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ext4 crypto: implement the ext4 decryption read path 

Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Ildar Muslukhov <ildarm@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Michael Halcrow 2015-04-12 00:56:10 -04:00 committed by Theodore Ts'o
parent 2058f83a72
commit c9c7429c2e
3 changed files with 88 additions and 3 deletions
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18
fs/ext4/file.c
View File

@ -218,6 +218,13 @@ static const struct vm_operations_struct ext4_file_vm_ops = {
static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
{
struct inode *inode = file->f_mapping->host;
if (ext4_encrypted_inode(inode)) {
int err = ext4_generate_encryption_key(inode);
if (err)
return 0;
}
file_accessed(file);
if (IS_DAX(file_inode(file))) {
vma->vm_ops = &ext4_dax_vm_ops;
@ -235,6 +242,7 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
struct vfsmount *mnt = filp->f_path.mnt;
struct path path;
char buf[64], *cp;
int ret;
if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
!(sb->s_flags & MS_RDONLY))) {
@ -273,11 +281,17 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
* writing and the journal is present
*/
if (filp->f_mode & FMODE_WRITE) {
int ret = ext4_inode_attach_jinode(inode);
ret = ext4_inode_attach_jinode(inode);
if (ret < 0)
return ret;
}
return dquot_file_open(inode, filp);
ret = dquot_file_open(inode, filp);
if (!ret && ext4_encrypted_inode(inode)) {
ret = ext4_generate_encryption_key(inode);
if (ret)
ret = -EACCES;
}
return ret;
}
/*

7
fs/ext4/inode.c
View File

@ -3370,6 +3370,13 @@ static int __ext4_block_zero_page_range(handle_t *handle,
/* Uhhuh. Read error. Complain and punt. */
if (!buffer_uptodate(bh))
goto unlock;
if (S_ISREG(inode->i_mode) &&
ext4_encrypted_inode(inode)) {
/* We expect the key to be set. */
BUG_ON(!ext4_has_encryption_key(inode));
BUG_ON(blocksize != PAGE_CACHE_SIZE);
WARN_ON_ONCE(ext4_decrypt_one(inode, page));
}
}
if (ext4_should_journal_data(inode)) {
BUFFER_TRACE(bh, "get write access");

66
fs/ext4/readpage.c
View File

@ -46,6 +46,46 @@
#include "ext4.h"
/*
* Call ext4_decrypt on every single page, reusing the encryption
* context.
*/
static void completion_pages(struct work_struct *work)
{
#ifdef CONFIG_EXT4_FS_ENCRYPTION
struct ext4_crypto_ctx *ctx =
container_of(work, struct ext4_crypto_ctx, work);
struct bio *bio = ctx->bio;
struct bio_vec *bv;
int i;
bio_for_each_segment_all(bv, bio, i) {
struct page *page = bv->bv_page;
int ret = ext4_decrypt(ctx, page);
if (ret) {
WARN_ON_ONCE(1);
SetPageError(page);
} else
SetPageUptodate(page);
unlock_page(page);
}
ext4_release_crypto_ctx(ctx);
bio_put(bio);
#else
BUG();
#endif
}
static inline bool ext4_bio_encrypted(struct bio *bio)
{
#ifdef CONFIG_EXT4_FS_ENCRYPTION
return unlikely(bio->bi_private != NULL);
#else
return false;
#endif
}
/*
* I/O completion handler for multipage BIOs.
*
@ -63,6 +103,18 @@ static void mpage_end_io(struct bio *bio, int err)
struct bio_vec *bv;
int i;
if (ext4_bio_encrypted(bio)) {
struct ext4_crypto_ctx *ctx = bio->bi_private;
if (err) {
ext4_release_crypto_ctx(ctx);
} else {
INIT_WORK(&ctx->work, completion_pages);
ctx->bio = bio;
queue_work(ext4_read_workqueue, &ctx->work);
return;
}
}
bio_for_each_segment_all(bv, bio, i) {
struct page *page = bv->bv_page;
@ -223,13 +275,25 @@ int ext4_mpage_readpages(struct address_space *mapping,
bio = NULL;
}
if (bio == NULL) {
struct ext4_crypto_ctx *ctx = NULL;
if (ext4_encrypted_inode(inode) &&
S_ISREG(inode->i_mode)) {
ctx = ext4_get_crypto_ctx(inode);
if (IS_ERR(ctx))
goto set_error_page;
}
bio = bio_alloc(GFP_KERNEL,
min_t(int, nr_pages, bio_get_nr_vecs(bdev)));
if (!bio)
if (!bio) {
if (ctx)
ext4_release_crypto_ctx(ctx);
goto set_error_page;
}
bio->bi_bdev = bdev;
bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9);
bio->bi_end_io = mpage_end_io;
bio->bi_private = ctx;
}
length = first_hole << blkbits;