From patchwork Tue Jul 27 14:48:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 12403023 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=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 B0F28C19F3E for ; Tue, 27 Jul 2021 14:51:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C0C561B04 for ; Tue, 27 Jul 2021 14:51:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237209AbhG0Ou7 (ORCPT ); Tue, 27 Jul 2021 10:50:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:36536 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236975AbhG0Otz (ORCPT ); Tue, 27 Jul 2021 10:49:55 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D9E2F61B1D; Tue, 27 Jul 2021 14:49:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627397383; bh=dPlYDstFTxk7KvXXSkILqtki5oTr7BN9WPbKn/8kEtM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bZ6SiXuwV201vvaDIV2Ua5zgTNHmbQ50GceUzNEOVnFQmjvQBjX5dzQtyK4Tl7xs5 7zDao+S8i4xpU7F2i4Cj3MoaxUvAqPyueMDk7tEWKRGJ2fruXb4OI+dC69QDO3sDjF p+7JadXON5ZaVQoIImfxjNgsP784PBt+6o4VOkBByDbh3iYSdRUfDswFq3OpdOBvEg iz9U0zHNQWsQmDUBeNSLb9zz3VS4WV20Ff4FKvy3cvlkGoXcNON60t/mTyIo/fF5kb dyc2rLUW4CnwqFSUrYoHMtlNL6KSXRo1J0G17Od1Fgw29s4tO7lgN4BRWZjKwPlHPL pEwIDZj5r/0XA== 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, Christoph Hellwig Subject: [PATCH v5 4/6] mm: simplify compat numa syscalls Date: Tue, 27 Jul 2021 16:48:57 +0200 Message-Id: <20210727144859.4150043-5-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 Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org From: Arnd Bergmann The compat implementations for mbind, get_mempolicy, set_mempolicy and migrate_pages are just there to handle the subtly different layout of bitmaps on 32-bit hosts. The compat implementation however lacks some of the checks that are present in the native one, in particular for checking that the extra bits are all zero when user space has a larger mask size than the kernel. Worse, those extra bits do not get cleared when copying in or out of the kernel, which can lead to incorrect data as well. Unify the implementation to handle the compat bitmap layout directly in the get_nodes() and copy_nodes_to_user() helpers. Splitting out the get_bitmap() helper from get_nodes() also helps readability of the native case. On x86, two additional problems are addressed by this: compat tasks can pass a bitmap at the end of a mapping, causing a fault when reading across the page boundary for a 64-bit word. x32 tasks might also run into problems with get_mempolicy corrupting data when an odd number of 32-bit words gets passed. On parisc the migrate_pages() system call apparently had the wrong calling convention, as big-endian architectures expect the words inside of a bitmap to be swapped. This is not a problem though since parisc has no NUMA support. Reviewed-by: Christoph Hellwig Signed-off-by: Arnd Bergmann --- include/linux/compat.h | 17 ++-- mm/mempolicy.c | 175 +++++++++++++---------------------------- 2 files changed, 63 insertions(+), 129 deletions(-) diff --git a/include/linux/compat.h b/include/linux/compat.h index 8e0598c7d1d1..3a2ac5afee30 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -395,14 +395,6 @@ struct compat_kexec_segment; struct compat_mq_attr; struct compat_msgbuf; -#define BITS_PER_COMPAT_LONG (8*sizeof(compat_long_t)) - -#define BITS_TO_COMPAT_LONGS(bits) DIV_ROUND_UP(bits, BITS_PER_COMPAT_LONG) - -long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask, - unsigned long bitmap_size); -long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask, - unsigned long bitmap_size); void copy_siginfo_to_external32(struct compat_siginfo *to, const struct kernel_siginfo *from); int copy_siginfo_from_user32(kernel_siginfo_t *to, @@ -976,6 +968,15 @@ static inline bool in_compat_syscall(void) { return false; } #endif /* CONFIG_COMPAT */ +#define BITS_PER_COMPAT_LONG (8*sizeof(compat_long_t)) + +#define BITS_TO_COMPAT_LONGS(bits) DIV_ROUND_UP(bits, BITS_PER_COMPAT_LONG) + +long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask, + unsigned long bitmap_size); +long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask, + unsigned long bitmap_size); + /* * Some legacy ABIs like the i386 one use less than natural alignment for 64-bit * types, and will need special compat treatment for that. Most architectures diff --git a/mm/mempolicy.c b/mm/mempolicy.c index e32360e90274..9bc5dabdb7a7 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1362,16 +1362,33 @@ static long do_mbind(unsigned long start, unsigned long len, /* * User space interface with variable sized bitmaps for nodelists. */ +static int get_bitmap(unsigned long *mask, const unsigned long __user *nmask, + unsigned long maxnode) +{ + unsigned long nlongs = BITS_TO_LONGS(maxnode); + int ret; + + if (in_compat_syscall()) + ret = compat_get_bitmap(mask, + (const compat_ulong_t __user *)nmask, + maxnode); + else + ret = copy_from_user(mask, nmask, + nlongs * sizeof(unsigned long)); + + if (ret) + return -EFAULT; + + if (maxnode % BITS_PER_LONG) + mask[nlongs - 1] &= (1UL << (maxnode % BITS_PER_LONG)) - 1; + + return 0; +} /* Copy a node mask from user space. */ static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask, unsigned long maxnode) { - unsigned long k; - unsigned long t; - unsigned long nlongs; - unsigned long endmask; - --maxnode; nodes_clear(*nodes); if (maxnode == 0 || !nmask) @@ -1379,49 +1396,29 @@ static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask, if (maxnode > PAGE_SIZE*BITS_PER_BYTE) return -EINVAL; - nlongs = BITS_TO_LONGS(maxnode); - if ((maxnode % BITS_PER_LONG) == 0) - endmask = ~0UL; - else - endmask = (1UL << (maxnode % BITS_PER_LONG)) - 1; - /* * When the user specified more nodes than supported just check - * if the non supported part is all zero. - * - * If maxnode have more longs than MAX_NUMNODES, check - * the bits in that area first. And then go through to - * check the rest bits which equal or bigger than MAX_NUMNODES. - * Otherwise, just check bits [MAX_NUMNODES, maxnode). + * if the non supported part is all zero, one word at a time, + * starting at the end. */ - if (nlongs > BITS_TO_LONGS(MAX_NUMNODES)) { - for (k = BITS_TO_LONGS(MAX_NUMNODES); k < nlongs; k++) { - if (get_user(t, nmask + k)) - return -EFAULT; - if (k == nlongs - 1) { - if (t & endmask) - return -EINVAL; - } else if (t) - return -EINVAL; - } - nlongs = BITS_TO_LONGS(MAX_NUMNODES); - endmask = ~0UL; - } + while (maxnode > MAX_NUMNODES) { + unsigned long bits = min_t(unsigned long, maxnode, BITS_PER_LONG); + unsigned long t; - if (maxnode > MAX_NUMNODES && MAX_NUMNODES % BITS_PER_LONG != 0) { - unsigned long valid_mask = endmask; - - valid_mask &= ~((1UL << (MAX_NUMNODES % BITS_PER_LONG)) - 1); - if (get_user(t, nmask + nlongs - 1)) + if (get_bitmap(&t, &nmask[maxnode / BITS_PER_LONG], bits)) return -EFAULT; - if (t & valid_mask) + + if (maxnode - bits >= MAX_NUMNODES) { + maxnode -= bits; + } else { + maxnode = MAX_NUMNODES; + t &= ~((1UL << (MAX_NUMNODES % BITS_PER_LONG)) - 1); + } + if (t) return -EINVAL; } - if (copy_from_user(nodes_addr(*nodes), nmask, nlongs*sizeof(unsigned long))) - return -EFAULT; - nodes_addr(*nodes)[nlongs-1] &= endmask; - return 0; + return get_bitmap(nodes_addr(*nodes), nmask, maxnode); } /* Copy a kernel node mask to user space */ @@ -1430,6 +1427,10 @@ static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode, { unsigned long copy = ALIGN(maxnode-1, 64) / 8; unsigned int nbytes = BITS_TO_LONGS(nr_node_ids) * sizeof(long); + bool compat = in_compat_syscall(); + + if (compat) + nbytes = BITS_TO_COMPAT_LONGS(nr_node_ids) * sizeof(compat_long_t); if (copy > nbytes) { if (copy > PAGE_SIZE) @@ -1438,6 +1439,11 @@ static int copy_nodes_to_user(unsigned long __user *mask, unsigned long maxnode, return -EFAULT; copy = nbytes; } + + if (compat) + return compat_put_bitmap((compat_ulong_t __user *)mask, + nodes_addr(*nodes), maxnode); + return copy_to_user(mask, nodes_addr(*nodes), copy) ? -EFAULT : 0; } @@ -1648,72 +1654,22 @@ COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, policy, compat_ulong_t, maxnode, compat_ulong_t, addr, compat_ulong_t, flags) { - long err; - unsigned long __user *nm = NULL; - unsigned long nr_bits, alloc_size; - DECLARE_BITMAP(bm, MAX_NUMNODES); - - nr_bits = min_t(unsigned long, maxnode-1, nr_node_ids); - alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8; - - if (nmask) - nm = compat_alloc_user_space(alloc_size); - - err = kernel_get_mempolicy(policy, nm, nr_bits+1, addr, flags); - - if (!err && nmask) { - unsigned long copy_size; - copy_size = min_t(unsigned long, sizeof(bm), alloc_size); - err = copy_from_user(bm, nm, copy_size); - /* ensure entire bitmap is zeroed */ - err |= clear_user(nmask, ALIGN(maxnode-1, 8) / 8); - err |= compat_put_bitmap(nmask, bm, nr_bits); - } - - return err; + return kernel_get_mempolicy(policy, (unsigned long __user *)nmask, + maxnode, addr, flags); } COMPAT_SYSCALL_DEFINE3(set_mempolicy, int, mode, compat_ulong_t __user *, nmask, compat_ulong_t, maxnode) { - unsigned long __user *nm = NULL; - unsigned long nr_bits, alloc_size; - DECLARE_BITMAP(bm, MAX_NUMNODES); - - nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES); - alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8; - - if (nmask) { - if (compat_get_bitmap(bm, nmask, nr_bits)) - return -EFAULT; - nm = compat_alloc_user_space(alloc_size); - if (copy_to_user(nm, bm, alloc_size)) - return -EFAULT; - } - - return kernel_set_mempolicy(mode, nm, nr_bits+1); + return kernel_set_mempolicy(mode, (unsigned long __user *)nmask, maxnode); } COMPAT_SYSCALL_DEFINE6(mbind, compat_ulong_t, start, compat_ulong_t, len, compat_ulong_t, mode, compat_ulong_t __user *, nmask, compat_ulong_t, maxnode, compat_ulong_t, flags) { - unsigned long __user *nm = NULL; - unsigned long nr_bits, alloc_size; - nodemask_t bm; - - nr_bits = min_t(unsigned long, maxnode-1, MAX_NUMNODES); - alloc_size = ALIGN(nr_bits, BITS_PER_LONG) / 8; - - if (nmask) { - if (compat_get_bitmap(nodes_addr(bm), nmask, nr_bits)) - return -EFAULT; - nm = compat_alloc_user_space(alloc_size); - if (copy_to_user(nm, nodes_addr(bm), alloc_size)) - return -EFAULT; - } - - return kernel_mbind(start, len, mode, nm, nr_bits+1, flags); + return kernel_mbind(start, len, mode, (unsigned long __user *)nmask, + maxnode, flags); } COMPAT_SYSCALL_DEFINE4(migrate_pages, compat_pid_t, pid, @@ -1721,32 +1677,9 @@ COMPAT_SYSCALL_DEFINE4(migrate_pages, compat_pid_t, pid, const compat_ulong_t __user *, old_nodes, const compat_ulong_t __user *, new_nodes) { - unsigned long __user *old = NULL; - unsigned long __user *new = NULL; - nodemask_t tmp_mask; - unsigned long nr_bits; - unsigned long size; - - nr_bits = min_t(unsigned long, maxnode - 1, MAX_NUMNODES); - size = ALIGN(nr_bits, BITS_PER_LONG) / 8; - if (old_nodes) { - if (compat_get_bitmap(nodes_addr(tmp_mask), old_nodes, nr_bits)) - return -EFAULT; - old = compat_alloc_user_space(new_nodes ? size * 2 : size); - if (new_nodes) - new = old + size / sizeof(unsigned long); - if (copy_to_user(old, nodes_addr(tmp_mask), size)) - return -EFAULT; - } - if (new_nodes) { - if (compat_get_bitmap(nodes_addr(tmp_mask), new_nodes, nr_bits)) - return -EFAULT; - if (new == NULL) - new = compat_alloc_user_space(size); - if (copy_to_user(new, nodes_addr(tmp_mask), size)) - return -EFAULT; - } - return kernel_migrate_pages(pid, nr_bits + 1, old, new); + return kernel_migrate_pages(pid, maxnode, + (const unsigned long __user *)old_nodes, + (const unsigned long __user *)new_nodes); } #endif /* CONFIG_COMPAT */