^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) * This contains functions for filename crypto management
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) * Copyright (C) 2015, Google, Inc.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) * Copyright (C) 2015, Motorola Mobility
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) * Written by Uday Savagaonkar, 2014.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) * Modified by Jaegeuk Kim, 2015.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) * This has not yet undergone a rigorous security audit.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) #include <linux/namei.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) #include <linux/scatterlist.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) #include <crypto/hash.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) #include <crypto/sha.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) #include <crypto/skcipher.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) #include "fscrypt_private.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) * struct fscrypt_nokey_name - identifier for directory entry when key is absent
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) * When userspace lists an encrypted directory without access to the key, the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) * filesystem must present a unique "no-key name" for each filename that allows
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) * it to find the directory entry again if requested. Naively, that would just
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) * mean using the ciphertext filenames. However, since the ciphertext filenames
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) * can contain illegal characters ('\0' and '/'), they must be encoded in some
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) * way. We use base64. But that can cause names to exceed NAME_MAX (255
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) * bytes), so we also need to use a strong hash to abbreviate long names.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) * The filesystem may also need another kind of hash, the "dirhash", to quickly
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) * find the directory entry. Since filesystems normally compute the dirhash
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) * over the on-disk filename (i.e. the ciphertext), it's not computable from
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) * no-key names that abbreviate the ciphertext using the strong hash to fit in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) * NAME_MAX. It's also not computable if it's a keyed hash taken over the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) * plaintext (but it may still be available in the on-disk directory entry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) * casefolded directories use this type of dirhash. At least in these cases,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) * each no-key name must include the name's dirhash too.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) * To meet all these requirements, we base64-encode the following
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) * variable-length structure. It contains the dirhash, or 0's if the filesystem
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) * didn't provide one; up to 149 bytes of the ciphertext name; and for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) * ciphertexts longer than 149 bytes, also the SHA-256 of the remaining bytes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) * This ensures that each no-key name contains everything needed to find the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) * directory entry again, contains only legal characters, doesn't exceed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) * NAME_MAX, is unambiguous unless there's a SHA-256 collision, and that we only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) * take the performance hit of SHA-256 on very long filenames (which are rare).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) struct fscrypt_nokey_name {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) u32 dirhash[2];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) u8 bytes[149];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) u8 sha256[SHA256_DIGEST_SIZE];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) }; /* 189 bytes => 252 bytes base64-encoded, which is <= NAME_MAX (255) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) * Decoded size of max-size nokey name, i.e. a name that was abbreviated using
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) * the strong hash and thus includes the 'sha256' field. This isn't simply
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) * sizeof(struct fscrypt_nokey_name), as the padding at the end isn't included.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) #define FSCRYPT_NOKEY_NAME_MAX offsetofend(struct fscrypt_nokey_name, sha256)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) if (str->len == 1 && str->name[0] == '.')
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) * fscrypt_fname_encrypt() - encrypt a filename
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) * @inode: inode of the parent directory (for regular filenames)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) * or of the symlink (for symlink targets)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) * @iname: the filename to encrypt
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) * @out: (output) the encrypted filename
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) * @olen: size of the encrypted filename. It must be at least @iname->len.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) * Any extra space is filled with NUL padding before encryption.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) * Return: 0 on success, -errno on failure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) u8 *out, unsigned int olen)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) struct skcipher_request *req = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) DECLARE_CRYPTO_WAIT(wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) const struct fscrypt_info *ci = inode->i_crypt_info;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) struct crypto_skcipher *tfm = ci->ci_enc_key.tfm;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) union fscrypt_iv iv;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) struct scatterlist sg;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) int res;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) * Copy the filename to the output buffer for encrypting in-place and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) * pad it with the needed number of NUL bytes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) if (WARN_ON(olen < iname->len))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) return -ENOBUFS;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) memcpy(out, iname->name, iname->len);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) memset(out + iname->len, 0, olen - iname->len);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) /* Initialize the IV */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) fscrypt_generate_iv(&iv, 0, ci);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) /* Set up the encryption request */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) req = skcipher_request_alloc(tfm, GFP_NOFS);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) if (!req)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) return -ENOMEM;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) skcipher_request_set_callback(req,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) crypto_req_done, &wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) sg_init_one(&sg, out, olen);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) skcipher_request_set_crypt(req, &sg, &sg, olen, &iv);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) /* Do the encryption */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) skcipher_request_free(req);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) if (res < 0) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) fscrypt_err(inode, "Filename encryption failed: %d", res);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) return res;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) * fname_decrypt() - decrypt a filename
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) * @inode: inode of the parent directory (for regular filenames)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) * or of the symlink (for symlink targets)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) * @iname: the encrypted filename to decrypt
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) * @oname: (output) the decrypted filename. The caller must have allocated
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) * enough space for this, e.g. using fscrypt_fname_alloc_buffer().
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) * Return: 0 on success, -errno on failure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) static int fname_decrypt(const struct inode *inode,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) const struct fscrypt_str *iname,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) struct fscrypt_str *oname)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) struct skcipher_request *req = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) DECLARE_CRYPTO_WAIT(wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) struct scatterlist src_sg, dst_sg;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) const struct fscrypt_info *ci = inode->i_crypt_info;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) struct crypto_skcipher *tfm = ci->ci_enc_key.tfm;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) union fscrypt_iv iv;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) int res;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) /* Allocate request */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) req = skcipher_request_alloc(tfm, GFP_NOFS);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) if (!req)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) return -ENOMEM;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) skcipher_request_set_callback(req,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) crypto_req_done, &wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) /* Initialize IV */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) fscrypt_generate_iv(&iv, 0, ci);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) /* Create decryption request */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) sg_init_one(&src_sg, iname->name, iname->len);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) sg_init_one(&dst_sg, oname->name, oname->len);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, &iv);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) skcipher_request_free(req);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) if (res < 0) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) fscrypt_err(inode, "Filename decryption failed: %d", res);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) return res;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) oname->len = strnlen(oname->name, iname->len);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) static const char lookup_table[65] =
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) #define BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) * base64_encode() - base64-encode some bytes
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) * @src: the bytes to encode
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) * @len: number of bytes to encode
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) * @dst: (output) the base64-encoded string. Not NUL-terminated.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) * Encodes the input string using characters from the set [A-Za-z0-9+,].
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) * The encoded string is roughly 4/3 times the size of the input string.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) * Return: length of the encoded string
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) static int base64_encode(const u8 *src, int len, char *dst)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) int i, bits = 0, ac = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) char *cp = dst;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) for (i = 0; i < len; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) ac += src[i] << bits;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) bits += 8;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) do {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) *cp++ = lookup_table[ac & 0x3f];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) ac >>= 6;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) bits -= 6;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) } while (bits >= 6);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) if (bits)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) *cp++ = lookup_table[ac & 0x3f];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) return cp - dst;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) static int base64_decode(const char *src, int len, u8 *dst)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) int i, bits = 0, ac = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) const char *p;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) u8 *cp = dst;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) for (i = 0; i < len; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) p = strchr(lookup_table, src[i]);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) if (p == NULL || src[i] == 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) return -2;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) ac += (p - lookup_table) << bits;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) bits += 6;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) if (bits >= 8) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) *cp++ = ac & 0xff;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) ac >>= 8;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) bits -= 8;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) if (ac)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) return -1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) return cp - dst;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) bool fscrypt_fname_encrypted_size(const union fscrypt_policy *policy,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) u32 orig_len, u32 max_len,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) u32 *encrypted_len_ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) int padding = 4 << (fscrypt_policy_flags(policy) &
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) FSCRYPT_POLICY_FLAGS_PAD_MASK);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) u32 encrypted_len;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) if (orig_len > max_len)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) encrypted_len = max(orig_len, (u32)FS_CRYPTO_BLOCK_SIZE);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) encrypted_len = round_up(encrypted_len, padding);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) *encrypted_len_ret = min(encrypted_len, max_len);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) * fscrypt_fname_alloc_buffer() - allocate a buffer for presented filenames
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254) * @max_encrypted_len: maximum length of encrypted filenames the buffer will be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255) * used to present
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) * @crypto_str: (output) buffer to allocate
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258) * Allocate a buffer that is large enough to hold any decrypted or encoded
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) * filename (null-terminated), for the given maximum encrypted filename length.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261) * Return: 0 on success, -errno on failure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) int fscrypt_fname_alloc_buffer(u32 max_encrypted_len,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264) struct fscrypt_str *crypto_str)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) const u32 max_encoded_len = BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267) u32 max_presented_len;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269) max_presented_len = max(max_encoded_len, max_encrypted_len);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271) crypto_str->name = kmalloc(max_presented_len + 1, GFP_NOFS);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272) if (!crypto_str->name)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273) return -ENOMEM;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) crypto_str->len = max_presented_len;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277) EXPORT_SYMBOL(fscrypt_fname_alloc_buffer);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) * fscrypt_fname_free_buffer() - free a buffer for presented filenames
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) * @crypto_str: the buffer to free
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283) * Free a buffer that was allocated by fscrypt_fname_alloc_buffer().
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285) void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287) if (!crypto_str)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288) return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) kfree(crypto_str->name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290) crypto_str->name = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) EXPORT_SYMBOL(fscrypt_fname_free_buffer);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295) * fscrypt_fname_disk_to_usr() - convert an encrypted filename to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) * user-presentable form
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297) * @inode: inode of the parent directory (for regular filenames)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) * or of the symlink (for symlink targets)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) * @hash: first part of the name's dirhash, if applicable. This only needs to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300) * be provided if the filename is located in an indexed directory whose
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) * encryption key may be unavailable. Not needed for symlink targets.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 302) * @minor_hash: second part of the name's dirhash, if applicable
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 303) * @iname: encrypted filename to convert. May also be "." or "..", which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 304) * aren't actually encrypted.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 305) * @oname: output buffer for the user-presentable filename. The caller must
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 306) * have allocated enough space for this, e.g. using
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 307) * fscrypt_fname_alloc_buffer().
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 308) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 309) * If the key is available, we'll decrypt the disk name. Otherwise, we'll
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 310) * encode it for presentation in fscrypt_nokey_name format.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 311) * See struct fscrypt_nokey_name for details.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 312) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 313) * Return: 0 on success, -errno on failure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 314) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 315) int fscrypt_fname_disk_to_usr(const struct inode *inode,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 316) u32 hash, u32 minor_hash,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 317) const struct fscrypt_str *iname,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 318) struct fscrypt_str *oname)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 319) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 320) const struct qstr qname = FSTR_TO_QSTR(iname);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 321) struct fscrypt_nokey_name nokey_name;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 322) u32 size; /* size of the unencoded no-key name */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 323)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 324) if (fscrypt_is_dot_dotdot(&qname)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 325) oname->name[0] = '.';
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 326) oname->name[iname->len - 1] = '.';
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 327) oname->len = iname->len;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 328) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 329) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 330)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 331) if (iname->len < FS_CRYPTO_BLOCK_SIZE)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 332) return -EUCLEAN;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 333)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 334) if (fscrypt_has_encryption_key(inode))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 335) return fname_decrypt(inode, iname, oname);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 336)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 337) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 338) * Sanity check that struct fscrypt_nokey_name doesn't have padding
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 339) * between fields and that its encoded size never exceeds NAME_MAX.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 340) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 341) BUILD_BUG_ON(offsetofend(struct fscrypt_nokey_name, dirhash) !=
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 342) offsetof(struct fscrypt_nokey_name, bytes));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 343) BUILD_BUG_ON(offsetofend(struct fscrypt_nokey_name, bytes) !=
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 344) offsetof(struct fscrypt_nokey_name, sha256));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 345) BUILD_BUG_ON(BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX) > NAME_MAX);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 346)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 347) nokey_name.dirhash[0] = hash;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 348) nokey_name.dirhash[1] = minor_hash;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 349)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 350) if (iname->len <= sizeof(nokey_name.bytes)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 351) memcpy(nokey_name.bytes, iname->name, iname->len);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 352) size = offsetof(struct fscrypt_nokey_name, bytes[iname->len]);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 353) } else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 354) memcpy(nokey_name.bytes, iname->name, sizeof(nokey_name.bytes));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 355) /* Compute strong hash of remaining part of name. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 356) sha256(&iname->name[sizeof(nokey_name.bytes)],
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 357) iname->len - sizeof(nokey_name.bytes),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 358) nokey_name.sha256);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 359) size = FSCRYPT_NOKEY_NAME_MAX;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 360) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 361) oname->len = base64_encode((const u8 *)&nokey_name, size, oname->name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 362) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 363) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 364) EXPORT_SYMBOL(fscrypt_fname_disk_to_usr);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 365)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 366) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 367) * fscrypt_setup_filename() - prepare to search a possibly encrypted directory
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 368) * @dir: the directory that will be searched
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 369) * @iname: the user-provided filename being searched for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 370) * @lookup: 1 if we're allowed to proceed without the key because it's
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 371) * ->lookup() or we're finding the dir_entry for deletion; 0 if we cannot
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 372) * proceed without the key because we're going to create the dir_entry.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 373) * @fname: the filename information to be filled in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 374) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 375) * Given a user-provided filename @iname, this function sets @fname->disk_name
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 376) * to the name that would be stored in the on-disk directory entry, if possible.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 377) * If the directory is unencrypted this is simply @iname. Else, if we have the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 378) * directory's encryption key, then @iname is the plaintext, so we encrypt it to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 379) * get the disk_name.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 380) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 381) * Else, for keyless @lookup operations, @iname should be a no-key name, so we
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 382) * decode it to get the struct fscrypt_nokey_name. Non-@lookup operations will
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 383) * be impossible in this case, so we fail them with ENOKEY.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 384) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 385) * If successful, fscrypt_free_filename() must be called later to clean up.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 386) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 387) * Return: 0 on success, -errno on failure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 388) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 389) int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 390) int lookup, struct fscrypt_name *fname)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 391) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 392) struct fscrypt_nokey_name *nokey_name;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 393) int ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 394)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 395) memset(fname, 0, sizeof(struct fscrypt_name));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 396) fname->usr_fname = iname;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 397)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 398) if (!IS_ENCRYPTED(dir) || fscrypt_is_dot_dotdot(iname)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 399) fname->disk_name.name = (unsigned char *)iname->name;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 400) fname->disk_name.len = iname->len;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 401) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 402) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 403) ret = fscrypt_get_encryption_info(dir, lookup);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 404) if (ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 405) return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 406)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 407) if (fscrypt_has_encryption_key(dir)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 408) if (!fscrypt_fname_encrypted_size(&dir->i_crypt_info->ci_policy,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 409) iname->len,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 410) dir->i_sb->s_cop->max_namelen,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 411) &fname->crypto_buf.len))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 412) return -ENAMETOOLONG;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 413) fname->crypto_buf.name = kmalloc(fname->crypto_buf.len,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 414) GFP_NOFS);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 415) if (!fname->crypto_buf.name)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 416) return -ENOMEM;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 417)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 418) ret = fscrypt_fname_encrypt(dir, iname, fname->crypto_buf.name,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 419) fname->crypto_buf.len);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 420) if (ret)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 421) goto errout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 422) fname->disk_name.name = fname->crypto_buf.name;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 423) fname->disk_name.len = fname->crypto_buf.len;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 424) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 425) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 426) if (!lookup)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 427) return -ENOKEY;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 428) fname->is_nokey_name = true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 429)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 430) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 431) * We don't have the key and we are doing a lookup; decode the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 432) * user-supplied name
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 433) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 434)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 435) if (iname->len > BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 436) return -ENOENT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 437)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 438) fname->crypto_buf.name = kmalloc(FSCRYPT_NOKEY_NAME_MAX, GFP_KERNEL);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 439) if (fname->crypto_buf.name == NULL)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 440) return -ENOMEM;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 441)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 442) ret = base64_decode(iname->name, iname->len, fname->crypto_buf.name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 443) if (ret < (int)offsetof(struct fscrypt_nokey_name, bytes[1]) ||
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 444) (ret > offsetof(struct fscrypt_nokey_name, sha256) &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 445) ret != FSCRYPT_NOKEY_NAME_MAX)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 446) ret = -ENOENT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 447) goto errout;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 448) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 449) fname->crypto_buf.len = ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 450)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 451) nokey_name = (void *)fname->crypto_buf.name;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 452) fname->hash = nokey_name->dirhash[0];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 453) fname->minor_hash = nokey_name->dirhash[1];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 454) if (ret != FSCRYPT_NOKEY_NAME_MAX) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 455) /* The full ciphertext filename is available. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 456) fname->disk_name.name = nokey_name->bytes;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 457) fname->disk_name.len =
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 458) ret - offsetof(struct fscrypt_nokey_name, bytes);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 459) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 460) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 461)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 462) errout:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 463) kfree(fname->crypto_buf.name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 464) return ret;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 465) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 466) EXPORT_SYMBOL(fscrypt_setup_filename);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 467)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 468) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 469) * fscrypt_match_name() - test whether the given name matches a directory entry
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 470) * @fname: the name being searched for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 471) * @de_name: the name from the directory entry
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 472) * @de_name_len: the length of @de_name in bytes
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 473) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 474) * Normally @fname->disk_name will be set, and in that case we simply compare
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 475) * that to the name stored in the directory entry. The only exception is that
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 476) * if we don't have the key for an encrypted directory and the name we're
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 477) * looking for is very long, then we won't have the full disk_name and instead
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 478) * we'll need to match against a fscrypt_nokey_name that includes a strong hash.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 479) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 480) * Return: %true if the name matches, otherwise %false.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 481) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 482) bool fscrypt_match_name(const struct fscrypt_name *fname,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 483) const u8 *de_name, u32 de_name_len)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 484) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 485) const struct fscrypt_nokey_name *nokey_name =
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 486) (const void *)fname->crypto_buf.name;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 487) u8 digest[SHA256_DIGEST_SIZE];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 488)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 489) if (likely(fname->disk_name.name)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 490) if (de_name_len != fname->disk_name.len)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 491) return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 492) return !memcmp(de_name, fname->disk_name.name, de_name_len);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 493) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 494) if (de_name_len <= sizeof(nokey_name->bytes))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 495) return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 496) if (memcmp(de_name, nokey_name->bytes, sizeof(nokey_name->bytes)))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 497) return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 498) sha256(&de_name[sizeof(nokey_name->bytes)],
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 499) de_name_len - sizeof(nokey_name->bytes), digest);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 500) return !memcmp(digest, nokey_name->sha256, sizeof(digest));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 501) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 502) EXPORT_SYMBOL_GPL(fscrypt_match_name);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 503)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 504) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 505) * fscrypt_fname_siphash() - calculate the SipHash of a filename
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 506) * @dir: the parent directory
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 507) * @name: the filename to calculate the SipHash of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 508) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 509) * Given a plaintext filename @name and a directory @dir which uses SipHash as
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 510) * its dirhash method and has had its fscrypt key set up, this function
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 511) * calculates the SipHash of that name using the directory's secret dirhash key.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 512) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 513) * Return: the SipHash of @name using the hash key of @dir
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 514) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 515) u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 516) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 517) const struct fscrypt_info *ci = dir->i_crypt_info;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 518)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 519) WARN_ON(!ci->ci_dirhash_key_initialized);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 520)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 521) return siphash(name->name, name->len, &ci->ci_dirhash_key);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 522) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 523) EXPORT_SYMBOL_GPL(fscrypt_fname_siphash);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 524)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 525) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 526) * Validate dentries in encrypted directories to make sure we aren't potentially
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 527) * caching stale dentries after a key has been added.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 528) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 529) int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 530) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 531) struct dentry *dir;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 532) int err;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 533) int valid;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 534)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 535) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 536) * Plaintext names are always valid, since fscrypt doesn't support
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 537) * reverting to no-key names without evicting the directory's inode
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 538) * -- which implies eviction of the dentries in the directory.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 539) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 540) if (!(dentry->d_flags & DCACHE_NOKEY_NAME))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 541) return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 542)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 543) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 544) * No-key name; valid if the directory's key is still unavailable.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 545) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 546) * Although fscrypt forbids rename() on no-key names, we still must use
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 547) * dget_parent() here rather than use ->d_parent directly. That's
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 548) * because a corrupted fs image may contain directory hard links, which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 549) * the VFS handles by moving the directory's dentry tree in the dcache
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 550) * each time ->lookup() finds the directory and it already has a dentry
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 551) * elsewhere. Thus ->d_parent can be changing, and we must safely grab
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 552) * a reference to some ->d_parent to prevent it from being freed.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 553) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 554)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 555) if (flags & LOOKUP_RCU)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 556) return -ECHILD;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 557)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 558) dir = dget_parent(dentry);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 559) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 560) * Pass allow_unsupported=true, so that files with an unsupported
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 561) * encryption policy can be deleted.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 562) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 563) err = fscrypt_get_encryption_info(d_inode(dir), true);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 564) valid = !fscrypt_has_encryption_key(d_inode(dir));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 565) dput(dir);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 566)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 567) if (err < 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 568) return err;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 569)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 570) return valid;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 571) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 572) EXPORT_SYMBOL_GPL(fscrypt_d_revalidate);
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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