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* [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode
@ 2017-04-28 15:32 Thomas Garnier
       [not found] ` <20170428153213.137279-1-thgarnie-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
                   ` (2 more replies)
  0 siblings, 3 replies; 89+ messages in thread
From: Thomas Garnier @ 2017-04-28 15:32 UTC (permalink / raw)
  To: Martin Schwidefsky, Heiko Carstens, Dave Hansen, Arnd Bergmann,
	Thomas Gleixner, David Howells, Thomas Garnier,
	René Nyffenegger, Andrew Morton, Paul E . McKenney,
	Ingo Molnar, Eric W . Biederman, Oleg Nesterov, Pavel Tikhomirov,
	Ingo Molnar, H . Peter Anvin, Andy Lutomirski, Paolo Bonzini,
	Rik van Riel
  Cc: linux-s390-u79uwXL29TY76Z2rM5mHXA,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA,
	linux-api-u79uwXL29TY76Z2rM5mHXA, x86-DgEjT+Ai2ygdnm+yROfE0A,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
	kernel-hardening-ZwoEplunGu1jrUoiu81ncdBPR1lH4CV8

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. This option is enabled by
default on s390 because a similar feature already exists.

[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..3d2ec084d5fc 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -64,6 +64,7 @@ config ARCH_SUPPORTS_UPROBES
 
 config S390
 	def_bool y
+	select ADDR_LIMIT_CHECK
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_GCOV_PROFILE_ALL
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 980c3c9b06f8..e534b93ce43a 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

^ permalink raw reply related	[flat|nested] 89+ messages in thread

end of thread, other threads:[~2017-05-13  7:21 UTC | newest]

Thread overview: 89+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-04-28 15:32 [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Thomas Garnier
     [not found] ` <20170428153213.137279-1-thgarnie-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2017-04-28 15:32   ` [PATCH v9 2/4] x86/syscalls: Optimize address limit check Thomas Garnier
2017-05-05 22:18   ` [PATCH v9 1/4] syscalls: Verify address limit before returning to user-mode Thomas Garnier
     [not found]     ` <CAJcbSZGQsRVg3QZ9QfLn2HBC+RP-7fUTab0bYDJ455d8y8GyNw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-08  7:33       ` Ingo Molnar
     [not found]         ` <20170508073352.caqe3fqf7nuxypgi-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-05-08  7:52           ` Ingo Molnar
     [not found]             ` <20170508075209.7aluvpwildw325rf-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-05-08 15:22               ` [kernel-hardening] " Daniel Micay
2017-05-08 15:26                 ` Kees Cook
2017-05-08 19:51                   ` Thomas Garnier
     [not found]                   ` <CAGXu5jL61K0bRSEg9a_LswNyrt3K1J57REbWVcvAXT54zWwtMA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-09  6:56                     ` Ingo Molnar
     [not found]                       ` <20170509065619.wmqa6z6w3n6xpvrw-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-05-09 11:10                         ` Greg KH
     [not found]                           ` <20170509111007.GA14702-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-05-09 14:29                             ` Thomas Garnier
     [not found]                               ` <CAJcbSZFswDWZoK-1UK+xkRMJ4ttSYbtH2Y5WD5_aPR-8ru6t8A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-11 23:17                                 ` Thomas Garnier
     [not found]                                   ` <CAJcbSZEoRyewUtBHvqmNZL9FtT_q42Vmmd-EuC50x-ZRASiHHg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-11 23:44                                     ` Linus Torvalds
     [not found]                                       ` <CA+55aFwvQfs_X+paQF6Luc0Rq+W3J2fKuHRou7=ANcquDdXdDA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12  5:28                                         ` Martin Schwidefsky
2017-05-12  5:34                                           ` Kees Cook
2017-05-12  5:54                                             ` Martin Schwidefsky
2017-05-12 19:01                                               ` Kees Cook
2017-05-12 19:08                                                 ` Russell King - ARM Linux
     [not found]                                                 ` <CAGXu5jL9vUrn4kpjO+qa4cHmWBypeqP17OGbrMs=5Nz0YpQMZw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12 19:08                                                   ` Linus Torvalds
     [not found]                                                     ` <CA+55aFzbiBqsYb7vwO=+L4Vp_GOgPu+DBOrq4fBnyzq5DbBehg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12 19:30                                                       ` Kees Cook
     [not found]                                                         ` <CAGXu5j+xmyJ6RhtPw9rUgs7k3sZ1KKWffvyGGG--oPfu9W42ng-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12 20:21                                                           ` Russell King - ARM Linux
2017-05-12 20:30                                                             ` Peter Zijlstra
     [not found]                                                               ` <20170512203044.GI4626-IIpfhp3q70z/8w/KjCw3T+5/BudmfyzbbVWyRVo5IupeoWH0uzbU5w@public.gmane.org>
2017-05-12 20:45                                                                 ` Russell King - ARM Linux
2017-05-12 21:00                                                                   ` Kees Cook
     [not found]                                                                     ` <CAGXu5jL6FPuShBpZfi6+XHqOk4gxocUJRYPHT5oR3HYh3xm+sA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12 21:04                                                                       ` Kees Cook
2017-05-13  7:21                                                               ` Christoph Hellwig
2017-05-12 21:06                                                             ` Al Viro
     [not found]                                                               ` <20170512210645.GS390-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-12 21:16                                                                 ` [kernel-hardening] " Daniel Micay
2017-05-12 21:17                                                                 ` Kees Cook
     [not found]                                                                   ` <CAGXu5jJu=VTqp2tzkPB4RAVxdGC+_SSQwrUwdzWpu24AA-zEcg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12 21:23                                                                     ` Daniel Micay
2017-05-12 21:41                                                                     ` Al Viro
2017-05-12 21:47                                                                       ` Rik van Riel
     [not found]                                                                         ` <1494625675.29205.21.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-05-12 22:57                                                                           ` Al Viro
     [not found]                                                                       ` <20170512214144.GT390-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-12 21:50                                                                         ` Kees Cook
     [not found]                                             ` <CAGXu5j+EatK=DYONRkgovwLgytAnbG8jnAZaMSLckZFNVj3gig-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-12  6:57                                               ` Ingo Molnar
2017-05-12  6:13                                       ` Andy Lutomirski
2017-05-12  6:58                                       ` Ingo Molnar
2017-05-12 17:05                                         ` Thomas Garnier
2017-05-09 16:30                       ` [kernel-hardening] " Kees Cook
2017-05-08 12:46           ` Greg KH
     [not found]             ` <20170508124621.GA20705-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org>
2017-05-09  6:45               ` Ingo Molnar
     [not found]                 ` <20170509064522.anusoikaalvlux3w-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-05-09  8:56                   ` Christoph Hellwig
2017-05-09 13:00                     ` Andy Lutomirski
2017-05-09 13:02                       ` [kernel-hardening] " Christoph Hellwig
2017-05-09 16:03                         ` Christoph Hellwig
2017-05-09 16:50                           ` Kees Cook
     [not found]                             ` <CAGXu5jKHVMRMKDfn+=kkbm+JkWPhoEtDwKx=QXAYxg1p9bn7PQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-09 22:52                               ` Andy Lutomirski
     [not found]                                 ` <CALCETrV73=cDvaSLOMvb299yaGNJYME8LC-=P+N6p7R1NN97Yg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-09 23:31                                   ` Kees Cook
2017-05-10  1:59                                     ` Andy Lutomirski
2017-05-10  7:15                                     ` Christoph Hellwig
     [not found]                                     ` <CAGXu5jL6PeQmmdxh5h--fgrMK8DW_XZYpNfDOvvv_o9E3-Kxdw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-11 11:22                                       ` Borislav Petkov
2017-05-10  6:46                             ` Christoph Hellwig
     [not found]                           ` <20170509160322.GA15902-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2017-05-10  2:11                             ` Al Viro
2017-05-10  2:45                               ` Al Viro
2017-05-10  3:12                                 ` Al Viro
     [not found]                                   ` <20170510031254.GC390-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-10  3:21                                     ` Al Viro
     [not found]                                       ` <20170510032137.GD390-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-10  3:39                                         ` Al Viro
2017-05-10  6:54                                           ` Christoph Hellwig
2017-05-10  6:53                                   ` Christoph Hellwig
2017-05-10  7:27                                     ` Al Viro
2017-05-10  7:35                                       ` Christoph Hellwig
2017-05-10  6:49                                 ` Christoph Hellwig
2017-05-10  7:28                             ` Arnd Bergmann
2017-05-10  7:35                               ` Christoph Hellwig
2017-05-09 16:05                       ` Brian Gerst
     [not found]                       ` <CALCETrUh8NO2scaqEM48K70Fo2+V3=Cpyk4JurCDiCYp4nm_+g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-10  7:37                         ` [kernel-hardening] " Arnd Bergmann
2017-05-10  8:08                           ` Al Viro
2017-05-10  8:14                             ` Christoph Hellwig
2017-05-11  0:18                               ` Andy Lutomirski
2017-05-12  7:00                         ` Ingo Molnar
2017-05-12  7:15                           ` Al Viro
2017-05-12  7:35                             ` Christoph Hellwig
2017-05-12  8:07                               ` Christoph Hellwig
2017-05-12  8:23                                 ` Greg KH
     [not found]                             ` <20170512071549.GP390-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-12  7:43                               ` [kernel-hardening] " Arnd Bergmann
2017-05-12  8:11                                 ` Christoph Hellwig
2017-05-12  8:16                                   ` Al Viro
2017-05-12  8:11                                 ` Al Viro
     [not found]                                   ` <20170512081154.GQ390-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-12  8:20                                     ` Arnd Bergmann
2017-05-12 23:20                               ` Andy Lutomirski
2017-05-08 13:09         ` Kees Cook
2017-05-08 14:02           ` Ingo Molnar
     [not found]             ` <20170508140230.23kxf2kfeazeo4zr-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-05-08 14:06               ` Jann Horn
     [not found]                 ` <CAG48ez0Hz=CimkPwuq903tgJkGj8gXUtiQJJb-P2zUes6bd6Hw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-08 20:48                   ` Al Viro
     [not found]                     ` <20170508204858.GT29622-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2017-05-12 23:15                       ` Andy Lutomirski
2017-05-08 15:24               ` Kees Cook
     [not found]                 ` <CAGXu5jJ4iY7QZ9wRu5dmm7RHtLh_V6TQh4huWwLCYPKOr63aiA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-05-09  6:34                   ` Ingo Molnar
2017-04-28 15:32 ` [PATCH v9 3/4] arm/syscalls: Optimize address limit check Thomas Garnier
2017-04-28 15:32 ` [PATCH v9 4/4] arm64/syscalls: " Thomas Garnier

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