[PATCH 1/3] fscrypto: use dget_parent() in fscrypt_d_revalidate()

[PATCH 1/3] fscrypto: use dget_parent() in fscrypt_d_revalidate()

[Jaegeuk Kim]

This patch updates fscrypto along with the below ext4 crypto change.

Fixes: 3d43bcfef5f0 ("ext4 crypto: use dget_parent() in ext4_d_revalidate()")
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/crypto/crypto.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 7f58045..58ae0ba 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -345,13 +345,17 @@ EXPORT_SYMBOL(fscrypt_zeroout_range);
  */
 static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
 {
-	struct inode *dir = d_inode(dentry->d_parent);
-	struct fscrypt_info *ci = dir->i_crypt_info;
+	struct dentry *dir;
+	struct fscrypt_info *ci;
 	int dir_has_key, cached_with_key;
 
-	if (!dir->i_sb->s_cop->is_encrypted(dir))
+	dir = dget_parent(dentry);
+	if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) {
+		dput(dir);
 		return 0;
+	}
 
+	ci = d_inode(dir)->i_crypt_info;
 	if (ci && ci->ci_keyring_key &&
 	    (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
 					  (1 << KEY_FLAG_REVOKED) |
@@ -363,6 +367,7 @@ static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
 	cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY;
 	spin_unlock(&dentry->d_lock);
 	dir_has_key = (ci != NULL);
+	dput(dir);
 
 	/*
 	 * If the dentry was cached without the key, and it is a
-- 
2.6.3

[PATCH 2/3] f2fs: use dget_parent and file_dentry in f2fs_file_open

[Jaegeuk Kim]

This patch synced with the below two ext4 crypto fixes together.

In 4.6-rc1, f2fs newly introduced accessing f_path.dentry which crashes
overlayfs. To fix, now we need to use file_dentry() to access that field.

Fixes: c0a37d487884 ("ext4: use file_dentry()")
Fixes: 9dd78d8c9a7b ("ext4: use dget_parent() in ext4_file_open()")
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/f2fs/file.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 443e077..90d1157 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -441,7 +441,7 @@ static int f2fs_file_mmap(struct file *file, struct vm_area_struct *vma)
 static int f2fs_file_open(struct inode *inode, struct file *filp)
 {
 	int ret = generic_file_open(inode, filp);
-	struct inode *dir = filp->f_path.dentry->d_parent->d_inode;
+	struct dentry *dir;
 
 	if (!ret && f2fs_encrypted_inode(inode)) {
 		ret = fscrypt_get_encryption_info(inode);
@@ -450,9 +450,13 @@ static int f2fs_file_open(struct inode *inode, struct file *filp)
 		if (!fscrypt_has_encryption_key(inode))
 			return -ENOKEY;
 	}
-	if (f2fs_encrypted_inode(dir) &&
-			!fscrypt_has_permitted_context(dir, inode))
+	dir = dget_parent(file_dentry(filp));
+	if (f2fs_encrypted_inode(d_inode(dir)) &&
+			!fscrypt_has_permitted_context(d_inode(dir), inode)) {
+		dput(dir);
 		return -EPERM;
+	}
+	dput(dir);
 	return ret;
 }
 
-- 
2.6.3

[PATCH 3/3] fscrypto: don't let data integrity writebacks fail with ENOMEM

[Jaegeuk Kim]

This patch fixes the issue introduced by the ext4 crypto fix in a same manner.
For F2FS, however, we flush the pending IOs and wait for a while to acquire free
memory.

Fixes: c9af28fdd4492 ("ext4 crypto: don't let data integrity writebacks fail with ENOMEM")
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/crypto/crypto.c       | 36 ++++++++++++++++++++----------------
 fs/f2fs/data.c           | 16 +++++++++++++---
 include/linux/fscrypto.h |  9 +++++----
 3 files changed, 38 insertions(+), 23 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 58ae0ba..da70520 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -81,13 +81,14 @@ 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(struct inode *inode)
+struct fscrypt_ctx *fscrypt_get_ctx(struct inode *inode, gfp_t gfp_flags)
 {
 	struct fscrypt_ctx *ctx = NULL;
 	struct fscrypt_info *ci = inode->i_crypt_info;
@@ -113,7 +114,7 @@ struct fscrypt_ctx *fscrypt_get_ctx(struct inode *inode)
 		list_del(&ctx->free_list);
 	spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
 	if (!ctx) {
-		ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS);
+		ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, gfp_flags);
 		if (!ctx)
 			return ERR_PTR(-ENOMEM);
 		ctx->flags |= FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
@@ -147,7 +148,8 @@ typedef enum {
 
 static int do_page_crypto(struct inode *inode,
 			fscrypt_direction_t rw, pgoff_t index,
-			struct page *src_page, struct page *dest_page)
+			struct page *src_page, struct page *dest_page,
+			gfp_t gfp_flags)
 {
 	u8 xts_tweak[FS_XTS_TWEAK_SIZE];
 	struct skcipher_request *req = NULL;
@@ -157,7 +159,7 @@ static int do_page_crypto(struct inode *inode,
 	struct crypto_skcipher *tfm = ci->ci_ctfm;
 	int res = 0;
 
-	req = skcipher_request_alloc(tfm, GFP_NOFS);
+	req = skcipher_request_alloc(tfm, gfp_flags);
 	if (!req) {
 		printk_ratelimited(KERN_ERR
 				"%s: crypto_request_alloc() failed\n",
@@ -199,10 +201,9 @@ static int do_page_crypto(struct inode *inode,
 	return 0;
 }
 
-static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx)
+static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags)
 {
-	ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool,
-							GFP_NOWAIT);
+	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_WRITE_PATH_FL;
@@ -213,6 +214,7 @@ static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx)
  * fscypt_encrypt_page() - Encrypts a page
  * @inode:          The inode for which the encryption should take place
  * @plaintext_page: The page to encrypt. Must be locked.
+ * @gfp_flags:      The gfp flag for memory allocation
  *
  * Allocates a ciphertext page and encrypts plaintext_page into it using the ctx
  * encryption context.
@@ -225,7 +227,7 @@ static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx)
  * error value or NULL.
  */
 struct page *fscrypt_encrypt_page(struct inode *inode,
-				struct page *plaintext_page)
+				struct page *plaintext_page, gfp_t gfp_flags)
 {
 	struct fscrypt_ctx *ctx;
 	struct page *ciphertext_page = NULL;
@@ -233,18 +235,19 @@ struct page *fscrypt_encrypt_page(struct inode *inode,
 
 	BUG_ON(!PageLocked(plaintext_page));
 
-	ctx = fscrypt_get_ctx(inode);
+	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 = alloc_bounce_page(ctx);
+	ciphertext_page = alloc_bounce_page(ctx, gfp_flags);
 	if (IS_ERR(ciphertext_page))
 		goto errout;
 
 	ctx->w.control_page = plaintext_page;
 	err = do_page_crypto(inode, FS_ENCRYPT, plaintext_page->index,
-					plaintext_page, ciphertext_page);
+					plaintext_page, ciphertext_page,
+					gfp_flags);
 	if (err) {
 		ciphertext_page = ERR_PTR(err);
 		goto errout;
@@ -275,7 +278,7 @@ int fscrypt_decrypt_page(struct page *page)
 	BUG_ON(!PageLocked(page));
 
 	return do_page_crypto(page->mapping->host,
-			FS_DECRYPT, page->index, page, page);
+			FS_DECRYPT, page->index, page, page, GFP_NOFS);
 }
 EXPORT_SYMBOL(fscrypt_decrypt_page);
 
@@ -289,11 +292,11 @@ int fscrypt_zeroout_range(struct inode *inode, pgoff_t lblk,
 
 	BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
 
-	ctx = fscrypt_get_ctx(inode);
+	ctx = fscrypt_get_ctx(inode, GFP_NOFS);
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
 
-	ciphertext_page = alloc_bounce_page(ctx);
+	ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT);
 	if (IS_ERR(ciphertext_page)) {
 		err = PTR_ERR(ciphertext_page);
 		goto errout;
@@ -301,11 +304,12 @@ int fscrypt_zeroout_range(struct inode *inode, pgoff_t lblk,
 
 	while (len--) {
 		err = do_page_crypto(inode, FS_ENCRYPT, lblk,
-						ZERO_PAGE(0), ciphertext_page);
+					ZERO_PAGE(0), ciphertext_page,
+					GFP_NOFS);
 		if (err)
 			goto errout;
 
-		bio = bio_alloc(GFP_KERNEL, 1);
+		bio = bio_alloc(GFP_NOWAIT, 1);
 		if (!bio) {
 			err = -ENOMEM;
 			goto errout;
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 53fec08..5dafb9c 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -992,7 +992,7 @@ submit_and_realloc:
 			if (f2fs_encrypted_inode(inode) &&
 					S_ISREG(inode->i_mode)) {
 
-				ctx = fscrypt_get_ctx(inode);
+				ctx = fscrypt_get_ctx(inode, GFP_NOFS);
 				if (IS_ERR(ctx))
 					goto set_error_page;
 
@@ -1092,14 +1092,24 @@ int do_write_data_page(struct f2fs_io_info *fio)
 	}
 
 	if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode)) {
+		gfp_t gfp_flags = GFP_NOFS;
 
 		/* wait for GCed encrypted page writeback */
 		f2fs_wait_on_encrypted_page_writeback(F2FS_I_SB(inode),
 							fio->old_blkaddr);
-
-		fio->encrypted_page = fscrypt_encrypt_page(inode, fio->page);
+retry_encrypt:
+		fio->encrypted_page = fscrypt_encrypt_page(inode, fio->page,
+								gfp_flags);
 		if (IS_ERR(fio->encrypted_page)) {
 			err = PTR_ERR(fio->encrypted_page);
+			if (err == -ENOMEM) {
+				/* flush pending ios and wait for a while */
+				f2fs_flush_merged_bios(F2FS_I_SB(inode));
+				congestion_wait(BLK_RW_ASYNC, HZ/50);
+				gfp_flags |= __GFP_NOFAIL;
+				err = 0;
+				goto retry_encrypt;
+			}
 			goto out_writepage;
 		}
 	}
diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h
index cd91f75..6027f6b 100644
--- a/include/linux/fscrypto.h
+++ b/include/linux/fscrypto.h
@@ -263,9 +263,9 @@ static inline void fscrypt_set_d_op(struct dentry *dentry)
 extern struct kmem_cache *fscrypt_info_cachep;
 int fscrypt_initialize(void);
 
-extern struct fscrypt_ctx *fscrypt_get_ctx(struct inode *);
+extern struct fscrypt_ctx *fscrypt_get_ctx(struct inode *, gfp_t);
 extern void fscrypt_release_ctx(struct fscrypt_ctx *);
-extern struct page *fscrypt_encrypt_page(struct inode *, struct page *);
+extern struct page *fscrypt_encrypt_page(struct inode *, struct page *, gfp_t);
 extern int fscrypt_decrypt_page(struct page *);
 extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *);
 extern void fscrypt_pullback_bio_page(struct page **, bool);
@@ -299,7 +299,8 @@ extern int fscrypt_fname_usr_to_disk(struct inode *, const struct qstr *,
 #endif
 
 /* crypto.c */
-static inline struct fscrypt_ctx *fscrypt_notsupp_get_ctx(struct inode *i)
+static inline struct fscrypt_ctx *fscrypt_notsupp_get_ctx(struct inode *i,
+							gfp_t f)
 {
 	return ERR_PTR(-EOPNOTSUPP);
 }
@@ -310,7 +311,7 @@ static inline void fscrypt_notsupp_release_ctx(struct fscrypt_ctx *c)
 }
 
 static inline struct page *fscrypt_notsupp_encrypt_page(struct inode *i,
-						struct page *p)
+						struct page *p, gfp_t f)
 {
 	return ERR_PTR(-EOPNOTSUPP);
 }
-- 
2.6.3

Re: [PATCH 1/3] fscrypto: use dget_parent() in fscrypt_d_revalidate()

[Al Viro]

On Tue, Apr 12, 2016 at 10:27:20AM -0700, Jaegeuk Kim wrote:
> This patch updates fscrypto along with the below ext4 crypto change.
> 
> Fixes: 3d43bcfef5f0 ("ext4 crypto: use dget_parent() in ext4_d_revalidate()")

>  static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
>  {
> -	struct inode *dir = d_inode(dentry->d_parent);
> -	struct fscrypt_info *ci = dir->i_crypt_info;
> +	struct dentry *dir;
> +	struct fscrypt_info *ci;
>  	int dir_has_key, cached_with_key;
>  
> -	if (!dir->i_sb->s_cop->is_encrypted(dir))
> +	dir = dget_parent(dentry);
> +	if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) {
> +		dput(dir);

... and as soon as you call it from RCU mode, you are screwed.

Re: [PATCH 1/3] fscrypto: use dget_parent() in fscrypt_d_revalidate()

[Jaegeuk Kim]

On Tue, Apr 12, 2016 at 11:33:03PM +0100, Al Viro wrote:
> On Tue, Apr 12, 2016 at 10:27:20AM -0700, Jaegeuk Kim wrote:
> > This patch updates fscrypto along with the below ext4 crypto change.
> > 
> > Fixes: 3d43bcfef5f0 ("ext4 crypto: use dget_parent() in ext4_d_revalidate()")
> 
> >  static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
> >  {
> > -	struct inode *dir = d_inode(dentry->d_parent);
> > -	struct fscrypt_info *ci = dir->i_crypt_info;
> > +	struct dentry *dir;
> > +	struct fscrypt_info *ci;
> >  	int dir_has_key, cached_with_key;
> >  
> > -	if (!dir->i_sb->s_cop->is_encrypted(dir))
> > +	dir = dget_parent(dentry);
> > +	if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) {
> > +		dput(dir);
> 
> ... and as soon as you call it from RCU mode, you are screwed.

Thank you for pointing this out.
IIUC, did you mean this?

Thanks,

>From a0ac7972189b7c366720a0b456e39516d622a6d4 Mon Sep 17 00:00:00 2001
From: Jaegeuk Kim <jaegeuk@kernel.org>
Date: Tue, 12 Apr 2016 16:05:36 -0700
Subject: [PATCH] ext4/fscrypto: avoid RCU lookup in d_revalidate

As Al pointed, d_revalidate should return RCU lookup before using d_inode.
This was originally introduced by:
commit 34286d666230 ("fs: rcu-walk aware d_revalidate method").

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: stable <stable@vger.kernel.org>
---
 fs/crypto/crypto.c | 4 ++++
 fs/ext4/crypto.c   | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index da70520..2fc8c43 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -26,6 +26,7 @@
 #include <linux/ratelimit.h>
 #include <linux/bio.h>
 #include <linux/dcache.h>
+#include <linux/namei.h>
 #include <linux/fscrypto.h>
 #include <linux/ecryptfs.h>
 
@@ -353,6 +354,9 @@ static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
 	struct fscrypt_info *ci;
 	int dir_has_key, cached_with_key;
 
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
 	dir = dget_parent(dentry);
 	if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) {
 		dput(dir);
diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index db9ae6e..6a6c273 100644
--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -32,6 +32,7 @@
 #include <linux/random.h>
 #include <linux/scatterlist.h>
 #include <linux/spinlock_types.h>
+#include <linux/namei.h>
 
 #include "ext4_extents.h"
 #include "xattr.h"
@@ -482,6 +483,9 @@ static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags)
 	struct ext4_crypt_info *ci;
 	int dir_has_key, cached_with_key;
 
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
 	dir = dget_parent(dentry);
 	if (!ext4_encrypted_inode(d_inode(dir))) {
 		dput(dir);
-- 
2.6.3