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authorEric Biggers <ebiggers@google.com>2018-01-11 23:30:08 -0500
committerTheodore Ts'o <tytso@mit.edu>2018-01-11 23:30:08 -0500
commitb9db0b4a68d373897119d1e0a3beebe1c1a23936 (patch)
tree3cb57195d294dae3eb19378428cabc75e78621e3 /fs/crypto
parent2cbadadcfdf0d8a538ce32ed12e18ef487773b07 (diff)
fscrypt: fix up fscrypt_fname_encrypted_size() for internal use
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@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/crypto')
-rw-r--r--fs/crypto/fname.c31
-rw-r--r--fs/crypto/fscrypt_private.h3
-rw-r--r--fs/crypto/hooks.c10
3 files changed, 23 insertions, 21 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 5bf38d94c5d2..28f9f059571d 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -143,12 +143,12 @@ 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;
}