5df87b21d3
transparent layering and better fragmentation. - Normalize functions that allocate memory to use kmem_* - Those that allocate address space are named kva_* - Those that operate on maps are named kmap_* - Implement recursive allocation handling for kmem_arena in vmem. Reviewed by: alc Tested by: pho Sponsored by: EMC / Isilon Storage Division
519 lines
16 KiB
C
519 lines
16 KiB
C
/*-
|
|
* Copyright (c) 2005, Bosko Milekic <bmilekic@FreeBSD.org>.
|
|
* Copyright (c) 2010 Isilon Systems, Inc. (http://www.isilon.com/)
|
|
* All rights reserved.
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
__FBSDID("$FreeBSD$");
|
|
|
|
/*
|
|
* MemGuard is a simple replacement allocator for debugging only
|
|
* which provides ElectricFence-style memory barrier protection on
|
|
* objects being allocated, and is used to detect tampering-after-free
|
|
* scenarios.
|
|
*
|
|
* See the memguard(9) man page for more information on using MemGuard.
|
|
*/
|
|
|
|
#include "opt_vm.h"
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/types.h>
|
|
#include <sys/queue.h>
|
|
#include <sys/lock.h>
|
|
#include <sys/mutex.h>
|
|
#include <sys/malloc.h>
|
|
#include <sys/sysctl.h>
|
|
#include <sys/vmem.h>
|
|
|
|
#include <vm/vm.h>
|
|
#include <vm/uma.h>
|
|
#include <vm/vm_param.h>
|
|
#include <vm/vm_page.h>
|
|
#include <vm/vm_map.h>
|
|
#include <vm/vm_object.h>
|
|
#include <vm/vm_extern.h>
|
|
#include <vm/uma_int.h>
|
|
#include <vm/memguard.h>
|
|
|
|
static SYSCTL_NODE(_vm, OID_AUTO, memguard, CTLFLAG_RW, NULL, "MemGuard data");
|
|
/*
|
|
* The vm_memguard_divisor variable controls how much of kmem_map should be
|
|
* reserved for MemGuard.
|
|
*/
|
|
static u_int vm_memguard_divisor;
|
|
SYSCTL_UINT(_vm_memguard, OID_AUTO, divisor, CTLFLAG_RDTUN,
|
|
&vm_memguard_divisor,
|
|
0, "(kmem_size/memguard_divisor) == memguard submap size");
|
|
|
|
/*
|
|
* Short description (ks_shortdesc) of memory type to monitor.
|
|
*/
|
|
static char vm_memguard_desc[128] = "";
|
|
static struct malloc_type *vm_memguard_mtype = NULL;
|
|
TUNABLE_STR("vm.memguard.desc", vm_memguard_desc, sizeof(vm_memguard_desc));
|
|
static int
|
|
memguard_sysctl_desc(SYSCTL_HANDLER_ARGS)
|
|
{
|
|
char desc[sizeof(vm_memguard_desc)];
|
|
int error;
|
|
|
|
strlcpy(desc, vm_memguard_desc, sizeof(desc));
|
|
error = sysctl_handle_string(oidp, desc, sizeof(desc), req);
|
|
if (error != 0 || req->newptr == NULL)
|
|
return (error);
|
|
|
|
mtx_lock(&malloc_mtx);
|
|
/*
|
|
* If mtp is NULL, it will be initialized in memguard_cmp().
|
|
*/
|
|
vm_memguard_mtype = malloc_desc2type(desc);
|
|
strlcpy(vm_memguard_desc, desc, sizeof(vm_memguard_desc));
|
|
mtx_unlock(&malloc_mtx);
|
|
return (error);
|
|
}
|
|
SYSCTL_PROC(_vm_memguard, OID_AUTO, desc,
|
|
CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 0,
|
|
memguard_sysctl_desc, "A", "Short description of memory type to monitor");
|
|
|
|
static vmem_t *memguard_map = NULL;
|
|
static vm_offset_t memguard_cursor;
|
|
static vm_offset_t memguard_base;
|
|
static vm_size_t memguard_mapsize;
|
|
static vm_size_t memguard_physlimit;
|
|
static u_long memguard_wasted;
|
|
static u_long memguard_wrap;
|
|
static u_long memguard_succ;
|
|
static u_long memguard_fail_kva;
|
|
static u_long memguard_fail_pgs;
|
|
|
|
SYSCTL_ULONG(_vm_memguard, OID_AUTO, cursor, CTLFLAG_RD,
|
|
&memguard_cursor, 0, "MemGuard cursor");
|
|
SYSCTL_ULONG(_vm_memguard, OID_AUTO, mapsize, CTLFLAG_RD,
|
|
&memguard_mapsize, 0, "MemGuard private arena size");
|
|
SYSCTL_ULONG(_vm_memguard, OID_AUTO, phys_limit, CTLFLAG_RD,
|
|
&memguard_physlimit, 0, "Limit on MemGuard memory consumption");
|
|
SYSCTL_ULONG(_vm_memguard, OID_AUTO, wasted, CTLFLAG_RD,
|
|
&memguard_wasted, 0, "Excess memory used through page promotion");
|
|
SYSCTL_ULONG(_vm_memguard, OID_AUTO, wrapcnt, CTLFLAG_RD,
|
|
&memguard_wrap, 0, "MemGuard cursor wrap count");
|
|
SYSCTL_ULONG(_vm_memguard, OID_AUTO, numalloc, CTLFLAG_RD,
|
|
&memguard_succ, 0, "Count of successful MemGuard allocations");
|
|
SYSCTL_ULONG(_vm_memguard, OID_AUTO, fail_kva, CTLFLAG_RD,
|
|
&memguard_fail_kva, 0, "MemGuard failures due to lack of KVA");
|
|
SYSCTL_ULONG(_vm_memguard, OID_AUTO, fail_pgs, CTLFLAG_RD,
|
|
&memguard_fail_pgs, 0, "MemGuard failures due to lack of pages");
|
|
|
|
#define MG_GUARD_AROUND 0x001
|
|
#define MG_GUARD_ALLLARGE 0x002
|
|
#define MG_GUARD_NOFREE 0x004
|
|
static int memguard_options = MG_GUARD_AROUND;
|
|
TUNABLE_INT("vm.memguard.options", &memguard_options);
|
|
SYSCTL_INT(_vm_memguard, OID_AUTO, options, CTLFLAG_RW,
|
|
&memguard_options, 0,
|
|
"MemGuard options:\n"
|
|
"\t0x001 - add guard pages around each allocation\n"
|
|
"\t0x002 - always use MemGuard for allocations over a page\n"
|
|
"\t0x004 - guard uma(9) zones with UMA_ZONE_NOFREE flag");
|
|
|
|
static u_int memguard_minsize;
|
|
static u_long memguard_minsize_reject;
|
|
SYSCTL_UINT(_vm_memguard, OID_AUTO, minsize, CTLFLAG_RW,
|
|
&memguard_minsize, 0, "Minimum size for page promotion");
|
|
SYSCTL_ULONG(_vm_memguard, OID_AUTO, minsize_reject, CTLFLAG_RD,
|
|
&memguard_minsize_reject, 0, "# times rejected for size");
|
|
|
|
static u_int memguard_frequency;
|
|
static u_long memguard_frequency_hits;
|
|
TUNABLE_INT("vm.memguard.frequency", &memguard_frequency);
|
|
SYSCTL_UINT(_vm_memguard, OID_AUTO, frequency, CTLFLAG_RW,
|
|
&memguard_frequency, 0, "Times in 100000 that MemGuard will randomly run");
|
|
SYSCTL_ULONG(_vm_memguard, OID_AUTO, frequency_hits, CTLFLAG_RD,
|
|
&memguard_frequency_hits, 0, "# times MemGuard randomly chose");
|
|
|
|
|
|
/*
|
|
* Return a fudged value to be used for vm_kmem_size for allocating
|
|
* the kmem_map. The memguard memory will be a submap.
|
|
*/
|
|
unsigned long
|
|
memguard_fudge(unsigned long km_size, const struct vm_map *parent_map)
|
|
{
|
|
u_long mem_pgs, parent_size;
|
|
|
|
vm_memguard_divisor = 10;
|
|
TUNABLE_INT_FETCH("vm.memguard.divisor", &vm_memguard_divisor);
|
|
|
|
parent_size = vm_map_max(parent_map) - vm_map_min(parent_map) +
|
|
PAGE_SIZE;
|
|
/* Pick a conservative value if provided value sucks. */
|
|
if ((vm_memguard_divisor <= 0) ||
|
|
((parent_size / vm_memguard_divisor) == 0))
|
|
vm_memguard_divisor = 10;
|
|
/*
|
|
* Limit consumption of physical pages to
|
|
* 1/vm_memguard_divisor of system memory. If the KVA is
|
|
* smaller than this then the KVA limit comes into play first.
|
|
* This prevents memguard's page promotions from completely
|
|
* using up memory, since most malloc(9) calls are sub-page.
|
|
*/
|
|
mem_pgs = cnt.v_page_count;
|
|
memguard_physlimit = (mem_pgs / vm_memguard_divisor) * PAGE_SIZE;
|
|
/*
|
|
* We want as much KVA as we can take safely. Use at most our
|
|
* allotted fraction of the parent map's size. Limit this to
|
|
* twice the physical memory to avoid using too much memory as
|
|
* pagetable pages (size must be multiple of PAGE_SIZE).
|
|
*/
|
|
memguard_mapsize = round_page(parent_size / vm_memguard_divisor);
|
|
if (memguard_mapsize / (2 * PAGE_SIZE) > mem_pgs)
|
|
memguard_mapsize = mem_pgs * 2 * PAGE_SIZE;
|
|
if (km_size + memguard_mapsize > parent_size)
|
|
memguard_mapsize = 0;
|
|
return (km_size + memguard_mapsize);
|
|
}
|
|
|
|
/*
|
|
* Initialize the MemGuard mock allocator. All objects from MemGuard come
|
|
* out of a single VM map (contiguous chunk of address space).
|
|
*/
|
|
void
|
|
memguard_init(vmem_t *parent)
|
|
{
|
|
vm_offset_t base;
|
|
|
|
vmem_alloc(parent, memguard_mapsize, M_WAITOK, &base);
|
|
memguard_map = vmem_create("memguard arena", base, memguard_mapsize,
|
|
PAGE_SIZE, 0, M_WAITOK);
|
|
memguard_cursor = base;
|
|
memguard_base = base;
|
|
|
|
printf("MEMGUARD DEBUGGING ALLOCATOR INITIALIZED:\n");
|
|
printf("\tMEMGUARD map base: 0x%lx\n", (u_long)base);
|
|
printf("\tMEMGUARD map size: %jd KBytes\n",
|
|
(uintmax_t)memguard_mapsize >> 10);
|
|
}
|
|
|
|
/*
|
|
* Run things that can't be done as early as memguard_init().
|
|
*/
|
|
static void
|
|
memguard_sysinit(void)
|
|
{
|
|
struct sysctl_oid_list *parent;
|
|
|
|
parent = SYSCTL_STATIC_CHILDREN(_vm_memguard);
|
|
|
|
SYSCTL_ADD_ULONG(NULL, parent, OID_AUTO, "mapstart", CTLFLAG_RD,
|
|
&memguard_base, "MemGuard KVA base");
|
|
SYSCTL_ADD_ULONG(NULL, parent, OID_AUTO, "maplimit", CTLFLAG_RD,
|
|
&memguard_mapsize, "MemGuard KVA size");
|
|
#if 0
|
|
SYSCTL_ADD_ULONG(NULL, parent, OID_AUTO, "mapused", CTLFLAG_RD,
|
|
&memguard_map->size, "MemGuard KVA used");
|
|
#endif
|
|
}
|
|
SYSINIT(memguard, SI_SUB_KLD, SI_ORDER_ANY, memguard_sysinit, NULL);
|
|
|
|
/*
|
|
* v2sizep() converts a virtual address of the first page allocated for
|
|
* an item to a pointer to u_long recording the size of the original
|
|
* allocation request.
|
|
*
|
|
* This routine is very similar to those defined by UMA in uma_int.h.
|
|
* The difference is that this routine stores the originally allocated
|
|
* size in one of the page's fields that is unused when the page is
|
|
* wired rather than the object field, which is used.
|
|
*/
|
|
static u_long *
|
|
v2sizep(vm_offset_t va)
|
|
{
|
|
vm_paddr_t pa;
|
|
struct vm_page *p;
|
|
|
|
pa = pmap_kextract(va);
|
|
if (pa == 0)
|
|
panic("MemGuard detected double-free of %p", (void *)va);
|
|
p = PHYS_TO_VM_PAGE(pa);
|
|
KASSERT(p->wire_count != 0 && p->queue == PQ_NONE,
|
|
("MEMGUARD: Expected wired page %p in vtomgfifo!", p));
|
|
return ((u_long *)&p->pageq.tqe_next);
|
|
}
|
|
|
|
static u_long *
|
|
v2sizev(vm_offset_t va)
|
|
{
|
|
vm_paddr_t pa;
|
|
struct vm_page *p;
|
|
|
|
pa = pmap_kextract(va);
|
|
if (pa == 0)
|
|
panic("MemGuard detected double-free of %p", (void *)va);
|
|
p = PHYS_TO_VM_PAGE(pa);
|
|
KASSERT(p->wire_count != 0 && p->queue == PQ_NONE,
|
|
("MEMGUARD: Expected wired page %p in vtomgfifo!", p));
|
|
return ((u_long *)&p->pageq.tqe_prev);
|
|
}
|
|
|
|
/*
|
|
* Allocate a single object of specified size with specified flags
|
|
* (either M_WAITOK or M_NOWAIT).
|
|
*/
|
|
void *
|
|
memguard_alloc(unsigned long req_size, int flags)
|
|
{
|
|
vm_offset_t addr;
|
|
u_long size_p, size_v;
|
|
int do_guard, rv;
|
|
|
|
size_p = round_page(req_size);
|
|
if (size_p == 0)
|
|
return (NULL);
|
|
/*
|
|
* To ensure there are holes on both sides of the allocation,
|
|
* request 2 extra pages of KVA. We will only actually add a
|
|
* vm_map_entry and get pages for the original request. Save
|
|
* the value of memguard_options so we have a consistent
|
|
* value.
|
|
*/
|
|
size_v = size_p;
|
|
do_guard = (memguard_options & MG_GUARD_AROUND) != 0;
|
|
if (do_guard)
|
|
size_v += 2 * PAGE_SIZE;
|
|
|
|
/*
|
|
* When we pass our memory limit, reject sub-page allocations.
|
|
* Page-size and larger allocations will use the same amount
|
|
* of physical memory whether we allocate or hand off to
|
|
* uma_large_alloc(), so keep those.
|
|
*/
|
|
if (vmem_size(memguard_map, VMEM_ALLOC) >= memguard_physlimit &&
|
|
req_size < PAGE_SIZE) {
|
|
addr = (vm_offset_t)NULL;
|
|
memguard_fail_pgs++;
|
|
goto out;
|
|
}
|
|
/*
|
|
* Keep a moving cursor so we don't recycle KVA as long as
|
|
* possible. It's not perfect, since we don't know in what
|
|
* order previous allocations will be free'd, but it's simple
|
|
* and fast, and requires O(1) additional storage if guard
|
|
* pages are not used.
|
|
*
|
|
* XXX This scheme will lead to greater fragmentation of the
|
|
* map, unless vm_map_findspace() is tweaked.
|
|
*/
|
|
for (;;) {
|
|
if (vmem_xalloc(memguard_map, size_v, 0, 0, 0, memguard_cursor,
|
|
VMEM_ADDR_MAX, M_BESTFIT | M_NOWAIT, &addr) == 0)
|
|
break;
|
|
/*
|
|
* The map has no space. This may be due to
|
|
* fragmentation, or because the cursor is near the
|
|
* end of the map.
|
|
*/
|
|
if (memguard_cursor == memguard_base) {
|
|
memguard_fail_kva++;
|
|
addr = (vm_offset_t)NULL;
|
|
goto out;
|
|
}
|
|
memguard_wrap++;
|
|
memguard_cursor = memguard_base;
|
|
}
|
|
if (do_guard)
|
|
addr += PAGE_SIZE;
|
|
rv = kmem_back(kmem_object, addr, size_p, flags);
|
|
if (rv != KERN_SUCCESS) {
|
|
vmem_xfree(memguard_map, addr, size_v);
|
|
memguard_fail_pgs++;
|
|
addr = (vm_offset_t)NULL;
|
|
goto out;
|
|
}
|
|
memguard_cursor = addr + size_v;
|
|
*v2sizep(trunc_page(addr)) = req_size;
|
|
*v2sizev(trunc_page(addr)) = size_v;
|
|
memguard_succ++;
|
|
if (req_size < PAGE_SIZE) {
|
|
memguard_wasted += (PAGE_SIZE - req_size);
|
|
if (do_guard) {
|
|
/*
|
|
* Align the request to 16 bytes, and return
|
|
* an address near the end of the page, to
|
|
* better detect array overrun.
|
|
*/
|
|
req_size = roundup2(req_size, 16);
|
|
addr += (PAGE_SIZE - req_size);
|
|
}
|
|
}
|
|
out:
|
|
return ((void *)addr);
|
|
}
|
|
|
|
int
|
|
is_memguard_addr(void *addr)
|
|
{
|
|
vm_offset_t a = (vm_offset_t)(uintptr_t)addr;
|
|
|
|
return (a >= memguard_base && a < memguard_base + memguard_mapsize);
|
|
}
|
|
|
|
/*
|
|
* Free specified single object.
|
|
*/
|
|
void
|
|
memguard_free(void *ptr)
|
|
{
|
|
vm_offset_t addr;
|
|
u_long req_size, size, sizev;
|
|
char *temp;
|
|
int i;
|
|
|
|
addr = trunc_page((uintptr_t)ptr);
|
|
req_size = *v2sizep(addr);
|
|
sizev = *v2sizev(addr);
|
|
size = round_page(req_size);
|
|
|
|
/*
|
|
* Page should not be guarded right now, so force a write.
|
|
* The purpose of this is to increase the likelihood of
|
|
* catching a double-free, but not necessarily a
|
|
* tamper-after-free (the second thread freeing might not
|
|
* write before freeing, so this forces it to and,
|
|
* subsequently, trigger a fault).
|
|
*/
|
|
temp = ptr;
|
|
for (i = 0; i < size; i += PAGE_SIZE)
|
|
temp[i] = 'M';
|
|
|
|
/*
|
|
* This requires carnal knowledge of the implementation of
|
|
* kmem_free(), but since we've already replaced kmem_malloc()
|
|
* above, it's not really any worse. We want to use the
|
|
* vm_map lock to serialize updates to memguard_wasted, since
|
|
* we had the lock at increment.
|
|
*/
|
|
kmem_unback(kmem_object, addr, size);
|
|
if (sizev > size)
|
|
addr -= PAGE_SIZE;
|
|
vmem_xfree(memguard_map, addr, sizev);
|
|
if (req_size < PAGE_SIZE)
|
|
memguard_wasted -= (PAGE_SIZE - req_size);
|
|
}
|
|
|
|
/*
|
|
* Re-allocate an allocation that was originally guarded.
|
|
*/
|
|
void *
|
|
memguard_realloc(void *addr, unsigned long size, struct malloc_type *mtp,
|
|
int flags)
|
|
{
|
|
void *newaddr;
|
|
u_long old_size;
|
|
|
|
/*
|
|
* Allocate the new block. Force the allocation to be guarded
|
|
* as the original may have been guarded through random
|
|
* chance, and that should be preserved.
|
|
*/
|
|
if ((newaddr = memguard_alloc(size, flags)) == NULL)
|
|
return (NULL);
|
|
|
|
/* Copy over original contents. */
|
|
old_size = *v2sizep(trunc_page((uintptr_t)addr));
|
|
bcopy(addr, newaddr, min(size, old_size));
|
|
memguard_free(addr);
|
|
return (newaddr);
|
|
}
|
|
|
|
static int
|
|
memguard_cmp(unsigned long size)
|
|
{
|
|
|
|
if (size < memguard_minsize) {
|
|
memguard_minsize_reject++;
|
|
return (0);
|
|
}
|
|
if ((memguard_options & MG_GUARD_ALLLARGE) != 0 && size >= PAGE_SIZE)
|
|
return (1);
|
|
if (memguard_frequency > 0 &&
|
|
(random() % 100000) < memguard_frequency) {
|
|
memguard_frequency_hits++;
|
|
return (1);
|
|
}
|
|
|
|
return (0);
|
|
}
|
|
|
|
int
|
|
memguard_cmp_mtp(struct malloc_type *mtp, unsigned long size)
|
|
{
|
|
|
|
if (memguard_cmp(size))
|
|
return(1);
|
|
|
|
#if 1
|
|
/*
|
|
* The safest way of comparsion is to always compare short description
|
|
* string of memory type, but it is also the slowest way.
|
|
*/
|
|
return (strcmp(mtp->ks_shortdesc, vm_memguard_desc) == 0);
|
|
#else
|
|
/*
|
|
* If we compare pointers, there are two possible problems:
|
|
* 1. Memory type was unloaded and new memory type was allocated at the
|
|
* same address.
|
|
* 2. Memory type was unloaded and loaded again, but allocated at a
|
|
* different address.
|
|
*/
|
|
if (vm_memguard_mtype != NULL)
|
|
return (mtp == vm_memguard_mtype);
|
|
if (strcmp(mtp->ks_shortdesc, vm_memguard_desc) == 0) {
|
|
vm_memguard_mtype = mtp;
|
|
return (1);
|
|
}
|
|
return (0);
|
|
#endif
|
|
}
|
|
|
|
int
|
|
memguard_cmp_zone(uma_zone_t zone)
|
|
{
|
|
|
|
if ((memguard_options & MG_GUARD_NOFREE) == 0 &&
|
|
zone->uz_flags & UMA_ZONE_NOFREE)
|
|
return (0);
|
|
|
|
if (memguard_cmp(zone->uz_size))
|
|
return (1);
|
|
|
|
/*
|
|
* The safest way of comparsion is to always compare zone name,
|
|
* but it is also the slowest way.
|
|
*/
|
|
return (strcmp(zone->uz_name, vm_memguard_desc) == 0);
|
|
}
|