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>
132 lines
3.7 KiB
C
132 lines
3.7 KiB
C
/*
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* thread_info.h: sparc low-level thread information
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* adapted from the ppc version by Pete Zaitcev, which was
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* adapted from the i386 version by Paul Mackerras
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*
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* Copyright (C) 2002 David Howells (dhowells@redhat.com)
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* Copyright (c) 2002 Pete Zaitcev (zaitcev@yahoo.com)
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* - Incorporating suggestions made by Linus Torvalds and Dave Miller
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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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#ifdef __KERNEL__
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#ifndef __ASSEMBLY__
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#include <asm/ptrace.h>
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#include <asm/page.h>
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/*
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* Low level task data.
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*
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* If you change this, change the TI_* offsets below to match.
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*/
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#define NSWINS 8
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struct thread_info {
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unsigned long uwinmask;
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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,
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<0 => BUG */
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int softirq_count;
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int hardirq_count;
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/* Context switch saved kernel state. */
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unsigned long ksp; /* ... ksp __attribute__ ((aligned (8))); */
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unsigned long kpc;
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unsigned long kpsr;
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unsigned long kwim;
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/* A place to store user windows and stack pointers
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* when the stack needs inspection.
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*/
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struct reg_window32 reg_window[NSWINS]; /* align for ldd! */
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unsigned long rwbuf_stkptrs[NSWINS];
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unsigned long w_saved;
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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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.uwinmask = 0, \
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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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/* how to get the thread information struct from C */
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register struct thread_info *current_thread_info_reg asm("g6");
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#define current_thread_info() (current_thread_info_reg)
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/*
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* thread information allocation
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*/
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#define THREAD_SIZE_ORDER 1
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#endif /* __ASSEMBLY__ */
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/* Size of kernel stack for each process */
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#define THREAD_SIZE (2 * PAGE_SIZE)
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/*
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* Offsets in thread_info structure, used in assembly code
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* The "#define REGWIN_SZ 0x40" was abolished, so no multiplications.
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*/
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#define TI_UWINMASK 0x00 /* uwinmask */
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#define TI_TASK 0x04
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#define TI_EXECDOMAIN 0x08 /* exec_domain */
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#define TI_FLAGS 0x0c
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#define TI_CPU 0x10
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#define TI_PREEMPT 0x14 /* preempt_count */
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#define TI_SOFTIRQ 0x18 /* softirq_count */
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#define TI_HARDIRQ 0x1c /* hardirq_count */
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#define TI_KSP 0x20 /* ksp */
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#define TI_KPC 0x24 /* kpc (ldd'ed with kpc) */
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#define TI_KPSR 0x28 /* kpsr */
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#define TI_KWIM 0x2c /* kwim (ldd'ed with kpsr) */
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#define TI_REG_WINDOW 0x30
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#define TI_RWIN_SPTRS 0x230
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#define TI_W_SAVED 0x250
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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_NOTIFY_RESUME 1 /* callback before returning to user */
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#define TIF_SIGPENDING 2 /* signal pending */
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#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
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#define TIF_RESTORE_SIGMASK 4 /* restore signal mask in do_signal() */
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#define TIF_USEDFPU 8 /* FPU was used by this task
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* this quantum (SMP) */
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#define TIF_POLLING_NRFLAG 9 /* true if poll_idle() is polling
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* TIF_NEED_RESCHED */
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#define TIF_MEMDIE 10 /* is terminating due to OOM killer */
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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_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
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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_USEDFPU (1<<TIF_USEDFPU)
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#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
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#define _TIF_DO_NOTIFY_RESUME_MASK (_TIF_NOTIFY_RESUME | \
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_TIF_SIGPENDING)
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#define is_32bit_task() (1)
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#endif /* __KERNEL__ */
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#endif /* _ASM_THREAD_INFO_H */
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