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
This commit is contained in:
mdf
parent
d548943ae9
commit
0737955344
@ -24,7 +24,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 31, 2006
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.Dd August 2, 2010
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.Dt MEMGUARD 9
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.Os
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.Sh NAME
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@ -41,54 +41,107 @@ multithreaded kernels where race conditions are more prevalent.
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.Pp
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Currently,
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.Nm
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can only take over
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can take over
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.Fn malloc ,
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.Fn realloc
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and
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.Fn free
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for a particular malloc type.
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for a single malloc type.
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.Nm
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can also guard all allocations larger than
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.Dv PAGE_SIZE ,
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and can guard a random fraction of all allocations.
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There is also a knob to prevent allocations smaller than a specified
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size from being guarded, to limit memory waste.
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.Sh EXAMPLES
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To use
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.Nm
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for memory type compiled into the kernel, one has to add the
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following line to the
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for a memory type, either add an entry to
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.Pa /boot/loader.conf :
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.Bd -literal -offset indent
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vm.memguard.desc=<memory_type>
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.Ed
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.Pp
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Where
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.Ar memory_type
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is a short description of memory type to monitor.
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The short description of memory type is the second argument to
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.Xr MALLOC_DEFINE 9 ,
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so one has to find it in the kernel source.
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.Pp
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To use
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.Nm
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for memory type defined in a kernel module, one has to set
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Or set the
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.Va vm.memguard.desc
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.Xr sysctl 8
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variable before loading the module:
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variable at run-time:
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.Bd -literal -offset indent
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sysctl vm.memguard.desc=<memory_type>
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.Ed
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.Pp
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Where
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.Ar memory_type
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is a short description of the memory type to monitor.
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Only allocations from that
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.Ar memory_type
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made after
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.Va vm.memguard.desc
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is set will potentially be guarded.
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If
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.Va vm.memguard.desc
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is modified at run-time then only allocations of the new
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.Ar memory_type
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will potentially be guarded once the
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.Xr sysctl 8
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is set.
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Existing guarded allocations will still be properly released by
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.Xr free 9 .
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.Pp
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The short description of a
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.Xr malloc 9
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type is the second argument to
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.Xr MALLOC_DEFINE 9 ,
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so one has to find it in the kernel source.
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.Pp
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The
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.Va vm.memguard.divisor
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boot-time tunable is used to scale how much of
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.Va kmem_map
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one wants to allocate for
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.Nm .
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The default is 10, so
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.Va kmem_size Ns /10
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bytes will be used.
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The
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.Va kmem_size
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value can be obtained via the
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.Va vm.kmem_size
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.Xr sysctl 8
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variable.
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boot-time tunable is used to scale how much of the system's physical
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memory
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.Nm
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is allowed to consume.
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The default is 10, so up to
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.Va cnt.v_page_count Ns /10
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pages can be used.
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.Nm
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will reserve
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.Va vm_kmem_max
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/
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.Va vm.memguard.divisor
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bytes of virtual address space, limited by twice the physical memory
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size.
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The physical limit is reported as
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.Va vm.memguard.phys_limit
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and the virtual space reserved for
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.Nm
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is reported as
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.Va vm.memguard.mapsize .
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.Pp
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.Nm
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will not do page promotions for any allocation smaller than
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.Va vm.memguard.minsize
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bytes.
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The default is 0, meaning all allocations can potentially be guarded.
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.Nm
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can guard sufficiently large allocations randomly, with average
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frequency of every one in 100000 /
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.Va vm.memguard.frequency
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allocations.
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The default is 0, meaning no allocations are randomly guarded.
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.Pp
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.Nm
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can optionally add unmapped guard pages around each allocation to
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detect overflow and underflow, if
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.Va vm.memguard.options
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has the 1 bit set.
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This option is enabled by default.
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.Nm
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will optionally guard all allocations of
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.Dv PAGE_SIZE
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or larger if
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.Va vm.memguard.options
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has the 2 bit set.
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This option is off by default.
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.Sh SEE ALSO
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.Xr sysctl 8 ,
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.Xr vmstat 8 ,
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@ -102,10 +155,13 @@ first appeared in
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.Sh AUTHORS
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.An -nosplit
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.Nm
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was written by
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was originally written by
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.An Bosko Milekic Aq bmilekic@FreeBSD.org .
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This manual page was written by
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This manual page was originally written by
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.An Christian Brueffer Aq brueffer@FreeBSD.org .
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Additions have been made by
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.An Matthew Fleming Aq mdf@FreeBSD.org
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to both the implementation and the documentation.
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.Sh BUGS
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Currently, it is not possible to override UMA
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.Xr zone 9
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@ -427,8 +427,12 @@ malloc(unsigned long size, struct malloc_type *mtp, int flags)
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("malloc(M_WAITOK) in interrupt context"));
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#ifdef DEBUG_MEMGUARD
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if (memguard_cmp(mtp))
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return memguard_alloc(size, flags);
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if (memguard_cmp(mtp, size)) {
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va = memguard_alloc(size, flags);
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if (va != NULL)
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return (va);
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/* This is unfortunate but should not be fatal. */
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}
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#endif
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#ifdef DEBUG_REDZONE
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@ -493,7 +497,7 @@ free(void *addr, struct malloc_type *mtp)
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return;
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#ifdef DEBUG_MEMGUARD
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if (memguard_cmp(mtp)) {
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if (is_memguard_addr(addr)) {
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memguard_free(addr);
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return;
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}
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@ -562,10 +566,11 @@ realloc(void *addr, unsigned long size, struct malloc_type *mtp, int flags)
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*/
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#ifdef DEBUG_MEMGUARD
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if (memguard_cmp(mtp)) {
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slab = NULL;
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alloc = size;
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} else {
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if (is_memguard_addr(addr)) {
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slab = NULL;
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alloc = size;
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goto remalloc;
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}
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#endif
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#ifdef DEBUG_REDZONE
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@ -591,7 +596,7 @@ if (memguard_cmp(mtp)) {
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#endif /* !DEBUG_REDZONE */
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#ifdef DEBUG_MEMGUARD
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}
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remalloc:
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#endif
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/* Allocate a new, bigger (or smaller) block */
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@ -625,7 +630,7 @@ static void
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kmeminit(void *dummy)
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{
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uint8_t indx;
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u_long mem_size;
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u_long mem_size, tmp;
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int i;
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mtx_init(&malloc_mtx, "malloc", NULL, MTX_DEF);
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@ -685,8 +690,13 @@ kmeminit(void *dummy)
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*/
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init_param3(vm_kmem_size / PAGE_SIZE);
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#ifdef DEBUG_MEMGUARD
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tmp = memguard_fudge(vm_kmem_size, vm_kmem_size_max);
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#else
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tmp = vm_kmem_size;
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#endif
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kmem_map = kmem_suballoc(kernel_map, &kmembase, &kmemlimit,
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vm_kmem_size, TRUE);
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tmp, TRUE);
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kmem_map->system_map = 1;
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#ifdef DEBUG_MEMGUARD
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@ -695,14 +705,7 @@ kmeminit(void *dummy)
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* replacement allocator used for detecting tamper-after-free
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* scenarios as they occur. It is only used for debugging.
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*/
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vm_memguard_divisor = 10;
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TUNABLE_INT_FETCH("vm.memguard.divisor", &vm_memguard_divisor);
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/* Pick a conservative value if provided value sucks. */
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if ((vm_memguard_divisor <= 0) ||
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((vm_kmem_size / vm_memguard_divisor) == 0))
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vm_memguard_divisor = 10;
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memguard_init(kmem_map, vm_kmem_size / vm_memguard_divisor);
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memguard_init(kmem_map);
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#endif
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uma_startup2();
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@ -1,6 +1,7 @@
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/*-
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* Copyright (c) 2005,
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* Bosko Milekic <bmilekic@FreeBSD.org>. All rights reserved.
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* Copyright (c) 2005, Bosko Milekic <bmilekic@FreeBSD.org>.
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* Copyright (c) 2010 Isilon Systems, Inc. (http://www.isilon.com/)
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* All rights reserved.
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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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@ -47,26 +48,22 @@ __FBSDID("$FreeBSD$");
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#include <sys/sysctl.h>
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#include <vm/vm.h>
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#include <vm/uma.h>
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#include <vm/vm_param.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_object.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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* The maximum number of pages allowed per allocation. If you're using
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* MemGuard to override very large items (> MAX_PAGES_PER_ITEM in size),
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* you need to increase MAX_PAGES_PER_ITEM.
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*/
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#define MAX_PAGES_PER_ITEM 64
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SYSCTL_NODE(_vm, OID_AUTO, memguard, CTLFLAG_RW, NULL, "MemGuard data");
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/*
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* The vm_memguard_divisor variable controls how much of kmem_map should be
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* reserved for MemGuard.
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*/
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u_int vm_memguard_divisor;
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SYSCTL_UINT(_vm_memguard, OID_AUTO, divisor, CTLFLAG_RD, &vm_memguard_divisor,
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static u_int vm_memguard_divisor;
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SYSCTL_UINT(_vm_memguard, OID_AUTO, divisor, CTLFLAG_RDTUN,
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&vm_memguard_divisor,
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0, "(kmem_size/memguard_divisor) == memguard submap size");
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/*
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@ -78,233 +75,343 @@ TUNABLE_STR("vm.memguard.desc", vm_memguard_desc, sizeof(vm_memguard_desc));
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static int
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memguard_sysctl_desc(SYSCTL_HANDLER_ARGS)
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{
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struct malloc_type_internal *mtip;
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struct malloc_type_stats *mtsp;
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struct malloc_type *mtp;
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char desc[128];
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long bytes;
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int error, i;
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char desc[sizeof(vm_memguard_desc)];
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int error;
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strlcpy(desc, vm_memguard_desc, sizeof(desc));
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error = sysctl_handle_string(oidp, desc, sizeof(desc), req);
|
||||
if (error != 0 || req->newptr == NULL)
|
||||
return (error);
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||||
|
||||
/*
|
||||
* We can change memory type when no memory has been allocated for it
|
||||
* or when there is no such memory type yet (ie. it will be loaded with
|
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* kernel module).
|
||||
*/
|
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bytes = 0;
|
||||
mtx_lock(&malloc_mtx);
|
||||
mtp = malloc_desc2type(desc);
|
||||
if (mtp != NULL) {
|
||||
mtip = mtp->ks_handle;
|
||||
for (i = 0; i < MAXCPU; i++) {
|
||||
mtsp = &mtip->mti_stats[i];
|
||||
bytes += mtsp->mts_memalloced;
|
||||
bytes -= mtsp->mts_memfreed;
|
||||
}
|
||||
}
|
||||
if (bytes > 0)
|
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error = EBUSY;
|
||||
else {
|
||||
/*
|
||||
* If mtp is NULL, it will be initialized in memguard_cmp().
|
||||
*/
|
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vm_memguard_mtype = mtp;
|
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strlcpy(vm_memguard_desc, desc, sizeof(vm_memguard_desc));
|
||||
}
|
||||
/*
|
||||
* If mtp is NULL, it will be initialized in memguard_cmp().
|
||||
*/
|
||||
vm_memguard_mtype = malloc_desc2type(desc);
|
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strlcpy(vm_memguard_desc, desc, sizeof(vm_memguard_desc));
|
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mtx_unlock(&malloc_mtx);
|
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return (error);
|
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}
|
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SYSCTL_PROC(_vm_memguard, OID_AUTO, desc, CTLTYPE_STRING | CTLFLAG_RW, 0, 0,
|
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SYSCTL_PROC(_vm_memguard, OID_AUTO, desc,
|
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CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 0,
|
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memguard_sysctl_desc, "A", "Short description of memory type to monitor");
|
||||
|
||||
/*
|
||||
* Global MemGuard data.
|
||||
*/
|
||||
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 {
|
||||
STAILQ_ENTRY(memguard_entry) entries;
|
||||
void *ptr;
|
||||
};
|
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static struct memguard_fifo {
|
||||
struct memguard_entry *stqh_first;
|
||||
struct memguard_entry **stqh_last;
|
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int index;
|
||||
} memguard_fifo_pool[MAX_PAGES_PER_ITEM];
|
||||
static vm_map_t memguard_map = NULL;
|
||||
static vm_offset_t memguard_cursor;
|
||||
static vm_size_t memguard_mapsize;
|
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static vm_size_t memguard_physlimit;
|
||||
static u_long memguard_wasted;
|
||||
static u_long memguard_wrap;
|
||||
static u_long memguard_succ;
|
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static u_long memguard_fail_kva;
|
||||
static u_long memguard_fail_pgs;
|
||||
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SYSCTL_ULONG(_vm_memguard, OID_AUTO, cursor, CTLFLAG_RD,
|
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&memguard_cursor, 0, "MemGuard cursor");
|
||||
SYSCTL_ULONG(_vm_memguard, OID_AUTO, mapsize, CTLFLAG_RD,
|
||||
&memguard_mapsize, 0, "MemGuard private vm_map 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,
|
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&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 0x001
|
||||
#define MG_ALLLARGE 0x002
|
||||
static int memguard_options = MG_GUARD;
|
||||
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");
|
||||
|
||||
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");
|
||||
|
||||
|
||||
/*
|
||||
* Local prototypes.
|
||||
* Return a fudged value to be used for vm_kmem_size for allocating
|
||||
* the kmem_map. The memguard memory will be a submap.
|
||||
*/
|
||||
static void memguard_guard(void *addr, int numpgs);
|
||||
static void memguard_unguard(void *addr, int numpgs);
|
||||
static struct memguard_fifo *vtomgfifo(vm_offset_t va);
|
||||
static void vsetmgfifo(vm_offset_t va, struct memguard_fifo *mgfifo);
|
||||
static void vclrmgfifo(vm_offset_t va);
|
||||
unsigned long
|
||||
memguard_fudge(unsigned long km_size, unsigned long km_max)
|
||||
{
|
||||
u_long mem_pgs = cnt.v_page_count;
|
||||
|
||||
/*
|
||||
* Local macros. MemGuard data is global, so replace these with whatever
|
||||
* your system uses to protect global data (if it is kernel-level
|
||||
* parallelized). This is for porting among BSDs.
|
||||
*/
|
||||
#define MEMGUARD_CRIT_SECTION_DECLARE static struct mtx memguard_mtx
|
||||
#define MEMGUARD_CRIT_SECTION_INIT \
|
||||
mtx_init(&memguard_mtx, "MemGuard mtx", NULL, MTX_DEF)
|
||||
#define MEMGUARD_CRIT_SECTION_ENTER mtx_lock(&memguard_mtx)
|
||||
#define MEMGUARD_CRIT_SECTION_EXIT mtx_unlock(&memguard_mtx)
|
||||
MEMGUARD_CRIT_SECTION_DECLARE;
|
||||
vm_memguard_divisor = 10;
|
||||
TUNABLE_INT_FETCH("vm.memguard.divisor", &vm_memguard_divisor);
|
||||
|
||||
/* Pick a conservative value if provided value sucks. */
|
||||
if ((vm_memguard_divisor <= 0) ||
|
||||
((km_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.
|
||||
*/
|
||||
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 kmem_max. Limit this to twice the
|
||||
* physical memory to avoid using too much memory as pagetable
|
||||
* pages.
|
||||
*/
|
||||
memguard_mapsize = km_max / vm_memguard_divisor;
|
||||
/* size must be multiple of PAGE_SIZE */
|
||||
memguard_mapsize = round_page(memguard_mapsize);
|
||||
if (memguard_mapsize / (2 * PAGE_SIZE) > mem_pgs)
|
||||
memguard_mapsize = mem_pgs * 2 * PAGE_SIZE;
|
||||
if (km_size + memguard_mapsize > km_max)
|
||||
return (km_max);
|
||||
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(vm_map_t parent_map, unsigned long size)
|
||||
memguard_init(vm_map_t parent_map)
|
||||
{
|
||||
char *base, *limit;
|
||||
int i;
|
||||
vm_offset_t base, limit;
|
||||
|
||||
/* size must be multiple of PAGE_SIZE */
|
||||
size /= PAGE_SIZE;
|
||||
size++;
|
||||
size *= PAGE_SIZE;
|
||||
|
||||
memguard_map = kmem_suballoc(parent_map, (vm_offset_t *)&base,
|
||||
(vm_offset_t *)&limit, (vm_size_t)size, FALSE);
|
||||
memguard_map = kmem_suballoc(parent_map, &base, &limit,
|
||||
memguard_mapsize, FALSE);
|
||||
memguard_map->system_map = 1;
|
||||
memguard_mapsize = size;
|
||||
memguard_mapused = 0;
|
||||
|
||||
MEMGUARD_CRIT_SECTION_INIT;
|
||||
MEMGUARD_CRIT_SECTION_ENTER;
|
||||
for (i = 0; i < MAX_PAGES_PER_ITEM; i++) {
|
||||
STAILQ_INIT(&memguard_fifo_pool[i]);
|
||||
memguard_fifo_pool[i].index = i;
|
||||
}
|
||||
MEMGUARD_CRIT_SECTION_EXIT;
|
||||
KASSERT(memguard_mapsize == limit - base,
|
||||
("Expected %lu, got %lu", (u_long)memguard_mapsize,
|
||||
(u_long)(limit - base)));
|
||||
memguard_cursor = base;
|
||||
|
||||
printf("MEMGUARD DEBUGGING ALLOCATOR INITIALIZED:\n");
|
||||
printf("\tMEMGUARD map base: %p\n", base);
|
||||
printf("\tMEMGUARD map limit: %p\n", limit);
|
||||
printf("\tMEMGUARD map size: %ld (Bytes)\n", size);
|
||||
printf("\tMEMGUARD map base: 0x%lx\n", (u_long)base);
|
||||
printf("\tMEMGUARD map limit: 0x%lx\n", (u_long)limit);
|
||||
printf("\tMEMGUARD map size: %jd KBytes\n",
|
||||
(uintmax_t)memguard_mapsize >> 10);
|
||||
}
|
||||
|
||||
/*
|
||||
* Allocate a single object of specified size with specified flags (either
|
||||
* M_WAITOK or M_NOWAIT).
|
||||
* 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_map->min_offset, "MemGuard KVA base");
|
||||
SYSCTL_ADD_ULONG(NULL, parent, OID_AUTO, "maplimit", CTLFLAG_RD,
|
||||
&memguard_map->max_offset, "MemGuard KVA end");
|
||||
SYSCTL_ADD_ULONG(NULL, parent, OID_AUTO, "mapused", CTLFLAG_RD,
|
||||
&memguard_map->size, "MemGuard KVA used");
|
||||
}
|
||||
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)
|
||||
{
|
||||
struct vm_page *p;
|
||||
|
||||
p = PHYS_TO_VM_PAGE(pmap_kextract(va));
|
||||
KASSERT(p->wire_count != 0 && p->queue == PQ_NONE,
|
||||
("MEMGUARD: Expected wired page %p in vtomgfifo!", p));
|
||||
return ((u_long *)&p->pageq.tqe_next);
|
||||
}
|
||||
|
||||
/*
|
||||
* Allocate a single object of specified size with specified flags
|
||||
* (either M_WAITOK or M_NOWAIT).
|
||||
*/
|
||||
void *
|
||||
memguard_alloc(unsigned long size, int flags)
|
||||
memguard_alloc(unsigned long req_size, int flags)
|
||||
{
|
||||
void *obj;
|
||||
struct memguard_entry *e = NULL;
|
||||
int numpgs;
|
||||
|
||||
numpgs = size / PAGE_SIZE;
|
||||
if ((size % PAGE_SIZE) != 0)
|
||||
numpgs++;
|
||||
if (numpgs > MAX_PAGES_PER_ITEM)
|
||||
panic("MEMGUARD: You must increase MAX_PAGES_PER_ITEM " \
|
||||
"in memguard.c (requested: %d pages)", numpgs);
|
||||
if (numpgs == 0)
|
||||
return NULL;
|
||||
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);
|
||||
/*
|
||||
* If we haven't exhausted the memguard_map yet, allocate from
|
||||
* it and grab a new page, even if we have recycled pages in our
|
||||
* FIFO. This is because we wish to allow recycled pages to live
|
||||
* guarded in the FIFO for as long as possible in order to catch
|
||||
* even very late tamper-after-frees, even though it means that
|
||||
* we end up wasting more memory, this is only a DEBUGGING allocator
|
||||
* after all.
|
||||
* 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.
|
||||
*/
|
||||
MEMGUARD_CRIT_SECTION_ENTER;
|
||||
if (memguard_mapused >= memguard_mapsize) {
|
||||
e = STAILQ_FIRST(&memguard_fifo_pool[numpgs - 1]);
|
||||
if (e != NULL) {
|
||||
STAILQ_REMOVE(&memguard_fifo_pool[numpgs - 1], e,
|
||||
memguard_entry, entries);
|
||||
MEMGUARD_CRIT_SECTION_EXIT;
|
||||
obj = e->ptr;
|
||||
free(e, M_TEMP);
|
||||
memguard_unguard(obj, numpgs);
|
||||
if (flags & M_ZERO)
|
||||
bzero(obj, PAGE_SIZE * numpgs);
|
||||
return obj;
|
||||
}
|
||||
MEMGUARD_CRIT_SECTION_EXIT;
|
||||
if (flags & M_WAITOK)
|
||||
panic("MEMGUARD: Failed with M_WAITOK: " \
|
||||
"memguard_map too small");
|
||||
return NULL;
|
||||
}
|
||||
memguard_mapused += (PAGE_SIZE * numpgs);
|
||||
MEMGUARD_CRIT_SECTION_EXIT;
|
||||
size_v = size_p;
|
||||
do_guard = (memguard_options & MG_GUARD) != 0;
|
||||
if (do_guard)
|
||||
size_v += 2 * PAGE_SIZE;
|
||||
|
||||
obj = (void *)kmem_malloc(memguard_map, PAGE_SIZE * numpgs, flags);
|
||||
if (obj != NULL) {
|
||||
vsetmgfifo((vm_offset_t)obj, &memguard_fifo_pool[numpgs - 1]);
|
||||
if (flags & M_ZERO)
|
||||
bzero(obj, PAGE_SIZE * numpgs);
|
||||
} else {
|
||||
MEMGUARD_CRIT_SECTION_ENTER;
|
||||
memguard_mapused -= (PAGE_SIZE * numpgs);
|
||||
MEMGUARD_CRIT_SECTION_EXIT;
|
||||
vm_map_lock(memguard_map);
|
||||
/*
|
||||
* 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 (memguard_map->size >= memguard_physlimit &&
|
||||
req_size < PAGE_SIZE) {
|
||||
addr = (vm_offset_t)NULL;
|
||||
memguard_fail_pgs++;
|
||||
goto out;
|
||||
}
|
||||
return obj;
|
||||
/*
|
||||
* 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 (;;) {
|
||||
rv = vm_map_findspace(memguard_map, memguard_cursor,
|
||||
size_v, &addr);
|
||||
if (rv == KERN_SUCCESS)
|
||||
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 == vm_map_min(memguard_map)) {
|
||||
memguard_fail_kva++;
|
||||
addr = (vm_offset_t)NULL;
|
||||
goto out;
|
||||
}
|
||||
memguard_wrap++;
|
||||
memguard_cursor = vm_map_min(memguard_map);
|
||||
}
|
||||
if (do_guard)
|
||||
addr += PAGE_SIZE;
|
||||
rv = kmem_back(memguard_map, addr, size_p, flags);
|
||||
if (rv != KERN_SUCCESS) {
|
||||
memguard_fail_pgs++;
|
||||
addr = (vm_offset_t)NULL;
|
||||
goto out;
|
||||
}
|
||||
memguard_cursor = addr + size_p;
|
||||
*v2sizep(trunc_page(addr)) = req_size;
|
||||
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:
|
||||
vm_map_unlock(memguard_map);
|
||||
return ((void *)addr);
|
||||
}
|
||||
|
||||
int
|
||||
is_memguard_addr(void *addr)
|
||||
{
|
||||
vm_offset_t a = (vm_offset_t)(uintptr_t)addr;
|
||||
|
||||
return (a >= memguard_map->min_offset && a < memguard_map->max_offset);
|
||||
}
|
||||
|
||||
/*
|
||||
* Free specified single object.
|
||||
*/
|
||||
void
|
||||
memguard_free(void *addr)
|
||||
memguard_free(void *ptr)
|
||||
{
|
||||
struct memguard_entry *e;
|
||||
struct memguard_fifo *mgfifo;
|
||||
int idx;
|
||||
int *temp;
|
||||
vm_offset_t addr;
|
||||
u_long req_size, size;
|
||||
char *temp;
|
||||
int i;
|
||||
|
||||
addr = (void *)trunc_page((unsigned long)addr);
|
||||
addr = trunc_page((uintptr_t)ptr);
|
||||
req_size = *v2sizep(addr);
|
||||
size = round_page(req_size);
|
||||
|
||||
/*
|
||||
* Page should not be guarded by 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).
|
||||
* 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 = (int *)((unsigned long)addr + (PAGE_SIZE/2)); /* in page */
|
||||
*temp = 0xd34dc0d3;
|
||||
temp = ptr;
|
||||
for (i = 0; i < size; i += PAGE_SIZE)
|
||||
temp[i] = 'M';
|
||||
|
||||
mgfifo = vtomgfifo((vm_offset_t)addr);
|
||||
idx = mgfifo->index;
|
||||
memguard_guard(addr, idx + 1);
|
||||
e = malloc(sizeof(struct memguard_entry), M_TEMP, M_NOWAIT);
|
||||
if (e == NULL) {
|
||||
MEMGUARD_CRIT_SECTION_ENTER;
|
||||
memguard_mapused -= (PAGE_SIZE * (idx + 1));
|
||||
MEMGUARD_CRIT_SECTION_EXIT;
|
||||
memguard_unguard(addr, idx + 1); /* just in case */
|
||||
vclrmgfifo((vm_offset_t)addr);
|
||||
kmem_free(memguard_map, (vm_offset_t)addr,
|
||||
PAGE_SIZE * (idx + 1));
|
||||
return;
|
||||
}
|
||||
e->ptr = addr;
|
||||
MEMGUARD_CRIT_SECTION_ENTER;
|
||||
STAILQ_INSERT_TAIL(mgfifo, e, entries);
|
||||
MEMGUARD_CRIT_SECTION_EXIT;
|
||||
/*
|
||||
* 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.
|
||||
*/
|
||||
vm_map_lock(memguard_map);
|
||||
if (req_size < PAGE_SIZE)
|
||||
memguard_wasted -= (PAGE_SIZE - req_size);
|
||||
(void)vm_map_delete(memguard_map, addr, addr + size);
|
||||
vm_map_unlock(memguard_map);
|
||||
}
|
||||
|
||||
int
|
||||
memguard_cmp(struct malloc_type *mtp)
|
||||
memguard_cmp(struct malloc_type *mtp, unsigned long size)
|
||||
{
|
||||
|
||||
if (size < memguard_minsize) {
|
||||
memguard_minsize_reject++;
|
||||
return (0);
|
||||
}
|
||||
if ((memguard_options & MG_ALLLARGE) != 0 && size >= PAGE_SIZE)
|
||||
return (1);
|
||||
if (memguard_frequency > 0 &&
|
||||
(random() % 100000) < memguard_frequency) {
|
||||
memguard_frequency_hits++;
|
||||
return (1);
|
||||
}
|
||||
#if 1
|
||||
/*
|
||||
* The safest way of comparsion is to always compare short description
|
||||
@ -328,78 +435,3 @@ memguard_cmp(struct malloc_type *mtp)
|
||||
return (0);
|
||||
#endif
|
||||
}
|
||||
|
||||
/*
|
||||
* Guard a page containing specified object (make it read-only so that
|
||||
* future writes to it fail).
|
||||
*/
|
||||
static void
|
||||
memguard_guard(void *addr, int numpgs)
|
||||
{
|
||||
void *a = (void *)trunc_page((unsigned long)addr);
|
||||
if (vm_map_protect(memguard_map, (vm_offset_t)a,
|
||||
(vm_offset_t)((unsigned long)a + (PAGE_SIZE * numpgs)),
|
||||
VM_PROT_READ, FALSE) != KERN_SUCCESS)
|
||||
panic("MEMGUARD: Unable to guard page!");
|
||||
}
|
||||
|
||||
/*
|
||||
* Unguard a page containing specified object (make it read-and-write to
|
||||
* allow full data access).
|
||||
*/
|
||||
static void
|
||||
memguard_unguard(void *addr, int numpgs)
|
||||
{
|
||||
void *a = (void *)trunc_page((unsigned long)addr);
|
||||
if (vm_map_protect(memguard_map, (vm_offset_t)a,
|
||||
(vm_offset_t)((unsigned long)a + (PAGE_SIZE * numpgs)),
|
||||
VM_PROT_DEFAULT, FALSE) != KERN_SUCCESS)
|
||||
panic("MEMGUARD: Unable to unguard page!");
|
||||
}
|
||||
|
||||
/*
|
||||
* vtomgfifo() converts a virtual address of the first page allocated for
|
||||
* an item to a memguard_fifo_pool reference for the corresponding item's
|
||||
* size.
|
||||
*
|
||||
* vsetmgfifo() sets a reference in an underlying page for the specified
|
||||
* virtual address to an appropriate memguard_fifo_pool.
|
||||
*
|
||||
* These routines are very similar to those defined by UMA in uma_int.h.
|
||||
* The difference is that these routines store the mgfifo in one of the
|
||||
* page's fields that is unused when the page is wired rather than the
|
||||
* object field, which is used.
|
||||
*/
|
||||
static struct memguard_fifo *
|
||||
vtomgfifo(vm_offset_t va)
|
||||
{
|
||||
vm_page_t p;
|
||||
struct memguard_fifo *mgfifo;
|
||||
|
||||
p = PHYS_TO_VM_PAGE(pmap_kextract(va));
|
||||
KASSERT(p->wire_count != 0 && p->queue == PQ_NONE,
|
||||
("MEMGUARD: Expected wired page in vtomgfifo!"));
|
||||
mgfifo = (struct memguard_fifo *)p->pageq.tqe_next;
|
||||
return mgfifo;
|
||||
}
|
||||
|
||||
static void
|
||||
vsetmgfifo(vm_offset_t va, struct memguard_fifo *mgfifo)
|
||||
{
|
||||
vm_page_t p;
|
||||
|
||||
p = PHYS_TO_VM_PAGE(pmap_kextract(va));
|
||||
KASSERT(p->wire_count != 0 && p->queue == PQ_NONE,
|
||||
("MEMGUARD: Expected wired page in vsetmgfifo!"));
|
||||
p->pageq.tqe_next = (vm_page_t)mgfifo;
|
||||
}
|
||||
|
||||
static void vclrmgfifo(vm_offset_t va)
|
||||
{
|
||||
vm_page_t p;
|
||||
|
||||
p = PHYS_TO_VM_PAGE(pmap_kextract(va));
|
||||
KASSERT(p->wire_count != 0 && p->queue == PQ_NONE,
|
||||
("MEMGUARD: Expected wired page in vclrmgfifo!"));
|
||||
p->pageq.tqe_next = NULL;
|
||||
}
|
||||
|
||||
@ -26,9 +26,20 @@
|
||||
* $FreeBSD$
|
||||
*/
|
||||
|
||||
extern u_int vm_memguard_divisor;
|
||||
#include "opt_vm.h"
|
||||
|
||||
void memguard_init(vm_map_t parent_map, unsigned long size);
|
||||
void *memguard_alloc(unsigned long size, int flags);
|
||||
void memguard_free(void *addr);
|
||||
int memguard_cmp(struct malloc_type *mtp);
|
||||
#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
|
||||
|
||||
@ -53,6 +53,7 @@ void kmem_free(vm_map_t, vm_offset_t, vm_size_t);
|
||||
void kmem_free_wakeup(vm_map_t, vm_offset_t, vm_size_t);
|
||||
void kmem_init(vm_offset_t, vm_offset_t);
|
||||
vm_offset_t kmem_malloc(vm_map_t map, vm_size_t size, int flags);
|
||||
int kmem_back(vm_map_t, vm_offset_t, vm_size_t, int);
|
||||
vm_map_t kmem_suballoc(vm_map_t, vm_offset_t *, vm_offset_t *, vm_size_t,
|
||||
boolean_t);
|
||||
void swapout_procs(int);
|
||||
|
||||
@ -301,11 +301,8 @@ kmem_malloc(map, size, flags)
|
||||
vm_size_t size;
|
||||
int flags;
|
||||
{
|
||||
vm_offset_t offset, i;
|
||||
vm_map_entry_t entry;
|
||||
vm_offset_t addr;
|
||||
vm_page_t m;
|
||||
int pflags;
|
||||
int i, rv;
|
||||
|
||||
size = round_page(size);
|
||||
addr = vm_map_min(map);
|
||||
@ -338,6 +335,30 @@ kmem_malloc(map, size, flags)
|
||||
return (0);
|
||||
}
|
||||
}
|
||||
|
||||
rv = kmem_back(map, addr, size, flags);
|
||||
vm_map_unlock(map);
|
||||
return (rv == KERN_SUCCESS ? addr : 0);
|
||||
}
|
||||
|
||||
/*
|
||||
* kmem_back:
|
||||
*
|
||||
* Allocate physical pages for the specified virtual address range.
|
||||
*/
|
||||
int
|
||||
kmem_back(vm_map_t map, vm_offset_t addr, vm_size_t size, int flags)
|
||||
{
|
||||
vm_offset_t offset, i;
|
||||
vm_map_entry_t entry;
|
||||
vm_page_t m;
|
||||
int pflags;
|
||||
|
||||
/*
|
||||
* XXX the map must be locked for write on entry, but there's
|
||||
* no easy way to assert that.
|
||||
*/
|
||||
|
||||
offset = addr - VM_MIN_KERNEL_ADDRESS;
|
||||
vm_object_reference(kmem_object);
|
||||
vm_map_insert(map, kmem_object, offset, addr, addr + size,
|
||||
@ -385,8 +406,7 @@ kmem_malloc(map, size, flags)
|
||||
}
|
||||
VM_OBJECT_UNLOCK(kmem_object);
|
||||
vm_map_delete(map, addr, addr + size);
|
||||
vm_map_unlock(map);
|
||||
return (0);
|
||||
return (KERN_NO_SPACE);
|
||||
}
|
||||
if (flags & M_ZERO && (m->flags & PG_ZERO) == 0)
|
||||
pmap_zero_page(m);
|
||||
@ -429,9 +449,8 @@ kmem_malloc(map, size, flags)
|
||||
vm_page_wakeup(m);
|
||||
}
|
||||
VM_OBJECT_UNLOCK(kmem_object);
|
||||
vm_map_unlock(map);
|
||||
|
||||
return (addr);
|
||||
return (KERN_SUCCESS);
|
||||
}
|
||||
|
||||
/*
|
||||
|
||||
Loading…
Reference in New Issue
Block a user