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kasan, vmalloc: add vmalloc tagging for SW_TAGS

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Add vmalloc tagging support to SW_TAGS KASAN.

 - __kasan_unpoison_vmalloc() now assigns a random pointer tag, poisons
   the virtual mapping accordingly, and embeds the tag into the returned
   pointer.

 - __get_vm_area_node() (used by vmalloc() and vmap()) and
   pcpu_get_vm_areas() save the tagged pointer into vm_struct->addr
   (note: not into vmap_area->addr).

   This requires putting kasan_unpoison_vmalloc() after
   setup_vmalloc_vm[_locked](); otherwise the latter will overwrite the
   tagged pointer. The tagged pointer then is naturally propagateed to
   vmalloc() and vmap().

 - vm_map_ram() returns the tagged pointer directly.

As a result of this change, vm_struct->addr is now tagged.

Enabling KASAN_VMALLOC with SW_TAGS is not yet allowed.

Link: https://lkml.kernel.org/r/4a78f3c064ce905e9070c29733aca1dd254a74f1.1643047180.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Konovalov 2022-03-24 18:11:13 -07:00 committed by Linus Torvalds
parent 51fb34de2a
commit 1d96320f8d
3 changed files with 22 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
include/linux/kasan.h
View File

@ -403,12 +403,13 @@ void kasan_release_vmalloc(unsigned long start, unsigned long end,
unsigned long free_region_start,
unsigned long free_region_end);
void __kasan_unpoison_vmalloc(const void *start, unsigned long size);
static __always_inline void kasan_unpoison_vmalloc(const void *start,
unsigned long size)
void *__kasan_unpoison_vmalloc(const void *start, unsigned long size);
static __always_inline void *kasan_unpoison_vmalloc(const void *start,
unsigned long size)
{
if (kasan_enabled())
__kasan_unpoison_vmalloc(start, size);
return __kasan_unpoison_vmalloc(start, size);
return (void *)start;
}
void __kasan_poison_vmalloc(const void *start, unsigned long size);
@ -433,8 +434,11 @@ static inline void kasan_release_vmalloc(unsigned long start,
unsigned long free_region_start,
unsigned long free_region_end) { }
static inline void kasan_unpoison_vmalloc(const void *start, unsigned long size)
{ }
static inline void *kasan_unpoison_vmalloc(const void *start,
unsigned long size)
{
return (void *)start;
}
static inline void kasan_poison_vmalloc(const void *start, unsigned long size)
{ }

6
mm/kasan/shadow.c
View File

@ -475,12 +475,14 @@ void kasan_release_vmalloc(unsigned long start, unsigned long end,
}
}
void __kasan_unpoison_vmalloc(const void *start, unsigned long size)
void *__kasan_unpoison_vmalloc(const void *start, unsigned long size)
{
if (!is_vmalloc_or_module_addr(start))
return;
return (void *)start;
start = set_tag(start, kasan_random_tag());
kasan_unpoison(start, size, false);
return (void *)start;
}
/*

14
mm/vmalloc.c
View File

@ -2231,7 +2231,7 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node)
mem = (void *)addr;
}
kasan_unpoison_vmalloc(mem, size);
mem = kasan_unpoison_vmalloc(mem, size);
if (vmap_pages_range(addr, addr + size, PAGE_KERNEL,
pages, PAGE_SHIFT) < 0) {
@ -2464,10 +2464,10 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
return NULL;
}
kasan_unpoison_vmalloc((void *)va->va_start, requested_size);
setup_vmalloc_vm(area, va, flags, caller);
area->addr = kasan_unpoison_vmalloc(area->addr, requested_size);
return area;
}
@ -3815,9 +3815,6 @@ retry:
for (area = 0; area < nr_vms; area++) {
if (kasan_populate_vmalloc(vas[area]->va_start, sizes[area]))
goto err_free_shadow;
kasan_unpoison_vmalloc((void *)vas[area]->va_start,
sizes[area]);
}
/* insert all vm's */
@ -3830,6 +3827,11 @@ retry:
}
spin_unlock(&vmap_area_lock);
/* mark allocated areas as accessible */
for (area = 0; area < nr_vms; area++)
vms[area]->addr = kasan_unpoison_vmalloc(vms[area]->addr,
vms[area]->size);
kfree(vas);
return vms;