| Message ID | 20201201161632.1234753-3-dja@axtens.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KASAN for powerpc64 radix | expand |
Le 01/12/2020 à 17:16, Daniel Axtens a écrit : > Allow architectures to define a kasan_arch_is_ready() hook that bails > out of any function that's about to touch the shadow unless the arch > says that it is ready for the memory to be accessed. This is fairly > uninvasive and should have a negligible performance penalty. > > This will only work in outline mode, so an arch must specify > HAVE_ARCH_NO_KASAN_INLINE if it requires this. > > Cc: Balbir Singh <bsingharora@gmail.com> > Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Did I signed that off one day ? I can't remember. Please update my email address, and maybe change it to a Suggested-by: ? I think the first Signed-off-by: has to be the author of the patch. > Signed-off-by: Daniel Axtens <dja@axtens.net> > > -- > > I discuss the justfication for this later in the series. Also, > both previous RFCs for ppc64 - by 2 different people - have > needed this trick! See: > - https://lore.kernel.org/patchwork/patch/592820/ # ppc64 hash series > - https://patchwork.ozlabs.org/patch/795211/ # ppc radix series > --- > include/linux/kasan.h | 4 ++++ > mm/kasan/common.c | 10 ++++++++++ > mm/kasan/generic.c | 3 +++ > 3 files changed, 17 insertions(+) > > diff --git a/include/linux/kasan.h b/include/linux/kasan.h > index 30d343b4a40a..3df66fdf6662 100644 > --- a/include/linux/kasan.h > +++ b/include/linux/kasan.h > @@ -20,6 +20,10 @@ struct kunit_kasan_expectation { > bool report_found; > }; > > +#ifndef kasan_arch_is_ready > +static inline bool kasan_arch_is_ready(void) { return true; } > +#endif > + > extern unsigned char kasan_early_shadow_page[PAGE_SIZE]; > extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE]; > extern pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD]; > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index 950fd372a07e..ba7744d3e319 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -117,6 +117,9 @@ void kasan_poison_shadow(const void *address, size_t size, u8 value) > { > void *shadow_start, *shadow_end; > > + if (!kasan_arch_is_ready()) > + return; > + > /* > * Perform shadow offset calculation based on untagged address, as > * some of the callers (e.g. kasan_poison_object_data) pass tagged > @@ -134,6 +137,9 @@ void kasan_unpoison_shadow(const void *address, size_t size) > { > u8 tag = get_tag(address); > > + if (!kasan_arch_is_ready()) > + return; > + > /* > * Perform shadow offset calculation based on untagged address, as > * some of the callers (e.g. kasan_unpoison_object_data) pass tagged > @@ -406,6 +412,10 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object, > if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU)) > return false; > > + /* We can't read the shadow byte if the arch isn't ready */ > + if (!kasan_arch_is_ready()) > + return false; > + > shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object)); > if (shadow_invalid(tag, shadow_byte)) { > kasan_report_invalid_free(tagged_object, ip); > diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c > index 248264b9cb76..e87404026b2b 100644 > --- a/mm/kasan/generic.c > +++ b/mm/kasan/generic.c > @@ -169,6 +169,9 @@ static __always_inline bool check_memory_region_inline(unsigned long addr, > size_t size, bool write, > unsigned long ret_ip) > { > + if (!kasan_arch_is_ready()) > + return true; > + > if (unlikely(size == 0)) > return true; > >
diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 30d343b4a40a..3df66fdf6662 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -20,6 +20,10 @@ struct kunit_kasan_expectation { bool report_found; }; +#ifndef kasan_arch_is_ready +static inline bool kasan_arch_is_ready(void) { return true; } +#endif + extern unsigned char kasan_early_shadow_page[PAGE_SIZE]; extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE]; extern pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD]; diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 950fd372a07e..ba7744d3e319 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -117,6 +117,9 @@ void kasan_poison_shadow(const void *address, size_t size, u8 value) { void *shadow_start, *shadow_end; + if (!kasan_arch_is_ready()) + return; + /* * Perform shadow offset calculation based on untagged address, as * some of the callers (e.g. kasan_poison_object_data) pass tagged @@ -134,6 +137,9 @@ void kasan_unpoison_shadow(const void *address, size_t size) { u8 tag = get_tag(address); + if (!kasan_arch_is_ready()) + return; + /* * Perform shadow offset calculation based on untagged address, as * some of the callers (e.g. kasan_unpoison_object_data) pass tagged @@ -406,6 +412,10 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object, if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU)) return false; + /* We can't read the shadow byte if the arch isn't ready */ + if (!kasan_arch_is_ready()) + return false; + shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object)); if (shadow_invalid(tag, shadow_byte)) { kasan_report_invalid_free(tagged_object, ip); diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index 248264b9cb76..e87404026b2b 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -169,6 +169,9 @@ static __always_inline bool check_memory_region_inline(unsigned long addr, size_t size, bool write, unsigned long ret_ip) { + if (!kasan_arch_is_ready()) + return true; + if (unlikely(size == 0)) return true;