From patchwork Mon Sep 16 16:30:49 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Enzo Matsumiya X-Patchwork-Id: 1986195 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=x8TU8mtB; dkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=NhfuZ8Vu; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=x8TU8mtB; dkim=neutral header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=NhfuZ8Vu; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=2604:1380:4601:e00::3; helo=am.mirrors.kernel.org; envelope-from=linux-cifs+bounces-2812-incoming=patchwork.ozlabs.org@vger.kernel.org; receiver=patchwork.ozlabs.org) Received: from am.mirrors.kernel.org (am.mirrors.kernel.org [IPv6:2604:1380:4601:e00::3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (secp384r1) server-digest SHA384) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4X6r5X0T54z1y1g for ; Tue, 17 Sep 2024 02:31:28 +1000 (AEST) Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by am.mirrors.kernel.org (Postfix) with ESMTPS id 02E811F22F10 for ; Mon, 16 Sep 2024 16:31:25 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 821A4266AB; Mon, 16 Sep 2024 16:31:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b="x8TU8mtB"; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b="NhfuZ8Vu"; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b="x8TU8mtB"; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b="NhfuZ8Vu" X-Original-To: linux-cifs@vger.kernel.org Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 252B917753 for ; Mon, 16 Sep 2024 16:31:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.130 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726504282; cv=none; b=d/68dudkbu1D5CacVSqFcw3QT0/dxEMvhLv9SIQCLC3XFmRyX4mLWYo9qxtsj0LygPvhPfYoYXzfoLrXcxDIuTLlW0oPKDXy2xU1f9WXYxrDWCB64qHYtyLNST1nw+IFBb6ovbDPnDwfOxwzheKqcVbnP1yuiwGnmiS3lNnIqZI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726504282; c=relaxed/simple; bh=WITxlsylckl2ORoQeOBH/YLb23eYOZBk/FE4KKS0VF8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=oM/05kRG9VfmdqAYivn/KHxPwlyGm4YO5kEaAtsO+xjpBtM19iVmitjG+HFWPp6HqVeVKFfFnguuBj+pwmshvcT+mf2k629bvt3HrZ9fRjvdxbaTiozBhodE4wwvIilf6pzNzfAzsP4un6cwnKGwDcR4L67Zd5CV6rAcciituzY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de; spf=pass smtp.mailfrom=suse.de; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b=x8TU8mtB; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b=NhfuZ8Vu; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b=x8TU8mtB; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b=NhfuZ8Vu; arc=none smtp.client-ip=195.135.223.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.de Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 3957721C15; Mon, 16 Sep 2024 16:31:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1726504278; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=hhbzZhZfl2oTqHTz0b6ljJ1GmefTjQZUbbKN8w2Vkgk=; b=x8TU8mtB8ol3p7HJCZG0CBe96UjTAScqc48x9eR0WxLhYEULXC3yoMOWRIYu+lBJAFycXC txV2NnozeS+/2+sH036JbevkV+leLiLTwLhQKwvidAYHE5sp07vbak3TVSr207NxspdHZ5 OSKx20xMbWHs1qE5xWMF0ay8MdPjfbY= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1726504278; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=hhbzZhZfl2oTqHTz0b6ljJ1GmefTjQZUbbKN8w2Vkgk=; b=NhfuZ8Vuq4sI+LCH2wb8rZ5geshzkBD1rNrwPX6OiK7p42AooBQ8IckG1q9OVTsl8S14It hDMnjHi3pjp4zUBg== Authentication-Results: smtp-out1.suse.de; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=x8TU8mtB; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=NhfuZ8Vu DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1726504278; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=hhbzZhZfl2oTqHTz0b6ljJ1GmefTjQZUbbKN8w2Vkgk=; b=x8TU8mtB8ol3p7HJCZG0CBe96UjTAScqc48x9eR0WxLhYEULXC3yoMOWRIYu+lBJAFycXC txV2NnozeS+/2+sH036JbevkV+leLiLTwLhQKwvidAYHE5sp07vbak3TVSr207NxspdHZ5 OSKx20xMbWHs1qE5xWMF0ay8MdPjfbY= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1726504278; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=hhbzZhZfl2oTqHTz0b6ljJ1GmefTjQZUbbKN8w2Vkgk=; b=NhfuZ8Vuq4sI+LCH2wb8rZ5geshzkBD1rNrwPX6OiK7p42AooBQ8IckG1q9OVTsl8S14It hDMnjHi3pjp4zUBg== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id AC089139CE; Mon, 16 Sep 2024 16:31:17 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id CZJIHFVd6GZQWgAAD6G6ig (envelope-from ); Mon, 16 Sep 2024 16:31:17 +0000 From: Enzo Matsumiya To: linux-cifs@vger.kernel.org Cc: smfrench@gmail.com, pc@manguebit.com, ronniesahlberg@gmail.com, sprasad@microsoft.com, tom@talpey.com, bharathsm@microsoft.com, henrique.carvalho@suse.com, Dan Carpenter Subject: [PATCH] smb: client: fix compression heuristic functions Date: Mon, 16 Sep 2024 13:30:49 -0300 Message-ID: <20240916163049.287477-1-ematsumiya@suse.de> X-Mailer: git-send-email 2.46.0 Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Rspamd-Queue-Id: 3957721C15 X-Spam-Level: X-Spamd-Result: default: False [-3.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FUZZY_BLOCKED(0.00)[rspamd.com]; FREEMAIL_CC(0.00)[gmail.com,manguebit.com,microsoft.com,talpey.com,suse.com,linaro.org]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,suse.de:dkim,suse.de:mid,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCPT_COUNT_SEVEN(0.00)[9]; DKIM_TRACE(0.00)[suse.de:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -3.01 X-Spam-Flag: NO Change is_compressible() return type to bool, use WARN_ON_ONCE(1) for internal errors and return false for those. Renames: check_repeated_data -> has_repeated_data check_ascii_bytes -> is_mostly_ascii (also refactor into a single loop) calc_shannon_entropy -> has_low_entropy Also wraps "wreq->Length" in le32_to_cpu() in should_compress() (caught by sparse). Signed-off-by: Enzo Matsumiya Reported-by: Dan Carpenter --- fs/smb/client/compress.c | 105 ++++++++++++++++++++------------------- 1 file changed, 55 insertions(+), 50 deletions(-) diff --git a/fs/smb/client/compress.c b/fs/smb/client/compress.c index 2c008e9f0206..63b5a55b7a57 100644 --- a/fs/smb/client/compress.c +++ b/fs/smb/client/compress.c @@ -45,7 +45,7 @@ struct bucket { }; /** - * calc_shannon_entropy() - Compute Shannon entropy of the sampled data. + * has_low_entropy() - Compute Shannon entropy of the sampled data. * @bkt: Bytes counts of the sample. * @slen: Size of the sample. * @@ -60,7 +60,7 @@ struct bucket { * Also Shannon entropy is the last computed heuristic; if we got this far and ended up * with uncertainty, just stay on the safe side and call it uncompressible. */ -static bool calc_shannon_entropy(struct bucket *bkt, size_t slen) +static bool has_low_entropy(struct bucket *bkt, size_t slen) { const size_t threshold = 65, max_entropy = 8 * ilog2(16); size_t i, p, p2, len, sum = 0; @@ -79,17 +79,21 @@ static bool calc_shannon_entropy(struct bucket *bkt, size_t slen) return ((sum * 100 / max_entropy) <= threshold); } +#define BYTE_DIST_BAD 0 +#define BYTE_DIST_GOOD 1 +#define BYTE_DIST_MAYBE 2 /** * calc_byte_distribution() - Compute byte distribution on the sampled data. * @bkt: Byte counts of the sample. * @slen: Size of the sample. * * Return: - * 1: High probability (normal (Gaussian) distribution) of the data being compressible. - * 0: A "hard no" for compression -- either a computed uniform distribution of the bytes (e.g. - * random or encrypted data), or calc_shannon_entropy() returned false (see above). - * 2: When computed byte distribution resulted in "low > n < high" grounds. - * calc_shannon_entropy() should be used for a final decision. + * BYTE_DIST_BAD: A "hard no" for compression -- a computed uniform distribution of + * the bytes (e.g. random or encrypted data). + * BYTE_DIST_GOOD: High probability (normal (Gaussian) distribution) of the data being + * compressible. + * BYTE_DIST_MAYBE: When computed byte distribution resulted in "low > n < high" + * grounds. has_low_entropy() should be used for a final decision. */ static int calc_byte_distribution(struct bucket *bkt, size_t slen) { @@ -101,7 +105,7 @@ static int calc_byte_distribution(struct bucket *bkt, size_t slen) sum += bkt[i].count; if (sum > threshold) - return i; + return BYTE_DIST_BAD; for (; i < high && bkt[i].count > 0; i++) { sum += bkt[i].count; @@ -110,36 +114,29 @@ static int calc_byte_distribution(struct bucket *bkt, size_t slen) } if (i <= low) - return 1; + return BYTE_DIST_GOOD; if (i >= high) - return 0; + return BYTE_DIST_BAD; - return 2; + return BYTE_DIST_MAYBE; } -static bool check_ascii_bytes(const struct bucket *bkt) +static bool is_mostly_ascii(const struct bucket *bkt) { - const size_t threshold = 64; size_t count = 0; int i; - for (i = 0; i < threshold; i++) + for (i = 0; i < 256; i++) if (bkt[i].count > 0) - count++; + /* Too many non-ASCII (0-63) bytes. */ + if (++count > 64) + return false; - for (; i < 256; i++) { - if (bkt[i].count > 0) { - count++; - if (count > threshold) - break; - } - } - - return (count < threshold); + return true; } -static bool check_repeated_data(const u8 *sample, size_t len) +static bool has_repeated_data(const u8 *sample, size_t len) { size_t s = len / 2; @@ -222,71 +219,79 @@ static int collect_sample(const struct iov_iter *iter, ssize_t max, u8 *sample) * is_compressible() - Determines if a chunk of data is compressible. * @data: Iterator containing uncompressed data. * - * Return: - * 0: @data is not compressible - * 1: @data is compressible - * -ENOMEM: failed to allocate memory for sample buffer + * Return: true if @data is compressible, false otherwise. * * Tests shows that this function is quite reliable in predicting data compressibility, * matching close to 1:1 with the behaviour of LZ77 compression success and failures. */ -static int is_compressible(const struct iov_iter *data) +static bool is_compressible(const struct iov_iter *data) { const size_t read_size = SZ_2K, bkt_size = 256, max = SZ_4M; struct bucket *bkt = NULL; - int i = 0, ret = 0; size_t len; u8 *sample; + bool ret = false; + int i; + /* Preventive double check -- already checked in should_compress(). */ len = iov_iter_count(data); - if (len < read_size) - return 0; + if (unlikely(len < read_size)) + return ret; if (len - read_size > max) len = max; sample = kvzalloc(len, GFP_KERNEL); - if (!sample) - return -ENOMEM; + if (!sample) { + WARN_ON_ONCE(1); + + return ret; + } /* Sample 2K bytes per page of the uncompressed data. */ - ret = collect_sample(data, len, sample); - if (ret < 0) + i = collect_sample(data, len, sample); + if (i <= 0) { + WARN_ON_ONCE(1); + goto out; + } - len = ret; - ret = 1; + len = i; + ret = true; - if (check_repeated_data(sample, len)) + if (has_repeated_data(sample, len)) goto out; bkt = kcalloc(bkt_size, sizeof(*bkt), GFP_KERNEL); if (!bkt) { - kvfree(sample); - return -ENOMEM; + WARN_ON_ONCE(1); + ret = false; + + goto out; } for (i = 0; i < len; i++) bkt[sample[i]].count++; - if (check_ascii_bytes(bkt)) + if (is_mostly_ascii(bkt)) goto out; /* Sort in descending order */ sort(bkt, bkt_size, sizeof(*bkt), cmp_bkt, NULL); - ret = calc_byte_distribution(bkt, len); - if (ret != 2) + i = calc_byte_distribution(bkt, len); + if (i != BYTE_DIST_MAYBE) { + ret = !!i; + goto out; + } - ret = calc_shannon_entropy(bkt, len); + ret = has_low_entropy(bkt, len); out: kvfree(sample); kfree(bkt); - WARN(ret < 0, "%s: ret=%d\n", __func__, ret); - - return !!ret; + return ret; } bool should_compress(const struct cifs_tcon *tcon, const struct smb_rqst *rq) @@ -305,7 +310,7 @@ bool should_compress(const struct cifs_tcon *tcon, const struct smb_rqst *rq) if (shdr->Command == SMB2_WRITE) { const struct smb2_write_req *wreq = rq->rq_iov->iov_base; - if (wreq->Length < SMB_COMPRESS_MIN_LEN) + if (le32_to_cpu(wreq->Length) < SMB_COMPRESS_MIN_LEN) return false; return is_compressible(&rq->rq_iter);