fscrypt: allow synchronous bio decryption

Cherry-pick from origin/upstream-f2fs-stable-linux-4.9.y:
  0509923bec1d ("fscrypt: allow synchronous bio decryption")

Currently, fscrypt provides fscrypt_decrypt_bio_pages() which decrypts a
bio's pages asynchronously, then unlocks them afterwards.  But, this
assumes that decryption is the last "postprocessing step" for the bio,
so it's incompatible with additional postprocessing steps such as
authenticity verification after decryption.

Therefore, rename the existing fscrypt_decrypt_bio_pages() to
fscrypt_enqueue_decrypt_bio().  Then, add fscrypt_decrypt_bio() which
decrypts the pages in the bio synchronously without unlocking the pages,
nor setting them Uptodate; and add fscrypt_enqueue_decrypt_work(), which
enqueues work on the fscrypt_read_workqueue.  The new functions will be
used by filesystems that support both fscrypt and fs-verity.

Change-Id: I3e39e4f2c38726664b01537b6c53fae674d7a3ee
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index 2596c9a..d7b4c48 100644 (file)
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -25,15 +25,8 @@
 #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)
+static void __fscrypt_decrypt_bio(struct bio *bio, bool done)
 {
-       struct fscrypt_ctx *ctx =
-               container_of(work, struct fscrypt_ctx, r.work);
-       struct bio *bio = ctx->r.bio;
        struct bio_vec *bv;
        int i;
 
@@ -45,22 +38,38 @@ static void completion_pages(struct work_struct *work)
                if (ret) {
                        WARN_ON_ONCE(1);
                        SetPageError(page);
-               } else {
+               } else if (done) {
                        SetPageUptodate(page);
                }
-               unlock_page(page);
+               if (done)
+                       unlock_page(page);
        }
+}
+
+void fscrypt_decrypt_bio(struct bio *bio)
+{
+       __fscrypt_decrypt_bio(bio, false);
+}
+EXPORT_SYMBOL(fscrypt_decrypt_bio);
+
+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;
+
+       __fscrypt_decrypt_bio(bio, true);
        fscrypt_release_ctx(ctx);
        bio_put(bio);
 }
 
-void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio)
+void fscrypt_enqueue_decrypt_bio(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);
+       fscrypt_enqueue_decrypt_work(&ctx->r.work);
 }
-EXPORT_SYMBOL(fscrypt_decrypt_bio_pages);
+EXPORT_SYMBOL(fscrypt_enqueue_decrypt_bio);
 
 void fscrypt_pullback_bio_page(struct page **page, bool restore)
 {

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index ce65452..0758d32 100644 (file)
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -45,12 +45,18 @@ static mempool_t *fscrypt_bounce_page_pool = NULL;
 static LIST_HEAD(fscrypt_free_ctxs);
 static DEFINE_SPINLOCK(fscrypt_ctx_lock);
 
-struct workqueue_struct *fscrypt_read_workqueue;
+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.

diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 1fe00fd..d36a648 100644 (file)
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -96,7 +96,6 @@ static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
 /* crypto.c */
 extern struct kmem_cache *fscrypt_info_cachep;
 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,

diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
index 2531cc1..c39a12d 100644 (file)
--- a/fs/ext4/readpage.c
+++ b/fs/ext4/readpage.c
@@ -91,7 +91,7 @@ static void mpage_end_io(struct bio *bio)
                if (bio->bi_error) {
                        fscrypt_release_ctx(bio->bi_private);
                } else {
-                       fscrypt_decrypt_bio_pages(bio->bi_private, bio);
+                       fscrypt_enqueue_decrypt_bio(bio->bi_private, bio);
                        return;
                }
        }

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index c676c78..b916613 100644 (file)
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -66,7 +66,7 @@ static void f2fs_read_end_io(struct bio *bio)
                if (bio->bi_error) {
                        fscrypt_release_ctx(bio->bi_private);
                } else {
-                       fscrypt_decrypt_bio_pages(bio->bi_private, bio);
+                       fscrypt_enqueue_decrypt_bio(bio->bi_private, bio);
                        return;
                }
        }

diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index ecf2ac8..6f97714 100644 (file)
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -24,6 +24,10 @@ static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
 }
 
 /* crypto.c */
+static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work)
+{
+}
+
 static inline struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *inode,
                                                  gfp_t gfp_flags)
 {
@@ -159,10 +163,13 @@ static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
 }
 
 /* bio.c */
-static inline void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx,
-                                            struct bio *bio)
+static inline void fscrypt_decrypt_bio(struct bio *bio)
+{
+}
+
+static inline void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
+                                              struct bio *bio)
 {
-       return;
 }
 
 static inline void fscrypt_pullback_bio_page(struct page **page, bool restore)

diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index f382cf3..1ed79ee 100644 (file)
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -58,6 +58,7 @@ static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
 }
 
 /* crypto.c */
+extern void fscrypt_enqueue_decrypt_work(struct work_struct *);
 extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t);
 extern void fscrypt_release_ctx(struct fscrypt_ctx *);
 extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
@@ -187,7 +188,9 @@ static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
 }
 
 /* bio.c */
-extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *);
+extern void fscrypt_decrypt_bio(struct bio *);
+extern void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
+                                       struct bio *bio);
 extern void fscrypt_pullback_bio_page(struct page **, bool);
 extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
                                 unsigned int);