linux-api.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Thomas Garnier <thgarnie-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
To: "Martin Schwidefsky"
	<schwidefsky-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>,
	"Heiko Carstens"
	<heiko.carstens-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>,
	"Dave Hansen"
	<dave.hansen-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	"Arnd Bergmann" <arnd-r2nGTMty4D4@public.gmane.org>,
	"Andrew Morton"
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	"Al Viro"
	<viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>,
	"Thomas Garnier"
	<thgarnie-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	"David Howells"
	<dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	"René Nyffenegger"
	<mail-gLCNRsNSrVdVZEhyV+6z5nIPMjoJpjVV@public.gmane.org>,
	"Paul E . McKenney"
	<paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>,
	"Ingo Molnar" <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	"Thomas Gleixner" <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>,
	"Eric W . Biederman"
	<ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>,
	"Oleg Nesterov" <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	"Pavel Tikhomirov"
	<ptikhomirov-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>,
	"Ingo Molnar" <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	"H . Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>,
	"Andy Lutomirski" <luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	"Paolo Bonzini" <pbonzini@redhat.c>
Cc: linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	kernel-hardening-ZwoEplunGu1jrUoiu81ncdBPR1lH4CV8@public.gmane.org
Subject: [PATCH v8 1/4] syscalls: Verify address limit before returning to user-mode
Date: Thu, 27 Apr 2017 07:42:27 -0700	[thread overview]
Message-ID: <20170427144227.113630-1-thgarnie@google.com> (raw)
In-Reply-To: <CAJcbSZENjCgn3TNDGzCBBSOXMvbTX8mBO7Trugdb5VRzhxwmHg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

Ensure that a syscall does not return to user-mode with a kernel address
limit. If that happens, a process can corrupt kernel-mode memory and
elevate privileges [1].

The CONFIG_ADDR_LIMIT_CHECK option disables the generic check so each
architecture can create optimized versions.

[1] https://bugs.chromium.org/p/project-zero/issues/detail?id=990

Signed-off-by: Thomas Garnier <thgarnie-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Tested-by: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
---
Based on next-20170426
---
 arch/s390/Kconfig        |  1 +
 include/linux/syscalls.h | 27 ++++++++++++++++++++++++++-
 init/Kconfig             |  6 ++++++
 kernel/sys.c             | 13 +++++++++++++
 4 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index d25435d94b6e..164de1d24e92 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 ADDR_LIMIT_CHECK
 	select ARCH_SAVE_PAGE_KEYS if HIBERNATION
 	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 980c3c9b06f8..ebde64f1622c 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -191,6 +191,28 @@ extern struct trace_event_functions exit_syscall_print_funcs;
 	SYSCALL_METADATA(sname, x, __VA_ARGS__)			\
 	__SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
 
+
+/*
+ * Called before coming back to user-mode. Returning to user-mode with an
+ * address limit different than USER_DS can allow to overwrite kernel memory.
+ */
+static inline void addr_limit_check_syscall(void)
+{
+	BUG_ON(!segment_eq(get_fs(), USER_DS));
+}
+
+#ifndef CONFIG_ADDR_LIMIT_CHECK
+#define ADDR_LIMIT_CHECK_PRE() \
+	bool user_caller = segment_eq(get_fs(), USER_DS)
+#define ADDR_LIMIT_CHECK_POST() \
+	if (user_caller) addr_limit_check_syscall()
+#else
+#define ADDR_LIMIT_CHECK_PRE()
+#define ADDR_LIMIT_CHECK_POST()
+asmlinkage void addr_limit_check_failed(void) __noreturn;
+#endif
+
+
 #define __PROTECT(...) asmlinkage_protect(__VA_ARGS__)
 #define __SYSCALL_DEFINEx(x, name, ...)					\
 	asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))	\
@@ -199,7 +221,10 @@ 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;						\
+		ADDR_LIMIT_CHECK_PRE();					\
+		ret = SYSC##name(__MAP(x,__SC_CAST,__VA_ARGS__));	\
+		ADDR_LIMIT_CHECK_POST();				\
 		__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 42a346b0df43..599d9fe30703 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1961,6 +1961,12 @@ config PROFILING
 config TRACEPOINTS
 	bool
 
+config ADDR_LIMIT_CHECK
+	bool
+	help
+	  Disable the generic address limit check. Allow each architecture to
+	  optimize how and when the verification is done.
+
 source "arch/Kconfig"
 
 endmenu		# General setup
diff --git a/kernel/sys.c b/kernel/sys.c
index 8a94b4eabcaa..a1cbcd715d62 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2458,3 +2458,16 @@ COMPAT_SYSCALL_DEFINE1(sysinfo, struct compat_sysinfo __user *, info)
 	return 0;
 }
 #endif /* CONFIG_COMPAT */
+
+#ifdef CONFIG_ADDR_LIMIT_CHECK
+/*
+ * Used when an architecture specific implementation detects an invalid address
+ * limit. This function does not return.
+ */
+asmlinkage void addr_limit_check_failed(void)
+{
+	/* Try to fail on the generic address limit check */
+	addr_limit_check_syscall();
+	panic("Invalid address limit before returning to user-mode");
+}
+#endif
-- 
2.13.0.rc0.306.g87b477812d-goog

  parent reply	other threads:[~2017-04-27 14:42 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-26 18:34 [PATCH v8 1/4] syscalls: Verify address limit before returning to user-mode Thomas Garnier
2017-04-26 18:34 ` [PATCH v8 2/4] x86/syscalls: Optimize address limit check Thomas Garnier
2017-04-26 18:34 ` [PATCH v8 3/4] arm/syscalls: " Thomas Garnier
2017-04-26 18:34 ` [PATCH v8 4/4] arm64/syscalls: " Thomas Garnier
     [not found] ` <20170426183425.32158-1-thgarnie-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2017-04-27  6:49   ` [PATCH v8 1/4] syscalls: Verify address limit before returning to user-mode Ingo Molnar
2017-04-27 14:16     ` Thomas Garnier
     [not found]       ` <CAJcbSZENjCgn3TNDGzCBBSOXMvbTX8mBO7Trugdb5VRzhxwmHg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-04-27 14:42         ` Thomas Garnier [this message]
     [not found]           ` <20170427144227.113630-1-thgarnie-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2017-04-28  6:35             ` Ingo Molnar
2017-04-28  6:33         ` Ingo Molnar

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170427144227.113630-1-thgarnie@google.com \
    --to=thgarnie-hpiqsd4aklfqt0dzr+alfa@public.gmane.org \
    --cc=akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org \
    --cc=arnd-r2nGTMty4D4@public.gmane.org \
    --cc=dave.hansen-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org \
    --cc=dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org \
    --cc=ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org \
    --cc=heiko.carstens-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org \
    --cc=hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org \
    --cc=kernel-hardening-ZwoEplunGu1jrUoiu81ncdBPR1lH4CV8@public.gmane.org \
    --cc=linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org \
    --cc=linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org \
    --cc=mail-gLCNRsNSrVdVZEhyV+6z5nIPMjoJpjVV@public.gmane.org \
    --cc=mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org \
    --cc=mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org \
    --cc=oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org \
    --cc=paulmck-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org \
    --cc=pbonzini@redhat.c \
    --cc=ptikhomirov-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org \
    --cc=schwidefsky-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org \
    --cc=tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org \
    --cc=viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org \
    --cc=x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).