Commit b9db0b4a authored by Eric Biggers's avatar Eric Biggers Committed by Theodore Ts'o
Browse files

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: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 2cbadadc

fs/crypto/fname.c

+15 −16
Original line number Diff line number Diff line
@@ -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;

	int padding = 4 << (inode->i_crypt_info->ci_flags &

			    FS_POLICY_FLAGS_PAD_MASK);

	u32 encrypted_len;



	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);

	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)

fs/crypto/fscrypt_private.h

+3 −0
Original line number Diff line number Diff line
@@ -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);

fs/crypto/hooks.c

+5 −5
Original line number Diff line number Diff line
@@ -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;

}

include/linux/fscrypt_notsupp.h

+0 −8
Original line number Diff line number Diff line
@@ -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)

include/linux/fscrypt_supp.h

+0 −1
Original line number Diff line number Diff line
@@ -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 *);

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