f56141e3e2
If an attacker can cause a controlled kernel stack overflow, overwriting the restart block is a very juicy exploit target. This is because the restart_block is held in the same memory allocation as the kernel stack. Moving the restart block to struct task_struct prevents this exploit by making the restart_block harder to locate. Note that there are other fields in thread_info that are also easy targets, at least on some architectures. It's also a decent simplification, since the restart code is more or less identical on all architectures. [james.hogan@imgtec.com: metag: align thread_info::supervisor_stack] Signed-off-by: Andy Lutomirski <luto@amacapital.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: David Miller <davem@davemloft.net> Acked-by: Richard Weinberger <richard@nod.at> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Steven Miao <realmz6@gmail.com> Cc: Mark Salter <msalter@redhat.com> Cc: Aurelien Jacquiot <a-jacquiot@ti.com> Cc: Mikael Starvik <starvik@axis.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: David Howells <dhowells@redhat.com> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Michal Simek <monstr@monstr.eu> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Jonas Bonn <jonas@southpole.se> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Chen Liqin <liqin.linux@gmail.com> Cc: Lennox Wu <lennox.wu@gmail.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: Chris Zankel <chris@zankel.net> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: James Hogan <james.hogan@imgtec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
112 lines
2.9 KiB
C
112 lines
2.9 KiB
C
/*
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* Copyright 2004-2010 Analog Devices Inc.
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*
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* Licensed under the GPL-2 or later.
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*/
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#ifndef _ASM_THREAD_INFO_H
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#define _ASM_THREAD_INFO_H
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#include <asm/page.h>
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#include <asm/entry.h>
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#include <asm/l1layout.h>
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#include <linux/compiler.h>
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#ifdef __KERNEL__
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/* Thread Align Mask to reach to the top of the stack
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* for any process
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*/
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#define ALIGN_PAGE_MASK 0xffffe000
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/*
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* Size of kernel stack for each process. This must be a power of 2...
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*/
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#define THREAD_SIZE_ORDER 1
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#define THREAD_SIZE 8192 /* 2 pages */
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#define STACK_WARN (THREAD_SIZE/8)
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#ifndef __ASSEMBLY__
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typedef unsigned long mm_segment_t;
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/*
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* low level task data.
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* If you change this, change the TI_* offsets below to match.
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*/
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struct thread_info {
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struct task_struct *task; /* main task structure */
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struct exec_domain *exec_domain; /* execution domain */
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unsigned long flags; /* low level flags */
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int cpu; /* cpu we're on */
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int preempt_count; /* 0 => preemptable, <0 => BUG */
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mm_segment_t addr_limit; /* address limit */
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#ifndef CONFIG_SMP
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struct l1_scratch_task_info l1_task_info;
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#endif
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};
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/*
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* macros/functions for gaining access to the thread information structure
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*/
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#define INIT_THREAD_INFO(tsk) \
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{ \
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.task = &tsk, \
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.exec_domain = &default_exec_domain, \
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.flags = 0, \
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.cpu = 0, \
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.preempt_count = INIT_PREEMPT_COUNT, \
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}
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#define init_thread_info (init_thread_union.thread_info)
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#define init_stack (init_thread_union.stack)
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/* Given a task stack pointer, you can find its corresponding
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* thread_info structure just by masking it to the THREAD_SIZE
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* boundary (currently 8K as you can see above).
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*/
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__attribute_const__
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static inline struct thread_info *current_thread_info(void)
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{
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struct thread_info *ti;
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__asm__("%0 = sp;" : "=da"(ti));
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return (struct thread_info *)((long)ti & ~((long)THREAD_SIZE-1));
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}
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#endif /* __ASSEMBLY__ */
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/*
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* Offsets in thread_info structure, used in assembly code
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*/
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#define TI_TASK 0
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#define TI_EXECDOMAIN 4
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#define TI_FLAGS 8
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#define TI_CPU 12
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#define TI_PREEMPT 16
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/*
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* thread information flag bit numbers
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*/
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#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
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#define TIF_SIGPENDING 1 /* signal pending */
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#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
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#define TIF_MEMDIE 4 /* is terminating due to OOM killer */
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#define TIF_RESTORE_SIGMASK 5 /* restore signal mask in do_signal() */
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#define TIF_IRQ_SYNC 7 /* sync pipeline stage */
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#define TIF_NOTIFY_RESUME 8 /* callback before returning to user */
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#define TIF_SINGLESTEP 9
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/* as above, but as bit values */
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#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
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#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
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#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
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#define _TIF_IRQ_SYNC (1<<TIF_IRQ_SYNC)
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#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
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#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
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#define _TIF_WORK_MASK 0x0000FFFE /* work to do on interrupt/exception return */
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#endif /* __KERNEL__ */
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#endif /* _ASM_THREAD_INFO_H */
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