diff options
| -rw-r--r-- | Documentation/dontdiff | 2 | ||||
| -rw-r--r-- | arch/Kconfig | 41 | ||||
| -rw-r--r-- | arch/arm/include/asm/assembler.h | 2 | ||||
| -rw-r--r-- | arch/arm/kernel/entry-armv.S | 5 | ||||
| -rw-r--r-- | arch/arm/mm/proc-macros.S | 10 | ||||
| -rw-r--r-- | include/linux/compiler-gcc.h | 13 | ||||
| -rw-r--r-- | include/linux/compiler.h | 12 | ||||
| -rw-r--r-- | include/linux/vermagic.h | 9 | ||||
| -rw-r--r-- | scripts/Makefile.gcc-plugins | 4 | ||||
| -rw-r--r-- | scripts/gcc-plugins/.gitignore | 1 | ||||
| -rw-r--r-- | scripts/gcc-plugins/Makefile | 8 | ||||
| -rw-r--r-- | scripts/gcc-plugins/gcc-common.h | 12 | ||||
| -rw-r--r-- | scripts/gcc-plugins/gen-random-seed.sh | 8 | ||||
| -rw-r--r-- | scripts/gcc-plugins/randomize_layout_plugin.c | 1028 |
14 files changed, 1146 insertions, 9 deletions
diff --git a/Documentation/dontdiff b/Documentation/dontdiff index f64a63b233c3..358b47c06ad4 100644 --- a/Documentation/dontdiff +++ b/Documentation/dontdiff @@ -206,6 +206,8 @@ r200_reg_safe.h r300_reg_safe.h r420_reg_safe.h r600_reg_safe.h +randomize_layout_hash.h +randomize_layout_seed.h recordmcount relocs rlim_names.h diff --git a/arch/Kconfig b/arch/Kconfig index f76b214cf7ad..dc26b6d9175e 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -425,7 +425,7 @@ config GCC_PLUGIN_STRUCTLEAK bool "Force initialization of variables containing userspace addresses" depends on GCC_PLUGINS help - This plugin zero-initializes any structures that containing a + This plugin zero-initializes any structures containing a __user attribute. This can prevent some classes of information exposures. @@ -443,6 +443,45 @@ config GCC_PLUGIN_STRUCTLEAK_VERBOSE initialized. Since not all existing initializers are detected by the plugin, this can produce false positive warnings. +config GCC_PLUGIN_RANDSTRUCT + bool "Randomize layout of sensitive kernel structures" + depends on GCC_PLUGINS + select MODVERSIONS if MODULES + help + If you say Y here, the layouts of structures explicitly + marked by __randomize_layout will be randomized at + compile-time. This can introduce the requirement of an + additional information exposure vulnerability for exploits + targeting these structure types. + + Enabling this feature will introduce some performance impact, + slightly increase memory usage, and prevent the use of forensic + tools like Volatility against the system (unless the kernel + source tree isn't cleaned after kernel installation). + + The seed used for compilation is located at + scripts/gcc-plgins/randomize_layout_seed.h. It remains after + a make clean to allow for external modules to be compiled with + the existing seed and will be removed by a make mrproper or + make distclean. + + Note that the implementation requires gcc 4.7 or newer. + + This plugin was ported from grsecurity/PaX. More information at: + * https://grsecurity.net/ + * https://pax.grsecurity.net/ + +config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE + bool "Use cacheline-aware structure randomization" + depends on GCC_PLUGIN_RANDSTRUCT + depends on !COMPILE_TEST + help + If you say Y here, the RANDSTRUCT randomization will make a + best effort at restricting randomization to cacheline-sized + groups of elements. It will further not randomize bitfields + in structures. This reduces the performance hit of RANDSTRUCT + at the cost of weakened randomization. + config HAVE_CC_STACKPROTECTOR bool help diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h index 68b06f9c65de..ad301f107dd2 100644 --- a/arch/arm/include/asm/assembler.h +++ b/arch/arm/include/asm/assembler.h @@ -87,6 +87,8 @@ #define CALGN(code...) #endif +#define IMM12_MASK 0xfff + /* * Enable and disable interrupts */ diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index 9f157e7c51e7..c731f0d2b2af 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -797,7 +797,10 @@ ENTRY(__switch_to) #if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP) ldr r7, [r2, #TI_TASK] ldr r8, =__stack_chk_guard - ldr r7, [r7, #TSK_STACK_CANARY] + .if (TSK_STACK_CANARY > IMM12_MASK) + add r7, r7, #TSK_STACK_CANARY & ~IMM12_MASK + .endif + ldr r7, [r7, #TSK_STACK_CANARY & IMM12_MASK] #endif #ifdef CONFIG_CPU_USE_DOMAINS mcr p15, 0, r6, c3, c0, 0 @ Set domain register diff --git a/arch/arm/mm/proc-macros.S b/arch/arm/mm/proc-macros.S index 0d40c285bd86..f944836da8a2 100644 --- a/arch/arm/mm/proc-macros.S +++ b/arch/arm/mm/proc-macros.S @@ -25,11 +25,6 @@ ldr \rd, [\rn, #VMA_VM_FLAGS] .endm - .macro tsk_mm, rd, rn - ldr \rd, [\rn, #TI_TASK] - ldr \rd, [\rd, #TSK_ACTIVE_MM] - .endm - /* * act_mm - get current->active_mm */ @@ -37,7 +32,10 @@ bic \rd, sp, #8128 bic \rd, \rd, #63 ldr \rd, [\rd, #TI_TASK] - ldr \rd, [\rd, #TSK_ACTIVE_MM] + .if (TSK_ACTIVE_MM > IMM12_MASK) + add \rd, \rd, #TSK_ACTIVE_MM & ~IMM12_MASK + .endif + ldr \rd, [\rd, #TSK_ACTIVE_MM & IMM12_MASK] .endm /* diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 0efef9cf014f..7deaae3dc87d 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -223,6 +223,11 @@ /* Mark a function definition as prohibited from being cloned. */ #define __noclone __attribute__((__noclone__, __optimize__("no-tracer"))) +#ifdef RANDSTRUCT_PLUGIN +#define __randomize_layout __attribute__((randomize_layout)) +#define __no_randomize_layout __attribute__((no_randomize_layout)) +#endif + #endif /* GCC_VERSION >= 40500 */ #if GCC_VERSION >= 40600 @@ -294,6 +299,14 @@ #define __no_sanitize_address __attribute__((no_sanitize_address)) #endif +#if GCC_VERSION >= 50100 +/* + * Mark structures as requiring designated initializers. + * https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html + */ +#define __designated_init __attribute__((designated_init)) +#endif + #endif /* gcc version >= 40000 specific checks */ #if !defined(__noclone) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 707242fdbb89..219f82f3ec1a 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -436,10 +436,22 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s # define __attribute_const__ /* unimplemented */ #endif +#ifndef __designated_init +# define __designated_init +#endif + #ifndef __latent_entropy # define __latent_entropy #endif +#ifndef __randomize_layout +# define __randomize_layout __designated_init +#endif + +#ifndef __no_randomize_layout +# define __no_randomize_layout +#endif + /* * Tell gcc if a function is cold. The compiler will assume any path * directly leading to the call is unlikely. diff --git a/include/linux/vermagic.h b/include/linux/vermagic.h index 6f8fbcf10dfb..af6c03f7f986 100644 --- a/include/linux/vermagic.h +++ b/include/linux/vermagic.h @@ -24,10 +24,17 @@ #ifndef MODULE_ARCH_VERMAGIC #define MODULE_ARCH_VERMAGIC "" #endif +#ifdef RANDSTRUCT_PLUGIN +#include <generated/randomize_layout_hash.h> +#define MODULE_RANDSTRUCT_PLUGIN "RANDSTRUCT_PLUGIN_" RANDSTRUCT_HASHED_SEED +#else +#define MODULE_RANDSTRUCT_PLUGIN +#endif #define VERMAGIC_STRING \ UTS_RELEASE " " \ MODULE_VERMAGIC_SMP MODULE_VERMAGIC_PREEMPT \ MODULE_VERMAGIC_MODULE_UNLOAD MODULE_VERMAGIC_MODVERSIONS \ - MODULE_ARCH_VERMAGIC + MODULE_ARCH_VERMAGIC \ + MODULE_RANDSTRUCT_PLUGIN diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins index 82335533620e..2e0e2eaa397f 100644 --- a/scripts/Makefile.gcc-plugins +++ b/scripts/Makefile.gcc-plugins @@ -29,6 +29,10 @@ ifdef CONFIG_GCC_PLUGINS gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK_VERBOSE) += -fplugin-arg-structleak_plugin-verbose gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STRUCTLEAK) += -DSTRUCTLEAK_PLUGIN + gcc-plugin-$(CONFIG_GCC_PLUGIN_RANDSTRUCT) += randomize_layout_plugin.so + gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_RANDSTRUCT) += -DRANDSTRUCT_PLUGIN + gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_RANDSTRUCT_PERFORMANCE) += -fplugin-arg-randomize_layout_plugin-performance-mode + GCC_PLUGINS_CFLAGS := $(strip $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) $(gcc-plugin-cflags-y)) export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGIN GCC_PLUGIN_SUBDIR diff --git a/scripts/gcc-plugins/.gitignore b/scripts/gcc-plugins/.gitignore new file mode 100644 index 000000000000..de92ed9e3d83 --- /dev/null +++ b/scripts/gcc-plugins/.gitignore @@ -0,0 +1 @@ +randomize_layout_seed.h diff --git a/scripts/gcc-plugins/Makefile b/scripts/gcc-plugins/Makefile index 8b29dc17c73c..214eb2335c31 100644 --- a/scripts/gcc-plugins/Makefile +++ b/scripts/gcc-plugins/Makefile @@ -18,6 +18,14 @@ endif export HOSTLIBS +$(obj)/randomize_layout_plugin.o: $(objtree)/$(obj)/randomize_layout_seed.h +quiet_cmd_create_randomize_layout_seed = GENSEED $@ +cmd_create_randomize_layout_seed = \ + $(CONFIG_SHELL) $(srctree)/$(src)/gen-random-seed.sh $@ $(objtree)/include/generated/randomize_layout_hash.h +$(objtree)/$(obj)/randomize_layout_seed.h: FORCE + $(call if_changed,create_randomize_layout_seed) +targets = randomize_layout_seed.h randomize_layout_hash.h + $(HOSTLIBS)-y := $(foreach p,$(GCC_PLUGIN),$(if $(findstring /,$(p)),,$(p))) always := $($(HOSTLIBS)-y) diff --git a/scripts/gcc-plugins/gcc-common.h b/scripts/gcc-plugins/gcc-common.h index b232ab15624c..6948898b3cdf 100644 --- a/scripts/gcc-plugins/gcc-common.h +++ b/scripts/gcc-plugins/gcc-common.h @@ -63,6 +63,13 @@ #endif #if BUILDING_GCC_VERSION >= 4006 +/* + * The c-family headers were moved into a subdirectory in GCC version + * 4.7, but most plugin-building users of GCC 4.6 are using the Debian + * or Ubuntu package, which has an out-of-tree patch to move this to the + * same location as found in 4.7 and later: + * https://sources.debian.net/src/gcc-4.6/4.6.3-14/debian/patches/pr45078.diff/ + */ #include "c-family/c-common.h" #else #include "c-common.h" @@ -946,4 +953,9 @@ static inline void debug_gimple_stmt(const_gimple s) get_inner_reference(exp, pbitsize, pbitpos, poffset, pmode, punsignedp, preversep, pvolatilep) #endif +#if BUILDING_GCC_VERSION < 7000 +#define SET_DECL_ALIGN(decl, align) DECL_ALIGN(decl) = (align) +#define SET_DECL_MODE(decl, mode) DECL_MODE(decl) = (mode) +#endif + #endif diff --git a/scripts/gcc-plugins/gen-random-seed.sh b/scripts/gcc-plugins/gen-random-seed.sh new file mode 100644 index 000000000000..7514850f4815 --- /dev/null +++ b/scripts/gcc-plugins/gen-random-seed.sh @@ -0,0 +1,8 @@ +#!/bin/sh + +if [ ! -f "$1" ]; then + SEED=`od -A n -t x8 -N 32 /dev/urandom | tr -d ' \n'` + echo "const char *randstruct_seed = \"$SEED\";" > "$1" + HASH=`echo -n "$SEED" | sha256sum | cut -d" " -f1 | tr -d ' \n'` + echo "#define RANDSTRUCT_HASHED_SEED \"$HASH\"" > "$2" +fi diff --git a/scripts/gcc-plugins/randomize_layout_plugin.c b/scripts/gcc-plugins/randomize_layout_plugin.c new file mode 100644 index 000000000000..cdaac8c66734 --- /dev/null +++ b/scripts/gcc-plugins/randomize_layout_plugin.c @@ -0,0 +1,1028 @@ +/* + * Copyright 2014-2016 by Open Source Security, Inc., Brad Spengler <spender@grsecurity.net> + * and PaX Team <pageexec@freemail.hu> + * Licensed under the GPL v2 + * + * Note: the choice of the license means that the compilation process is + * NOT 'eligible' as defined by gcc's library exception to the GPL v3, + * but for the kernel it doesn't matter since it doesn't link against + * any of the gcc libraries + * + * Usage: + * $ # for 4.5/4.6/C based 4.7 + * $ gcc -I`gcc -print-file-name=plugin`/include -I`gcc -print-file-name=plugin`/include/c-family -fPIC -shared -O2 -o randomize_layout_plugin.so randomize_layout_plugin.c + * $ # for C++ based 4.7/4.8+ + * $ g++ -I`g++ -print-file-name=plugin`/include -I`g++ -print-file-name=plugin`/include/c-family -fPIC -shared -O2 -o randomize_layout_plugin.so randomize_layout_plugin.c + * $ gcc -fplugin=./randomize_layout_plugin.so test.c -O2 + */ + +#include "gcc-common.h" +#include "randomize_layout_seed.h" + +#if BUILDING_GCC_MAJOR < 4 || (BUILDING_GCC_MAJOR == 4 && BUILDING_GCC_MINOR < 7) +#error "The RANDSTRUCT plugin requires GCC 4.7 or newer." +#endif + +#define ORIG_TYPE_NAME(node) \ + (TYPE_NAME(TYPE_MAIN_VARIANT(node)) != NULL_TREE ? ((const unsigned char *)IDENTIFIER_POINTER(TYPE_NAME(TYPE_MAIN_VARIANT(node)))) : (const unsigned char *)"anonymous") + +#define INFORM(loc, msg, ...) inform(loc, "randstruct: " msg, ##__VA_ARGS__) +#define MISMATCH(loc, how, ...) INFORM(loc, "casting between randomized structure pointer types (" how "): %qT and %qT\n", __VA_ARGS__) + +__visible int plugin_is_GPL_compatible; + +static int performance_mode; + +static struct plugin_info randomize_layout_plugin_info = { + .version = "201402201816vanilla", + .help = "disable\t\t\tdo not activate plugin\n" + "performance-mode\tenable cacheline-aware layout randomization\n" +}; + +struct whitelist_entry { + const char *pathname; + const char *lhs; + const char *rhs; +}; + +static const struct whitelist_entry whitelist[] = { + /* NIU overloads mapping with page struct */ + { "drivers/net/ethernet/sun/niu.c", "page", "address_space" }, + /* unix_skb_parms via UNIXCB() buffer */ + { "net/unix/af_unix.c", "unix_skb_parms", "char" }, + /* big_key payload.data struct splashing */ + { "security/keys/big_key.c", "path", "void *" }, + /* walk struct security_hook_heads as an array of struct list_head */ + { "security/security.c", "list_head", "security_hook_heads" }, + { } +}; + +/* from old Linux dcache.h */ +static inline unsigned long +partial_name_hash(unsigned long c, unsigned long prevhash) +{ + return (prevhash + (c << 4) + (c >> 4)) * 11; +} +static inline unsigned int +name_hash(const unsigned char *name) +{ + unsigned long hash = 0; + unsigned int len = strlen((const char *)name); + while (len--) + hash = partial_name_hash(*name++, hash); + return (unsigned int)hash; +} + +static tree handle_randomize_layout_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) +{ + tree type; + + *no_add_attrs = true; + if (TREE_CODE(*node) == FUNCTION_DECL) { + error("%qE attribute does not apply to functions (%qF)", name, *node); + return NULL_TREE; + } + + if (TREE_CODE(*node) == PARM_DECL) { + error("%qE attribute does not apply to function parameters (%qD)", name, *node); + return NULL_TREE; + } + + if (TREE_CODE(*node) == VAR_DECL) { + error("%qE attribute does not apply to variables (%qD)", name, *node); + return NULL_TREE; + } + + if (TYPE_P(*node)) { + type = *node; + } else { + gcc_assert(TREE_CODE(*node) == TYPE_DECL); + type = TREE_TYPE(*node); + } + + if (TREE_CODE(type) != RECORD_TYPE) { + error("%qE attribute used on %qT applies to struct types only", name, type); + return NULL_TREE; + } + + if (lookup_attribute(IDENTIFIER_POINTER(name), TYPE_ATTRIBUTES(type))) { + error("%qE attribute is already applied to the type %qT", name, type); + return NULL_TREE; + } + + *no_add_attrs = false; + + return NULL_TREE; +} + +/* set on complete types that we don't need to inspect further at all */ +static tree handle_randomize_considered_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) +{ + *no_add_attrs = false; + return NULL_TREE; +} + +/* + * set on types that we've performed a shuffle on, to prevent re-shuffling + * this does not preclude us from inspecting its fields for potential shuffles + */ +static tree handle_randomize_performed_attr(tree *node, tree name, tree args, int flags, bool *no_add_attrs) +{ + *no_add_attrs = false; + return NULL_TREE; +} + +/* + * 64bit variant of Bob Jenkins' public domain PRNG + * 256 bits of internal state + */ + +typedef unsigned long long u64; + +typedef struct ranctx { u64 a; u64 b; u64 c; u64 d; } ranctx; + +#define rot(x,k) (((x)<<(k))|((x)>>(64-(k)))) +static u64 ranval(ranctx *x) { + u64 e = x->a - rot(x->b, 7); + x->a = x->b ^ rot(x->c, 13); + x->b = x->c + rot(x->d, 37); + x->c = x->d + e; + x->d = e + x->a; + return x->d; +} + +static void raninit(ranctx *x, u64 *seed) { + int i; + + x->a = seed[0]; + x->b = seed[1]; + x->c = seed[2]; + x->d = seed[3]; + + for (i=0; i < 30; ++i) + (void)ranval(x); +} + +static u64 shuffle_seed[4]; + +struct partition_group { + tree tree_start; + unsigned long start; + unsigned long length; +}; + +static void partition_struct(tree *fields, unsigned long length, struct partition_group *size_groups, unsigned long *num_groups) +{ + unsigned long i; + unsigned long accum_size = 0; + unsigned long accum_length = 0; + unsigned long group_idx = 0; + + gcc_assert(length < INT_MAX); + + memset(size_groups, 0, sizeof(struct partition_group) * length); + + for (i = 0; i < length; i++) { + if (size_groups[group_idx].tree_start == NULL_TREE) { + size_groups[group_idx].tree_start = fields[i]; + size_groups[group_idx].start = i; + accum_length = 0; + accum_size = 0; + } + accum_size += (unsigned long)int_size_in_bytes(TREE_TYPE(fields[i])); + accum_length++; + if (accum_size >= 64) { + size_groups[group_idx].length = accum_length; + accum_length = 0; + group_idx++; + } + } + + if (size_groups[group_idx].tree_start != NULL_TREE && + !size_groups[group_idx].length) { + size_groups[group_idx].length = accum_length; + group_idx++; + } + + *num_groups = group_idx; +} + +static void performance_shuffle(tree *newtree, unsigned long length, ranctx *prng_state) +{ + unsigned long i, x; + struct partition_group size_group[length]; + unsigned long num_groups = 0; + unsigned long randnum; + + partition_struct(newtree, length, (struct partition_group *)&size_group, &num_groups); + for (i = num_groups - 1; i > 0; i--) { + struct partition_group tmp; + randnum = ranval(prng_state) % (i + 1); + tmp = size_group[i]; + size_group[i] = size_group[randnum]; + size_group[randnum] = tmp; + } + + for (x = 0; x < num_groups; x++) { + for (i = size_group[x].start + size_group[x].length - 1; i > size_group[x].start; i--) { + tree tmp; + if (DECL_BIT_FIELD_TYPE(newtree[i])) + continue; + randnum = ranval(prng_state) % (i + 1); + // we could handle this case differently if desired + if (DECL_BIT_FIELD_TYPE(newtree[randnum])) + continue; + tmp = newtree[i]; + newtree[i] = newtree[randnum]; + newtree[randnum] = tmp; + } + } +} + +static void full_shuffle(tree *newtree, unsigned long length, ranctx *prng_state) +{ + unsigned long i, randnum; + + for (i = length - 1; i > 0; i--) { + tree tmp; + randnum = ranval(prng_state) % (i + 1); + tmp = newtree[i]; + newtree[i] = newtree[randnum]; + newtree[randnum] = tmp; + } +} + +/* modern in-place Fisher-Yates shuffle */ +static void shuffle(const_tree type, tree *newtree, unsigned long length) +{ + unsigned long i; + u64 seed[4]; + ranctx prng_state; + const unsigned char *structname; + + if (length == 0) + return; + + gcc_assert(TREE_CODE(type) == RECORD_TYPE); + + structname = ORIG_TYPE_NAME(type); + +#ifdef __DEBUG_PLUGIN + fprintf(stderr, "Shuffling struct %s %p\n", (const char *)structname, type); +#ifdef __DEBUG_VERBOSE + debug_tree((tree)type); +#endif +#endif + + for (i = 0; i < 4; i++) { + seed[i] = shuffle_seed[i]; + seed[i] ^= name_hash(structname); + } + + raninit(&prng_state, (u64 *)&seed); + + if (performance_mode) + performance_shuffle(newtree, length, &prng_state); + else + full_shuffle(newtree, length, &prng_state); +} + +static bool is_flexible_array(const_tree field) +{ + const_tree fieldtype; + const_tree typesize; + const_tree elemtype; + const_tree elemsize; + + fieldtype = TREE_TYPE(field); + typesize = TYPE_SIZE(fieldtype); + + if (TREE_CODE(fieldtype) != ARRAY_TYPE) + return false; + + elemtype = TREE_TYPE(fieldtype); + elemsize = TYPE_SIZE(elemtype); + + /* size of type is represented in bits */ + + if (typesize == NULL_TREE && TYPE_DOMAIN(fieldtype) != NULL_TREE && + TYPE_MAX_VALUE(TYPE_DOMAIN(fieldtype)) == NULL_TREE) + return true; + + if (typesize != NULL_TREE && + (TREE_CONSTANT(typesize) && (!tree_to_uhwi(typesize) || + tree_to_uhwi(typesize) == tree_to_uhwi(elemsize)))) + return true; + + return false; +} + +static int relayout_struct(tree type) +{ + unsigned long num_fields = (unsigned long)list_length(TYPE_FIELDS(type)); + unsigned long shuffle_length = num_fields; + tree field; + tree newtree[num_fields]; + unsigned long i; + tree list; + tree variant; + tree main_variant; + expanded_location xloc; + bool has_flexarray = false; + + if (TYPE_FIELDS(type) == NULL_TREE) + return 0; + + if (num_fields < 2) + return 0; + + gcc_assert(TREE_CODE(type) == RECORD_TYPE); + + gcc_assert(num_fields < INT_MAX); + + if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type)) || + lookup_attribute("no_randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type)))) + return 0; + + /* Workaround for 3rd-party VirtualBox source that we can't modify ourselves */ + if (!strcmp((const char *)ORIG_TYPE_NAME(type), "INTNETTRUNKFACTORY") || + !strcmp((const char *)ORIG_TYPE_NAME(type), "RAWPCIFACTORY")) + return 0; + + /* throw out any structs in uapi */ + xloc = expand_location(DECL_SOURCE_LOCATION(TYPE_FIELDS(type))); + + if (strstr(xloc.file, "/uapi/")) + error(G_("attempted to randomize userland API struct %s"), ORIG_TYPE_NAME(type)); + + for (field = TYPE_FIELDS(type), i = 0; field; field = TREE_CHAIN(field), i++) { + gcc_assert(TREE_CODE(field) == FIELD_DECL); + newtree[i] = field; + } + + /* + * enforce that we don't randomize the layout of the last + * element of a struct if it's a 0 or 1-length array + * or a proper flexible array + */ + if (is_flexible_array(newtree[num_fields - 1])) { + has_flexarray = true; + shuffle_length--; + } + + shuffle(type, (tree *)newtree, shuffle_length); + + /* + * set up a bogus anonymous struct field designed to error out on unnamed struct initializers + * as gcc provides no other way to detect such code + */ + list = make_node(FIELD_DECL); + TREE_CHAIN(list) = newtree[0]; + TREE_TYPE(list) = void_type_node; + DECL_SIZE(list) = bitsize_zero_node; + DECL_NONADDRESSABLE_P(list) = 1; + DECL_FIELD_BIT_OFFSET(list) = bitsize_zero_node; + DECL_SIZE_UNIT(list) = size_zero_node; + DECL_FIELD_OFFSET(list) = size_zero_node; + DECL_CONTEXT(list) = type; + // to satisfy the constify plugin + TREE_READONLY(list) = 1; + + for (i = 0; i < num_fields - 1; i++) + TREE_CHAIN(newtree[i]) = newtree[i+1]; + TREE_CHAIN(newtree[num_fields - 1]) = NULL_TREE; + + main_variant = TYPE_MAIN_VARIANT(type); + for (variant = main_variant; variant; variant = TYPE_NEXT_VARIANT(variant)) { + TYPE_FIELDS(variant) = list; + TYPE_ATTRIBUTES(variant) = copy_list(TYPE_ATTRIBUTES(variant)); + TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("randomize_performed"), NULL_TREE, TYPE_ATTRIBUTES(variant)); + TYPE_ATTRIBUTES(variant) = tree_cons(get_identifier("designated_init"), NULL_TREE, TYPE_ATTRIBUTES(variant)); + if (has_flexarray) + TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("has_flexarray"), NULL_TREE, TYPE_ATTRIBUTES(type)); + } + + /* + * force a re-layout of the main variant + * the TYPE_SIZE for all variants will be recomputed + * by finalize_type_size() + */ + TYPE_SIZE(main_variant) = NULL_TREE; + layout_type(main_variant); + gcc_assert(TYPE_SIZE(main_variant) != NULL_TREE); + + return 1; +} + +/* from constify plugin */ +static const_tree get_field_type(const_tree field) +{ + return strip_array_types(TREE_TYPE(field)); +} + +/* from constify plugin */ +static bool is_fptr(const_tree fieldtype) +{ + if (TREE_CODE(fieldtype) != POINTER_TYPE) + return false; + + return TREE_CODE(TREE_TYPE(fieldtype)) == FUNCTION_TYPE; +} + +/* derived from constify plugin */ +static int is_pure_ops_struct(const_tree node) +{ + const_tree field; + + gcc_assert(TREE_CODE(node) == RECORD_TYPE || TREE_CODE(node) == UNION_TYPE); + + /* XXX: Do not apply randomization to all-ftpr structs yet. */ + return 0; + + for (field = TYPE_FIELDS(node); field; field = TREE_CHAIN(field)) { + const_tree fieldtype = get_field_type(field); + enum tree_code code = TREE_CODE(fieldtype); + + if (node == fieldtype) + continue; + + if (!is_fptr(fieldtype)) + return 0; + + if (code != RECORD_TYPE && code != UNION_TYPE) + continue; + + if (!is_pure_ops_struct(fieldtype)) + return 0; + } + + return 1; +} + +static void randomize_type(tree type) +{ + tree variant; + + gcc_assert(TREE_CODE(type) == RECORD_TYPE); + + if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type))) + return; + + if (lookup_attribute("randomize_layout", TYPE_ATTRIBUTES(TYPE_MAIN_VARIANT(type))) || is_pure_ops_struct(type)) + relayout_struct(type); + + for (variant = TYPE_MAIN_VARIANT(type); variant; variant = TYPE_NEXT_VARIANT(variant)) { + TYPE_ATTRIBUTES(type) = copy_list(TYPE_ATTRIBUTES(type)); + TYPE_ATTRIBUTES(type) = tree_cons(get_identifier("randomize_considered"), NULL_TREE, TYPE_ATTRIBUTES(type)); + } +#ifdef __DEBUG_PLUGIN + fprintf(stderr, "Marking randomize_considered on struct %s\n", ORIG_TYPE_NAME(type)); +#ifdef __DEBUG_VERBOSE + debug_tree(type); +#endif +#endif +} + +static void update_decl_size(tree decl) +{ + tree lastval, lastidx, field, init, type, flexsize; + unsigned HOST_WIDE_INT len; + + type = TREE_TYPE(decl); + + if (!lookup_attribute("has_flexarray", TYPE_ATTRIBUTES(type))) + return; + + init = DECL_INITIAL(decl); + if (init == NULL_TREE || init == error_mark_node) + return; + + if (TREE_CODE(init) != CONSTRUCTOR) + return; + + len = CONSTRUCTOR_NELTS(init); + if (!len) + return; + + lastval = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->value; + lastidx = CONSTRUCTOR_ELT(init, CONSTRUCTOR_NELTS(init) - 1)->index; + + for (field = TYPE_FIELDS(TREE_TYPE(decl)); TREE_CHAIN(field); field = TREE_CHAIN(field)) + ; + + if (lastidx != field) + return; + + if (TREE_CODE(lastval) != STRING_CST) { + error("Only string constants are supported as initializers " + "for randomized structures with flexible arrays"); + return; + } + + flexsize = bitsize_int(TREE_STRING_LENGTH(lastval) * + tree_to_uhwi(TYPE_SIZE(TREE_TYPE(TREE_TYPE(lastval))))); + + DECL_SIZE(decl) = size_binop(PLUS_EXPR, TYPE_SIZE(type), flexsize); + + return; +} + + +static void randomize_layout_finish_decl(void *event_data, void *data) +{ + tree decl = (tree)event_data; + tree type; + + if (decl == NULL_TREE || decl == error_mark_node) + return; + + type = TREE_TYPE(decl); + + if (TREE_CODE(decl) != VAR_DECL) + return; + + if (TREE_CODE(type) != RECORD_TYPE && TREE_CODE(type) != UNION_TYPE) + return; + + if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(type))) + return; + + DECL_SIZE(decl) = 0; + DECL_SIZE_UNIT(decl) = 0; + SET_DECL_ALIGN(decl, 0); + SET_DECL_MODE (decl, VOIDmode); + SET_DECL_RTL(decl, 0); + update_decl_size(decl); + layout_decl(decl, 0); +} + +static void finish_type(void *event_data, void *data) +{ + tree type = (tree)event_data; + + if (type == NULL_TREE || type == error_mark_node) + return; + + if (TREE_CODE(type) != RECORD_TYPE) + return; + + if (TYPE_FIELDS(type) == NULL_TREE) + return; + + if (lookup_attribute("randomize_considered", TYPE_ATTRIBUTES(type))) + return; + +#ifdef __DEBUG_PLUGIN + fprintf(stderr, "Calling randomize_type on %s\n", ORIG_TYPE_NAME(type)); +#endif +#ifdef __DEBUG_VERBOSE + debug_tree(type); +#endif + randomize_type(type); + + return; +} + +static struct attribute_spec randomize_layout_attr = { + .name = "randomize_layout", + // related to args + .min_length = 0, + .max_length = 0, + .decl_required = false, + // need type declaration + .type_required = true, + .function_type_required = false, + .handler = handle_randomize_layout_attr, +#if BUILDING_GCC_VERSION >= 4007 + .affects_type_identity = true +#endif +}; + +static struct attribute_spec no_randomize_layout_attr = { + .name = "no_randomize_layout", + // related to args + .min_length = 0, + .max_length = 0, + .decl_required = false, + // need type declaration + .type_required = true, + .function_type_required = false, + .handler = handle_randomize_layout_attr, +#if BUILDING_GCC_VERSION >= 4007 + .affects_type_identity = true +#endif +}; + +static struct attribute_spec randomize_considered_attr = { + .name = "randomize_considered", + // related to args + .min_length = 0, + .max_length = 0, + .decl_required = false, + // need type declaration + .type_required = true, + .function_type_required = false, + .handler = handle_randomize_considered_attr, +#if BUILDING_GCC_VERSION >= 4007 + .affects_type_identity = false +#endif +}; + +static struct attribute_spec randomize_performed_attr = { + .name = "randomize_performed", + // related to args + .min_length = 0, + .max_length = 0, + .decl_required = false, + // need type declaration + .type_required = true, + .function_type_required = false, + .handler = handle_randomize_performed_attr, +#if BUILDING_GCC_VERSION >= 4007 + .affects_type_identity = false +#endif +}; + +static void register_attributes(void *event_data, void *data) +{ + register_attribute(&randomize_layout_attr); + register_attribute(&no_randomize_layout_attr); + register_attribute(&randomize_considered_attr); + register_attribute(&randomize_performed_attr); +} + +static void check_bad_casts_in_constructor(tree var, tree init) +{ + unsigned HOST_WIDE_INT idx; + tree field, val; + tree field_type, val_type; + + FOR_EACH_CONSTRUCTOR_ELT(CONSTRUCTOR_ELTS(init), idx, field, val) { + if (TREE_CODE(val) == CONSTRUCTOR) { + check_bad_casts_in_constructor(var, val); + continue; + } + + /* pipacs' plugin creates franken-arrays that differ from those produced by + normal code which all have valid 'field' trees. work around this */ + if (field == NULL_TREE) + continue; + field_type = TREE_TYPE(field); + val_type = TREE_TYPE(val); + + if (TREE_CODE(field_type) != POINTER_TYPE || TREE_CODE(val_type) != POINTER_TYPE) + continue; + + if (field_type == val_type) + continue; + + field_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(field_type)))); + val_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(val_type)))); + + if (field_type == void_type_node) + continue; + if (field_type == val_type) + continue; + if (TREE_CODE(val_type) != RECORD_TYPE) + continue; + + if (!lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(val_type))) + continue; + MISMATCH(DECL_SOURCE_LOCATION(var), "constructor\n", TYPE_MAIN_VARIANT(field_type), TYPE_MAIN_VARIANT(val_type)); + } +} + +/* derived from the constify plugin */ +static void check_global_variables(void *event_data, void *data) +{ + struct varpool_node *node; + tree init; + + FOR_EACH_VARIABLE(node) { + tree var = NODE_DECL(node); + init = DECL_INITIAL(var); + if (init == NULL_TREE) + continue; + + if (TREE_CODE(init) != CONSTRUCTOR) + continue; + + check_bad_casts_in_constructor(var, init); + } +} + +static bool dominated_by_is_err(const_tree rhs, basic_block bb) +{ + basic_block dom; + gimple dom_stmt; + gimple call_stmt; + const_tree dom_lhs; + const_tree poss_is_err_cond; + const_tree poss_is_err_func; + const_tree is_err_arg; + + dom = get_immediate_dominator(CDI_DOMINATORS, bb); + if (!dom) + return false; + + dom_stmt = last_stmt(dom); + if (!dom_stmt) + return false; + + if (gimple_code(dom_stmt) != GIMPLE_COND) + return false; + + if (gimple_cond_code(dom_stmt) != NE_EXPR) + return false; + + if (!integer_zerop(gimple_cond_rhs(dom_stmt))) + return false; + + poss_is_err_cond = gimple_cond_lhs(dom_stmt); + + if (TREE_CODE(poss_is_err_cond) != SSA_NAME) + return false; + + call_stmt = SSA_NAME_DEF_STMT(poss_is_err_cond); + + if (gimple_code(call_stmt) != GIMPLE_CALL) + return false; + + dom_lhs = gimple_get_lhs(call_stmt); + poss_is_err_func = gimple_call_fndecl(call_stmt); + if (!poss_is_err_func) + return false; + if (dom_lhs != poss_is_err_cond) + return false; + if (strcmp(DECL_NAME_POINTER(poss_is_err_func), "IS_ERR")) + return false; + + is_err_arg = gimple_call_arg(call_stmt, 0); + if (!is_err_arg) + return false; + + if (is_err_arg != rhs) + return false; + + return true; +} + +static void handle_local_var_initializers(void) +{ + tree var; + unsigned int i; + + FOR_EACH_LOCAL_DECL(cfun, i, var) { + tree init = DECL_INITIAL(var); + if (!init) + continue; + if (TREE_CODE(init) != CONSTRUCTOR) + continue; + check_bad_casts_in_constructor(var, init); + } +} + +static bool type_name_eq(gimple stmt, const_tree type_tree, const char *wanted_name) +{ + const char *type_name; + + if (type_tree == NULL_TREE) + return false; + + switch (TREE_CODE(type_tree)) { + case RECORD_TYPE: + type_name = TYPE_NAME_POINTER(type_tree); + break; + case INTEGER_TYPE: + if (TYPE_PRECISION(type_tree) == CHAR_TYPE_SIZE) + type_name = "char"; + else { + INFORM(gimple_location(stmt), "found non-char INTEGER_TYPE cast comparison: %qT\n", type_tree); + debug_tree(type_tree); + return false; + } + break; + case POINTER_TYPE: + if (TREE_CODE(TREE_TYPE(type_tree)) == VOID_TYPE) { + type_name = "void *"; + break; + } else { + INFORM(gimple_location(stmt), "found non-void POINTER_TYPE cast comparison %qT\n", type_tree); + debug_tree(type_tree); + return false; + } + default: + INFORM(gimple_location(stmt), "unhandled cast comparison: %qT\n", type_tree); + debug_tree(type_tree); + return false; + } + + return strcmp(type_name, wanted_name) == 0; +} + +static bool whitelisted_cast(gimple stmt, const_tree lhs_tree, const_tree rhs_tree) +{ + const struct whitelist_entry *entry; + expanded_location xloc = expand_location(gimple_location(stmt)); + + for (entry = whitelist; entry->pathname; entry++) { + if (!strstr(xloc.file, entry->pathname)) + continue; + + if (type_name_eq(stmt, lhs_tree, entry->lhs) && type_name_eq(stmt, rhs_tree, entry->rhs)) + return true; + } + + return false; +} + +/* + * iterate over all statements to find "bad" casts: + * those where the address of the start of a structure is cast + * to a pointer of a structure of a different type, or a + * structure pointer type is cast to a different structure pointer type + */ +static unsigned int find_bad_casts_execute(void) +{ + basic_block bb; + + handle_local_var_initializers(); + + FOR_EACH_BB_FN(bb, cfun) { + gimple_stmt_iterator gsi; + + for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) { + gimple stmt; + const_tree lhs; + const_tree lhs_type; + const_tree rhs1; + const_tree rhs_type; + const_tree ptr_lhs_type; + const_tree ptr_rhs_type; + const_tree op0; + const_tree op0_type; + enum tree_code rhs_code; + + stmt = gsi_stmt(gsi); + +#ifdef __DEBUG_PLUGIN +#ifdef __DEBUG_VERBOSE + debug_gimple_stmt(stmt); + debug_tree(gimple_get_lhs(stmt)); +#endif +#endif + + if (gimple_code(stmt) != GIMPLE_ASSIGN) + continue; + +#ifdef __DEBUG_PLUGIN +#ifdef __DEBUG_VERBOSE + debug_tree(gimple_assign_rhs1(stmt)); +#endif +#endif + + + rhs_code = gimple_assign_rhs_code(stmt); + + if (rhs_code != ADDR_EXPR && rhs_code != SSA_NAME) + continue; + + lhs = gimple_get_lhs(stmt); + lhs_type = TREE_TYPE(lhs); + rhs1 = gimple_assign_rhs1(stmt); + rhs_type = TREE_TYPE(rhs1); + + if (TREE_CODE(rhs_type) != POINTER_TYPE || + TREE_CODE(lhs_type) != POINTER_TYPE) + continue; + + ptr_lhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(lhs_type)))); + ptr_rhs_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(rhs_type)))); + + if (ptr_rhs_type == void_type_node) + continue; + + if (ptr_lhs_type == void_type_node) + continue; + + if (dominated_by_is_err(rhs1, bb)) + continue; + + if (TREE_CODE(ptr_rhs_type) != RECORD_TYPE) { +#ifndef __DEBUG_PLUGIN + if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_lhs_type))) +#endif + { + if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type)) + MISMATCH(gimple_location(stmt), "rhs", ptr_lhs_type, ptr_rhs_type); + } + continue; + } + + if (rhs_code == SSA_NAME && ptr_lhs_type == ptr_rhs_type) + continue; + + if (rhs_code == ADDR_EXPR) { + op0 = TREE_OPERAND(rhs1, 0); + + if (op0 == NULL_TREE) + continue; + + if (TREE_CODE(op0) != VAR_DECL) + continue; + + op0_type = TYPE_MAIN_VARIANT(strip_array_types(TYPE_MAIN_VARIANT(TREE_TYPE(op0)))); + if (op0_type == ptr_lhs_type) + continue; + +#ifndef __DEBUG_PLUGIN + if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(op0_type))) +#endif + { + if (!whitelisted_cast(stmt, ptr_lhs_type, op0_type)) + MISMATCH(gimple_location(stmt), "op0", ptr_lhs_type, op0_type); + } + } else { + const_tree ssa_name_var = SSA_NAME_VAR(rhs1); + /* skip bogus type casts introduced by container_of */ + if (ssa_name_var != NULL_TREE && DECL_NAME(ssa_name_var) && + !strcmp((const char *)DECL_NAME_POINTER(ssa_name_var), "__mptr")) + continue; +#ifndef __DEBUG_PLUGIN + if (lookup_attribute("randomize_performed", TYPE_ATTRIBUTES(ptr_rhs_type))) +#endif + { + if (!whitelisted_cast(stmt, ptr_lhs_type, ptr_rhs_type)) + MISMATCH(gimple_location(stmt), "ssa", ptr_lhs_type, ptr_rhs_type); + } + } + + } + } + return 0; +} + +#define PASS_NAME find_bad_casts +#define NO_GATE +#define TODO_FLAGS_FINISH TODO_dump_func +#include "gcc-generate-gimple-pass.h" + +__visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version) +{ + int i; + const char * const plugin_name = plugin_info->base_name; + const int argc = plugin_info->argc; + const struct plugin_argument * const argv = plugin_info->argv; + bool enable = true; + int obtained_seed = 0; + struct register_pass_info find_bad_casts_pass_info; + + find_bad_casts_pass_info.pass = make_find_bad_casts_pass(); + find_bad_casts_pass_info.reference_pass_name = "ssa"; + find_bad_casts_pass_info.ref_pass_instance_number = 1; + find_bad_casts_pass_info.pos_op = PASS_POS_INSERT_AFTER; + + if (!plugin_default_version_check(version, &gcc_version)) { + error(G_("incompatible gcc/plugin versions")); + return 1; + } + + if (strncmp(lang_hooks.name, "GNU C", 5) && !strncmp(lang_hooks.name, "GNU C+", 6)) { + inform(UNKNOWN_LOCATION, G_("%s supports C only, not %s"), plugin_name, lang_hooks.name); + enable = false; + } + + for (i = 0; i < argc; ++i) { + if (!strcmp(argv[i].key, "disable")) { + enable = false; + continue; + } + if (!strcmp(argv[i].key, "performance-mode")) { + performance_mode = 1; + continue; + } + error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key); + } + + if (strlen(randstruct_seed) != 64) { + error(G_("invalid seed value supplied for %s plugin"), plugin_name); + return 1; + } + obtained_seed = sscanf(randstruct_seed, "%016llx%016llx%016llx%016llx", + &shuffle_seed[0], &shuffle_seed[1], &shuffle_seed[2], &shuffle_seed[3]); + if (obtained_seed != 4) { + error(G_("Invalid seed supplied for %s plugin"), plugin_name); + return 1; + } + + register_callback(plugin_name, PLUGIN_INFO, NULL, &randomize_layout_plugin_info); + if (enable) { + register_callback(plugin_name, PLUGIN_ALL_IPA_PASSES_START, check_global_variables, NULL); + register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &find_bad_casts_pass_info); + register_callback(plugin_name, PLUGIN_FINISH_TYPE, finish_type, NULL); + register_callback(plugin_name, PLUGIN_FINISH_DECL, randomize_layout_finish_decl, NULL); + } + register_callback(plugin_name, PLUGIN_ATTRIBUTES, register_attributes, NULL); + + return 0; +} |
