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Date: Fri, 21 Oct 2016 10:14:39 -0700
From: Michael Halcrow <mhalcrow@...gle.com>
To: Richard Weinberger <richard@....at>
Cc: linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org, dedekind1@...il.com,
adrian.hunter@...el.com, tytso@....edu, jaegeuk@...nel.org,
david@...ma-star.at, wd@...x.de, sbabic@...x.de,
dengler@...utronix.de
Subject: Re: [PATCH 15/26] ubifs: Implement encrypt/decrypt for all IO
On Fri, Oct 21, 2016 at 02:48:30PM +0200, Richard Weinberger wrote:
> Signed-off-by: Richard Weinberger <richard@....at>
> ---
> fs/ubifs/file.c | 36 ++++++++++++++++++
> fs/ubifs/journal.c | 105 +++++++++++++++++++++++++++++++++++++++++++----------
> fs/ubifs/super.c | 6 ++-
> fs/ubifs/ubifs.h | 6 +++
> 4 files changed, 131 insertions(+), 22 deletions(-)
>
> diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
> index bd0049788e24..60e089d50c82 100644
> --- a/fs/ubifs/file.c
> +++ b/fs/ubifs/file.c
> @@ -78,6 +78,24 @@ static int read_block(struct inode *inode, void *addr, unsigned int block,
> goto dump;
>
> dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
> +
> + if (ubifs_crypt_is_encrypted(inode)) {
> + int clen = le16_to_cpu(dn->compr_size);
> +
> + if (clen <= 0 || clen > UBIFS_BLOCK_SIZE || clen > dlen)
> + goto dump;
> +
> + ubifs_assert(dlen <= UBIFS_BLOCK_SIZE);
> + err = fscrypt_decrypt_buffer(inode, &dn->data, &dn->data, dlen, block, GFP_NOFS);
> + if (err) {
> + ubifs_err(c, "fscrypt_decrypt_buffer failed: %i", err);
> + return err;
> + }
> +
> + ubifs_assert(clen <= dlen);
> + dlen = clen;
> + }
> +
> out_len = UBIFS_BLOCK_SIZE;
> err = ubifs_decompress(c, &dn->data, dlen, addr, &out_len,
> le16_to_cpu(dn->compr_type));
> @@ -650,6 +668,24 @@ static int populate_page(struct ubifs_info *c, struct page *page,
>
> dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
> out_len = UBIFS_BLOCK_SIZE;
> +
> + if (ubifs_crypt_is_encrypted(inode)) {
> + int clen = le16_to_cpu(dn->compr_size);
> +
> + if (clen <= 0 || clen > UBIFS_BLOCK_SIZE || clen > dlen)
> + goto out_err;
> +
> + ubifs_assert(dlen <= UBIFS_BLOCK_SIZE);
> + err = fscrypt_decrypt_buffer(inode, &dn->data, &dn->data, dlen, page_block, GFP_NOFS);
> + if (err) {
> + ubifs_err(c, "fscrypt_decrypt_buffer failed: %i", err);
> + goto out_err;
> + }
> +
> + ubifs_assert(clen <= dlen);
> + dlen = clen;
> + }
> +
> err = ubifs_decompress(c, &dn->data, dlen, addr, &out_len,
> le16_to_cpu(dn->compr_type));
> if (err || len != out_len)
> diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
> index a643de4e3d91..da694e520ec8 100644
> --- a/fs/ubifs/journal.c
> +++ b/fs/ubifs/journal.c
> @@ -691,11 +691,15 @@ int ubifs_jnl_write_data(struct ubifs_info *c, const struct inode *inode,
> int err, lnum, offs, compr_type, out_len;
> int dlen = COMPRESSED_DATA_NODE_BUF_SZ, allocated = 1;
> struct ubifs_inode *ui = ubifs_inode(inode);
> + bool encrypted = ubifs_crypt_is_encrypted(inode);
>
> dbg_jnlk(key, "ino %lu, blk %u, len %d, key ",
> (unsigned long)key_inum(c, key), key_block(c, key), len);
> ubifs_assert(len <= UBIFS_BLOCK_SIZE);
>
> + if (encrypted)
> + dlen += UBIFS_CIPHER_BLOCK_SIZE;
> +
> data = kmalloc(dlen, GFP_NOFS | __GFP_NOWARN);
> if (!data) {
> /*
> @@ -724,6 +728,26 @@ int ubifs_jnl_write_data(struct ubifs_info *c, const struct inode *inode,
> ubifs_compress(c, buf, len, &data->data, &out_len, &compr_type);
Compress-before-encrypt is a hazard.
http://www.iacr.org/cryptodb/archive/2002/FSE/3091/3091.pdf
> ubifs_assert(out_len <= UBIFS_BLOCK_SIZE);
>
> + if (encrypted) {
> + void *p = &data->data;
> + int plen = round_up(out_len, UBIFS_CIPHER_BLOCK_SIZE);
> +
> + data->compr_size = cpu_to_le16(out_len);
> +
> + if (plen != out_len) {
> + memset(p + out_len, 0, plen - out_len);
> + out_len = plen;
> + }
> +
> + err = fscrypt_encrypt_buffer(inode, &data->data, &data->data, out_len, key_block(c, key), GFP_NOFS);
> + if (err) {
> + ubifs_err(c, "fscrypt_encrypt_buffer failed: %i", err);
> + goto out_free;
> + }
> + } else {
> + data->compr_size = 0;
> + }
> +
> dlen = UBIFS_DATA_NODE_SZ + out_len;
> data->compr_type = cpu_to_le16(compr_type);
>
> @@ -1083,31 +1107,79 @@ out_free:
> }
>
> /**
> - * recomp_data_node - re-compress a truncated data node.
> + * truncate_data_node - re-compress/encrypt a truncated data node.
> + * @c: UBIFS file-system description object
> + * @inode: inode which referes to the data node
> + * @block: data block number
> * @dn: data node to re-compress
> * @new_len: new length
> *
> * This function is used when an inode is truncated and the last data node of
> - * the inode has to be re-compressed and re-written.
> + * the inode has to be re-compressed/encrypted and re-written.
> */
> -static int recomp_data_node(const struct ubifs_info *c,
> - struct ubifs_data_node *dn, int *new_len)
> +static int truncate_data_node(const struct ubifs_info *c, struct inode *inode,
> + unsigned int block, struct ubifs_data_node *dn,
> + int *new_len)
> {
> void *buf;
> - int err, len, compr_type, out_len;
> + int err, dlen, compr_type, out_len, old_dlen;
>
> out_len = le32_to_cpu(dn->size);
> buf = kmalloc(out_len * WORST_COMPR_FACTOR, GFP_NOFS);
> if (!buf)
> return -ENOMEM;
>
> - len = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
> + dlen = old_dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
> compr_type = le16_to_cpu(dn->compr_type);
> - err = ubifs_decompress(c, &dn->data, len, buf, &out_len, compr_type);
> - if (err)
> - goto out;
>
> - ubifs_compress(c, buf, *new_len, &dn->data, &out_len, &compr_type);
> + if (ubifs_crypt_is_encrypted(inode)) {
> + int clen = le16_to_cpu(dn->compr_size);
> +
> + if (clen <= 0 || clen > UBIFS_BLOCK_SIZE || clen > dlen) {
> + ubifs_err(c, "bad compr_size: %i", clen);
> + err = -EINVAL;
> + goto out;
> + }
> +
> + err = fscrypt_decrypt_buffer(inode, &dn->data, &dn->data, dlen, block, GFP_NOFS);
> + if (err) {
> + ubifs_err(c, "fscrypt_decrypt_buffer failed: %i", err);
> + goto out;
> + }
> +
> + ubifs_assert(clen <= dlen);
> + dlen = clen;
> + }
> +
> + if (compr_type != UBIFS_COMPR_NONE) {
> + err = ubifs_decompress(c, &dn->data, dlen, buf, &out_len, compr_type);
> + if (err)
> + goto out;
> +
> + ubifs_compress(c, buf, *new_len, &dn->data, &out_len, &compr_type);
> + }
> +
> + if (ubifs_crypt_is_encrypted(inode)) {
> + void *p = &dn->data;
> + int plen = round_up(out_len, UBIFS_CIPHER_BLOCK_SIZE);
> +
> + ubifs_assert(old_dlen >= plen);
> + dn->compr_size = cpu_to_le16(out_len);
> +
> + if (plen != out_len) {
> + memset(p + out_len, 0, plen - out_len);
> + out_len = plen;
> + }
> +
> + err = fscrypt_encrypt_buffer(inode, &dn->data, &dn->data, out_len, block, GFP_NOFS);
> + if (err) {
> + ubifs_msg(c, "fscrypt_encrypt_buffer failed: %i", err);
> + goto out;
> + }
> + } else {
> + dn->compr_size = 0;
> + }
> +
> ubifs_assert(out_len <= UBIFS_BLOCK_SIZE);
> dn->compr_type = cpu_to_le16(compr_type);
> dn->size = cpu_to_le32(*new_len);
> @@ -1179,16 +1251,9 @@ int ubifs_jnl_truncate(struct ubifs_info *c, const struct inode *inode,
> if (le32_to_cpu(dn->size) <= dlen)
> dlen = 0; /* Nothing to do */
> else {
> - int compr_type = le16_to_cpu(dn->compr_type);
> -
> - if (compr_type != UBIFS_COMPR_NONE) {
> - err = recomp_data_node(c, dn, &dlen);
> - if (err)
> - goto out_free;
> - } else {
> - dn->size = cpu_to_le32(dlen);
> - dlen += UBIFS_DATA_NODE_SZ;
> - }
> + err = truncate_data_node(c, inode, blk, dn, &dlen);
> + if (err)
> + goto out_free;
> }
> }
> }
> diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
> index a31222947265..ae25c908fbe5 100644
> --- a/fs/ubifs/super.c
> +++ b/fs/ubifs/super.c
> @@ -1210,7 +1210,8 @@ static int mount_ubifs(struct ubifs_info *c)
> bu_init(c);
>
> if (!c->ro_mount) {
> - c->write_reserve_buf = kmalloc(COMPRESSED_DATA_NODE_BUF_SZ,
> + c->write_reserve_buf = kmalloc(COMPRESSED_DATA_NODE_BUF_SZ + \
> + UBIFS_CIPHER_BLOCK_SIZE,
> GFP_KERNEL);
> if (!c->write_reserve_buf)
> goto out_free;
> @@ -1623,7 +1624,8 @@ static int ubifs_remount_rw(struct ubifs_info *c)
> goto out;
> }
>
> - c->write_reserve_buf = kmalloc(COMPRESSED_DATA_NODE_BUF_SZ, GFP_KERNEL);
> + c->write_reserve_buf = kmalloc(COMPRESSED_DATA_NODE_BUF_SZ + \
> + UBIFS_CIPHER_BLOCK_SIZE, GFP_KERNEL);
> if (!c->write_reserve_buf) {
> err = -ENOMEM;
> goto out;
> diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
> index 63dd027727ca..6c56a08afcd7 100644
> --- a/fs/ubifs/ubifs.h
> +++ b/fs/ubifs/ubifs.h
> @@ -139,6 +139,12 @@
> */
> #define WORST_COMPR_FACTOR 2
>
> +#ifdef CONFIG_UBIFS_FS_ENCRYPTION
> +#define UBIFS_CIPHER_BLOCK_SIZE FS_CRYPTO_BLOCK_SIZE
> +#else
> +#define UBIFS_CIPHER_BLOCK_SIZE 0
> +#endif
> +
> /*
> * How much memory is needed for a buffer where we compress a data node.
> */
> --
> 2.7.3
>
> --
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