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: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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@ -204,37 +204,36 @@ u32 fscrypt_fname_encrypted_size(const struct inode *inode, u32 ilen)
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EXPORT_SYMBOL(fscrypt_fname_encrypted_size);
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/**
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* fscrypt_fname_crypto_alloc_obuff() -
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* fscrypt_fname_alloc_buffer - allocate a buffer for presented filenames
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*
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* Allocates an output buffer that is sufficient for the crypto operation
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* specified by the context and the direction.
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* Allocate a buffer that is large enough to hold any decrypted or encoded
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* filename (null-terminated), for the given maximum encrypted filename length.
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*
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* Return: 0 on success, -errno on failure
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*/
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int fscrypt_fname_alloc_buffer(const struct inode *inode,
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u32 ilen, struct fscrypt_str *crypto_str)
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u32 max_encrypted_len,
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struct fscrypt_str *crypto_str)
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{
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u32 olen = fscrypt_fname_encrypted_size(inode, ilen);
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const u32 max_encoded_len =
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max_t(u32, BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE),
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1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name)));
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u32 max_presented_len;
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crypto_str->len = olen;
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olen = max(olen, max_encoded_len);
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max_presented_len = max(max_encoded_len, max_encrypted_len);
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/*
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* Allocated buffer can hold one more character to null-terminate the
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* string
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*/
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crypto_str->name = kmalloc(olen + 1, GFP_NOFS);
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if (!(crypto_str->name))
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crypto_str->name = kmalloc(max_presented_len + 1, GFP_NOFS);
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if (!crypto_str->name)
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return -ENOMEM;
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crypto_str->len = max_presented_len;
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return 0;
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}
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EXPORT_SYMBOL(fscrypt_fname_alloc_buffer);
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/**
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* fscrypt_fname_crypto_free_buffer() -
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* fscrypt_fname_free_buffer - free the buffer for presented filenames
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*
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* Frees the buffer allocated for crypto operation.
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* Free the buffer allocated by fscrypt_fname_alloc_buffer().
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*/
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void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
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{
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@ -140,7 +140,7 @@ static inline u32 fscrypt_fname_encrypted_size(const struct inode *inode,
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}
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static inline int fscrypt_fname_alloc_buffer(const struct inode *inode,
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u32 ilen,
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u32 max_encrypted_len,
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struct fscrypt_str *crypto_str)
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{
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return -EOPNOTSUPP;
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