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Date: Wed, 14 Sep 2016 16:00:45 -0700
From: Eric Biggers <ebiggers@...gle.com>
To: linux-fsdevel@...r.kernel.org
Cc: linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net,
tytso@....edu, jaegeuk@...nel.org,
Eric Biggers <ebiggers@...gle.com>
Subject: [PATCH] fscrypto: make filename crypto functions return 0 on success
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 <ebiggers@...gle.com>
---
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
--
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