2016-09-22 20:31:47

by Eric Biggers

Subject: [PATCH] ext4: do not unnecessarily null-terminate encrypted symlink data

Null-terminating the fscrypt_symlink_data on read is unnecessary because
it is not string data --- it contains binary ciphertext.

Signed-off-by: Eric Biggers <[email protected]>
---
fs/ext4/symlink.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/fs/ext4/symlink.c b/fs/ext4/symlink.c
index 0a26cbd..fdf1c61 100644
--- a/fs/ext4/symlink.c
+++ b/fs/ext4/symlink.c
@@ -30,7 +30,6 @@ static const char *ext4_encrypted_get_link(struct dentry *dentry,
char *caddr, *paddr = NULL;
struct fscrypt_str cstr, pstr;
struct fscrypt_symlink_data *sd;
- loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
int res;
u32 max_size = inode->i_sb->s_blocksize;

@@ -49,7 +48,6 @@ static const char *ext4_encrypted_get_link(struct dentry *dentry,
if (IS_ERR(cpage))
return ERR_CAST(cpage);
caddr = page_address(cpage);
- caddr[size] = 0;
}

/* Symlink is encrypted */
--
2.8.0.rc3.226.g39d4020

2016-09-22 20:32:25

by Eric Biggers

Subject: [PATCH] f2fs: do not unnecessarily null-terminate encrypted symlink data

Null-terminating the fscrypt_symlink_data on read is unnecessary because
it is not string data --- it contains binary ciphertext.

Signed-off-by: Eric Biggers <[email protected]>
---
fs/f2fs/namei.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index afd5633..5b4733e 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -1010,7 +1010,6 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
struct fscrypt_str cstr = FSTR_INIT(NULL, 0);
struct fscrypt_str pstr = FSTR_INIT(NULL, 0);
struct fscrypt_symlink_data *sd;
- loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
u32 max_size = inode->i_sb->s_blocksize;
int res;

@@ -1025,7 +1024,6 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
if (IS_ERR(cpage))
return ERR_CAST(cpage);
caddr = page_address(cpage);
- caddr[size] = 0;

/* Symlink is encrypted */
sd = (struct fscrypt_symlink_data *)caddr;
--
2.8.0.rc3.226.g39d4020

2016-09-22 20:31:49

by Eric Biggers

Subject: [PATCH] fscrypto: use standard macros to compute length of fname ciphertext

Signed-off-by: Eric Biggers <[email protected]>
---
fs/crypto/fname.c | 17 +++++------------
1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index 90697c7..9a28133 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -14,11 +14,6 @@
#include <linux/ratelimit.h>
#include <linux/fscrypto.h>

-static u32 size_round_up(size_t size, size_t blksize)
-{
- return ((size + blksize - 1) / blksize) * blksize;
-}
-
/**
* fname_crypt_complete() - completion callback for filename crypto
* @req: The asynchronous cipher request context
@@ -60,10 +55,9 @@ static int fname_encrypt(struct inode *inode,
if (iname->len <= 0 || iname->len > lim)
return -EIO;

- ciphertext_len = (iname->len < FS_CRYPTO_BLOCK_SIZE) ?
- FS_CRYPTO_BLOCK_SIZE : iname->len;
- ciphertext_len = size_round_up(ciphertext_len, padding);
- ciphertext_len = (ciphertext_len > lim) ? lim : ciphertext_len;
+ ciphertext_len = max(iname->len, (u32)FS_CRYPTO_BLOCK_SIZE);
+ ciphertext_len = round_up(ciphertext_len, padding);
+ ciphertext_len = min(ciphertext_len, lim);

if (ciphertext_len <= sizeof(buf)) {
workbuf = buf;
@@ -233,9 +227,8 @@ u32 fscrypt_fname_encrypted_size(struct inode *inode, u32 ilen)

if (ci)
padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK);
- if (ilen < FS_CRYPTO_BLOCK_SIZE)
- ilen = FS_CRYPTO_BLOCK_SIZE;
- return size_round_up(ilen, padding);
+ ilen = max(ilen, (u32)FS_CRYPTO_BLOCK_SIZE);
+ return round_up(ilen, padding);
}
EXPORT_SYMBOL(fscrypt_fname_encrypted_size);

--
2.8.0.rc3.226.g39d4020

2016-09-30 05:45:28

by Theodore Ts'o

Subject: Re: [PATCH] ext4: do not unnecessarily null-terminate encrypted symlink data

On Thu, Sep 22, 2016 at 01:31:47PM -0700, Eric Biggers wrote:
> Null-terminating the fscrypt_symlink_data on read is unnecessary because
> it is not string data --- it contains binary ciphertext.
>
> Signed-off-by: Eric Biggers <[email protected]>

Thanks, applied.

- Ted

2016-09-30 05:47:38

by Theodore Ts'o

Subject: Re: [PATCH] fscrypto: use standard macros to compute length of fname ciphertext

On Thu, Sep 22, 2016 at 01:31:49PM -0700, Eric Biggers wrote:
> Signed-off-by: Eric Biggers <[email protected]>

Thanks, applied.

- Ted