diff options
Diffstat (limited to 'fs/cachefiles/key.c')
| -rw-r--r-- | fs/cachefiles/key.c | 201 |
1 files changed, 92 insertions, 109 deletions
diff --git a/fs/cachefiles/key.c b/fs/cachefiles/key.c index 7f94efc97e23..bf935e25bdbe 100644 --- a/fs/cachefiles/key.c +++ b/fs/cachefiles/key.c @@ -1,7 +1,7 @@ // SPDX-License-Identifier: GPL-2.0-or-later /* Key to pathname encoder * - * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) */ @@ -22,134 +22,117 @@ static const char cachefiles_filecharmap[256] = { [48 ... 127] = 1, /* '0' -> '~' */ }; +static inline unsigned int how_many_hex_digits(unsigned int x) +{ + return x ? round_up(ilog2(x) + 1, 4) / 4 : 0; +} + /* * turn the raw key into something cooked - * - the raw key should include the length in the two bytes at the front - * - the key may be up to 514 bytes in length (including the length word) + * - the key may be up to NAME_MAX in length (including the length word) * - "base64" encode the strange keys, mapping 3 bytes of raw to four of * cooked * - need to cut the cooked key into 252 char lengths (189 raw bytes) */ -char *cachefiles_cook_key(const u8 *raw, int keylen, uint8_t type) +bool cachefiles_cook_key(struct cachefiles_object *object) { - unsigned char csum, ch; - unsigned int acc; - char *key; - int loop, len, max, seg, mark, print; + const u8 *key = fscache_get_key(object->cookie), *kend; + unsigned char ch; + unsigned int acc, i, n, nle, nbe, keylen = object->cookie->key_len; + unsigned int b64len, len, print, pad; + char *name, sep; - _enter(",%d", keylen); + _enter(",%u,%*phN", keylen, keylen, key); - BUG_ON(keylen < 2 || keylen > 514); + BUG_ON(keylen > NAME_MAX - 3); - csum = raw[0] + raw[1]; print = 1; - for (loop = 2; loop < keylen; loop++) { - ch = raw[loop]; - csum += ch; + for (i = 0; i < keylen; i++) { + ch = key[i]; print &= cachefiles_filecharmap[ch]; } + /* If the path is usable ASCII, then we render it directly */ if (print) { - /* if the path is usable ASCII, then we render it directly */ - max = keylen - 2; - max += 2; /* two base64'd length chars on the front */ - max += 5; /* @checksum/M */ - max += 3 * 2; /* maximum number of segment dividers (".../M") - * is ((514 + 251) / 252) = 3 - */ - max += 1; /* NUL on end */ - } else { - /* calculate the maximum length of the cooked key */ - keylen = (keylen + 2) / 3; - - max = keylen * 4; - max += 5; /* @checksum/M */ - max += 3 * 2; /* maximum number of segment dividers (".../M") - * is ((514 + 188) / 189) = 3 - */ - max += 1; /* NUL on end */ + len = 1 + keylen; + name = kmalloc(len + 1, GFP_KERNEL); + if (!name) + return false; + + name[0] = 'D'; /* Data object type, string encoding */ + memcpy(name + 1, key, keylen); + goto success; } - max += 1; /* 2nd NUL on end */ - - _debug("max: %d", max); - - key = kmalloc(max, cachefiles_gfp); - if (!key) - return NULL; - - len = 0; - - /* build the cooked key */ - sprintf(key, "@%02x%c+", (unsigned) csum, 0); - len = 5; - mark = len - 1; - - if (print) { - acc = *(uint16_t *) raw; - raw += 2; - - key[len + 1] = cachefiles_charmap[acc & 63]; - acc >>= 6; - key[len] = cachefiles_charmap[acc & 63]; - len += 2; - - seg = 250; - for (loop = keylen; loop > 0; loop--) { - if (seg <= 0) { - key[len++] = '\0'; - mark = len; - key[len++] = '+'; - seg = 252; - } - - key[len++] = *raw++; - ASSERT(len < max); - } - - switch (type) { - case FSCACHE_COOKIE_TYPE_INDEX: type = 'I'; break; - case FSCACHE_COOKIE_TYPE_DATAFILE: type = 'D'; break; - default: type = 'S'; break; - } - } else { - seg = 252; - for (loop = keylen; loop > 0; loop--) { - if (seg <= 0) { - key[len++] = '\0'; - mark = len; - key[len++] = '+'; - seg = 252; - } - - acc = *raw++; - acc |= *raw++ << 8; - acc |= *raw++ << 16; - - _debug("acc: %06x", acc); - - key[len++] = cachefiles_charmap[acc & 63]; - acc >>= 6; - key[len++] = cachefiles_charmap[acc & 63]; - acc >>= 6; - key[len++] = cachefiles_charmap[acc & 63]; - acc >>= 6; - key[len++] = cachefiles_charmap[acc & 63]; - - ASSERT(len < max); - } + /* See if it makes sense to encode it as "hex,hex,hex" for each 32-bit + * chunk. We rely on the key having been padded out to a whole number + * of 32-bit words. + */ + n = round_up(keylen, 4); + nbe = nle = 0; + for (i = 0; i < n; i += 4) { + u32 be = be32_to_cpu(*(__be32 *)(key + i)); + u32 le = le32_to_cpu(*(__le32 *)(key + i)); + + nbe += 1 + how_many_hex_digits(be); + nle += 1 + how_many_hex_digits(le); + } - switch (type) { - case FSCACHE_COOKIE_TYPE_INDEX: type = 'J'; break; - case FSCACHE_COOKIE_TYPE_DATAFILE: type = 'E'; break; - default: type = 'T'; break; + b64len = DIV_ROUND_UP(keylen, 3); + pad = b64len * 3 - keylen; + b64len = 2 + b64len * 4; /* Length if we base64-encode it */ + _debug("len=%u nbe=%u nle=%u b64=%u", keylen, nbe, nle, b64len); + if (nbe < b64len || nle < b64len) { + unsigned int nlen = min(nbe, nle) + 1; + name = kmalloc(nlen, GFP_KERNEL); + if (!name) + return false; + sep = (nbe <= nle) ? 'S' : 'T'; /* Encoding indicator */ + len = 0; + for (i = 0; i < n; i += 4) { + u32 x; + if (nbe <= nle) + x = be32_to_cpu(*(__be32 *)(key + i)); + else + x = le32_to_cpu(*(__le32 *)(key + i)); + name[len++] = sep; + if (x != 0) + len += snprintf(name + len, nlen - len, "%x", x); + sep = ','; } + goto success; } - key[mark] = type; - key[len++] = 0; - key[len] = 0; + /* We need to base64-encode it */ + name = kmalloc(b64len + 1, GFP_KERNEL); + if (!name) + return false; + + name[0] = 'E'; + name[1] = '0' + pad; + len = 2; + kend = key + keylen; + do { + acc = *key++; + if (key < kend) { + acc |= *key++ << 8; + if (key < kend) + acc |= *key++ << 16; + } - _leave(" = %s %d", key, len); - return key; + name[len++] = cachefiles_charmap[acc & 63]; + acc >>= 6; + name[len++] = cachefiles_charmap[acc & 63]; + acc >>= 6; + name[len++] = cachefiles_charmap[acc & 63]; + acc >>= 6; + name[len++] = cachefiles_charmap[acc & 63]; + } while (key < kend); + +success: + name[len] = 0; + object->d_name = name; + object->d_name_len = len; + _leave(" = %s", object->d_name); + return true; } |