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Message-Id: <20171215174225.31583-24-ebiggers3@gmail.com>
Date: Fri, 15 Dec 2017 09:42:24 -0800
From: Eric Biggers <ebiggers3@...il.com>
To: linux-fscrypt@...r.kernel.org
Cc: "Theodore Y . Ts'o" <tytso@....edu>,
Jaegeuk Kim <jaegeuk@...nel.org>, linux-ext4@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net,
linux-mtd@...ts.infradead.org, Eric Biggers <ebiggers@...gle.com>
Subject: [PATCH 23/24] fscrypt: fix up fscrypt_fname_encrypted_size() for internal use
From: Eric Biggers <ebiggers@...gle.com>
Filesystems don't need fscrypt_fname_encrypted_size() anymore, so
unexport it and move it to fscrypt_private.h.
We also never calculate the encrypted size of a filename without having
the fscrypt_info present since it is needed to know the amount of
NUL-padding which is determined by the encryption policy, and also we
will always truncate the NUL-padding to the maximum filename length.
Therefore, also make fscrypt_fname_encrypted_size() assume that the
fscrypt_info is present, and make it truncate the returned length to the
specified max_len.
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
fs/crypto/fname.c | 31 +++++++++++++++----------------
fs/crypto/fscrypt_private.h | 3 +++
fs/crypto/hooks.c | 10 +++++-----
include/linux/fscrypt_notsupp.h | 8 --------
include/linux/fscrypt_supp.h | 1 -
5 files changed, 23 insertions(+), 30 deletions(-)
diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index 44ddd094b7c5..e33f3d3c5ade 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -191,17 +191,20 @@ static int digest_decode(const char *src, int len, char *dst)
return cp - dst;
}
-u32 fscrypt_fname_encrypted_size(const struct inode *inode, u32 ilen)
+bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
+ u32 max_len, u32 *encrypted_len_ret)
{
- int padding = 32;
- struct fscrypt_info *ci = inode->i_crypt_info;
-
- if (ci)
- padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK);
- ilen = max(ilen, (u32)FS_CRYPTO_BLOCK_SIZE);
- return round_up(ilen, padding);
+ int padding = 4 << (inode->i_crypt_info->ci_flags &
+ FS_POLICY_FLAGS_PAD_MASK);
+ u32 encrypted_len;
+
+ if (orig_len > max_len)
+ return false;
+ encrypted_len = max(orig_len, (u32)FS_CRYPTO_BLOCK_SIZE);
+ encrypted_len = round_up(encrypted_len, padding);
+ *encrypted_len_ret = min(encrypted_len, max_len);
+ return true;
}
-EXPORT_SYMBOL(fscrypt_fname_encrypted_size);
/**
* fscrypt_fname_alloc_buffer - allocate a buffer for presented filenames
@@ -342,14 +345,10 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
return ret;
if (dir->i_crypt_info) {
- unsigned int max_len = dir->i_sb->s_cop->max_namelen(dir);
-
- if (iname->len > max_len)
+ if (!fscrypt_fname_encrypted_size(dir, iname->len,
+ dir->i_sb->s_cop->max_namelen(dir),
+ &fname->crypto_buf.len))
return -ENAMETOOLONG;
-
- fname->crypto_buf.len =
- min(fscrypt_fname_encrypted_size(dir, iname->len),
- max_len);
fname->crypto_buf.name = kmalloc(fname->crypto_buf.len,
GFP_NOFS);
if (!fname->crypto_buf.name)
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 053917587200..ad6722bae8b7 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -110,6 +110,9 @@ extern struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
/* fname.c */
extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
u8 *out, unsigned int olen);
+extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
+ u32 orig_len, u32 max_len,
+ u32 *encrypted_len_ret);
/* keyinfo.c */
extern void __exit fscrypt_essiv_cleanup(void);
diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index ff20cacdea94..3e84d92215a1 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -139,12 +139,12 @@ int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
* counting it (even though it is meaningless for ciphertext) is simpler
* for now since filesystems will assume it is there and subtract it.
*/
- if (sizeof(struct fscrypt_symlink_data) + len > max_len)
+ if (!fscrypt_fname_encrypted_size(dir, len,
+ max_len - sizeof(struct fscrypt_symlink_data),
+ &disk_link->len))
return -ENAMETOOLONG;
- disk_link->len = min_t(unsigned int,
- sizeof(struct fscrypt_symlink_data) +
- fscrypt_fname_encrypted_size(dir, len),
- max_len);
+ disk_link->len += sizeof(struct fscrypt_symlink_data);
+
disk_link->name = NULL;
return 0;
}
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index c9592e307df5..342eb97e0476 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -131,14 +131,6 @@ static inline void fscrypt_free_filename(struct fscrypt_name *fname)
return;
}
-static inline u32 fscrypt_fname_encrypted_size(const struct inode *inode,
- u32 ilen)
-{
- /* never happens */
- WARN_ON(1);
- return 0;
-}
-
static inline int fscrypt_fname_alloc_buffer(const struct inode *inode,
u32 max_encrypted_len,
struct fscrypt_str *crypto_str)
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index e00191deb0d6..2dd5767c77b0 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -107,7 +107,6 @@ static inline void fscrypt_free_filename(struct fscrypt_name *fname)
kfree(fname->crypto_buf.name);
}
-extern u32 fscrypt_fname_encrypted_size(const struct inode *, u32);
extern int fscrypt_fname_alloc_buffer(const struct inode *, u32,
struct fscrypt_str *);
extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
--
2.15.1
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