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Thu, 23 Jan 2020 13:59:52 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id yUXeLRtE7w0P; Thu, 23 Jan 2020 13:59:52 +0100 (CET) Received: from po14934vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 8A9BD8B826; Thu, 23 Jan 2020 13:59:52 +0100 (CET) Received: by po14934vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 3E63F651C0; Thu, 23 Jan 2020 12:59:52 +0000 (UTC) Message-Id: From: Christophe Leroy Subject: [PATCH v3 1/7] fs/readdir: Fix filldir() and filldir64() use of user_access_begin() To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Linus Torvalds , Alexander Viro , Andrew Morton Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Date: Thu, 23 Jan 2020 12:59:52 +0000 (UTC) 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: Some architectures grant full access to userspace regardless of the address/len passed to user_access_begin(), but other architectures only grant access to the requested area. For example, on 32 bits powerpc (book3s/32), access is granted by segments of 256 Mbytes. Modify filldir() and filldir64() to request the real area they need to get access to, i.e. the area covering the parent dirent (if any) and the contiguous current dirent. Suggested-by: Linus Torvalds Fixes: 9f79b78ef744 ("Convert filldir[64]() from __put_user() to unsafe_put_user()") Signed-off-by: Christophe Leroy --- v2: have user_access_begin() cover both parent dirent (if any) and current dirent v3: replaced by patch from Linus --- fs/readdir.c | 70 +++++++++++++++++++++++++--------------------------- 1 file changed, 34 insertions(+), 36 deletions(-) diff --git a/fs/readdir.c b/fs/readdir.c index d26d5ea4de7b..4b466cbb0f3a 100644 --- a/fs/readdir.c +++ b/fs/readdir.c @@ -206,7 +206,7 @@ struct linux_dirent { struct getdents_callback { struct dir_context ctx; struct linux_dirent __user * current_dir; - struct linux_dirent __user * previous; + int prev_reclen; int count; int error; }; @@ -214,12 +214,13 @@ struct getdents_callback { static int filldir(struct dir_context *ctx, const char *name, int namlen, loff_t offset, u64 ino, unsigned int d_type) { - struct linux_dirent __user * dirent; + struct linux_dirent __user *dirent, *prev; struct getdents_callback *buf = container_of(ctx, struct getdents_callback, ctx); unsigned long d_ino; int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2, sizeof(long)); + int prev_reclen; buf->error = verify_dirent_name(name, namlen); if (unlikely(buf->error)) @@ -232,28 +233,24 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen, buf->error = -EOVERFLOW; return -EOVERFLOW; } - dirent = buf->previous; - if (dirent && signal_pending(current)) + prev_reclen = buf->prev_reclen; + if (prev_reclen && signal_pending(current)) return -EINTR; - - /* - * Note! This range-checks 'previous' (which may be NULL). - * The real range was checked in getdents - */ - if (!user_access_begin(dirent, sizeof(*dirent))) - goto efault; - if (dirent) - unsafe_put_user(offset, &dirent->d_off, efault_end); dirent = buf->current_dir; + prev = (void __user *)dirent - prev_reclen; + if (!user_access_begin(prev, reclen + prev_reclen)) + goto efault; + + /* This might be 'dirent->d_off', but if so it will get overwritten */ + unsafe_put_user(offset, &prev->d_off, efault_end); unsafe_put_user(d_ino, &dirent->d_ino, efault_end); unsafe_put_user(reclen, &dirent->d_reclen, efault_end); unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end); unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); user_access_end(); - buf->previous = dirent; - dirent = (void __user *)dirent + reclen; - buf->current_dir = dirent; + buf->current_dir = (void __user *)dirent + reclen; + buf->prev_reclen = reclen; buf->count -= reclen; return 0; efault_end: @@ -267,7 +264,6 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd, struct linux_dirent __user *, dirent, unsigned int, count) { struct fd f; - struct linux_dirent __user * lastdirent; struct getdents_callback buf = { .ctx.actor = filldir, .count = count, @@ -285,8 +281,10 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd, error = iterate_dir(f.file, &buf.ctx); if (error >= 0) error = buf.error; - lastdirent = buf.previous; - if (lastdirent) { + if (buf.prev_reclen) { + struct linux_dirent __user *lastdirent; + lastdirent = (void __user *)buf.current_dir - buf.prev_reclen; + if (put_user(buf.ctx.pos, &lastdirent->d_off)) error = -EFAULT; else @@ -299,7 +297,7 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd, struct getdents_callback64 { struct dir_context ctx; struct linux_dirent64 __user * current_dir; - struct linux_dirent64 __user * previous; + int prev_reclen; int count; int error; }; @@ -307,11 +305,12 @@ struct getdents_callback64 { static int filldir64(struct dir_context *ctx, const char *name, int namlen, loff_t offset, u64 ino, unsigned int d_type) { - struct linux_dirent64 __user *dirent; + struct linux_dirent64 __user *dirent, *prev; struct getdents_callback64 *buf = container_of(ctx, struct getdents_callback64, ctx); int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1, sizeof(u64)); + int prev_reclen; buf->error = verify_dirent_name(name, namlen); if (unlikely(buf->error)) @@ -319,30 +318,28 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen, buf->error = -EINVAL; /* only used if we fail.. */ if (reclen > buf->count) return -EINVAL; - dirent = buf->previous; - if (dirent && signal_pending(current)) + prev_reclen = buf->prev_reclen; + if (prev_reclen && signal_pending(current)) return -EINTR; - - /* - * Note! This range-checks 'previous' (which may be NULL). - * The real range was checked in getdents - */ - if (!user_access_begin(dirent, sizeof(*dirent))) - goto efault; - if (dirent) - unsafe_put_user(offset, &dirent->d_off, efault_end); dirent = buf->current_dir; + prev = (void __user *)dirent - prev_reclen; + if (!user_access_begin(prev, reclen + prev_reclen)) + goto efault; + + /* This might be 'dirent->d_off', but if so it will get overwritten */ + unsafe_put_user(offset, &prev->d_off, efault_end); unsafe_put_user(ino, &dirent->d_ino, efault_end); unsafe_put_user(reclen, &dirent->d_reclen, efault_end); unsafe_put_user(d_type, &dirent->d_type, efault_end); unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); user_access_end(); - buf->previous = dirent; + buf->prev_reclen = reclen; dirent = (void __user *)dirent + reclen; buf->current_dir = dirent; buf->count -= reclen; return 0; + efault_end: user_access_end(); efault: @@ -354,7 +351,6 @@ int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent, unsigned int count) { struct fd f; - struct linux_dirent64 __user * lastdirent; struct getdents_callback64 buf = { .ctx.actor = filldir64, .count = count, @@ -372,9 +368,11 @@ int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent, error = iterate_dir(f.file, &buf.ctx); if (error >= 0) error = buf.error; - lastdirent = buf.previous; - if (lastdirent) { + if (buf.prev_reclen) { + struct linux_dirent64 __user *lastdirent; typeof(lastdirent->d_off) d_off = buf.ctx.pos; + + lastdirent = (void __user *)buf.current_dir - buf.prev_reclen; if (__put_user(d_off, &lastdirent->d_off)) error = -EFAULT; else From patchwork Thu Jan 23 12:59:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 11347725 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4F8EF17EF for ; Thu, 23 Jan 2020 12:59:59 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0193524684 for ; Thu, 23 Jan 2020 12:59:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=c-s.fr header.i=@c-s.fr header.b="cpigVkHf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0193524684 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=c-s.fr Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9EB4E6B0007; Thu, 23 Jan 2020 07:59:56 -0500 (EST) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 99C0F6B0008; Thu, 23 Jan 2020 07:59:56 -0500 (EST) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8B1DF6B000A; Thu, 23 Jan 2020 07:59:56 -0500 (EST) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0244.hostedemail.com [216.40.44.244]) by kanga.kvack.org (Postfix) with ESMTP id 7362D6B0007 for ; Thu, 23 Jan 2020 07:59:56 -0500 (EST) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 26FFA4DB7 for ; Thu, 23 Jan 2020 12:59:56 +0000 (UTC) X-FDA: 76408906392.06.wool03_398daa8d21146 X-Spam-Summary: 2,0,0,3471d455b089591e,d41d8cd98f00b204,christophe.leroy@c-s.fr,:benh@kernel.crashing.org:paulus@samba.org:mpe@ellerman.id.au:torvalds@linux-foundation.org:viro@zeniv.linux.org.uk:akpm@linux-foundation.org:tglx@linutronix.de:mingo@redhat.com:bp@alien8.de:hpa@zytor.com:jani.nikula@linux.intel.com:linux-kernel@vger.kernel.org:linuxppc-dev@lists.ozlabs.org:linux-fsdevel@vger.kernel.org::dri-devel@lists.freedesktop.org:x86@kernel.org,RULES_HIT:4:41:355:379:421:800:960:966:973:988:989:1260:1261:1345:1359:1437:1605:1730:1747:1777:1792:1801:2194:2196:2199:2200:2380:2393:2559:2562:2640:2693:2901:3138:3139:3140:3141:3142:3865:3866:3867:3868:3871:3872:3873:3874:4321:4385:4605:5007:6261:6653:6737:7875:7903:8603:8634:9010:10004:10226:11026:11473:11657:11658:11914:12043:12048:12257:12296:12297:12438:12555:12679:12895:12986:14096:14394:21063:21080:21324:21433:21451:21627:21795:21990:30029:30046:30051:30054:30062:30070:30075:30079,0,RBL:93.17.236.30:@c-s.fr:.lbl8.mailshell.n et-62.2. X-HE-Tag: wool03_398daa8d21146 X-Filterd-Recvd-Size: 17314 Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Thu, 23 Jan 2020 12:59:55 +0000 (UTC) Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 483Mn46sR5z9vB4Z; Thu, 23 Jan 2020 13:59:52 +0100 (CET) Authentication-Results: localhost; dkim=pass reason="1024-bit key; insecure key" header.d=c-s.fr header.i=@c-s.fr header.b=cpigVkHf; dkim-adsp=pass; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id ye82euo1eSlt; Thu, 23 Jan 2020 13:59:52 +0100 (CET) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 483Mn45Rmtz9vB4X; Thu, 23 Jan 2020 13:59:52 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=c-s.fr; s=mail; t=1579784392; bh=y3mCq62z8QvBHB/lDe1I9sTNmtZcrMNh5y5Vki0onEE=; h=In-Reply-To:References:From:Subject:To:Cc:Date:From; b=cpigVkHfJgSSTDA00DxU2scK4Rca1sAxhbjcOWb8jiWHowf2s1qShrxF+apnrpyXN L93hAuZNOjAXZqV1WnCT8GVRnd8hPVboEyKyK1neBsuGJrcG6uagLhkUCI3C/6/2si +I2qMd4mFfI3MY/I7H1HrpG47DrkCldDbPruXlkQ= Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 0B6F18B82C; Thu, 23 Jan 2020 13:59:54 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id yFkjLN7K3l7s; Thu, 23 Jan 2020 13:59:53 +0100 (CET) Received: from po14934vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 6F9738B826; Thu, 23 Jan 2020 13:59:53 +0100 (CET) Received: by po14934vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 3DE38651C0; Thu, 23 Jan 2020 12:59:53 +0000 (UTC) Message-Id: In-Reply-To: References: From: Christophe Leroy Subject: [PATCH v3 2/7] uaccess: Tell user_access_begin() if it's for a write or not To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Linus Torvalds , Alexander Viro , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Jani Nikula Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, dri-devel@lists.freedesktop.org, x86@kernel.org Date: Thu, 23 Jan 2020 12:59:53 +0000 (UTC) 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: On 32 bits powerPC (book3s/32), only write accesses to user are protected and there is no point spending time on unlocking for reads. On 64 bits powerpc (book3s/64 at least), access can be granted read only, write only or read/write. Add an argument to user_access_begin() to tell when it's for write and return an opaque key that will be used by user_access_end() to know what was done by user_access_begin(). Signed-off-by: Christophe Leroy Reported-by: kbuild test robot --- v3: new --- arch/x86/include/asm/uaccess.h | 5 +++-- drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 15 ++++++++++----- fs/readdir.c | 16 ++++++++++------ include/linux/uaccess.h | 4 ++-- kernel/compat.c | 16 ++++++++++------ kernel/exit.c | 17 +++++++++++------ lib/strncpy_from_user.c | 6 ++++-- lib/strnlen_user.c | 6 ++++-- lib/usercopy.c | 8 +++++--- 9 files changed, 59 insertions(+), 34 deletions(-) diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 61d93f062a36..05eccdc0366a 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -709,7 +709,8 @@ extern struct movsl_mask { * checking before using them, but you have to surround them with the * user_access_begin/end() pair. */ -static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len) +static __must_check __always_inline unsigned long +user_access_begin(const void __user *ptr, size_t len, bool write) { if (unlikely(!access_ok(ptr,len))) return 0; @@ -717,7 +718,7 @@ static __must_check __always_inline bool user_access_begin(const void __user *pt return 1; } #define user_access_begin(a,b) user_access_begin(a,b) -#define user_access_end() __uaccess_end() +#define user_access_end(x) __uaccess_end() #define user_access_save() smap_save() #define user_access_restore(x) smap_restore(x) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c index bc3a67226163..509bfb6116ac 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c @@ -1615,6 +1615,7 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb) const unsigned int count = eb->buffer_count; unsigned int i; int err; + unsigned long key; for (i = 0; i < count; i++) { const unsigned int nreloc = eb->exec[i].relocation_count; @@ -1662,14 +1663,15 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb) * happened we would make the mistake of assuming that the * relocations were valid. */ - if (!user_access_begin(urelocs, size)) + key = user_access_begin(urelocs, size, true); + if (!key) goto end; for (copied = 0; copied < nreloc; copied++) unsafe_put_user(-1, &urelocs[copied].presumed_offset, end_user); - user_access_end(); + user_access_end(key); eb->exec[i].relocs_ptr = (uintptr_t)relocs; } @@ -1677,7 +1679,7 @@ static int eb_copy_relocations(const struct i915_execbuffer *eb) return 0; end_user: - user_access_end(); + user_access_end(key); end: kvfree(relocs); err = -EFAULT; @@ -2906,6 +2908,7 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data, struct drm_i915_gem_exec_object2 __user *user_exec_list = u64_to_user_ptr(args->buffers_ptr); unsigned int i; + unsigned long key; /* Copy the new buffer offsets back to the user's exec list. */ /* @@ -2915,7 +2918,9 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data, * And this range already got effectively checked earlier * when we did the "copy_from_user()" above. */ - if (!user_access_begin(user_exec_list, count * sizeof(*user_exec_list))) + key = user_access_begin(user_exec_list, + count * sizeof(*user_exec_list), true); + if (!key) goto end; for (i = 0; i < args->buffer_count; i++) { @@ -2929,7 +2934,7 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data, end_user); } end_user: - user_access_end(); + user_access_end(key); end:; } diff --git a/fs/readdir.c b/fs/readdir.c index 4b466cbb0f3a..47b9ef97e16e 100644 --- a/fs/readdir.c +++ b/fs/readdir.c @@ -221,6 +221,7 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen, int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2, sizeof(long)); int prev_reclen; + unsigned long key; buf->error = verify_dirent_name(name, namlen); if (unlikely(buf->error)) @@ -238,7 +239,8 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen, return -EINTR; dirent = buf->current_dir; prev = (void __user *)dirent - prev_reclen; - if (!user_access_begin(prev, reclen + prev_reclen)) + key = user_access_begin(prev, reclen + prev_reclen, true); + if (!key) goto efault; /* This might be 'dirent->d_off', but if so it will get overwritten */ @@ -247,14 +249,14 @@ static int filldir(struct dir_context *ctx, const char *name, int namlen, unsafe_put_user(reclen, &dirent->d_reclen, efault_end); unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end); unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); - user_access_end(); + user_access_end(key); buf->current_dir = (void __user *)dirent + reclen; buf->prev_reclen = reclen; buf->count -= reclen; return 0; efault_end: - user_access_end(); + user_access_end(key); efault: buf->error = -EFAULT; return -EFAULT; @@ -311,6 +313,7 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen, int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1, sizeof(u64)); int prev_reclen; + unsigned long key; buf->error = verify_dirent_name(name, namlen); if (unlikely(buf->error)) @@ -323,7 +326,8 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen, return -EINTR; dirent = buf->current_dir; prev = (void __user *)dirent - prev_reclen; - if (!user_access_begin(prev, reclen + prev_reclen)) + key = user_access_begin(prev, reclen + prev_reclen, true); + if (!key) goto efault; /* This might be 'dirent->d_off', but if so it will get overwritten */ @@ -332,7 +336,7 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen, unsafe_put_user(reclen, &dirent->d_reclen, efault_end); unsafe_put_user(d_type, &dirent->d_type, efault_end); unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end); - user_access_end(); + user_access_end(key); buf->prev_reclen = reclen; dirent = (void __user *)dirent + reclen; @@ -341,7 +345,7 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen, return 0; efault_end: - user_access_end(); + user_access_end(key); efault: buf->error = -EFAULT; return -EFAULT; diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 67f016010aad..394f5029a727 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -369,8 +369,8 @@ extern long strnlen_unsafe_user(const void __user *unsafe_addr, long count); probe_kernel_read(&retval, addr, sizeof(retval)) #ifndef user_access_begin -#define user_access_begin(ptr,len) access_ok(ptr, len) -#define user_access_end() do { } while (0) +#define user_access_begin(ptr, len, write) access_ok(ptr, len) +#define user_access_end(x) do { } while (0) #define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0) #define unsafe_get_user(x,p,e) unsafe_op_wrap(__get_user(x,p),e) #define unsafe_put_user(x,p,e) unsafe_op_wrap(__put_user(x,p),e) diff --git a/kernel/compat.c b/kernel/compat.c index 95005f849c68..4bcbe1cd761b 100644 --- a/kernel/compat.c +++ b/kernel/compat.c @@ -258,12 +258,14 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask, unsigned long bitmap_size) { unsigned long nr_compat_longs; + unsigned long key; /* align bitmap up to nearest compat_long_t boundary */ bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG); nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size); - if (!user_access_begin(umask, bitmap_size / 8)) + key = user_access_begin(umask, bitmap_size / 8, false); + if (!key) return -EFAULT; while (nr_compat_longs > 1) { @@ -275,11 +277,11 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask, } if (nr_compat_longs) unsafe_get_user(*mask, umask++, Efault); - user_access_end(); + user_access_end(key); return 0; Efault: - user_access_end(); + user_access_end(key); return -EFAULT; } @@ -287,12 +289,14 @@ long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask, unsigned long bitmap_size) { unsigned long nr_compat_longs; + unsigned long key; /* align bitmap up to nearest compat_long_t boundary */ bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG); nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size); - if (!user_access_begin(umask, bitmap_size / 8)) + key = user_access_begin(umask, bitmap_size / 8, true); + if (!key) return -EFAULT; while (nr_compat_longs > 1) { @@ -303,10 +307,10 @@ long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask, } if (nr_compat_longs) unsafe_put_user((compat_ulong_t)*mask, umask++, Efault); - user_access_end(); + user_access_end(key); return 0; Efault: - user_access_end(); + user_access_end(key); return -EFAULT; } diff --git a/kernel/exit.c b/kernel/exit.c index 2833ffb0c211..1cb9c8a879d2 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1553,6 +1553,7 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, struct waitid_info info = {.status = 0}; long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); int signo = 0; + unsigned long key; if (err > 0) { signo = SIGCHLD; @@ -1563,7 +1564,8 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, if (!infop) return err; - if (!user_access_begin(infop, sizeof(*infop))) + key = user_access_begin(infop, sizeof(*infop), true); + if (!key) return -EFAULT; unsafe_put_user(signo, &infop->si_signo, Efault); @@ -1572,10 +1574,10 @@ SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, unsafe_put_user(info.pid, &infop->si_pid, Efault); unsafe_put_user(info.uid, &infop->si_uid, Efault); unsafe_put_user(info.status, &infop->si_status, Efault); - user_access_end(); + user_access_end(key); return err; Efault: - user_access_end(); + user_access_end(key); return -EFAULT; } @@ -1673,6 +1675,8 @@ COMPAT_SYSCALL_DEFINE5(waitid, struct waitid_info info = {.status = 0}; long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL); int signo = 0; + unsigned long key; + if (err > 0) { signo = SIGCHLD; err = 0; @@ -1690,7 +1694,8 @@ COMPAT_SYSCALL_DEFINE5(waitid, if (!infop) return err; - if (!user_access_begin(infop, sizeof(*infop))) + key = user_access_begin(infop, sizeof(*infop), true); + if (!key) return -EFAULT; unsafe_put_user(signo, &infop->si_signo, Efault); @@ -1699,10 +1704,10 @@ COMPAT_SYSCALL_DEFINE5(waitid, unsafe_put_user(info.pid, &infop->si_pid, Efault); unsafe_put_user(info.uid, &infop->si_uid, Efault); unsafe_put_user(info.status, &infop->si_status, Efault); - user_access_end(); + user_access_end(key); return err; Efault: - user_access_end(); + user_access_end(key); return -EFAULT; } #endif diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c index dccb95af6003..7184fb766439 100644 --- a/lib/strncpy_from_user.c +++ b/lib/strncpy_from_user.c @@ -113,12 +113,14 @@ long strncpy_from_user(char *dst, const char __user *src, long count) if (likely(src_addr < max_addr)) { unsigned long max = max_addr - src_addr; long retval; + unsigned long key; kasan_check_write(dst, count); check_object_size(dst, count, false); - if (user_access_begin(src, max)) { + key = user_access_begin(src, max, false); + if (key) { retval = do_strncpy_from_user(dst, src, count, max); - user_access_end(); + user_access_end(key); return retval; } } diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c index 6c0005d5dd5c..819e355b8608 100644 --- a/lib/strnlen_user.c +++ b/lib/strnlen_user.c @@ -108,10 +108,12 @@ long strnlen_user(const char __user *str, long count) if (likely(src_addr < max_addr)) { unsigned long max = max_addr - src_addr; long retval; + unsigned long key; - if (user_access_begin(str, max)) { + key = user_access_begin(str, max, false); + if (key) { retval = do_strnlen_user(str, count, max); - user_access_end(); + user_access_end(key); return retval; } } diff --git a/lib/usercopy.c b/lib/usercopy.c index cbb4d9ec00f2..9e03ca88ad32 100644 --- a/lib/usercopy.c +++ b/lib/usercopy.c @@ -51,6 +51,7 @@ int check_zeroed_user(const void __user *from, size_t size) { unsigned long val; uintptr_t align = (uintptr_t) from % sizeof(unsigned long); + unsigned long key; if (unlikely(size == 0)) return 1; @@ -58,7 +59,8 @@ int check_zeroed_user(const void __user *from, size_t size) from -= align; size += align; - if (!user_access_begin(from, size)) + key = user_access_begin(from, size, false); + if (!key) return -EFAULT; unsafe_get_user(val, (unsigned long __user *) from, err_fault); @@ -79,10 +81,10 @@ int check_zeroed_user(const void __user *from, size_t size) val &= aligned_byte_mask(size); done: - user_access_end(); + user_access_end(key); return (val == 0); err_fault: - user_access_end(); + user_access_end(key); return -EFAULT; } EXPORT_SYMBOL(check_zeroed_user); From patchwork Thu Jan 23 12:59:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 11347727 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9EA44921 for ; 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Thu, 23 Jan 2020 13:59:54 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id kZ62ky9AMEwp; Thu, 23 Jan 2020 13:59:54 +0100 (CET) Received: from po14934vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 714C98B826; Thu, 23 Jan 2020 13:59:54 +0100 (CET) Received: by po14934vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 44CEB651C0; Thu, 23 Jan 2020 12:59:54 +0000 (UTC) Message-Id: <584ce843dc9d1982934c2b64dd9e64f21ac84c9a.1579783936.git.christophe.leroy@c-s.fr> In-Reply-To: References: From: Christophe Leroy Subject: [PATCH v3 3/7] powerpc/32s: Fix bad_kuap_fault() To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Date: Thu, 23 Jan 2020 12:59:54 +0000 (UTC) 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: At the moment, bad_kuap_fault() reports a fault only if a bad access to userspace occurred while access to userspace was not granted. But if a fault occurs for a write outside the allowed userspace segment(s) that have been unlocked, bad_kuap_fault() fails to detect it and the kernel loops forever in do_page_fault(). Fix it by checking that the accessed address is within the allowed range. Fixes: a68c31fc01ef ("powerpc/32s: Implement Kernel Userspace Access Protection") Cc: stable@vger.kernel.org Signed-off-by: Christophe Leroy --- v2: added missing address parametre to bad_kuap_fault() in asm/kup.h v3: no change --- arch/powerpc/include/asm/book3s/32/kup.h | 9 +++++++-- arch/powerpc/include/asm/book3s/64/kup-radix.h | 3 ++- arch/powerpc/include/asm/kup.h | 6 +++++- arch/powerpc/include/asm/nohash/32/kup-8xx.h | 3 ++- arch/powerpc/mm/fault.c | 2 +- 5 files changed, 17 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index f9dc597b0b86..d88008c8eb85 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -131,12 +131,17 @@ static inline void prevent_user_access(void __user *to, const void __user *from, kuap_update_sr(mfsrin(addr) | SR_KS, addr, end); /* set Ks */ } -static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) +static inline bool +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) { + unsigned long begin = regs->kuap & 0xf0000000; + unsigned long end = regs->kuap << 28; + if (!is_write) return false; - return WARN(!regs->kuap, "Bug: write fault blocked by segment registers !"); + return WARN(address < begin || address >= end, + "Bug: write fault blocked by segment registers !"); } #endif /* CONFIG_PPC_KUAP */ diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h b/arch/powerpc/include/asm/book3s/64/kup-radix.h index f254de956d6a..dbbd22cb80f5 100644 --- a/arch/powerpc/include/asm/book3s/64/kup-radix.h +++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h @@ -95,7 +95,8 @@ static inline void prevent_user_access(void __user *to, const void __user *from, set_kuap(AMR_KUAP_BLOCKED); } -static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) +static inline bool +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) { return WARN(mmu_has_feature(MMU_FTR_RADIX_KUAP) && (regs->kuap & (is_write ? AMR_KUAP_BLOCK_WRITE : AMR_KUAP_BLOCK_READ)), diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h index 5b5e39643a27..812e66f31934 100644 --- a/arch/powerpc/include/asm/kup.h +++ b/arch/powerpc/include/asm/kup.h @@ -45,7 +45,11 @@ static inline void allow_user_access(void __user *to, const void __user *from, unsigned long size) { } static inline void prevent_user_access(void __user *to, const void __user *from, unsigned long size) { } -static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) { return false; } +static inline bool +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) +{ + return false; +} #endif /* CONFIG_PPC_KUAP */ static inline void allow_read_from_user(const void __user *from, unsigned long size) diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h index 1006a427e99c..f2fea603b929 100644 --- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h +++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h @@ -46,7 +46,8 @@ static inline void prevent_user_access(void __user *to, const void __user *from, mtspr(SPRN_MD_AP, MD_APG_KUAP); } -static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) +static inline bool +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) { return WARN(!((regs->kuap ^ MD_APG_KUAP) & 0xf0000000), "Bug: fault blocked by AP register !"); diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index b5047f9b5dec..1baeb045f7f4 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -233,7 +233,7 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code, // Read/write fault in a valid region (the exception table search passed // above), but blocked by KUAP is bad, it can never succeed. - if (bad_kuap_fault(regs, is_write)) + if (bad_kuap_fault(regs, address, is_write)) return true; // What's left? 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Thu, 23 Jan 2020 13:59:55 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id u-vpBJS8Yh3Y; Thu, 23 Jan 2020 13:59:55 +0100 (CET) Received: from po14934vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 769698B826; Thu, 23 Jan 2020 13:59:55 +0100 (CET) Received: by po14934vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 4EEED651C0; Thu, 23 Jan 2020 12:59:55 +0000 (UTC) Message-Id: <5557b2d5115d450ef50ab45249dad4fb31a03c5c.1579783936.git.christophe.leroy@c-s.fr> In-Reply-To: References: From: Christophe Leroy Subject: [PATCH v3 4/7] powerpc/kuap: Fix set direction in allow/prevent_user_access() To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Date: Thu, 23 Jan 2020 12:59:55 +0000 (UTC) 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: __builtin_constant_p() always return 0 for pointers, so on RADIX we always end up opening both direction (by writing 0 in SPR29): 0000000000000170 <._copy_to_user>: ... 1b0: 4c 00 01 2c isync 1b4: 39 20 00 00 li r9,0 1b8: 7d 3d 03 a6 mtspr 29,r9 1bc: 4c 00 01 2c isync 1c0: 48 00 00 01 bl 1c0 <._copy_to_user+0x50> 1c0: R_PPC64_REL24 .__copy_tofrom_user ... 0000000000000220 <._copy_from_user>: ... 2ac: 4c 00 01 2c isync 2b0: 39 20 00 00 li r9,0 2b4: 7d 3d 03 a6 mtspr 29,r9 2b8: 4c 00 01 2c isync 2bc: 7f c5 f3 78 mr r5,r30 2c0: 7f 83 e3 78 mr r3,r28 2c4: 48 00 00 01 bl 2c4 <._copy_from_user+0xa4> 2c4: R_PPC64_REL24 .__copy_tofrom_user ... Use an explicit parameter for direction selection, so that GCC is able to see it is a constant: 00000000000001b0 <._copy_to_user>: ... 1f0: 4c 00 01 2c isync 1f4: 3d 20 40 00 lis r9,16384 1f8: 79 29 07 c6 rldicr r9,r9,32,31 1fc: 7d 3d 03 a6 mtspr 29,r9 200: 4c 00 01 2c isync 204: 48 00 00 01 bl 204 <._copy_to_user+0x54> 204: R_PPC64_REL24 .__copy_tofrom_user ... 0000000000000260 <._copy_from_user>: ... 2ec: 4c 00 01 2c isync 2f0: 39 20 ff ff li r9,-1 2f4: 79 29 00 04 rldicr r9,r9,0,0 2f8: 7d 3d 03 a6 mtspr 29,r9 2fc: 4c 00 01 2c isync 300: 7f c5 f3 78 mr r5,r30 304: 7f 83 e3 78 mr r3,r28 308: 48 00 00 01 bl 308 <._copy_from_user+0xa8> 308: R_PPC64_REL24 .__copy_tofrom_user ... Signed-off-by: Christophe Leroy --- v2: no change v3: no change --- arch/powerpc/include/asm/book3s/32/kup.h | 13 ++++++-- .../powerpc/include/asm/book3s/64/kup-radix.h | 11 +++---- arch/powerpc/include/asm/kup.h | 30 ++++++++++++++----- arch/powerpc/include/asm/nohash/32/kup-8xx.h | 4 +-- arch/powerpc/include/asm/uaccess.h | 4 +-- 5 files changed, 43 insertions(+), 19 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index d88008c8eb85..d765515bd1c1 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -102,11 +102,13 @@ static inline void kuap_update_sr(u32 sr, u32 addr, u32 end) isync(); /* Context sync required after mtsrin() */ } -static inline void allow_user_access(void __user *to, const void __user *from, u32 size) +static __always_inline void allow_user_access(void __user *to, const void __user *from, + u32 size, unsigned long dir) { u32 addr, end; - if (__builtin_constant_p(to) && to == NULL) + BUILD_BUG_ON(!__builtin_constant_p(dir)); + if (!(dir & KUAP_W)) return; addr = (__force u32)to; @@ -119,11 +121,16 @@ static inline void allow_user_access(void __user *to, const void __user *from, u kuap_update_sr(mfsrin(addr) & ~SR_KS, addr, end); /* Clear Ks */ } -static inline void prevent_user_access(void __user *to, const void __user *from, u32 size) +static __always_inline void prevent_user_access(void __user *to, const void __user *from, + u32 size, unsigned long dir) { u32 addr = (__force u32)to; u32 end = min(addr + size, TASK_SIZE); + BUILD_BUG_ON(!__builtin_constant_p(dir)); + if (!(dir & KUAP_W)) + return; + if (!addr || addr >= TASK_SIZE || !size) return; diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h b/arch/powerpc/include/asm/book3s/64/kup-radix.h index dbbd22cb80f5..f11315306d41 100644 --- a/arch/powerpc/include/asm/book3s/64/kup-radix.h +++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h @@ -77,20 +77,21 @@ static inline void set_kuap(unsigned long value) isync(); } -static inline void allow_user_access(void __user *to, const void __user *from, - unsigned long size) +static __always_inline void allow_user_access(void __user *to, const void __user *from, + unsigned long size, unsigned long dir) { // This is written so we can resolve to a single case at build time - if (__builtin_constant_p(to) && to == NULL) + BUILD_BUG_ON(!__builtin_constant_p(dir)); + if (dir == KUAP_R) set_kuap(AMR_KUAP_BLOCK_WRITE); - else if (__builtin_constant_p(from) && from == NULL) + else if (dir == KUAP_W) set_kuap(AMR_KUAP_BLOCK_READ); else set_kuap(0); } static inline void prevent_user_access(void __user *to, const void __user *from, - unsigned long size) + unsigned long size, unsigned long dir) { set_kuap(AMR_KUAP_BLOCKED); } diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h index 812e66f31934..ff57bfcb88f7 100644 --- a/arch/powerpc/include/asm/kup.h +++ b/arch/powerpc/include/asm/kup.h @@ -2,6 +2,10 @@ #ifndef _ASM_POWERPC_KUP_H_ #define _ASM_POWERPC_KUP_H_ +#define KUAP_R 1 +#define KUAP_W 2 +#define KUAP_RW (KUAP_R | KUAP_W) + #ifdef CONFIG_PPC64 #include #endif @@ -42,9 +46,9 @@ void setup_kuap(bool disabled); #else static inline void setup_kuap(bool disabled) { } static inline void allow_user_access(void __user *to, const void __user *from, - unsigned long size) { } + unsigned long size, unsigned long dir) { } static inline void prevent_user_access(void __user *to, const void __user *from, - unsigned long size) { } + unsigned long size, unsigned long dir) { } static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) { @@ -54,24 +58,36 @@ bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) static inline void allow_read_from_user(const void __user *from, unsigned long size) { - allow_user_access(NULL, from, size); + allow_user_access(NULL, from, size, KUAP_R); } static inline void allow_write_to_user(void __user *to, unsigned long size) { - allow_user_access(to, NULL, size); + allow_user_access(to, NULL, size, KUAP_W); +} + +static inline void allow_read_write_user(void __user *to, const void __user *from, + unsigned long size) +{ + allow_user_access(to, from, size, KUAP_RW); } static inline void prevent_read_from_user(const void __user *from, unsigned long size) { - prevent_user_access(NULL, from, size); + prevent_user_access(NULL, from, size, KUAP_R); } static inline void prevent_write_to_user(void __user *to, unsigned long size) { - prevent_user_access(to, NULL, size); + prevent_user_access(to, NULL, size, KUAP_W); +} + +static inline void prevent_read_write_user(void __user *to, const void __user *from, + unsigned long size) +{ + prevent_user_access(to, from, size, KUAP_RW); } #endif /* !__ASSEMBLY__ */ -#endif /* _ASM_POWERPC_KUP_H_ */ +#endif /* _ASM_POWERPC_KUAP_H_ */ diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h index f2fea603b929..1d70c80366fd 100644 --- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h +++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h @@ -35,13 +35,13 @@ #include static inline void allow_user_access(void __user *to, const void __user *from, - unsigned long size) + unsigned long size, unsigned long dir) { mtspr(SPRN_MD_AP, MD_APG_INIT); } static inline void prevent_user_access(void __user *to, const void __user *from, - unsigned long size) + unsigned long size, unsigned long dir) { mtspr(SPRN_MD_AP, MD_APG_KUAP); } diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h index c92fe7fe9692..cafad1960e76 100644 --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -313,9 +313,9 @@ raw_copy_in_user(void __user *to, const void __user *from, unsigned long n) unsigned long ret; barrier_nospec(); - allow_user_access(to, from, n); + allow_read_write_user(to, from, n); ret = __copy_tofrom_user(to, from, n); - prevent_user_access(to, from, n); + prevent_read_write_user(to, from, n); return ret; } #endif /* __powerpc64__ */ From patchwork Thu Jan 23 12:59:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 11347731 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4CEB7921 for ; 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Thu, 23 Jan 2020 13:59:56 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id 14fKxtcIuTAx; Thu, 23 Jan 2020 13:59:56 +0100 (CET) Received: from po14934vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 804798B826; Thu, 23 Jan 2020 13:59:56 +0100 (CET) Received: by po14934vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 5757E651C0; Thu, 23 Jan 2020 12:59:56 +0000 (UTC) Message-Id: <8374d73eced8ac93d756e606ca64c6c3140c8ea8.1579783936.git.christophe.leroy@c-s.fr> In-Reply-To: References: From: Christophe Leroy Subject: [PATCH v3 5/7] powerpc/32s: Drop NULL addr verification To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Date: Thu, 23 Jan 2020 12:59:56 +0000 (UTC) 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: NULL addr is a user address. Don't waste time checking it. If someone tries to access it, it will SIGFAULT the same way as for address 1, so no need to make it special. The special case is when not doing a write, in that case we want to drop the entire function. This is now handled by 'dir' param and not by the nulity of 'to' anymore. Also make beginning of prevent_user_access() similar to beginning of allow_user_access(), and tell the compiler that writing in kernel space or with a 0 length is unlikely Signed-off-by: Christophe Leroy --- v2: no change v3: no change --- arch/powerpc/include/asm/book3s/32/kup.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index d765515bd1c1..3c1798e56b55 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -113,7 +113,7 @@ static __always_inline void allow_user_access(void __user *to, const void __user addr = (__force u32)to; - if (!addr || addr >= TASK_SIZE || !size) + if (unlikely(addr >= TASK_SIZE || !size)) return; end = min(addr + size, TASK_SIZE); @@ -124,16 +124,18 @@ static __always_inline void allow_user_access(void __user *to, const void __user static __always_inline void prevent_user_access(void __user *to, const void __user *from, u32 size, unsigned long dir) { - u32 addr = (__force u32)to; - u32 end = min(addr + size, TASK_SIZE); + u32 addr, end; BUILD_BUG_ON(!__builtin_constant_p(dir)); if (!(dir & KUAP_W)) return; - if (!addr || addr >= TASK_SIZE || !size) + addr = (__force u32)to; + + if (unlikely(addr >= TASK_SIZE || !size)) return; + end = min(addr + size, TASK_SIZE); current->thread.kuap = 0; kuap_update_sr(mfsrin(addr) | SR_KS, addr, end); /* set Ks */ } From patchwork Thu Jan 23 12:59:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 11347735 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 32F1F92A for ; Thu, 23 Jan 2020 13:00:10 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E902B24125 for ; Thu, 23 Jan 2020 13:00:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=c-s.fr header.i=@c-s.fr header.b="FrIBpB+S" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E902B24125 Authentication-Results: mail.kernel.org; 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Thu, 23 Jan 2020 13:59:57 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id MYYQpzE1hRXB; Thu, 23 Jan 2020 13:59:57 +0100 (CET) Received: from po14934vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 880168B82C; Thu, 23 Jan 2020 13:59:57 +0100 (CET) Received: by po14934vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 5DE51651C0; Thu, 23 Jan 2020 12:59:57 +0000 (UTC) Message-Id: <408c90c4068b00ea8f1c41cca45b84ec23d4946b.1579783936.git.christophe.leroy@c-s.fr> In-Reply-To: References: From: Christophe Leroy Subject: [PATCH v3 6/7] powerpc/32s: Prepare allow_user_access() for user_access_begin() To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Date: Thu, 23 Jan 2020 12:59:57 +0000 (UTC) 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: In preparation of implementing user_access_begin and friends on powerpc, allow_user_access() need to be prepared for user_access_begin() user_access_end() doesn't provide the address and size which were passed to user_access_begin(), required by prevent_user_access() to know which segment to modify. But user_access_end() takes an opaque value returned by user_access_begin(). Make allow_user_access() return the value it writes to current->kuap. This will allow user_access_end() to recalculate the segment range without having to read current->kuap. Signed-off-by: Christophe Leroy --- v3: Replaces the patch "Prepare prevent_user_access() for user_access_end()" --- arch/powerpc/include/asm/book3s/32/kup.h | 15 ++++++++++----- arch/powerpc/include/asm/book3s/64/kup-radix.h | 7 +++++-- arch/powerpc/include/asm/kup.h | 8 ++++++-- arch/powerpc/include/asm/nohash/32/kup-8xx.h | 6 ++++-- 4 files changed, 25 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index 3c1798e56b55..128dcbf3a19d 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -102,23 +102,28 @@ static inline void kuap_update_sr(u32 sr, u32 addr, u32 end) isync(); /* Context sync required after mtsrin() */ } -static __always_inline void allow_user_access(void __user *to, const void __user *from, - u32 size, unsigned long dir) +/* Make sure we never return 0. We only use top and bottom 4 bits */ +static __always_inline unsigned long +allow_user_access(void __user *to, const void __user *from, u32 size, unsigned long dir) { u32 addr, end; + unsigned long kuap; BUILD_BUG_ON(!__builtin_constant_p(dir)); if (!(dir & KUAP_W)) - return; + return 0x100; addr = (__force u32)to; if (unlikely(addr >= TASK_SIZE || !size)) - return; + return 0x100; end = min(addr + size, TASK_SIZE); - current->thread.kuap = (addr & 0xf0000000) | ((((end - 1) >> 28) + 1) & 0xf); + kuap = (addr & 0xf0000000) | ((((end - 1) >> 28) + 1) & 0xf); + current->thread.kuap = kuap; kuap_update_sr(mfsrin(addr) & ~SR_KS, addr, end); /* Clear Ks */ + + return kuap; } static __always_inline void prevent_user_access(void __user *to, const void __user *from, diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h b/arch/powerpc/include/asm/book3s/64/kup-radix.h index f11315306d41..183f0c87017b 100644 --- a/arch/powerpc/include/asm/book3s/64/kup-radix.h +++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h @@ -77,8 +77,9 @@ static inline void set_kuap(unsigned long value) isync(); } -static __always_inline void allow_user_access(void __user *to, const void __user *from, - unsigned long size, unsigned long dir) +static __always_inline unsigned long +allow_user_access(void __user *to, const void __user *from, + unsigned long size, unsigned long dir) { // This is written so we can resolve to a single case at build time BUILD_BUG_ON(!__builtin_constant_p(dir)); @@ -88,6 +89,8 @@ static __always_inline void allow_user_access(void __user *to, const void __user set_kuap(AMR_KUAP_BLOCK_READ); else set_kuap(0); + + return 1; } static inline void prevent_user_access(void __user *to, const void __user *from, diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h index ff57bfcb88f7..691fec5afd4a 100644 --- a/arch/powerpc/include/asm/kup.h +++ b/arch/powerpc/include/asm/kup.h @@ -45,8 +45,12 @@ static inline void setup_kuep(bool disabled) { } void setup_kuap(bool disabled); #else static inline void setup_kuap(bool disabled) { } -static inline void allow_user_access(void __user *to, const void __user *from, - unsigned long size, unsigned long dir) { } +static inline unsigned long allow_user_access(void __user *to, const void __user *from, + unsigned long size, unsigned long dir) +{ + return 1; +} + static inline void prevent_user_access(void __user *to, const void __user *from, unsigned long size, unsigned long dir) { } static inline bool diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h index 1d70c80366fd..ee673d3c0ab6 100644 --- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h +++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h @@ -34,10 +34,12 @@ #include -static inline void allow_user_access(void __user *to, const void __user *from, - unsigned long size, unsigned long dir) +static inline unsigned long allow_user_access(void __user *to, const void __user *from, + unsigned long size, unsigned long dir) { mtspr(SPRN_MD_AP, MD_APG_INIT); + + return 1; } static inline void prevent_user_access(void __user *to, const void __user *from, From patchwork Thu Jan 23 12:59:58 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 11347741 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 339C7921 for ; 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Thu, 23 Jan 2020 13:59:58 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id p7cn4rlmlrk1; Thu, 23 Jan 2020 13:59:58 +0100 (CET) Received: from po14934vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 8C1FA8B826; Thu, 23 Jan 2020 13:59:58 +0100 (CET) Received: by po14934vm.idsi0.si.c-s.fr (Postfix, from userid 0) id 638C9651C0; Thu, 23 Jan 2020 12:59:58 +0000 (UTC) Message-Id: <4cf9d1d96e2d4f7c196eb492501362b533f0fd4b.1579783936.git.christophe.leroy@c-s.fr> In-Reply-To: References: From: Christophe Leroy Subject: [PATCH v3 7/7] powerpc: Implement user_access_begin and friends To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Date: Thu, 23 Jan 2020 12:59:58 +0000 (UTC) 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: Today, when a function like strncpy_from_user() is called, the userspace access protection is de-activated and re-activated for every word read. By implementing user_access_begin and friends, the protection is de-activated at the beginning of the copy and re-activated at the end. Implement user_access_begin(), user_access_end() and unsafe_get_user(), unsafe_put_user() and unsafe_copy_to_user() For the time being, we keep user_access_save() and user_access_restore() as nops. Signed-off-by: Christophe Leroy --- v2: no change v3: adapted to the new format of user_access_begin/end() --- arch/powerpc/include/asm/uaccess.h | 100 ++++++++++++++++++++++++++--- 1 file changed, 90 insertions(+), 10 deletions(-) diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h index cafad1960e76..30204e80df1b 100644 --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -91,9 +91,14 @@ static inline int __access_ok(unsigned long addr, unsigned long size, __put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) #define __get_user(x, ptr) \ - __get_user_nocheck((x), (ptr), sizeof(*(ptr))) + __get_user_nocheck((x), (ptr), sizeof(*(ptr)), true) #define __put_user(x, ptr) \ - __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) + __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), true) + +#define __get_user_allowed(x, ptr) \ + __get_user_nocheck((x), (ptr), sizeof(*(ptr)), false) +#define __put_user_allowed(x, ptr) \ + __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), false) #define __get_user_inatomic(x, ptr) \ __get_user_nosleep((x), (ptr), sizeof(*(ptr))) @@ -138,10 +143,9 @@ extern long __put_user_bad(void); : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err)) #endif /* __powerpc64__ */ -#define __put_user_size(x, ptr, size, retval) \ +#define __put_user_size_allowed(x, ptr, size, retval) \ do { \ retval = 0; \ - allow_write_to_user(ptr, size); \ switch (size) { \ case 1: __put_user_asm(x, ptr, retval, "stb"); break; \ case 2: __put_user_asm(x, ptr, retval, "sth"); break; \ @@ -149,17 +153,26 @@ do { \ case 8: __put_user_asm2(x, ptr, retval); break; \ default: __put_user_bad(); \ } \ +} while (0) + +#define __put_user_size(x, ptr, size, retval) \ +do { \ + allow_write_to_user(ptr, size); \ + __put_user_size_allowed(x, ptr, size, retval); \ prevent_write_to_user(ptr, size); \ } while (0) -#define __put_user_nocheck(x, ptr, size) \ +#define __put_user_nocheck(x, ptr, size, allow) \ ({ \ long __pu_err; \ __typeof__(*(ptr)) __user *__pu_addr = (ptr); \ if (!is_kernel_addr((unsigned long)__pu_addr)) \ might_fault(); \ __chk_user_ptr(ptr); \ - __put_user_size((x), __pu_addr, (size), __pu_err); \ + if (allow) \ + __put_user_size((x), __pu_addr, (size), __pu_err); \ + else \ + __put_user_size_allowed((x), __pu_addr, (size), __pu_err); \ __pu_err; \ }) @@ -236,13 +249,12 @@ extern long __get_user_bad(void); : "b" (addr), "i" (-EFAULT), "0" (err)) #endif /* __powerpc64__ */ -#define __get_user_size(x, ptr, size, retval) \ +#define __get_user_size_allowed(x, ptr, size, retval) \ do { \ retval = 0; \ __chk_user_ptr(ptr); \ if (size > sizeof(x)) \ (x) = __get_user_bad(); \ - allow_read_from_user(ptr, size); \ switch (size) { \ case 1: __get_user_asm(x, ptr, retval, "lbz"); break; \ case 2: __get_user_asm(x, ptr, retval, "lhz"); break; \ @@ -250,6 +262,12 @@ do { \ case 8: __get_user_asm2(x, ptr, retval); break; \ default: (x) = __get_user_bad(); \ } \ +} while (0) + +#define __get_user_size(x, ptr, size, retval) \ +do { \ + allow_read_from_user(ptr, size); \ + __get_user_size_allowed(x, ptr, size, retval); \ prevent_read_from_user(ptr, size); \ } while (0) @@ -260,7 +278,7 @@ do { \ #define __long_type(x) \ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) -#define __get_user_nocheck(x, ptr, size) \ +#define __get_user_nocheck(x, ptr, size, allow) \ ({ \ long __gu_err; \ __long_type(*(ptr)) __gu_val; \ @@ -269,7 +287,10 @@ do { \ if (!is_kernel_addr((unsigned long)__gu_addr)) \ might_fault(); \ barrier_nospec(); \ - __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \ + if (allow) \ + __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \ + else \ + __get_user_size_allowed(__gu_val, __gu_addr, (size), __gu_err); \ (x) = (__typeof__(*(ptr)))__gu_val; \ __gu_err; \ }) @@ -387,6 +408,34 @@ static inline unsigned long raw_copy_to_user(void __user *to, return ret; } +static inline unsigned long +raw_copy_to_user_allowed(void __user *to, const void *from, unsigned long n) +{ + unsigned long ret; + if (__builtin_constant_p(n) && (n) <= 8) { + ret = 1; + + switch (n) { + case 1: + __put_user_size_allowed(*(u8 *)from, (u8 __user *)to, 1, ret); + break; + case 2: + __put_user_size_allowed(*(u16 *)from, (u16 __user *)to, 2, ret); + break; + case 4: + __put_user_size_allowed(*(u32 *)from, (u32 __user *)to, 4, ret); + break; + case 8: + __put_user_size_allowed(*(u64 *)from, (u64 __user *)to, 8, ret); + break; + } + if (ret == 0) + return 0; + } + + return __copy_tofrom_user(to, (__force const void __user *)from, n); +} + static __always_inline unsigned long __must_check copy_to_user_mcsafe(void __user *to, const void *from, unsigned long n) { @@ -428,4 +477,35 @@ extern long __copy_from_user_flushcache(void *dst, const void __user *src, extern void memcpy_page_flushcache(char *to, struct page *page, size_t offset, size_t len); +static __must_check inline unsigned long +user_access_begin(const void __user *ptr, size_t len, bool write) +{ + if (unlikely(!access_ok(ptr, len))) + return 0; + return allow_user_access((void __user *)ptr, ptr, len, write ? KUAP_RW : KUAP_R); +} +#define user_access_begin user_access_begin + +static inline void user_access_end(unsigned long key) +{ + if (IS_ENABLED(CONFIG_PPC_BOOK3S_32)) { + void __user *ptr = (__force void __user *)(key & 0xf0000000); + u32 size = (key << 28) - (key & 0xf0000000); + + prevent_user_access(ptr, ptr, size, key & 0xf000000f ? KUAP_RW : KUAP_R); + } else { + prevent_user_access(NULL, NULL, ~0UL, KUAP_RW); + } +} +#define user_access_end user_access_end + +static inline unsigned long user_access_save(void) { return 0UL; } +static inline void user_access_restore(unsigned long flags) { } + +#define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0) +#define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e) +#define unsafe_put_user(x, p, e) unsafe_op_wrap(__put_user_allowed(x, p), e) +#define unsafe_copy_to_user(d, s, l, e) \ + unsafe_op_wrap(raw_copy_to_user_allowed(d, s, l), e) + #endif /* _ARCH_POWERPC_UACCESS_H */