--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This contains functions for filename crypto management
+ *
+ * Copyright (C) 2015, Google, Inc.
+ * Copyright (C) 2015, Motorola Mobility
+ *
+ * Written by Uday Savagaonkar, 2014.
+ * Modified by Jaegeuk Kim, 2015.
+ *
+ * This has not yet undergone a rigorous security audit.
+ */
+/*
+ * Linux commit 219d54332a09
+ * tags/v5.4
+ */
+
+#include <linux/scatterlist.h>
+#include <crypto/skcipher.h>
+#include "llcrypt_private.h"
+
+static inline bool llcrypt_is_dot_dotdot(const struct qstr *str)
+{
+ if (str->len == 1 && str->name[0] == '.')
+ return true;
+
+ if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
+ return true;
+
+ return false;
+}
+
+/**
+ * fname_encrypt() - encrypt a filename
+ *
+ * The output buffer must be at least as large as the input buffer.
+ * Any extra space is filled with NUL padding before encryption.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int fname_encrypt(struct inode *inode, const struct qstr *iname,
+ u8 *out, unsigned int olen)
+{
+ struct skcipher_request *req = NULL;
+ DECLARE_CRYPTO_WAIT(wait);
+ struct llcrypt_info *ci = llcrypt_info(inode);
+ struct crypto_skcipher *tfm = ci->ci_ctfm;
+ union llcrypt_iv iv;
+ struct scatterlist sg;
+ int res;
+
+ /*
+ * Copy the filename to the output buffer for encrypting in-place and
+ * pad it with the needed number of NUL bytes.
+ */
+ if (WARN_ON(olen < iname->len))
+ return -ENOBUFS;
+ memcpy(out, iname->name, iname->len);
+ memset(out + iname->len, 0, olen - iname->len);
+
+ /* Initialize the IV */
+ llcrypt_generate_iv(&iv, 0, ci);
+
+ /* Set up the encryption request */
+ req = skcipher_request_alloc(tfm, GFP_NOFS);
+ if (!req)
+ return -ENOMEM;
+ skcipher_request_set_callback(req,
+ CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+ crypto_req_done, &wait);
+ sg_init_one(&sg, out, olen);
+ skcipher_request_set_crypt(req, &sg, &sg, olen, &iv);
+
+ /* Do the encryption */
+ res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
+ skcipher_request_free(req);
+ if (res < 0) {
+ llcrypt_err(inode, "Filename encryption failed: %d", res);
+ return res;
+ }
+
+ return 0;
+}
+
+/**
+ * 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 llcrypt_str *iname,
+ struct llcrypt_str *oname)
+{
+ struct skcipher_request *req = NULL;
+ DECLARE_CRYPTO_WAIT(wait);
+ struct scatterlist src_sg, dst_sg;
+ struct llcrypt_info *ci = llcrypt_info(inode);
+ struct crypto_skcipher *tfm = ci->ci_ctfm;
+ union llcrypt_iv iv;
+ int res;
+
+ /* Allocate request */
+ req = skcipher_request_alloc(tfm, GFP_NOFS);
+ if (!req)
+ return -ENOMEM;
+ skcipher_request_set_callback(req,
+ CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+ crypto_req_done, &wait);
+
+ /* Initialize IV */
+ llcrypt_generate_iv(&iv, 0, ci);
+
+ /* Create decryption request */
+ sg_init_one(&src_sg, iname->name, iname->len);
+ sg_init_one(&dst_sg, oname->name, oname->len);
+ skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, &iv);
+ res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait);
+ skcipher_request_free(req);
+ if (res < 0) {
+ llcrypt_err(inode, "Filename decryption failed: %d", res);
+ return res;
+ }
+
+ oname->len = strnlen(oname->name, iname->len);
+ return 0;
+}
+
+static const char lookup_table[65] =
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
+
+#define BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3)
+
+/**
+ * base64_encode() -
+ *
+ * Encodes the input string using characters from the set [A-Za-z0-9+,].
+ * The encoded string is roughly 4/3 times the size of the input string.
+ *
+ * Return: length of the encoded string
+ */
+static int base64_encode(const u8 *src, int len, char *dst)
+{
+ int i, bits = 0, ac = 0;
+ char *cp = dst;
+
+ for (i = 0; i < len; i++) {
+ ac += src[i] << bits;
+ bits += 8;
+ do {
+ *cp++ = lookup_table[ac & 0x3f];
+ ac >>= 6;
+ bits -= 6;
+ } while (bits >= 6);
+ }
+ if (bits)
+ *cp++ = lookup_table[ac & 0x3f];
+ return cp - dst;
+}
+
+static int base64_decode(const char *src, int len, u8 *dst)
+{
+ int i, bits = 0, ac = 0;
+ const char *p;
+ u8 *cp = dst;
+
+ for (i = 0; i < len; i++) {
+ p = strchr(lookup_table, src[i]);
+ if (p == NULL || src[i] == 0)
+ return -2;
+ ac += (p - lookup_table) << bits;
+ bits += 6;
+ if (bits >= 8) {
+ *cp++ = ac & 0xff;
+ ac >>= 8;
+ bits -= 8;
+ }
+ }
+ if (ac)
+ return -1;
+ return cp - dst;
+}
+
+bool llcrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
+ u32 max_len, u32 *encrypted_len_ret)
+{
+ const struct llcrypt_info *ci = llcrypt_info(inode);
+ int padding = 4 << (llcrypt_policy_flags(&ci->ci_policy) &
+ LLCRYPT_POLICY_FLAGS_PAD_MASK);
+ u32 encrypted_len;
+
+ if (orig_len > max_len)
+ return false;
+ encrypted_len = max(orig_len, (u32)LL_CRYPTO_BLOCK_SIZE);
+ encrypted_len = round_up(encrypted_len, padding);
+ *encrypted_len_ret = min(encrypted_len, max_len);
+ return true;
+}
+
+/**
+ * llcrypt_fname_alloc_buffer - allocate a buffer for presented filenames
+ *
+ * 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 llcrypt_fname_alloc_buffer(const struct inode *inode,
+ u32 max_encrypted_len,
+ struct llcrypt_str *crypto_str)
+{
+ const u32 max_encoded_len =
+ max_t(u32, BASE64_CHARS(LLCRYPT_FNAME_MAX_UNDIGESTED_SIZE),
+ 1 + BASE64_CHARS(sizeof(struct llcrypt_digested_name)));
+ u32 max_presented_len;
+
+ max_presented_len = max(max_encoded_len, max_encrypted_len);
+
+ 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(llcrypt_fname_alloc_buffer);
+
+/**
+ * llcrypt_fname_free_buffer - free the buffer for presented filenames
+ *
+ * Free the buffer allocated by llcrypt_fname_alloc_buffer().
+ */
+void llcrypt_fname_free_buffer(struct llcrypt_str *crypto_str)
+{
+ if (!crypto_str)
+ return;
+ kfree(crypto_str->name);
+ crypto_str->name = NULL;
+}
+EXPORT_SYMBOL(llcrypt_fname_free_buffer);
+
+/**
+ * llcrypt_fname_disk_to_usr() - converts a filename from disk space to user
+ * space
+ *
+ * The caller must have allocated sufficient memory for the @oname string.
+ *
+ * If the key is available, we'll decrypt the disk name; otherwise, we'll encode
+ * it for presentation. Short names are directly base64-encoded, while long
+ * names are encoded in llcrypt_digested_name format.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int llcrypt_fname_disk_to_usr(struct inode *inode,
+ u32 hash, u32 minor_hash,
+ const struct llcrypt_str *iname,
+ struct llcrypt_str *oname)
+{
+ const struct qstr qname = LLTR_TO_QSTR(iname);
+ struct llcrypt_digested_name digested_name;
+
+ if (llcrypt_is_dot_dotdot(&qname)) {
+ oname->name[0] = '.';
+ oname->name[iname->len - 1] = '.';
+ oname->len = iname->len;
+ return 0;
+ }
+
+ if (iname->len < LL_CRYPTO_BLOCK_SIZE)
+ return -EUCLEAN;
+
+ if (llcrypt_has_encryption_key(inode))
+ return fname_decrypt(inode, iname, oname);
+
+ if (iname->len <= LLCRYPT_FNAME_MAX_UNDIGESTED_SIZE) {
+ oname->len = base64_encode(iname->name, iname->len,
+ oname->name);
+ return 0;
+ }
+ if (hash) {
+ digested_name.hash = hash;
+ digested_name.minor_hash = minor_hash;
+ } else {
+ digested_name.hash = 0;
+ digested_name.minor_hash = 0;
+ }
+ memcpy(digested_name.digest,
+ LLCRYPT_FNAME_DIGEST(iname->name, iname->len),
+ LLCRYPT_FNAME_DIGEST_SIZE);
+ oname->name[0] = '_';
+ oname->len = 1 + base64_encode((const u8 *)&digested_name,
+ sizeof(digested_name), oname->name + 1);
+ return 0;
+}
+EXPORT_SYMBOL(llcrypt_fname_disk_to_usr);
+
+/**
+ * llcrypt_setup_filename() - prepare to search a possibly encrypted directory
+ * @dir: the directory that will be searched
+ * @iname: the user-provided filename being searched for
+ * @lookup: 1 if we're allowed to proceed without the key because it's
+ * ->lookup() or we're finding the dir_entry for deletion; 0 if we cannot
+ * proceed without the key because we're going to create the dir_entry.
+ * @fname: the filename information to be filled in
+ *
+ * Given a user-provided filename @iname, this function sets @fname->disk_name
+ * to the name that would be stored in the on-disk directory entry, if possible.
+ * If the directory is unencrypted this is simply @iname. Else, if we have the
+ * directory's encryption key, then @iname is the plaintext, so we encrypt it to
+ * get the disk_name.
+ *
+ * Else, for keyless @lookup operations, @iname is the presented ciphertext, so
+ * we decode it to get either the ciphertext disk_name (for short names) or the
+ * llcrypt_digested_name (for long names). Non-@lookup operations will be
+ * impossible in this case, so we fail them with ENOKEY.
+ *
+ * If successful, llcrypt_free_filename() must be called later to clean up.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int llcrypt_setup_filename(struct inode *dir, const struct qstr *iname,
+ int lookup, struct llcrypt_name *fname)
+{
+ int ret;
+ int digested;
+
+ memset(fname, 0, sizeof(struct llcrypt_name));
+ fname->usr_fname = iname;
+
+ if (!IS_ENCRYPTED(dir) || llcrypt_is_dot_dotdot(iname)) {
+ fname->disk_name.name = (unsigned char *)iname->name;
+ fname->disk_name.len = iname->len;
+ return 0;
+ }
+ ret = llcrypt_get_encryption_info(dir);
+ if (ret)
+ return ret;
+
+ if (llcrypt_has_encryption_key(dir)) {
+ struct lustre_sb_info *lsi = s2lsi(dir->i_sb);
+
+ if (!llcrypt_fname_encrypted_size(dir, iname->len,
+ lsi ?
+ lsi->lsi_cop->max_namelen :
+ NAME_MAX,
+ &fname->crypto_buf.len))
+ return -ENAMETOOLONG;
+ fname->crypto_buf.name = kmalloc(fname->crypto_buf.len,
+ GFP_NOFS);
+ if (!fname->crypto_buf.name)
+ return -ENOMEM;
+
+ ret = fname_encrypt(dir, iname, fname->crypto_buf.name,
+ fname->crypto_buf.len);
+ if (ret)
+ goto errout;
+ fname->disk_name.name = fname->crypto_buf.name;
+ fname->disk_name.len = fname->crypto_buf.len;
+ return 0;
+ }
+ if (!lookup)
+ return -ENOKEY;
+ fname->is_ciphertext_name = true;
+
+ /*
+ * We don't have the key and we are doing a lookup; decode the
+ * user-supplied name
+ */
+ if (iname->name[0] == '_') {
+ if (iname->len !=
+ 1 + BASE64_CHARS(sizeof(struct llcrypt_digested_name)))
+ return -ENOENT;
+ digested = 1;
+ } else {
+ if (iname->len >
+ BASE64_CHARS(LLCRYPT_FNAME_MAX_UNDIGESTED_SIZE))
+ return -ENOENT;
+ digested = 0;
+ }
+
+ fname->crypto_buf.name =
+ kmalloc(max_t(size_t, LLCRYPT_FNAME_MAX_UNDIGESTED_SIZE,
+ sizeof(struct llcrypt_digested_name)),
+ GFP_KERNEL);
+ if (fname->crypto_buf.name == NULL)
+ return -ENOMEM;
+
+ ret = base64_decode(iname->name + digested, iname->len - digested,
+ fname->crypto_buf.name);
+ if (ret < 0) {
+ ret = -ENOENT;
+ goto errout;
+ }
+ fname->crypto_buf.len = ret;
+ if (digested) {
+ const struct llcrypt_digested_name *n =
+ (const void *)fname->crypto_buf.name;
+ fname->hash = n->hash;
+ fname->minor_hash = n->minor_hash;
+ } else {
+ fname->disk_name.name = fname->crypto_buf.name;
+ fname->disk_name.len = fname->crypto_buf.len;
+ }
+ return 0;
+
+errout:
+ kfree(fname->crypto_buf.name);
+ return ret;
+}
+EXPORT_SYMBOL(llcrypt_setup_filename);
git://git.whamcloud.com / fs / lustre-release.git / blobdiff