eca64e79b5
I meant trunc_page. It's only a coincidence this hasn't caused problems yet. Pointed out by: Antoine Brodin <antoine.brodin@laposte.net>
223 lines
6.5 KiB
C
223 lines
6.5 KiB
C
/*
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* Copyright (c) 2005,
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* Bosko Milekic <bmilekic@freebsd.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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/*
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* MemGuard is a simple replacement allocator for debugging only
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* which provides ElectricFence-style memory barrier protection on
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* objects being allocated, and is used to detect tampering-after-free
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* scenarios.
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*
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* See the memguard(9) man page for more information on using MemGuard.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/types.h>
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#include <sys/queue.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/malloc.h>
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#include <vm/vm.h>
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#include <vm/vm_page.h>
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#include <vm/vm_map.h>
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#include <vm/vm_extern.h>
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#include <vm/memguard.h>
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/*
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* Global MemGuard data.
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*/
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static vm_map_t memguard_map;
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static unsigned long memguard_mapsize;
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static unsigned long memguard_mapused;
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struct memguard_entry {
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STAILQ_ENTRY(memguard_entry) entries;
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void *ptr;
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};
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static STAILQ_HEAD(memguard_fifo, memguard_entry) memguard_fifo_pool;
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/*
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* Local prototypes.
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*/
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static void memguard_guard(void *addr);
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static void memguard_unguard(void *addr);
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/*
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* Local macros. MemGuard data is global, so replace these with whatever
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* your system uses to protect global data (if it is kernel-level
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* parallelized). This is for porting among BSDs.
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*/
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#define MEMGUARD_CRIT_SECTION_DECLARE static struct mtx memguard_mtx
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#define MEMGUARD_CRIT_SECTION_INIT \
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mtx_init(&memguard_mtx, "MemGuard mtx", NULL, MTX_DEF)
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#define MEMGUARD_CRIT_SECTION_ENTER mtx_lock(&memguard_mtx)
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#define MEMGUARD_CRIT_SECTION_EXIT mtx_unlock(&memguard_mtx)
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MEMGUARD_CRIT_SECTION_DECLARE;
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/*
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* Initialize the MemGuard mock allocator. All objects from MemGuard come
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* out of a single VM map (contiguous chunk of address space).
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*/
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void
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memguard_init(vm_map_t parent_map, unsigned long size)
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{
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char *base, *limit;
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/* size must be multiple of PAGE_SIZE */
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size /= PAGE_SIZE;
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size++;
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size *= PAGE_SIZE;
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memguard_map = kmem_suballoc(parent_map, (vm_offset_t *)&base,
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(vm_offset_t *)&limit, (vm_size_t)size);
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memguard_map->system_map = 1;
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memguard_mapsize = size;
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memguard_mapused = 0;
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MEMGUARD_CRIT_SECTION_INIT;
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MEMGUARD_CRIT_SECTION_ENTER;
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STAILQ_INIT(&memguard_fifo_pool);
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MEMGUARD_CRIT_SECTION_EXIT;
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printf("MEMGUARD DEBUGGING ALLOCATOR INITIALIZED:\n");
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printf("\tMEMGUARD map base: %p\n", base);
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printf("\tMEMGUARD map limit: %p\n", limit);
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printf("\tMEMGUARD map size: %ld (Bytes)\n", size);
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}
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/*
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* Allocate a single object of specified size with specified flags (either
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* M_WAITOK or M_NOWAIT).
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*/
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void *
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memguard_alloc(unsigned long size, int flags)
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{
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void *obj = NULL;
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struct memguard_entry *e = NULL;
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/* XXX: MemGuard does not handle > PAGE_SIZE objects. */
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if (size > PAGE_SIZE)
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panic("MEMGUARD: Cannot handle objects > PAGE_SIZE");
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/*
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* If we haven't exhausted the memguard_map yet, allocate from
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* it and grab a new page, even if we have recycled pages in our
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* FIFO. This is because we wish to allow recycled pages to live
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* guarded in the FIFO for as long as possible in order to catch
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* even very late tamper-after-frees, even though it means that
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* we end up wasting more memory, this is only a DEBUGGING allocator
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* after all.
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*/
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MEMGUARD_CRIT_SECTION_ENTER;
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if (memguard_mapused >= memguard_mapsize) {
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e = STAILQ_FIRST(&memguard_fifo_pool);
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if (e != NULL) {
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STAILQ_REMOVE(&memguard_fifo_pool, e,
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memguard_entry, entries);
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MEMGUARD_CRIT_SECTION_EXIT;
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obj = e->ptr;
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free(e, M_TEMP);
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memguard_unguard(obj);
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if (flags & M_ZERO)
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bzero(obj, PAGE_SIZE);
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return obj;
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}
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MEMGUARD_CRIT_SECTION_EXIT;
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if (flags & M_WAITOK)
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panic("MEMGUARD: Failed with M_WAITOK: " \
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"memguard_map too small");
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return NULL;
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} else
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memguard_mapused += PAGE_SIZE;
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MEMGUARD_CRIT_SECTION_EXIT;
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if (obj == NULL)
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obj = (void *)kmem_malloc(memguard_map, PAGE_SIZE, flags);
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if (obj != NULL) {
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memguard_unguard(obj);
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if (flags & M_ZERO)
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bzero(obj, PAGE_SIZE);
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} else {
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MEMGUARD_CRIT_SECTION_ENTER;
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memguard_mapused -= PAGE_SIZE;
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MEMGUARD_CRIT_SECTION_EXIT;
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}
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return obj;
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}
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/*
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* Free specified single object.
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*/
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void
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memguard_free(void *addr)
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{
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struct memguard_entry *e;
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memguard_guard(addr);
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e = malloc(sizeof(struct memguard_entry), M_TEMP, M_NOWAIT);
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if (e == NULL) {
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MEMGUARD_CRIT_SECTION_ENTER;
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memguard_mapused -= PAGE_SIZE;
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MEMGUARD_CRIT_SECTION_EXIT;
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kmem_free(memguard_map, (vm_offset_t)trunc_page(
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(unsigned long)addr), PAGE_SIZE);
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return;
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}
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e->ptr = (void *)trunc_page((unsigned long)addr);
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MEMGUARD_CRIT_SECTION_ENTER;
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STAILQ_INSERT_TAIL(&memguard_fifo_pool, e, entries);
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MEMGUARD_CRIT_SECTION_EXIT;
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}
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/*
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* Guard a page containing specified object (make it read-only so that
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* future writes to it fail).
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*/
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static void
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memguard_guard(void *addr)
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{
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void *a = (void *)trunc_page((unsigned long)addr);
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(void)vm_map_protect(memguard_map, (vm_offset_t)a,
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(vm_offset_t)((unsigned long)a + PAGE_SIZE), VM_PROT_READ, 0);
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}
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/*
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* Unguard a page containing specified object (make it read-and-write to
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* allow full data access).
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*/
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static void
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memguard_unguard(void *addr)
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{
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void *a = (void *)trunc_page((unsigned long)addr);
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(void)vm_map_protect(memguard_map, (vm_offset_t)a,
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(vm_offset_t)((unsigned long)a + PAGE_SIZE),
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VM_PROT_READ | VM_PROT_WRITE, 0);
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}
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