From patchwork Sat Mar 11 00:04:58 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Garnier X-Patchwork-Id: 9618223 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 90E786046A for ; Sat, 11 Mar 2017 00:05:42 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 80581287A9 for ; Sat, 11 Mar 2017 00:05:42 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 73F58287B7; Sat, 11 Mar 2017 00:05:42 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, RCVD_IN_DNSWL_MED, T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 53BE4287A9 for ; Sat, 11 Mar 2017 00:05:40 +0000 (UTC) Received: (qmail 26600 invoked by uid 550); 11 Mar 2017 00:05:32 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 26566 invoked from network); 11 Mar 2017 00:05:31 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=E6EHK/gGWM6VJXKo7h65Cf9Ifa4/tA/IjWGURVFljZw=; b=oo8/Xf3Vl9+zcHD8uBwX/nkdbTCNTYHpUljmr3yo104MySsNHwOXRYUX0HC6G+OzF/ exyklYt91QySVeJwJLcvK0tSzy3F9aL24O7iLjHFjkaandtV2nZnt2HH3BWc07X+R4XZ NrwrhZtmkPCQVxG9mAN7/qs/HzPS2a9AtSSGDKKVgsTWH33KqrBHgAN8xeso44SkuKLq y83JAzeFTyuJlTw//F5m972wySfFoTzoyar624+gzRXGXjMVngSQrAXqzAbd1CBoKWMM 4fXmWxi8Xz/4Snk6n7j6eHZKoaypbPZl6FCJ3dcdQrAq4vqTloAbEkSOcQE9+5TEwGmd 7yNw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=E6EHK/gGWM6VJXKo7h65Cf9Ifa4/tA/IjWGURVFljZw=; b=uB5V3/IM7SShiwBEE6uci1INfJI2tzlBN0pGUTEjkq8kd0+llnQ14Y/01+lSmxdMgG DuXCIXt2AtVFzylRVfy9OF48hxfwCcJ4svBUNa3KOylpWLwQ+xrvuAgb5LFgPIUq5je0 M15VrPQbHL/6siN+gdoTdS7DDWRaizVTE39zsVd7cTD+w+5Dt0jCohHaLPv3mLSpCF2/ kgDGhnXDEyIS3trN5tXTR95lnKlgZX82VwRxy00KG4XdUwqsNiMrVDYCel/JyWwvoffH 82GjsU+H0X4PpeYc2hOU4FrsgJdlUvVGGrCiPlhT3eju6xumFcBd3uJ892EZjAFx3MZ9 8Krg== X-Gm-Message-State: AMke39muK8oL/lovg8Q3Ia8NQ3M9E5KtNfft5359KQxCzYr9l9BPRQ3F1SwSOVD5yJNP4hb4 X-Received: by 10.98.62.82 with SMTP id l79mr23952590pfa.164.1489190719004; Fri, 10 Mar 2017 16:05:19 -0800 (PST) From: Thomas Garnier To: Martin Schwidefsky , Heiko Carstens , David Howells , Arnd Bergmann , Al Viro , Dave Hansen , Thomas Garnier , =?UTF-8?q?Ren=C3=A9=20Nyffenegger?= , Andrew Morton , Kees Cook , "Paul E . McKenney" , Andy Lutomirski , Ard Biesheuvel , Nicolas Pitre , Petr Mladek , Sebastian Andrzej Siewior , Sergey Senozhatsky , Helge Deller , Rik van Riel , Ingo Molnar , John Stultz , Thomas Gleixner , Oleg Nesterov , Stephen Smalley , Pavel Tikhomirov , Frederic Weisbecker , Stanislav Kinsburskiy , Ingo Molnar , "H . Peter Anvin" , Paolo Bonzini , Dmitry Safonov , Borislav Petkov , Josh Poimboeuf , Brian Gerst , Jan Beulich , Christian Borntraeger , Fenghua Yu , He Chen , Russell King , Vladimir Murzin , Will Deacon , Catalin Marinas , Mark Rutland , James Morse , "David A . Long" , Pratyush Anand , Laura Abbott , Andre Przywara , Chris Metcalf Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, kernel-hardening@lists.openwall.com Date: Fri, 10 Mar 2017 16:04:58 -0800 Message-Id: <20170311000501.46607-1-thgarnie@google.com> X-Mailer: git-send-email 2.12.0.246.ga2ecc84866-goog Subject: [kernel-hardening] [PATCH v3 1/4] syscalls: Restore address limit after a syscall X-Virus-Scanned: ClamAV using ClamSMTP This patch ensures a syscall does not return to user-mode with a kernel address limit. If that happened, a process can corrupt kernel-mode memory and elevate privileges. For example, it would mitigation this bug: - https://bugs.chromium.org/p/project-zero/issues/detail?id=990 If the CONFIG_BUG_ON_DATA_CORRUPTION option is enabled, an incorrect state will result in a BUG_ON. The CONFIG_ARCH_NO_SYSCALL_VERIFY_PRE_USERMODE_STATE option is also added so each architecture can optimize this change. Signed-off-by: Thomas Garnier --- Based on next-20170308 --- arch/s390/Kconfig | 1 + include/linux/syscalls.h | 18 +++++++++++++++++- init/Kconfig | 7 +++++++ kernel/sys.c | 8 ++++++++ 4 files changed, 33 insertions(+), 1 deletion(-) diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index a2dcef0aacc7..b73f5b87bc99 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -103,6 +103,7 @@ config S390 select ARCH_INLINE_WRITE_UNLOCK_BH select ARCH_INLINE_WRITE_UNLOCK_IRQ select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE + select ARCH_NO_SYSCALL_VERIFY_PRE_USERMODE_STATE select ARCH_SAVE_PAGE_KEYS if HIBERNATION select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_NUMA_BALANCING diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 980c3c9b06f8..e659076adf6c 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -191,6 +191,19 @@ extern struct trace_event_functions exit_syscall_print_funcs; SYSCALL_METADATA(sname, x, __VA_ARGS__) \ __SYSCALL_DEFINEx(x, sname, __VA_ARGS__) +asmlinkage void verify_pre_usermode_state(void); + +#ifndef CONFIG_ARCH_NO_SYSCALL_VERIFY_PRE_USERMODE_STATE +#define __CHECK_USER_CALLER() \ + bool user_caller = segment_eq(get_fs(), USER_DS) +#define __VERIFY_PRE_USERMODE_STATE() \ + if (user_caller) verify_pre_usermode_state() +#else +#define __CHECK_USER_CALLER() +#define __VERIFY_PRE_USERMODE_STATE() +#endif + + #define __PROTECT(...) asmlinkage_protect(__VA_ARGS__) #define __SYSCALL_DEFINEx(x, name, ...) \ asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \ @@ -199,7 +212,10 @@ extern struct trace_event_functions exit_syscall_print_funcs; asmlinkage long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ asmlinkage long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ { \ - long ret = SYSC##name(__MAP(x,__SC_CAST,__VA_ARGS__)); \ + long ret; \ + __CHECK_USER_CALLER(); \ + ret = SYSC##name(__MAP(x,__SC_CAST,__VA_ARGS__)); \ + __VERIFY_PRE_USERMODE_STATE(); \ __MAP(x,__SC_TEST,__VA_ARGS__); \ __PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \ return ret; \ diff --git a/init/Kconfig b/init/Kconfig index c859c993c26f..c4efc3a95e4a 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1929,6 +1929,13 @@ config PROFILING config TRACEPOINTS bool +# +# Set by each architecture that want to optimize how verify_pre_usermode_state +# is called. +# +config ARCH_NO_SYSCALL_VERIFY_PRE_USERMODE_STATE + bool + source "arch/Kconfig" endmenu # General setup diff --git a/kernel/sys.c b/kernel/sys.c index 196c7134bee6..411163ac9dc3 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2459,3 +2459,11 @@ COMPAT_SYSCALL_DEFINE1(sysinfo, struct compat_sysinfo __user *, info) return 0; } #endif /* CONFIG_COMPAT */ + +/* Called before coming back to user-mode */ +asmlinkage void verify_pre_usermode_state(void) +{ + if (CHECK_DATA_CORRUPTION(!segment_eq(get_fs(), USER_DS), + "incorrect get_fs() on user-mode return")) + set_fs(USER_DS); +}