From: Eric Biggers Subject: [PATCH] fscrypto: make filename crypto functions return 0 on success Date: Wed, 14 Sep 2016 16:00:45 -0700 Message-ID: <1473894045-65215-1-git-send-email-ebiggers@google.com> Cc: linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, tytso@mit.edu, jaegeuk@kernel.org, Eric Biggers To: linux-fsdevel@vger.kernel.org Return-path: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Several filename crypto functions: fname_decrypt(), fscrypt_fname_disk_to_usr(), and fscrypt_fname_usr_to_disk(), returned the output length on success or -errno on failure. However, the output length was redundant with the value written to 'oname->len'. It is also potentially error-prone to make callers have to check for '< 0' instead of '!= 0'. Therefore, make these functions return 0 instead of a length, and make the callers who cared about the return value being a length use 'oname->len' instead. This change also fixes the inconsistency of fname_encrypt() actually already returning 0 on success, not a length like the other filename crypto functions and as documented in its function comment. Signed-off-by: Eric Biggers --- fs/crypto/fname.c | 52 ++++++++++++++++++++++++++++++---------------------- fs/ext4/dir.c | 5 +++-- fs/ext4/symlink.c | 5 ++--- fs/f2fs/namei.c | 4 ++-- 4 files changed, 37 insertions(+), 29 deletions(-) diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c index 6bbc3b1..49fd564 100644 --- a/fs/crypto/fname.c +++ b/fs/crypto/fname.c @@ -35,11 +35,11 @@ static void fname_crypt_complete(struct crypto_async_request *req, int res) } /** - * fname_encrypt() - + * fname_encrypt() - encrypt a filename * - * This function encrypts the input filename, and returns the length of the - * ciphertext. Errors are returned as negative numbers. We trust the caller to - * allocate sufficient memory to oname string. + * The caller must have allocated sufficient memory for the @oname string. + * + * Return: 0 on success, -errno on failure */ static int fname_encrypt(struct inode *inode, const struct qstr *iname, struct fscrypt_str *oname) @@ -105,20 +105,22 @@ static int fname_encrypt(struct inode *inode, } kfree(alloc_buf); skcipher_request_free(req); - if (res < 0) + if (res < 0) { printk_ratelimited(KERN_ERR "%s: Error (error code %d)\n", __func__, res); + return res; + } oname->len = ciphertext_len; - return res; + return 0; } -/* - * fname_decrypt() - * This function decrypts the input filename, and returns - * the length of the plaintext. - * Errors are returned as negative numbers. - * We trust the caller to allocate sufficient memory to oname string. +/** + * fname_decrypt() - decrypt a filename + * + * The caller must have allocated sufficient memory for the @oname string. + * + * Return: 0 on success, -errno on failure */ static int fname_decrypt(struct inode *inode, const struct fscrypt_str *iname, @@ -168,7 +170,7 @@ static int fname_decrypt(struct inode *inode, } oname->len = strnlen(oname->name, iname->len); - return oname->len; + return 0; } static const char *lookup_table = @@ -279,6 +281,10 @@ EXPORT_SYMBOL(fscrypt_fname_free_buffer); /** * fscrypt_fname_disk_to_usr() - converts a filename from disk space to user * space + * + * The caller must have allocated sufficient memory for the @oname string. + * + * Return: 0 on success, -errno on failure */ int fscrypt_fname_disk_to_usr(struct inode *inode, u32 hash, u32 minor_hash, @@ -287,13 +293,12 @@ int fscrypt_fname_disk_to_usr(struct inode *inode, { const struct qstr qname = FSTR_TO_QSTR(iname); char buf[24]; - int ret; if (fscrypt_is_dot_dotdot(&qname)) { oname->name[0] = '.'; oname->name[iname->len - 1] = '.'; oname->len = iname->len; - return oname->len; + return 0; } if (iname->len < FS_CRYPTO_BLOCK_SIZE) @@ -303,9 +308,9 @@ int fscrypt_fname_disk_to_usr(struct inode *inode, return fname_decrypt(inode, iname, oname); if (iname->len <= FS_FNAME_CRYPTO_DIGEST_SIZE) { - ret = digest_encode(iname->name, iname->len, oname->name); - oname->len = ret; - return ret; + oname->len = digest_encode(iname->name, iname->len, + oname->name); + return 0; } if (hash) { memcpy(buf, &hash, 4); @@ -315,15 +320,18 @@ int fscrypt_fname_disk_to_usr(struct inode *inode, } memcpy(buf + 8, iname->name + iname->len - 16, 16); oname->name[0] = '_'; - ret = digest_encode(buf, 24, oname->name + 1); - oname->len = ret + 1; - return ret + 1; + oname->len = 1 + digest_encode(buf, 24, oname->name + 1); + return 0; } EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); /** * fscrypt_fname_usr_to_disk() - converts a filename from user space to disk * space + * + * The caller must have allocated sufficient memory for the @oname string. + * + * Return: 0 on success, -errno on failure */ int fscrypt_fname_usr_to_disk(struct inode *inode, const struct qstr *iname, @@ -333,7 +341,7 @@ int fscrypt_fname_usr_to_disk(struct inode *inode, oname->name[0] = '.'; oname->name[iname->len - 1] = '.'; oname->len = iname->len; - return oname->len; + return 0; } if (inode->i_crypt_info) return fname_encrypt(inode, iname, oname); diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c index 67415e0..4d4b910 100644 --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -260,11 +260,12 @@ static int ext4_readdir(struct file *file, struct dir_context *ctx) /* Directory is encrypted */ err = fscrypt_fname_disk_to_usr(inode, 0, 0, &de_name, &fstr); + de_name = fstr; fstr.len = save_len; - if (err < 0) + if (err) goto errout; if (!dir_emit(ctx, - fstr.name, err, + de_name.name, de_name.len, le32_to_cpu(de->inode), get_dtype(sb, de->file_type))) goto done; diff --git a/fs/ext4/symlink.c b/fs/ext4/symlink.c index 4d83d9e..55aaf30 100644 --- a/fs/ext4/symlink.c +++ b/fs/ext4/symlink.c @@ -67,14 +67,13 @@ static const char *ext4_encrypted_get_link(struct dentry *dentry, goto errout; res = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr); - if (res < 0) + if (res) goto errout; paddr = pstr.name; /* Null-terminate the name */ - if (res <= pstr.len) - paddr[res] = '\0'; + paddr[pstr.len] = '\0'; if (cpage) put_page(cpage); set_delayed_call(done, kfree_link, paddr); diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c index 73fa356..a5468c2 100644 --- a/fs/f2fs/namei.c +++ b/fs/f2fs/namei.c @@ -1048,7 +1048,7 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry, goto errout; res = fscrypt_fname_disk_to_usr(inode, 0, 0, &cstr, &pstr); - if (res < 0) + if (res) goto errout; /* this is broken symlink case */ @@ -1060,7 +1060,7 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry, paddr = pstr.name; /* Null-terminate the name */ - paddr[res] = '\0'; + paddr[pstr.len] = '\0'; put_page(cpage); set_delayed_call(done, kfree_link, paddr); -- 2.8.0.rc3.226.g39d4020