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Commit 7919cba9 authored by Eric Biggers's avatar Eric Biggers Committed by Jaegeuk Kim
Browse files

fscrypt: define fscrypt_fname_alloc_buffer() to be for presented names 



Previously fscrypt_fname_alloc_buffer() was used to allocate buffers for
both presented (decrypted or encoded) and encrypted filenames.  That was
confusing, because it had to allocate the worst-case size for either,
e.g. including NUL-padding even when it was meaningless.

But now that fscrypt_setup_filename() no longer calls it, it is only
used in the ->get_link() and ->readdir() paths, which specifically want
a buffer for presented filenames.  Therefore, switch the behavior over
to allocating the buffer for presented filenames only.

Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent aef0017f

fs/crypto/fname.c

+14 −15
Original line number Diff line number Diff line
@@ -204,37 +204,36 @@ u32 fscrypt_fname_encrypted_size(const struct inode *inode, u32 ilen) 
EXPORT_SYMBOL(fscrypt_fname_encrypted_size);



/**

 * fscrypt_fname_crypto_alloc_obuff() -

 * fscrypt_fname_alloc_buffer - allocate a buffer for presented filenames

 *

 * Allocates an output buffer that is sufficient for the crypto operation

 * specified by the context and the direction.

 * Allocate a buffer that is large enough to hold any decrypted or encoded

 * filename (null-terminated), for the given maximum encrypted filename length.

 *

 * Return: 0 on success, -errno on failure

 */

int fscrypt_fname_alloc_buffer(const struct inode *inode,

				u32 ilen, struct fscrypt_str *crypto_str)

			       u32 max_encrypted_len,

			       struct fscrypt_str *crypto_str)

{

	u32 olen = fscrypt_fname_encrypted_size(inode, ilen);

	const u32 max_encoded_len =

		max_t(u32, BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE),

		      1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name)));

	u32 max_presented_len;



	crypto_str->len = olen;

	olen = max(olen, max_encoded_len);

	max_presented_len = max(max_encoded_len, max_encrypted_len);



	/*

	 * Allocated buffer can hold one more character to null-terminate the

	 * string

	 */

	crypto_str->name = kmalloc(olen + 1, GFP_NOFS);

	if (!(crypto_str->name))

	crypto_str->name = kmalloc(max_presented_len + 1, GFP_NOFS);

	if (!crypto_str->name)

		return -ENOMEM;

	crypto_str->len = max_presented_len;

	return 0;

}

EXPORT_SYMBOL(fscrypt_fname_alloc_buffer);



/**

 * fscrypt_fname_crypto_free_buffer() -

 * fscrypt_fname_free_buffer - free the buffer for presented filenames

 *

 * Frees the buffer allocated for crypto operation.

 * Free the buffer allocated by fscrypt_fname_alloc_buffer().

 */

void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)

{

include/linux/fscrypt_notsupp.h

+1 −1
Original line number Diff line number Diff line
@@ -140,7 +140,7 @@ static inline u32 fscrypt_fname_encrypted_size(const struct inode *inode, 
}



static inline int fscrypt_fname_alloc_buffer(const struct inode *inode,

					     u32 ilen,

					     u32 max_encrypted_len,

					     struct fscrypt_str *crypto_str)

{

	return -EOPNOTSUPP;