aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorAlex Shi <alex.shi@linaro.org>2016-09-24 18:15:07 +0800
committerAlex Shi <alex.shi@linaro.org>2016-09-24 18:15:07 +0800
commit76c4472115cbc591c3132007ffb68553464c86af (patch)
tree92536e81d1790510e260800c4b35a79bbf874f6f
parentfabf4bd22caee598e1227f00a85973540a545be2 (diff)
parentdaa56e80f38501651e9fd9d7f76920c4e9f5c6e9 (diff)
downloadlinux-linaro-stable-76c4472115cbc591c3132007ffb68553464c86af.tar.gz
Merge branch 'linux-linaro-lsk-v4.4' into linux-linaro-lsk-v4.4-rtlsk-v4.4-16.09-rt
-rw-r--r--arch/x86/include/asm/uaccess.h16
-rw-r--r--include/linux/slub_def.h1
-rw-r--r--include/linux/uaccess.h4
-rw-r--r--lib/strncpy_from_user.c8
-rw-r--r--lib/strnlen_user.c7
-rw-r--r--mm/slub.c100
-rw-r--r--mm/usercopy.c63
-rw-r--r--security/Kconfig11
8 files changed, 136 insertions, 74 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index dd73cf9..be439e2 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -773,21 +773,21 @@ copy_to_user(void __user *to, const void *from, unsigned long n)
#define user_access_begin() __uaccess_begin()
#define user_access_end() __uaccess_end()
-#define unsafe_put_user(x, ptr) \
-({ \
+#define unsafe_put_user(x, ptr, err_label) \
+do { \
int __pu_err; \
__put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT); \
- __builtin_expect(__pu_err, 0); \
-})
+ if (unlikely(__pu_err)) goto err_label; \
+} while (0)
-#define unsafe_get_user(x, ptr) \
-({ \
+#define unsafe_get_user(x, ptr, err_label) \
+do { \
int __gu_err; \
unsigned long __gu_val; \
__get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT); \
(x) = (__force __typeof__(*(ptr)))__gu_val; \
- __builtin_expect(__gu_err, 0); \
-})
+ if (unlikely(__gu_err)) goto err_label; \
+} while (0)
#endif /* _ASM_X86_UACCESS_H */
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 3388511..f4e857e 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -81,6 +81,7 @@ struct kmem_cache {
int reserved; /* Reserved bytes at the end of slabs */
const char *name; /* Name (only for display!) */
struct list_head list; /* List of slab caches */
+ int red_left_pad; /* Left redzone padding size */
#ifdef CONFIG_SYSFS
struct kobject kobj; /* For sysfs */
#endif
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 1d65e4f..83bf0f7 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -116,8 +116,8 @@ extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
#ifndef user_access_begin
#define user_access_begin() do { } while (0)
#define user_access_end() do { } while (0)
-#define unsafe_get_user(x, ptr) __get_user(x, ptr)
-#define unsafe_put_user(x, ptr) __put_user(x, ptr)
+#define unsafe_get_user(x, ptr, err) do { if (unlikely(__get_user(x, ptr))) goto err; } while (0)
+#define unsafe_put_user(x, ptr, err) do { if (unlikely(__put_user(x, ptr))) goto err; } while (0)
#endif
#endif /* __LINUX_UACCESS_H__ */
diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
index 3384032..5a003a2 100644
--- a/lib/strncpy_from_user.c
+++ b/lib/strncpy_from_user.c
@@ -39,8 +39,8 @@ static inline long do_strncpy_from_user(char *dst, const char __user *src, long
unsigned long c, data;
/* Fall back to byte-at-a-time if we get a page fault */
- if (unlikely(unsafe_get_user(c,(unsigned long __user *)(src+res))))
- break;
+ unsafe_get_user(c, (unsigned long __user *)(src+res), byte_at_a_time);
+
*(unsigned long *)(dst+res) = c;
if (has_zero(c, &data, &constants)) {
data = prep_zero_mask(c, data, &constants);
@@ -55,8 +55,7 @@ byte_at_a_time:
while (max) {
char c;
- if (unlikely(unsafe_get_user(c,src+res)))
- return -EFAULT;
+ unsafe_get_user(c,src+res, efault);
dst[res] = c;
if (!c)
return res;
@@ -75,6 +74,7 @@ byte_at_a_time:
* Nope: we hit the address space limit, and we still had more
* characters the caller would have wanted. That's an EFAULT.
*/
+efault:
return -EFAULT;
}
diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c
index 2625943..8e105ed 100644
--- a/lib/strnlen_user.c
+++ b/lib/strnlen_user.c
@@ -45,8 +45,7 @@ static inline long do_strnlen_user(const char __user *src, unsigned long count,
src -= align;
max += align;
- if (unlikely(unsafe_get_user(c,(unsigned long __user *)src)))
- return 0;
+ unsafe_get_user(c, (unsigned long __user *)src, efault);
c |= aligned_byte_mask(align);
for (;;) {
@@ -61,8 +60,7 @@ static inline long do_strnlen_user(const char __user *src, unsigned long count,
if (unlikely(max <= sizeof(unsigned long)))
break;
max -= sizeof(unsigned long);
- if (unlikely(unsafe_get_user(c,(unsigned long __user *)(src+res))))
- return 0;
+ unsafe_get_user(c, (unsigned long __user *)(src+res), efault);
}
res -= align;
@@ -77,6 +75,7 @@ static inline long do_strnlen_user(const char __user *src, unsigned long count,
* Nope: we hit the address space limit, and we still had more
* characters the caller would have wanted. That's 0.
*/
+efault:
return 0;
}
diff --git a/mm/slub.c b/mm/slub.c
index db528a1..68ee088 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -124,6 +124,14 @@ static inline int kmem_cache_debug(struct kmem_cache *s)
#endif
}
+static inline void *fixup_red_left(struct kmem_cache *s, void *p)
+{
+ if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE)
+ p += s->red_left_pad;
+
+ return p;
+}
+
static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
{
#ifdef CONFIG_SLUB_CPU_PARTIAL
@@ -224,24 +232,6 @@ static inline void stat(const struct kmem_cache *s, enum stat_item si)
* Core slab cache functions
*******************************************************************/
-/* Verify that a pointer has an address that is valid within a slab page */
-static inline int check_valid_pointer(struct kmem_cache *s,
- struct page *page, const void *object)
-{
- void *base;
-
- if (!object)
- return 1;
-
- base = page_address(page);
- if (object < base || object >= base + page->objects * s->size ||
- (object - base) % s->size) {
- return 0;
- }
-
- return 1;
-}
-
static inline void *get_freepointer(struct kmem_cache *s, void *object)
{
return *(void **)(object + s->offset);
@@ -271,12 +261,14 @@ static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
/* Loop over all objects in a slab */
#define for_each_object(__p, __s, __addr, __objects) \
- for (__p = (__addr); __p < (__addr) + (__objects) * (__s)->size;\
- __p += (__s)->size)
+ for (__p = fixup_red_left(__s, __addr); \
+ __p < (__addr) + (__objects) * (__s)->size; \
+ __p += (__s)->size)
#define for_each_object_idx(__p, __idx, __s, __addr, __objects) \
- for (__p = (__addr), __idx = 1; __idx <= __objects;\
- __p += (__s)->size, __idx++)
+ for (__p = fixup_red_left(__s, __addr), __idx = 1; \
+ __idx <= __objects; \
+ __p += (__s)->size, __idx++)
/* Determine object index from a given position */
static inline int slab_index(void *p, struct kmem_cache *s, void *addr)
@@ -456,6 +448,22 @@ static void get_map(struct kmem_cache *s, struct page *page, unsigned long *map)
set_bit(slab_index(p, s, addr), map);
}
+static inline int size_from_object(struct kmem_cache *s)
+{
+ if (s->flags & SLAB_RED_ZONE)
+ return s->size - s->red_left_pad;
+
+ return s->size;
+}
+
+static inline void *restore_red_left(struct kmem_cache *s, void *p)
+{
+ if (s->flags & SLAB_RED_ZONE)
+ p -= s->red_left_pad;
+
+ return p;
+}
+
/*
* Debug settings:
*/
@@ -489,6 +497,26 @@ static inline void metadata_access_disable(void)
/*
* Object debugging
*/
+
+/* Verify that a pointer has an address that is valid within a slab page */
+static inline int check_valid_pointer(struct kmem_cache *s,
+ struct page *page, void *object)
+{
+ void *base;
+
+ if (!object)
+ return 1;
+
+ base = page_address(page);
+ object = restore_red_left(s, object);
+ if (object < base || object >= base + page->objects * s->size ||
+ (object - base) % s->size) {
+ return 0;
+ }
+
+ return 1;
+}
+
static void print_section(char *text, u8 *addr, unsigned int length)
{
metadata_access_enable();
@@ -628,7 +656,9 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
pr_err("INFO: Object 0x%p @offset=%tu fp=0x%p\n\n",
p, p - addr, get_freepointer(s, p));
- if (p > addr + 16)
+ if (s->flags & SLAB_RED_ZONE)
+ print_section("Redzone ", p - s->red_left_pad, s->red_left_pad);
+ else if (p > addr + 16)
print_section("Bytes b4 ", p - 16, 16);
print_section("Object ", p, min_t(unsigned long, s->object_size,
@@ -645,9 +675,9 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
if (s->flags & SLAB_STORE_USER)
off += 2 * sizeof(struct track);
- if (off != s->size)
+ if (off != size_from_object(s))
/* Beginning of the filler is the free pointer */
- print_section("Padding ", p + off, s->size - off);
+ print_section("Padding ", p + off, size_from_object(s) - off);
dump_stack();
}
@@ -677,6 +707,9 @@ static void init_object(struct kmem_cache *s, void *object, u8 val)
{
u8 *p = object;
+ if (s->flags & SLAB_RED_ZONE)
+ memset(p - s->red_left_pad, val, s->red_left_pad);
+
if (s->flags & __OBJECT_POISON) {
memset(p, POISON_FREE, s->object_size - 1);
p[s->object_size - 1] = POISON_END;
@@ -769,11 +802,11 @@ static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p)
/* We also have user information there */
off += 2 * sizeof(struct track);
- if (s->size == off)
+ if (size_from_object(s) == off)
return 1;
return check_bytes_and_report(s, page, p, "Object padding",
- p + off, POISON_INUSE, s->size - off);
+ p + off, POISON_INUSE, size_from_object(s) - off);
}
/* Check the pad bytes at the end of a slab page */
@@ -818,6 +851,10 @@ static int check_object(struct kmem_cache *s, struct page *page,
if (s->flags & SLAB_RED_ZONE) {
if (!check_bytes_and_report(s, page, object, "Redzone",
+ object - s->red_left_pad, val, s->red_left_pad))
+ return 0;
+
+ if (!check_bytes_and_report(s, page, object, "Redzone",
endobject, val, s->inuse - s->object_size))
return 0;
} else {
@@ -1481,7 +1518,7 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
set_freepointer(s, p, NULL);
}
- page->freelist = start;
+ page->freelist = fixup_red_left(s, start);
page->inuse = page->objects;
page->frozen = 1;
@@ -3347,7 +3384,7 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
*/
size += 2 * sizeof(struct track);
- if (flags & SLAB_RED_ZONE)
+ if (flags & SLAB_RED_ZONE) {
/*
* Add some empty padding so that we can catch
* overwrites from earlier objects rather than let
@@ -3356,6 +3393,11 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
* of the object.
*/
size += sizeof(void *);
+
+ s->red_left_pad = sizeof(void *);
+ s->red_left_pad = ALIGN(s->red_left_pad, s->align);
+ size += s->red_left_pad;
+ }
#endif
/*
diff --git a/mm/usercopy.c b/mm/usercopy.c
index 8ebae91..c56b97b 100644
--- a/mm/usercopy.c
+++ b/mm/usercopy.c
@@ -83,7 +83,7 @@ static bool overlaps(const void *ptr, unsigned long n, unsigned long low,
unsigned long check_high = check_low + n;
/* Does not overlap if entirely above or entirely below. */
- if (check_low >= high || check_high < low)
+ if (check_low >= high || check_high <= low)
return false;
return true;
@@ -134,31 +134,16 @@ static inline const char *check_bogus_address(const void *ptr, unsigned long n)
return NULL;
}
-static inline const char *check_heap_object(const void *ptr, unsigned long n,
- bool to_user)
+/* Checks for allocs that are marked in some way as spanning multiple pages. */
+static inline const char *check_page_span(const void *ptr, unsigned long n,
+ struct page *page, bool to_user)
{
- struct page *page, *endpage;
+#ifdef CONFIG_HARDENED_USERCOPY_PAGESPAN
const void *end = ptr + n - 1;
+ struct page *endpage;
bool is_reserved, is_cma;
/*
- * Some architectures (arm64) return true for virt_addr_valid() on
- * vmalloced addresses. Work around this by checking for vmalloc
- * first.
- */
- if (is_vmalloc_addr(ptr))
- return NULL;
-
- if (!virt_addr_valid(ptr))
- return NULL;
-
- page = virt_to_head_page(ptr);
-
- /* Check slab allocator for flags and size. */
- if (PageSlab(page))
- return __check_heap_object(ptr, n, page);
-
- /*
* Sometimes the kernel data regions are not marked Reserved (see
* check below). And sometimes [_sdata,_edata) does not cover
* rodata and/or bss, so check each range explicitly.
@@ -186,7 +171,7 @@ static inline const char *check_heap_object(const void *ptr, unsigned long n,
((unsigned long)end & (unsigned long)PAGE_MASK)))
return NULL;
- /* Allow if start and end are inside the same compound page. */
+ /* Allow if fully inside the same compound (__GFP_COMP) page. */
endpage = virt_to_head_page(end);
if (likely(endpage == page))
return NULL;
@@ -199,20 +184,44 @@ static inline const char *check_heap_object(const void *ptr, unsigned long n,
is_reserved = PageReserved(page);
is_cma = is_migrate_cma_page(page);
if (!is_reserved && !is_cma)
- goto reject;
+ return "<spans multiple pages>";
for (ptr += PAGE_SIZE; ptr <= end; ptr += PAGE_SIZE) {
page = virt_to_head_page(ptr);
if (is_reserved && !PageReserved(page))
- goto reject;
+ return "<spans Reserved and non-Reserved pages>";
if (is_cma && !is_migrate_cma_page(page))
- goto reject;
+ return "<spans CMA and non-CMA pages>";
}
+#endif
return NULL;
+}
+
+static inline const char *check_heap_object(const void *ptr, unsigned long n,
+ bool to_user)
+{
+ struct page *page;
+
+ /*
+ * Some architectures (arm64) return true for virt_addr_valid() on
+ * vmalloced addresses. Work around this by checking for vmalloc
+ * first.
+ */
+ if (is_vmalloc_addr(ptr))
+ return NULL;
+
+ if (!virt_addr_valid(ptr))
+ return NULL;
+
+ page = virt_to_head_page(ptr);
+
+ /* Check slab allocator for flags and size. */
+ if (PageSlab(page))
+ return __check_heap_object(ptr, n, page);
-reject:
- return "<spans multiple pages>";
+ /* Verify object does not incorrectly span multiple pages. */
+ return check_page_span(ptr, n, page, to_user);
}
/*
diff --git a/security/Kconfig b/security/Kconfig
index 46c00a6..ddb3e8a 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -146,6 +146,17 @@ config HARDENED_USERCOPY
or are part of the kernel text. This kills entire classes
of heap overflow exploits and similar kernel memory exposures.
+config HARDENED_USERCOPY_PAGESPAN
+ bool "Refuse to copy allocations that span multiple pages"
+ depends on HARDENED_USERCOPY
+ depends on !COMPILE_TEST
+ help
+ When a multi-page allocation is done without __GFP_COMP,
+ hardened usercopy will reject attempts to copy it. There are,
+ however, several cases of this in the kernel that have not all
+ been removed. This config is intended to be used only while
+ trying to find such users.
+
source security/selinux/Kconfig
source security/smack/Kconfig
source security/tomoyo/Kconfig