From patchwork Tue Jul 27 14:48:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 12402989 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B125C4338F for ; Tue, 27 Jul 2021 14:49:34 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CA33E61B03 for ; Tue, 27 Jul 2021 14:49:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org CA33E61B03 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 6EF276B0070; Tue, 27 Jul 2021 10:49:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 69EDD6B0071; Tue, 27 Jul 2021 10:49:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 567D08D0001; Tue, 27 Jul 2021 10:49:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0224.hostedemail.com [216.40.44.224]) by kanga.kvack.org (Postfix) with ESMTP id 161106B0070 for ; Tue, 27 Jul 2021 10:49:33 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 987B08249980 for ; Tue, 27 Jul 2021 14:49:32 +0000 (UTC) X-FDA: 78408651384.05.A8470CF Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf22.hostedemail.com (Postfix) with ESMTP id 390DD4656 for ; Tue, 27 Jul 2021 14:49:32 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id F238F61B05; Tue, 27 Jul 2021 14:49:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627397371; bh=uEwQ9C0cLg3IwMIORY/37dlh5O4fu4jNkU/FjsRvIrE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kj/IVvXy3JHWkqM0XFNYDPQdxSxj8JggLNuER9Hto8/iywRcIWO4ntU+1XOU+vznN nwEKRsA+VKIKup4+NtVyRDYRpls5U2TXGCwqj3BJNmiv5sKmAucefRYvBWnZGg/gWZ c82xtneZYpDFHr8DZcbROOlVG3lPysp9nfW3etc11bBGulX+P5auZXokAklC34LE09 zwwS/wKlWBr3BJYnxmJQmo/nNvm9893oVZ0YfCEUg2WJgjbqKzN5nBIr50IymV9mHv xGRSVKAvWuWMXXuS4LWxtdDEitvbuLrJU8AGGYaPMslKu0GUWYCUOcXlo8lTk6GhMM d1I9fnI2UDWGQ== From: Arnd Bergmann To: Andrew Morton Cc: Arnd Bergmann , Catalin Marinas , Will Deacon , Thomas Bogendoerfer , "James E.J. Bottomley" , Helge Deller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , "David S. Miller" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Al Viro , "Eric W. Biederman" , Christoph Hellwig , Feng Tang , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v5 2/6] kexec: avoid compat_alloc_user_space Date: Tue, 27 Jul 2021 16:48:55 +0200 Message-Id: <20210727144859.4150043-3-arnd@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210727144859.4150043-1-arnd@kernel.org> References: <20210727144859.4150043-1-arnd@kernel.org> MIME-Version: 1.0 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 390DD4656 Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="kj/IVvXy"; spf=pass (imf22.hostedemail.com: domain of arnd@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=arnd@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-Stat-Signature: 8atjhbyzkp87zw5n9kpjkup88omwzekr X-HE-Tag: 1627397372-364224 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Arnd Bergmann kimage_alloc_init() expects a __user pointer, so compat_sys_kexec_load() uses compat_alloc_user_space() to convert the layout and put it back onto the user space caller stack. Moving the user space access into the syscall handler directly actually makes the code simpler, as the conversion for compat mode can now be done on kernel memory. Co-developed-by: Eric Biederman Co-developed-by: Christoph Hellwig Link: https://lore.kernel.org/lkml/YPbtsU4GX6PL7%2F42@infradead.org/ Link: https://lore.kernel.org/lkml/m1y2cbzmnw.fsf@fess.ebiederm.org/ Signed-off-by: Arnd Bergmann Acked-by: "Eric W. Biederman" --- kernel/kexec.c | 61 +++++++++++++++++++++----------------------------- 1 file changed, 25 insertions(+), 36 deletions(-) diff --git a/kernel/kexec.c b/kernel/kexec.c index 9c7aef8f4bb6..b5e40f069768 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -19,26 +19,9 @@ #include "kexec_internal.h" -static int copy_user_segment_list(struct kimage *image, - unsigned long nr_segments, - struct kexec_segment __user *segments) -{ - int ret; - size_t segment_bytes; - - /* Read in the segments */ - image->nr_segments = nr_segments; - segment_bytes = nr_segments * sizeof(*segments); - ret = copy_from_user(image->segment, segments, segment_bytes); - if (ret) - ret = -EFAULT; - - return ret; -} - static int kimage_alloc_init(struct kimage **rimage, unsigned long entry, unsigned long nr_segments, - struct kexec_segment __user *segments, + struct kexec_segment *segments, unsigned long flags) { int ret; @@ -58,10 +41,8 @@ static int kimage_alloc_init(struct kimage **rimage, unsigned long entry, return -ENOMEM; image->start = entry; - - ret = copy_user_segment_list(image, nr_segments, segments); - if (ret) - goto out_free_image; + image->nr_segments = nr_segments; + memcpy(image->segment, segments, nr_segments * sizeof(*segments)); if (kexec_on_panic) { /* Enable special crash kernel control page alloc policy. */ @@ -104,7 +85,7 @@ static int kimage_alloc_init(struct kimage **rimage, unsigned long entry, } static int do_kexec_load(unsigned long entry, unsigned long nr_segments, - struct kexec_segment __user *segments, unsigned long flags) + struct kexec_segment *segments, unsigned long flags) { struct kimage **dest_image, *image; unsigned long i; @@ -250,7 +231,8 @@ static inline int kexec_load_check(unsigned long nr_segments, SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments, struct kexec_segment __user *, segments, unsigned long, flags) { - int result; + struct kexec_segment *ksegments; + unsigned long result; result = kexec_load_check(nr_segments, flags); if (result) @@ -261,7 +243,12 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments, ((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT)) return -EINVAL; - result = do_kexec_load(entry, nr_segments, segments, flags); + ksegments = memdup_user(segments, nr_segments * sizeof(ksegments[0])); + if (IS_ERR(ksegments)) + return PTR_ERR(ksegments); + + result = do_kexec_load(entry, nr_segments, ksegments, flags); + kfree(ksegments); return result; } @@ -273,7 +260,7 @@ COMPAT_SYSCALL_DEFINE4(kexec_load, compat_ulong_t, entry, compat_ulong_t, flags) { struct compat_kexec_segment in; - struct kexec_segment out, __user *ksegments; + struct kexec_segment *ksegments; unsigned long i, result; result = kexec_load_check(nr_segments, flags); @@ -286,24 +273,26 @@ COMPAT_SYSCALL_DEFINE4(kexec_load, compat_ulong_t, entry, if ((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_DEFAULT) return -EINVAL; - ksegments = compat_alloc_user_space(nr_segments * sizeof(out)); + ksegments = kmalloc_array(nr_segments, sizeof(ksegments[0]), + GFP_KERNEL); + if (!ksegments) + return -ENOMEM; + for (i = 0; i < nr_segments; i++) { result = copy_from_user(&in, &segments[i], sizeof(in)); if (result) - return -EFAULT; + goto fail; - out.buf = compat_ptr(in.buf); - out.bufsz = in.bufsz; - out.mem = in.mem; - out.memsz = in.memsz; - - result = copy_to_user(&ksegments[i], &out, sizeof(out)); - if (result) - return -EFAULT; + ksegments[i].buf = compat_ptr(in.buf); + ksegments[i].bufsz = in.bufsz; + ksegments[i].mem = in.mem; + ksegments[i].memsz = in.memsz; } result = do_kexec_load(entry, nr_segments, ksegments, flags); +fail: + kfree(ksegments); return result; } #endif