bi_iter.bi_sector =
-                        pblk << (inode->i_sb->s_blocksize_bits - 9);
-                bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
-                ret = bio_add_page(bio, ciphertext_page,
-                                        inode->i_sb->s_blocksize, 0);
-                if (ret != inode->i_sb->s_blocksize) {
-                        /* should never happen! */
-                        WARN_ON(1);
-                        bio_put(bio);
-                        err = -EIO;
-                        goto errout;
-                }
-                err = submit_bio_wait(bio);
-                if ((err == 0) && bio->bi_error)
-                        err = -EIO;
-                bio_put(bio);
-                if (err)
-                        goto errout;
-                lblk++;
-                pblk++;
-        }
-        err = 0;
-errout:
-        fscrypt_release_ctx(ctx);
-        return err;
-}
-EXPORT_SYMBOL(fscrypt_zeroout_range);
-
 /*
  * Validate dentries for encrypted directories to make sure we aren't
  * potentially caching stale data after a key has been added or
@@ -442,64 +375,6 @@ const struct dentry_operations fscrypt_d_ops = {
 };
 EXPORT_SYMBOL(fscrypt_d_ops);
 
-/*
- * Call fscrypt_decrypt_page on every single page, reusing the encryption
- * context.
- */
-static void completion_pages(struct work_struct *work)
-{
-        struct fscrypt_ctx *ctx =
-                container_of(work, struct fscrypt_ctx, r.work);
-        struct bio *bio = ctx->r.bio;
-        struct bio_vec *bv;
-        int i;
-
-        bio_for_each_segment_all(bv, bio, i) {
-                struct page *page = bv->bv_page;
-                int ret = fscrypt_decrypt_page(page->mapping->host, page,
-                                PAGE_SIZE, 0, page->index);
-
-                if (ret) {
-                        WARN_ON_ONCE(1);
-                        SetPageError(page);
-                } else {
-                        SetPageUptodate(page);
-                }
-                unlock_page(page);
-        }
-        fscrypt_release_ctx(ctx);
-        bio_put(bio);
-}
-
-void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio)
-{
-        INIT_WORK(&ctx->r.work, completion_pages);
-        ctx->r.bio = bio;
-        queue_work(fscrypt_read_workqueue, &ctx->r.work);
-}
-EXPORT_SYMBOL(fscrypt_decrypt_bio_pages);
-
-void fscrypt_pullback_bio_page(struct page **page, bool restore)
-{
-        struct fscrypt_ctx *ctx;
-        struct page *bounce_page;
-
-        /* The bounce data pages are unmapped. */
-        if ((*page)->mapping)
-                return;
-
-        /* The bounce data page is unmapped. */
-        bounce_page = *page;
-        ctx = (struct fscrypt_ctx *)page_private(bounce_page);
-
-        /* restore control page */
-        *page = ctx->w.control_page;
-
-        if (restore)
-                fscrypt_restore_control_page(bounce_page);
-}
-EXPORT_SYMBOL(fscrypt_pullback_bio_page);
-
 void fscrypt_restore_control_page(struct page *page)
 {
         struct fscrypt_ctx *ctx;
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index aeab032d7d35..7bff7b4c7498 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -71,6 +71,11 @@ struct fscrypt_info {
         u8 ci_master_key[FS_KEY_DESCRIPTOR_SIZE];
 };
 
+typedef enum {
+        FS_DECRYPT = 0,
+        FS_ENCRYPT,
+} fscrypt_direction_t;
+
 #define FS_CTX_REQUIRES_FREE_ENCRYPT_FL         0x00000001
 #define FS_CTX_HAS_BOUNCE_BUFFER_FL             0x00000002
 
@@ -85,7 +90,16 @@ struct fscrypt_completion_result {
 
 
 /* crypto.c */
-int fscrypt_initialize(unsigned int cop_flags);
+extern int fscrypt_initialize(unsigned int cop_flags);
+extern struct workqueue_struct *fscrypt_read_workqueue;
+extern 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);
+extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
+                                              gfp_t gfp_flags);
 
 /* keyinfo.c */
 extern int fscrypt_get_crypt_info(struct inode *);