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Date: Tue, 5 May 2015 11:18:12 -0400
From: Theodore Ts'o <tytso@....edu>
To: Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc: mhalcrow@...gle.com, savagaon@...gle.com,
Theodore Ts'o <tytso@....edu>
Subject: [PATCH 2/4] ext4 crypto: don't allocate a page when encrypting/decrypting file names
Signed-off-by: Theodore Ts'o <tytso@....edu>
---
fs/ext4/crypto_fname.c | 72 ++++++++++++++------------------------------------
fs/ext4/dir.c | 3 +++
fs/ext4/ext4_crypto.h | 2 --
fs/ext4/namei.c | 4 +++
fs/ext4/symlink.c | 1 +
5 files changed, 28 insertions(+), 54 deletions(-)
diff --git a/fs/ext4/crypto_fname.c b/fs/ext4/crypto_fname.c
index ad5e328..23d7f1d 100644
--- a/fs/ext4/crypto_fname.c
+++ b/fs/ext4/crypto_fname.c
@@ -65,9 +65,9 @@ static int ext4_fname_encrypt(struct ext4_fname_crypto_ctx *ctx,
struct crypto_ablkcipher *tfm = ctx->ctfm;
int res = 0;
char iv[EXT4_CRYPTO_BLOCK_SIZE];
- struct scatterlist sg[1];
+ struct scatterlist src_sg, dst_sg;
int padding = 4 << (ctx->flags & EXT4_POLICY_FLAGS_PAD_MASK);
- char *workbuf;
+ char *workbuf, buf[32], *alloc_buf = NULL;
if (iname->len <= 0 || iname->len > ctx->lim)
return -EIO;
@@ -78,20 +78,27 @@ static int ext4_fname_encrypt(struct ext4_fname_crypto_ctx *ctx,
ciphertext_len = (ciphertext_len > ctx->lim)
? ctx->lim : ciphertext_len;
+ if (ciphertext_len <= sizeof(buf)) {
+ workbuf = buf;
+ } else {
+ alloc_buf = kmalloc(ciphertext_len, GFP_NOFS);
+ if (!alloc_buf)
+ return -ENOMEM;
+ workbuf = alloc_buf;
+ }
+
/* Allocate request */
req = ablkcipher_request_alloc(tfm, GFP_NOFS);
if (!req) {
printk_ratelimited(
KERN_ERR "%s: crypto_request_alloc() failed\n", __func__);
+ kfree(alloc_buf);
return -ENOMEM;
}
ablkcipher_request_set_callback(req,
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
ext4_dir_crypt_complete, &ecr);
- /* Map the workpage */
- workbuf = kmap(ctx->workpage);
-
/* Copy the input */
memcpy(workbuf, iname->name, iname->len);
if (iname->len < ciphertext_len)
@@ -101,21 +108,16 @@ static int ext4_fname_encrypt(struct ext4_fname_crypto_ctx *ctx,
memset(iv, 0, EXT4_CRYPTO_BLOCK_SIZE);
/* Create encryption request */
- sg_init_table(sg, 1);
- sg_set_page(sg, ctx->workpage, PAGE_SIZE, 0);
- ablkcipher_request_set_crypt(req, sg, sg, ciphertext_len, iv);
+ sg_init_one(&src_sg, workbuf, ciphertext_len);
+ sg_init_one(&dst_sg, oname->name, ciphertext_len);
+ ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
res = crypto_ablkcipher_encrypt(req);
if (res == -EINPROGRESS || res == -EBUSY) {
BUG_ON(req->base.data != &ecr);
wait_for_completion(&ecr.completion);
res = ecr.res;
}
- if (res >= 0) {
- /* Copy the result to output */
- memcpy(oname->name, workbuf, ciphertext_len);
- res = ciphertext_len;
- }
- kunmap(ctx->workpage);
+ kfree(alloc_buf);
ablkcipher_request_free(req);
if (res < 0) {
printk_ratelimited(
@@ -139,11 +141,10 @@ static int ext4_fname_decrypt(struct ext4_fname_crypto_ctx *ctx,
struct ext4_str tmp_in[2], tmp_out[1];
struct ablkcipher_request *req = NULL;
DECLARE_EXT4_COMPLETION_RESULT(ecr);
- struct scatterlist sg[1];
+ struct scatterlist src_sg, dst_sg;
struct crypto_ablkcipher *tfm = ctx->ctfm;
int res = 0;
char iv[EXT4_CRYPTO_BLOCK_SIZE];
- char *workbuf;
if (iname->len <= 0 || iname->len > ctx->lim)
return -EIO;
@@ -163,31 +164,19 @@ static int ext4_fname_decrypt(struct ext4_fname_crypto_ctx *ctx,
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
ext4_dir_crypt_complete, &ecr);
- /* Map the workpage */
- workbuf = kmap(ctx->workpage);
-
- /* Copy the input */
- memcpy(workbuf, iname->name, iname->len);
-
/* Initialize IV */
memset(iv, 0, EXT4_CRYPTO_BLOCK_SIZE);
/* Create encryption request */
- sg_init_table(sg, 1);
- sg_set_page(sg, ctx->workpage, PAGE_SIZE, 0);
- ablkcipher_request_set_crypt(req, sg, sg, iname->len, iv);
+ sg_init_one(&src_sg, iname->name, iname->len);
+ sg_init_one(&dst_sg, oname->name, oname->len);
+ ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
res = crypto_ablkcipher_decrypt(req);
if (res == -EINPROGRESS || res == -EBUSY) {
BUG_ON(req->base.data != &ecr);
wait_for_completion(&ecr.completion);
res = ecr.res;
}
- if (res >= 0) {
- /* Copy the result to output */
- memcpy(oname->name, workbuf, iname->len);
- res = iname->len;
- }
- kunmap(ctx->workpage);
ablkcipher_request_free(req);
if (res < 0) {
printk_ratelimited(
@@ -267,8 +256,6 @@ void ext4_free_fname_crypto_ctx(struct ext4_fname_crypto_ctx *ctx)
crypto_free_ablkcipher(ctx->ctfm);
if (ctx->htfm && !IS_ERR(ctx->htfm))
crypto_free_hash(ctx->htfm);
- if (ctx->workpage && !IS_ERR(ctx->workpage))
- __free_page(ctx->workpage);
kfree(ctx);
}
@@ -322,7 +309,6 @@ struct ext4_fname_crypto_ctx *ext4_alloc_fname_crypto_ctx(
ctx->ctfm_key_is_ready = 0;
ctx->ctfm = NULL;
ctx->htfm = NULL;
- ctx->workpage = NULL;
return ctx;
}
@@ -390,24 +376,6 @@ struct ext4_fname_crypto_ctx *ext4_get_fname_crypto_ctx(
ext4_put_fname_crypto_ctx(&ctx);
return ERR_PTR(-ENOMEM);
}
- if (ctx->workpage == NULL)
- ctx->workpage = alloc_page(GFP_NOFS);
- if (IS_ERR(ctx->workpage)) {
- res = PTR_ERR(ctx->workpage);
- printk(
- KERN_DEBUG "%s: error (%d) allocating work page\n",
- __func__, res);
- ctx->workpage = NULL;
- ext4_put_fname_crypto_ctx(&ctx);
- return ERR_PTR(res);
- }
- if (ctx->workpage == NULL) {
- printk(
- KERN_DEBUG "%s: could not allocate work page\n",
- __func__);
- ext4_put_fname_crypto_ctx(&ctx);
- return ERR_PTR(-ENOMEM);
- }
ctx->lim = max_ciphertext_len;
crypto_ablkcipher_clear_flags(ctx->ctfm, ~0);
crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctx->ctfm),
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index 5665d82..d799d5d 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -247,9 +247,12 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx)
get_dtype(sb, de->file_type)))
goto done;
} else {
+ int save_len = fname_crypto_str.len;
+
/* Directory is encrypted */
err = ext4_fname_disk_to_usr(enc_ctx,
NULL, de, &fname_crypto_str);
+ fname_crypto_str.len = save_len;
if (err < 0)
goto errout;
if (!dir_emit(ctx,
diff --git a/fs/ext4/ext4_crypto.h b/fs/ext4/ext4_crypto.h
index d75159c..552424a 100644
--- a/fs/ext4/ext4_crypto.h
+++ b/fs/ext4/ext4_crypto.h
@@ -123,10 +123,8 @@ struct ext4_str {
struct ext4_fname_crypto_ctx {
u32 lim;
- char tmp_buf[EXT4_CRYPTO_BLOCK_SIZE];
struct crypto_ablkcipher *ctfm;
struct crypto_hash *htfm;
- struct page *workpage;
struct ext4_encryption_key key;
unsigned flags : 8;
unsigned has_valid_key : 1;
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 56c60cb..b340643 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -998,6 +998,8 @@ static int htree_dirblock_to_tree(struct file *dir_file,
hinfo->hash, hinfo->minor_hash, de,
&tmp_str);
} else {
+ int save_len = fname_crypto_str.len;
+
/* Directory is encrypted */
err = ext4_fname_disk_to_usr(ctx, hinfo, de,
&fname_crypto_str);
@@ -1008,6 +1010,7 @@ static int htree_dirblock_to_tree(struct file *dir_file,
err = ext4_htree_store_dirent(dir_file,
hinfo->hash, hinfo->minor_hash, de,
&fname_crypto_str);
+ fname_crypto_str.len = save_len;
}
if (err != 0) {
count = err;
@@ -3126,6 +3129,7 @@ static int ext4_symlink(struct inode *dir,
istr.name = (const unsigned char *) symname;
istr.len = len;
ostr.name = sd->encrypted_path;
+ ostr.len = disk_link.len;
err = ext4_fname_usr_to_disk(ctx, &istr, &ostr);
ext4_put_fname_crypto_ctx(&ctx);
if (err < 0)
diff --git a/fs/ext4/symlink.c b/fs/ext4/symlink.c
index 187b789..ca65d45 100644
--- a/fs/ext4/symlink.c
+++ b/fs/ext4/symlink.c
@@ -74,6 +74,7 @@ static void *ext4_follow_link(struct dentry *dentry, struct nameidata *nd)
goto errout;
}
pstr.name = paddr;
+ pstr.len = plen;
res = _ext4_fname_disk_to_usr(ctx, NULL, &cstr, &pstr);
if (res < 0)
goto errout;
--
2.3.0
--
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