From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6626C433EF for ; Wed, 1 Dec 2021 05:46:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234654AbhLAFt3 (ORCPT ); Wed, 1 Dec 2021 00:49:29 -0500 Received: from out30-56.freemail.mail.aliyun.com ([115.124.30.56]:37247 "EHLO out30-56.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230497AbhLAFt2 (ORCPT ); Wed, 1 Dec 2021 00:49:28 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R151e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=18;SR=0;TI=SMTPD_---0UywY0em_1638337562; Received: from 30.225.24.24(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0UywY0em_1638337562) by smtp.aliyun-inc.com(127.0.0.1); Wed, 01 Dec 2021 13:46:04 +0800 Message-ID: Date: Wed, 1 Dec 2021 13:46:02 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [PATCH 44/64] cachefiles: Implement key to filename encoding Content-Language: en-US To: David Howells , linux-cachefs@redhat.com Cc: Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet , Jeff Layton , Matthew Wilcox , Alexander Viro , Omar Sandoval , Linus Torvalds , linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <163819575444.215744.318477214576928110.stgit@warthog.procyon.org.uk> <163819640393.215744.15212364106412961104.stgit@warthog.procyon.org.uk> From: JeffleXu In-Reply-To: <163819640393.215744.15212364106412961104.stgit@warthog.procyon.org.uk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org On 11/29/21 10:33 PM, David Howells wrote: > +/* > + * turn the raw key into something cooked > + * - 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) > + */ > +bool cachefiles_cook_key(struct cachefiles_object *object) > +{ > + 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(",%u,%*phN", keylen, keylen, key); > + > + BUG_ON(keylen > NAME_MAX - 3); > + > + print = 1; > + 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) { > + len = 1 + keylen + 1; > + name = kmalloc(len, GFP_KERNEL); > + if (!name) > + return false; > + > + name[0] = 'D'; /* Data object type, string encoding */ > + name[1 + keylen] = 0; > + memcpy(name + 1, key, keylen); > + goto success; ^ If we goto success from here, > + } > + > + /* 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); > + } > + > + 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; > + } > + > + /* 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; > + } > + > + 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; ^ then it seems that this will cause an out-of-boundary access. > + object->d_name = name; > + object->d_name_len = len; > + _leave(" = %s", object->d_name); > + return true; > +} > -- Thanks, Jeffle