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freebsd-dev/sys/vm/memguard.h

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Start copyright notice with /*-
2010-04-07 16:29:10 +00:00
/*-
Bring in MemGuard, a very simple and small replacement allocator designed to help detect tamper-after-free scenarios, a problem more and more common and likely with multithreaded kernels where race conditions are more prevalent. Currently MemGuard can only take over malloc()/realloc()/free() for particular (a) malloc type(s) and the code brought in with this change manually instruments it to take over M_SUBPROC allocations as an example. If you are planning to use it, for now you must: 1) Put "options DEBUG_MEMGUARD" in your kernel config. 2) Edit src/sys/kern/kern_malloc.c manually, look for "XXX CHANGEME" and replace the M_SUBPROC comparison with the appropriate malloc type (this might require additional but small/simple code modification if, say, the malloc type is declared out of scope). 3) Build and install your kernel. Tune vm.memguard_divisor boot-time tunable which is used to scale how much of kmem_map you want to allott for MemGuard's use. The default is 10, so kmem_size/10. ToDo: 1) Bring in a memguard(9) man page. 2) Better instrumentation (e.g., boot-time) of MemGuard taking over malloc types. 3) Teach UMA about MemGuard to allow MemGuard to override zone allocations too. 4) Improve MemGuard if necessary. This work is partly based on some old patches from Ian Dowse.
2005-01-21 18:09:17 +00:00
* Copyright (c) 2005,
Well, it seems that I pre-maturely removed the "All rights reserved" statement from some files, so re-add it for the moment, until the related legalese is sorted out. This change affects: sys/kern/kern_mbuf.c sys/vm/memguard.c sys/vm/memguard.h sys/vm/uma.h sys/vm/uma_core.c sys/vm/uma_dbg.c sys/vm/uma_dbg.h sys/vm/uma_int.h
2005-02-16 21:45:59 +00:00
* Bosko Milekic <bmilekic@FreeBSD.org>. All rights reserved.
Bring in MemGuard, a very simple and small replacement allocator designed to help detect tamper-after-free scenarios, a problem more and more common and likely with multithreaded kernels where race conditions are more prevalent. Currently MemGuard can only take over malloc()/realloc()/free() for particular (a) malloc type(s) and the code brought in with this change manually instruments it to take over M_SUBPROC allocations as an example. If you are planning to use it, for now you must: 1) Put "options DEBUG_MEMGUARD" in your kernel config. 2) Edit src/sys/kern/kern_malloc.c manually, look for "XXX CHANGEME" and replace the M_SUBPROC comparison with the appropriate malloc type (this might require additional but small/simple code modification if, say, the malloc type is declared out of scope). 3) Build and install your kernel. Tune vm.memguard_divisor boot-time tunable which is used to scale how much of kmem_map you want to allott for MemGuard's use. The default is 10, so kmem_size/10. ToDo: 1) Bring in a memguard(9) man page. 2) Better instrumentation (e.g., boot-time) of MemGuard taking over malloc types. 3) Teach UMA about MemGuard to allow MemGuard to override zone allocations too. 4) Improve MemGuard if necessary. This work is partly based on some old patches from Ian Dowse.
2005-01-21 18:09:17 +00:00
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice unmodified, this list of conditions, and the following
* disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD$
*/
Rework memguard(9) to reserve significantly more KVA to detect use-after-free over a longer time. Also release the backing pages of a guarded allocation at free(9) time to reduce the overhead of using memguard(9). Allow setting and varying the malloc type at run-time. Add knobs to allow: - randomly guarding memory - adding un-backed KVA guard pages to detect underflow and overflow - a lower limit on the size of allocations that are guarded Reviewed by: alc Reviewed by: brueffer, Ulrich Spörlein <uqs spoerlein net> (man page) Silence from: -arch Approved by: zml (mentor) MFC after: 1 month
2010-08-11 22:10:37 +00:00
#include "opt_vm.h"
Improve memguard a bit: - Provide tunable vm.memguard.desc, so one can specify memory type without changing the code and recompiling the kernel. - Allow to use memguard for kernel modules by providing sysctl vm.memguard.desc, which can be changed to short description of memory type before module is loaded. - Move as much memguard code as possible to memguard.c. - Add sysctl node vm.memguard. and move memguard-specific sysctl there. - Add malloc_desc2type() function for finding memory type based on its short description (ks_shortdesc field). - Memory type can be changed (via vm.memguard.desc sysctl) only if it doesn't exist (will be loaded later) or when no memory is allocated yet. If there is allocated memory for the given memory type, return EBUSY. - Implement two ways of memory types comparsion and make safer/slower the default.
2005-12-30 11:45:07 +00:00
Rework memguard(9) to reserve significantly more KVA to detect use-after-free over a longer time. Also release the backing pages of a guarded allocation at free(9) time to reduce the overhead of using memguard(9). Allow setting and varying the malloc type at run-time. Add knobs to allow: - randomly guarding memory - adding un-backed KVA guard pages to detect underflow and overflow - a lower limit on the size of allocations that are guarded Reviewed by: alc Reviewed by: brueffer, Ulrich Spörlein <uqs spoerlein net> (man page) Silence from: -arch Approved by: zml (mentor) MFC after: 1 month
2010-08-11 22:10:37 +00:00
#ifdef DEBUG_MEMGUARD
unsigned long memguard_fudge(unsigned long, unsigned long);
void memguard_init(struct vm_map *);
void *memguard_alloc(unsigned long, int);
void memguard_free(void *);
int memguard_cmp(struct malloc_type *, unsigned long);
int is_memguard_addr(void *);
#else
#define memguard_fudge(size, xxx) (size)
#define memguard_init(map) do { } while (0)
#define memguard_alloc(size, flags) NULL
#define memguard_free(addr) do { } while (0)
#define memguard_cmp(mtp, size) 0
#define is_memguard_addr(addr) 0
#endif
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