From patchwork Thu Jun 4 13:49:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Popov X-Patchwork-Id: 11588007 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8E8CA739 for ; Thu, 4 Jun 2020 13:51:00 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id C8A92207D0 for ; Thu, 4 Jun 2020 13:50:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C8A92207D0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18920-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 7335 invoked by uid 550); 4 Jun 2020 13:50:57 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 7259 invoked from network); 4 Jun 2020 13:50:56 -0000 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=HscaqQ3a9rlG7LMvxfetj9PZadqBQlxA9luDvY709kI=; b=VlAcWbxTO2bVAGAHOvP62xKoRJaUI4B/DdQURLhBS0w5W7ZedLOl8vECMg4zUpewD2 /ygIEymXNE5jVhm+MdRTxgOqoChz6shgOHWh+uCSsYhgzOIEL+WRSkRBhOyvANu2cC+R ZdAPti3JInxFJbUEvnZQQjRpr6mnqFHvQdJTQQu0rjB1/nSgSfRVva8PC1woBp29wyNa hP5dH/AZqZgiwJ+QtzogDCvZ5aHR4RCstDpGsyHFT/+zhqShKmg9pBq9WVJCn6kuAMm3 YvBsXUdHJBaCuKuzNJ/NX0+MD4Ba6CwO3EE2oXpk7+Eh7z/zH1Ug2zpThpj8jgcil0/j ow7Q== X-Gm-Message-State: AOAM530dQDbZE6WQB/ag9weQCXqUci006yug0KNHf6ViJx6f3kwxcoJE StFpjnxXDEXD51XwHoSeGSQ= X-Google-Smtp-Source: ABdhPJwFgNnX9eJFc5s+1RCeoml4wry3jADSZr+Uk82Gr4M4947yFLD4wkmGdf/0gl0X9+wHhybHLA== X-Received: by 2002:a2e:8ec9:: with SMTP id e9mr2378478ljl.152.1591278644807; Thu, 04 Jun 2020 06:50:44 -0700 (PDT) From: Alexander Popov To: Kees Cook , Emese Revfy , Miguel Ojeda , Masahiro Yamada , Michal Marek , Andrew Morton , Masahiro Yamada , Thiago Jung Bauermann , Luis Chamberlain , Jessica Yu , Sven Schnelle , Iurii Zaikin , Catalin Marinas , Will Deacon , Vincenzo Frascino , Thomas Gleixner , Peter Collingbourne , Naohiro Aota , Alexander Monakov , Mathias Krause , PaX Team , Brad Spengler , Laura Abbott , Florian Weimer , Alexander Popov , kernel-hardening@lists.openwall.com, linux-kbuild@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, gcc@gcc.gnu.org Cc: notify@kernel.org Subject: [PATCH 1/5] gcc-plugins/stackleak: Exclude alloca() from the instrumentation logic Date: Thu, 4 Jun 2020 16:49:53 +0300 Message-Id: <20200604134957.505389-2-alex.popov@linux.com> X-Mailer: git-send-email 2.25.2 In-Reply-To: <20200604134957.505389-1-alex.popov@linux.com> References: <20200604134957.505389-1-alex.popov@linux.com> MIME-Version: 1.0 Some time ago Variable Length Arrays (VLA) were removed from the kernel. The kernel is built with '-Wvla'. Let's exclude alloca() from the instrumentation logic and make it simpler. The build-time assertion against alloca() is added instead. Unfortunately, for that assertion we can't simply check cfun->calls_alloca during RTL phase. It turned out that gcc before version 7 called allocate_dynamic_stack_space() from expand_stack_vars() for runtime alignment of constant-sized stack variables. That caused cfun->calls_alloca to be set for functions that don't use alloca(). Signed-off-by: Alexander Popov --- scripts/gcc-plugins/stackleak_plugin.c | 51 +++++++++++--------------- 1 file changed, 21 insertions(+), 30 deletions(-) diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c index cc75eeba0be1..1ecfe50d0bf5 100644 --- a/scripts/gcc-plugins/stackleak_plugin.c +++ b/scripts/gcc-plugins/stackleak_plugin.c @@ -9,10 +9,9 @@ * any of the gcc libraries * * This gcc plugin is needed for tracking the lowest border of the kernel stack. - * It instruments the kernel code inserting stackleak_track_stack() calls: - * - after alloca(); - * - for the functions with a stack frame size greater than or equal - * to the "track-min-size" plugin parameter. + * It instruments the kernel code inserting stackleak_track_stack() calls + * for the functions with a stack frame size greater than or equal to + * the "track-min-size" plugin parameter. * * This plugin is ported from grsecurity/PaX. For more information see: * https://grsecurity.net/ @@ -46,7 +45,7 @@ static struct plugin_info stackleak_plugin_info = { "disable\t\tdo not activate the plugin\n" }; -static void stackleak_add_track_stack(gimple_stmt_iterator *gsi, bool after) +static void stackleak_add_track_stack(gimple_stmt_iterator *gsi) { gimple stmt; gcall *stackleak_track_stack; @@ -56,12 +55,7 @@ static void stackleak_add_track_stack(gimple_stmt_iterator *gsi, bool after) /* Insert call to void stackleak_track_stack(void) */ stmt = gimple_build_call(track_function_decl, 0); stackleak_track_stack = as_a_gcall(stmt); - if (after) { - gsi_insert_after(gsi, stackleak_track_stack, - GSI_CONTINUE_LINKING); - } else { - gsi_insert_before(gsi, stackleak_track_stack, GSI_SAME_STMT); - } + gsi_insert_before(gsi, stackleak_track_stack, GSI_SAME_STMT); /* Update the cgraph */ bb = gimple_bb(stackleak_track_stack); @@ -87,14 +81,13 @@ static bool is_alloca(gimple stmt) /* * Work with the GIMPLE representation of the code. Insert the - * stackleak_track_stack() call after alloca() and into the beginning - * of the function if it is not instrumented. + * stackleak_track_stack() call into the beginning of the function. */ static unsigned int stackleak_instrument_execute(void) { basic_block bb, entry_bb; - bool prologue_instrumented = false, is_leaf = true; - gimple_stmt_iterator gsi; + bool is_leaf = true; + gimple_stmt_iterator gsi = { 0 }; /* * ENTRY_BLOCK_PTR is a basic block which represents possible entry @@ -111,27 +104,17 @@ static unsigned int stackleak_instrument_execute(void) */ FOR_EACH_BB_FN(bb, cfun) { for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) { - gimple stmt; - - stmt = gsi_stmt(gsi); + gimple stmt = gsi_stmt(gsi); /* Leaf function is a function which makes no calls */ if (is_gimple_call(stmt)) is_leaf = false; - if (!is_alloca(stmt)) - continue; - - /* Insert stackleak_track_stack() call after alloca() */ - stackleak_add_track_stack(&gsi, true); - if (bb == entry_bb) - prologue_instrumented = true; + /* Variable Length Arrays are forbidden in the kernel */ + gcc_assert(!is_alloca(stmt)); } } - if (prologue_instrumented) - return 0; - /* * Special cases to skip the instrumentation. * @@ -168,7 +151,7 @@ static unsigned int stackleak_instrument_execute(void) bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun)); } gsi = gsi_after_labels(bb); - stackleak_add_track_stack(&gsi, false); + stackleak_add_track_stack(&gsi); return 0; } @@ -185,12 +168,20 @@ static bool large_stack_frame(void) /* * Work with the RTL representation of the code. * Remove the unneeded stackleak_track_stack() calls from the functions - * which don't call alloca() and don't have a large enough stack frame size. + * that don't have a large enough stack frame size. */ static unsigned int stackleak_cleanup_execute(void) { rtx_insn *insn, *next; + /* + * gcc before version 7 called allocate_dynamic_stack_space() from + * expand_stack_vars() for runtime alignment of constant-sized stack + * variables. That caused cfun->calls_alloca to be set for functions + * that don't use alloca(). + * For more info see gcc commit 7072df0aae0c59ae437e. + * Let's leave such functions instrumented. + */ if (cfun->calls_alloca) return 0; From patchwork Thu Jun 4 13:49:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Popov X-Patchwork-Id: 11588017 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1409890 for ; Thu, 4 Jun 2020 13:51:11 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 2513120823 for ; Thu, 4 Jun 2020 13:51:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2513120823 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18921-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 8023 invoked by uid 550); 4 Jun 2020 13:51:05 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 7952 invoked from network); 4 Jun 2020 13:51:04 -0000 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=veE4ryhNxfX6ZFy5y/056vSNcU7CVnJM+8TvlXBsnxg=; b=toAMUap+Opy6vbl/Muwlv2rTo6bXzjZ62kcv7Uo0KXANnS8N2IAF4vaA+lfDmNE5hr VW4uDuUmSQYESaZigVCieGdY/splhKZF5QRf+OkBdHqlUIotGBM09X5m+sV9Ser/LHOV A3Ig7qnDuuxLGr+vLTENydpz/tzid2wYNMlTkDHKAno+5rq4nM6/TyrNmtWtg83Fe4gj m5FNGKlWFJgYq1QEY6QYd3Qmrm4cSj9rlNjiZUkkaI63YxnqBtTMvsp+8ggzEqYZ8xC+ 8WGhjsxFzMaX8nLzEv1bERBXMkvz1Jpc3F0jQ3AC/1Bvz0Qd20aVOHv9WnYwms2+vOSj 4Tmw== X-Gm-Message-State: AOAM531pjNr8MljdtOspAi+lGrXDOif627byW4Rvq2sNdIuVKSxZl94r kNi/vDe/zD7PZ8sns+3D5kY= X-Google-Smtp-Source: ABdhPJz45dvq67oRkAcFtWa0JEo3iXihFP3HlC8qTG+v1AYwJ3zV75VqaPI1cWNLL3tULYWeEuqGdw== X-Received: by 2002:a2e:85da:: with SMTP id h26mr465715ljj.170.1591278652554; Thu, 04 Jun 2020 06:50:52 -0700 (PDT) From: Alexander Popov To: Kees Cook , Emese Revfy , Miguel Ojeda , Masahiro Yamada , Michal Marek , Andrew Morton , Masahiro Yamada , Thiago Jung Bauermann , Luis Chamberlain , Jessica Yu , Sven Schnelle , Iurii Zaikin , Catalin Marinas , Will Deacon , Vincenzo Frascino , Thomas Gleixner , Peter Collingbourne , Naohiro Aota , Alexander Monakov , Mathias Krause , PaX Team , Brad Spengler , Laura Abbott , Florian Weimer , Alexander Popov , kernel-hardening@lists.openwall.com, linux-kbuild@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, gcc@gcc.gnu.org Cc: notify@kernel.org Subject: [PATCH 2/5] gcc-plugins/stackleak: Use asm instrumentation to avoid useless register saving Date: Thu, 4 Jun 2020 16:49:54 +0300 Message-Id: <20200604134957.505389-3-alex.popov@linux.com> X-Mailer: git-send-email 2.25.2 In-Reply-To: <20200604134957.505389-1-alex.popov@linux.com> References: <20200604134957.505389-1-alex.popov@linux.com> MIME-Version: 1.0 The kernel code instrumentation in stackleak gcc plugin works in two stages. At first, stack tracking is added to GIMPLE representation of every function (except some special cases). And later, when stack frame size info is available, stack tracking is removed from the RTL representation of the functions with small stack frame. There is an unwanted side-effect for these functions: some of them do useless work with caller-saved registers. As an example of such case, proc_sys_write without instrumentation: 55 push %rbp 41 b8 01 00 00 00 mov $0x1,%r8d 48 89 e5 mov %rsp,%rbp e8 11 ff ff ff callq ffffffff81284610 5d pop %rbp c3 retq 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1) 00 00 00 proc_sys_write with instrumentation: 55 push %rbp 48 89 e5 mov %rsp,%rbp 41 56 push %r14 41 55 push %r13 41 54 push %r12 53 push %rbx 49 89 f4 mov %rsi,%r12 48 89 fb mov %rdi,%rbx 49 89 d5 mov %rdx,%r13 49 89 ce mov %rcx,%r14 4c 89 f1 mov %r14,%rcx 4c 89 ea mov %r13,%rdx 4c 89 e6 mov %r12,%rsi 48 89 df mov %rbx,%rdi 41 b8 01 00 00 00 mov $0x1,%r8d e8 f2 fe ff ff callq ffffffff81298e80 5b pop %rbx 41 5c pop %r12 41 5d pop %r13 41 5e pop %r14 5d pop %rbp c3 retq 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1) 00 00 Let's improve the instrumentation to avoid this: 1. Make stackleak_track_stack() save all register that it works with. Use no_caller_saved_registers attribute for that function. This attribute is available for x86_64 and i386 starting from gcc-7. 2. Insert calling stackleak_track_stack() in asm: asm volatile("call stackleak_track_stack" :: "r" (current_stack_pointer)) Here we use ASM_CALL_CONSTRAINT trick from arch/x86/include/asm/asm.h. The input constraint is taken into account during gcc shrink-wrapping optimization. It is needed to be sure that stackleak_track_stack() call is inserted after the prologue of the containing function, when the stack frame is prepared. This work is a deep reengineering of the idea described on grsecurity blog https://grsecurity.net/resolving_an_unfortunate_stackleak_interaction Signed-off-by: Alexander Popov Acked-by: Miguel Ojeda --- include/linux/compiler_attributes.h | 13 ++ kernel/stackleak.c | 16 +- scripts/Makefile.gcc-plugins | 2 + scripts/gcc-plugins/stackleak_plugin.c | 206 +++++++++++++++++++++---- 4 files changed, 196 insertions(+), 41 deletions(-) diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index cdf016596659..522d57ae8532 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -41,6 +41,7 @@ # define __GCC4_has_attribute___nonstring__ 0 # define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8) # define __GCC4_has_attribute___fallthrough__ 0 +# define __GCC4_has_attribute___no_caller_saved_registers__ 0 #endif /* @@ -175,6 +176,18 @@ */ #define __mode(x) __attribute__((__mode__(x))) +/* + * Optional: only supported since gcc >= 7 + * + * gcc: https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html#index-no_005fcaller_005fsaved_005fregisters-function-attribute_002c-x86 + * clang: https://clang.llvm.org/docs/AttributeReference.html#no-caller-saved-registers + */ +#if __has_attribute(__no_caller_saved_registers__) +# define __no_caller_saved_registers __attribute__((__no_caller_saved_registers__)) +#else +# define __no_caller_saved_registers +#endif + /* * Optional: not supported by clang * diff --git a/kernel/stackleak.c b/kernel/stackleak.c index b193a59fc05b..a8fc9ae1d03d 100644 --- a/kernel/stackleak.c +++ b/kernel/stackleak.c @@ -104,19 +104,9 @@ asmlinkage void notrace stackleak_erase(void) } NOKPROBE_SYMBOL(stackleak_erase); -void __used notrace stackleak_track_stack(void) +void __used __no_caller_saved_registers notrace stackleak_track_stack(void) { - /* - * N.B. stackleak_erase() fills the kernel stack with the poison value, - * which has the register width. That code assumes that the value - * of 'lowest_stack' is aligned on the register width boundary. - * - * That is true for x86 and x86_64 because of the kernel stack - * alignment on these platforms (for details, see 'cc_stack_align' in - * arch/x86/Makefile). Take care of that when you port STACKLEAK to - * new platforms. - */ - unsigned long sp = (unsigned long)&sp; + unsigned long sp = current_stack_pointer; /* * Having CONFIG_STACKLEAK_TRACK_MIN_SIZE larger than @@ -125,6 +115,8 @@ void __used notrace stackleak_track_stack(void) */ BUILD_BUG_ON(CONFIG_STACKLEAK_TRACK_MIN_SIZE > STACKLEAK_SEARCH_DEPTH); + /* 'lowest_stack' should be aligned on the register width boundary */ + sp = ALIGN(sp, sizeof(unsigned long)); if (sp < current->lowest_stack && sp >= (unsigned long)task_stack_page(current) + sizeof(unsigned long)) { diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins index 5f7df50cfe7a..952e46876329 100644 --- a/scripts/Makefile.gcc-plugins +++ b/scripts/Makefile.gcc-plugins @@ -33,6 +33,8 @@ gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \ += -DSTACKLEAK_PLUGIN gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \ += -fplugin-arg-stackleak_plugin-track-min-size=$(CONFIG_STACKLEAK_TRACK_MIN_SIZE) +gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \ + += -fplugin-arg-stackleak_plugin-arch=$(SRCARCH) ifdef CONFIG_GCC_PLUGIN_STACKLEAK DISABLE_STACKLEAK_PLUGIN += -fplugin-arg-stackleak_plugin-disable endif diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c index 1ecfe50d0bf5..0769c5b9156d 100644 --- a/scripts/gcc-plugins/stackleak_plugin.c +++ b/scripts/gcc-plugins/stackleak_plugin.c @@ -19,7 +19,7 @@ * * Debugging: * - use fprintf() to stderr, debug_generic_expr(), debug_gimple_stmt(), - * print_rtl() and print_simple_rtl(); + * print_rtl_single() and debug_rtx(); * - add "-fdump-tree-all -fdump-rtl-all" to the plugin CFLAGS in * Makefile.gcc-plugins to see the verbose dumps of the gcc passes; * - use gcc -E to understand the preprocessing shenanigans; @@ -31,6 +31,7 @@ __visible int plugin_is_GPL_compatible; static int track_frame_size = -1; +static bool build_for_x86 = false; static const char track_function[] = "stackleak_track_stack"; /* @@ -42,27 +43,28 @@ static GTY(()) tree track_function_decl; static struct plugin_info stackleak_plugin_info = { .version = "201707101337", .help = "track-min-size=nn\ttrack stack for functions with a stack frame size >= nn bytes\n" + "arch=target_arch\tspecify target build arch\n" "disable\t\tdo not activate the plugin\n" }; -static void stackleak_add_track_stack(gimple_stmt_iterator *gsi) +static void add_stack_tracking_gcall(gimple_stmt_iterator *gsi) { gimple stmt; - gcall *stackleak_track_stack; + gcall *gimple_call; cgraph_node_ptr node; basic_block bb; - /* Insert call to void stackleak_track_stack(void) */ + /* Insert calling stackleak_track_stack() */ stmt = gimple_build_call(track_function_decl, 0); - stackleak_track_stack = as_a_gcall(stmt); - gsi_insert_before(gsi, stackleak_track_stack, GSI_SAME_STMT); + gimple_call = as_a_gcall(stmt); + gsi_insert_before(gsi, gimple_call, GSI_SAME_STMT); /* Update the cgraph */ - bb = gimple_bb(stackleak_track_stack); + bb = gimple_bb(gimple_call); node = cgraph_get_create_node(track_function_decl); gcc_assert(node); cgraph_create_edge(cgraph_get_node(current_function_decl), node, - stackleak_track_stack, bb->count, + gimple_call, bb->count, compute_call_stmt_bb_frequency(current_function_decl, bb)); } @@ -79,6 +81,76 @@ static bool is_alloca(gimple stmt) return false; } +static tree get_current_stack_pointer_decl(void) +{ + varpool_node_ptr node; + + FOR_EACH_VARIABLE(node) { + tree var = NODE_DECL(node); + tree name = DECL_NAME(var); + + if (DECL_NAME_LENGTH(var) != sizeof("current_stack_pointer") - 1) + continue; + + if (strcmp(IDENTIFIER_POINTER(name), "current_stack_pointer")) + continue; + + return var; + } + + return NULL_TREE; +} + +static void add_stack_tracking_gasm(gimple_stmt_iterator *gsi) +{ + gasm *asm_call = NULL; + tree sp_decl, input; + vec *inputs = NULL; + + /* 'no_caller_saved_registers' is currently supported only for x86 */ + gcc_assert(build_for_x86); + + /* + * Insert calling stackleak_track_stack() in asm: + * asm volatile("call stackleak_track_stack" + * :: "r" (current_stack_pointer)) + * Use ASM_CALL_CONSTRAINT trick from arch/x86/include/asm/asm.h. + * This constraint is taken into account during gcc shrink-wrapping + * optimization. It is needed to be sure that stackleak_track_stack() + * call is inserted after the prologue of the containing function, + * when the stack frame is prepared. + */ + sp_decl = get_current_stack_pointer_decl(); + if (sp_decl == NULL_TREE) { + add_stack_tracking_gcall(gsi); + return; + } + input = build_tree_list(NULL_TREE, build_const_char_string(2, "r")); + input = chainon(NULL_TREE, build_tree_list(input, sp_decl)); + vec_safe_push(inputs, input); + asm_call = gimple_build_asm_vec("call stackleak_track_stack", + inputs, NULL, NULL, NULL); + gimple_asm_set_volatile(asm_call, true); + gsi_insert_before(gsi, asm_call, GSI_SAME_STMT); + update_stmt(asm_call); +} + +static void add_stack_tracking(gimple_stmt_iterator *gsi) +{ + /* + * The 'no_caller_saved_registers' attribute is used for + * stackleak_track_stack(). If the compiler supports this attribute for + * the target arch, we can add calling stackleak_track_stack() in asm. + * That improves performance: we avoid useless operations with the + * caller-saved registers in the functions from which we will remove + * stackleak_track_stack() call during the stackleak_cleanup pass. + */ + if (lookup_attribute_spec(get_identifier("no_caller_saved_registers"))) + add_stack_tracking_gasm(gsi); + else + add_stack_tracking_gcall(gsi); +} + /* * Work with the GIMPLE representation of the code. Insert the * stackleak_track_stack() call into the beginning of the function. @@ -151,7 +223,7 @@ static unsigned int stackleak_instrument_execute(void) bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun)); } gsi = gsi_after_labels(bb); - stackleak_add_track_stack(&gsi); + add_stack_tracking(&gsi); return 0; } @@ -165,29 +237,10 @@ static bool large_stack_frame(void) #endif } -/* - * Work with the RTL representation of the code. - * Remove the unneeded stackleak_track_stack() calls from the functions - * that don't have a large enough stack frame size. - */ -static unsigned int stackleak_cleanup_execute(void) +static void remove_stack_tracking_gcall(void) { rtx_insn *insn, *next; - /* - * gcc before version 7 called allocate_dynamic_stack_space() from - * expand_stack_vars() for runtime alignment of constant-sized stack - * variables. That caused cfun->calls_alloca to be set for functions - * that don't use alloca(). - * For more info see gcc commit 7072df0aae0c59ae437e. - * Let's leave such functions instrumented. - */ - if (cfun->calls_alloca) - return 0; - - if (large_stack_frame()) - return 0; - /* * Find stackleak_track_stack() calls. Loop through the chain of insns, * which is an RTL representation of the code for a function. @@ -248,6 +301,92 @@ static unsigned int stackleak_cleanup_execute(void) } #endif } +} + +static bool remove_stack_tracking_gasm(void) +{ + bool removed = false; + rtx_insn *insn, *next; + + /* 'no_caller_saved_registers' is currently supported only for x86 */ + gcc_assert(build_for_x86); + + /* + * Find stackleak_track_stack() asm calls. Loop through the chain of + * insns, which is an RTL representation of the code for a function. + * + * The example of a matching insn: + * (insn 11 5 12 2 (parallel [ (asm_operands/v + * ("call stackleak_track_stack") ("") 0 + * [ (reg/v:DI 7 sp [ current_stack_pointer ]) ] + * [ (asm_input:DI ("r")) ] []) + * (clobber (reg:CC 17 flags)) ]) -1 (nil)) + */ + for (insn = get_insns(); insn; insn = next) { + rtx body; + + next = NEXT_INSN(insn); + + /* Check the expression code of the insn */ + if (!NONJUMP_INSN_P(insn)) + continue; + + /* + * Check the expression code of the insn body, which is an RTL + * Expression (RTX) describing the side effect performed by + * that insn. + */ + body = PATTERN(insn); + + if (GET_CODE(body) != PARALLEL) + continue; + + body = XVECEXP(body, 0, 0); + + if (GET_CODE(body) != ASM_OPERANDS) + continue; + + if (strcmp(ASM_OPERANDS_TEMPLATE(body), + "call stackleak_track_stack")) { + continue; + } + + delete_insn_and_edges(insn); + gcc_assert(!removed); + removed = true; + } + + return removed; +} + +/* + * Work with the RTL representation of the code. + * Remove the unneeded stackleak_track_stack() calls from the functions + * that don't have a large enough stack frame size. + */ +static unsigned int stackleak_cleanup_execute(void) +{ + bool removed = false; + + /* + * gcc before version 7 called allocate_dynamic_stack_space() from + * expand_stack_vars() for runtime alignment of constant-sized stack + * variables. That caused cfun->calls_alloca to be set for functions + * that don't use alloca(). + * For more info see gcc commit 7072df0aae0c59ae437e. + * Let's leave such functions instrumented. + */ + if (cfun->calls_alloca) + return 0; + + if (large_stack_frame()) + return 0; + + if (lookup_attribute_spec(get_identifier("no_caller_saved_registers"))) + removed = remove_stack_tracking_gasm(); + + if (!removed) + remove_stack_tracking_gcall(); return 0; } @@ -383,6 +522,15 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, plugin_name, argv[i].key, argv[i].value); return 1; } + } else if (!strcmp(argv[i].key, "arch")) { + if (!argv[i].value) { + error(G_("no value supplied for option '-fplugin-arg-%s-%s'"), + plugin_name, argv[i].key); + return 1; + } + + if (!strcmp(argv[i].value, "x86")) + build_for_x86 = true; } else { error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key); From patchwork Thu Jun 4 13:49:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Popov X-Patchwork-Id: 11588021 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B068D90 for ; Thu, 4 Jun 2020 13:51:21 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 23ACF20772 for ; Thu, 4 Jun 2020 13:51:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 23ACF20772 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18922-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 9497 invoked by uid 550); 4 Jun 2020 13:51:11 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 9440 invoked from network); 4 Jun 2020 13:51:11 -0000 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=bKAdfvJmk5cJtK5g50ZHk8hu9sp158iPwKZPpTWkeYg=; b=UsOyl0hhAxV2O+vPGpZXS8K+qqt4BWh3U4xzCyoW5mTmpXk/E7cFCzt4KB1WDPaGJ0 CiPLNH3MJBdatLZIMlDlaiprSXNS9DDKL6WmI1BCGX6ecR3YpjSBwRZMiQm55c3qG3mn QGzrJMCDzNVoMIGGRsSwvFDS5L3xIB+RNfsuzmOpeLotrELcN11aWcXNGHhB7P5DIzky EfQ2BV5qsh5g8o/G4CpC5co1hE7806nFtI2dECJAvwZcXevgqwou0Nk0x9NhjXvgMdln ePz26UVexCsdRXK3kohwYlNR1+rhMg2UNAtiQifgLC38USx0gnO0Sse+o/Kx5HiWWh3g UiJA== X-Gm-Message-State: AOAM531Z4YACCBh6SO3njR8+d184JHfk+QjZRr96d8ewUuYLCfgpZfqp eA99WM7Y38K+RIrOvvSHpoo= X-Google-Smtp-Source: ABdhPJyaEJiFG1nukoZekZitzyjRXSvRiSbJSp8S8jS/4CPjpOJZ15oCqdnMtSvYh0QGwlrPyIn8nA== X-Received: by 2002:a2e:9917:: with SMTP id v23mr2338833lji.225.1591278660052; Thu, 04 Jun 2020 06:51:00 -0700 (PDT) From: Alexander Popov To: Kees Cook , Emese Revfy , Miguel Ojeda , Masahiro Yamada , Michal Marek , Andrew Morton , Masahiro Yamada , Thiago Jung Bauermann , Luis Chamberlain , Jessica Yu , Sven Schnelle , Iurii Zaikin , Catalin Marinas , Will Deacon , Vincenzo Frascino , Thomas Gleixner , Peter Collingbourne , Naohiro Aota , Alexander Monakov , Mathias Krause , PaX Team , Brad Spengler , Laura Abbott , Florian Weimer , Alexander Popov , kernel-hardening@lists.openwall.com, linux-kbuild@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, gcc@gcc.gnu.org Cc: notify@kernel.org Subject: [PATCH 3/5] gcc-plugins/stackleak: Add 'verbose' plugin parameter Date: Thu, 4 Jun 2020 16:49:55 +0300 Message-Id: <20200604134957.505389-4-alex.popov@linux.com> X-Mailer: git-send-email 2.25.2 In-Reply-To: <20200604134957.505389-1-alex.popov@linux.com> References: <20200604134957.505389-1-alex.popov@linux.com> MIME-Version: 1.0 Add 'verbose' plugin parameter for stackleak gcc plugin. It can be used for printing additional info about the kernel code instrumentation. For using it add the following to scripts/Makefile.gcc-plugins: gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \ += -fplugin-arg-stackleak_plugin-verbose Signed-off-by: Alexander Popov Acked-by: Kees Cook --- scripts/gcc-plugins/stackleak_plugin.c | 31 +++++++++++++++++++++----- 1 file changed, 26 insertions(+), 5 deletions(-) diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c index 0769c5b9156d..19358712d4ed 100644 --- a/scripts/gcc-plugins/stackleak_plugin.c +++ b/scripts/gcc-plugins/stackleak_plugin.c @@ -33,6 +33,8 @@ __visible int plugin_is_GPL_compatible; static int track_frame_size = -1; static bool build_for_x86 = false; static const char track_function[] = "stackleak_track_stack"; +static bool disable = false; +static bool verbose = false; /* * Mark these global variables (roots) for gcc garbage collector since @@ -45,6 +47,7 @@ static struct plugin_info stackleak_plugin_info = { .help = "track-min-size=nn\ttrack stack for functions with a stack frame size >= nn bytes\n" "arch=target_arch\tspecify target build arch\n" "disable\t\tdo not activate the plugin\n" + "verbose\t\tprint info about the instrumentation\n" }; static void add_stack_tracking_gcall(gimple_stmt_iterator *gsi) @@ -98,6 +101,10 @@ static tree get_current_stack_pointer_decl(void) return var; } + if (verbose) { + fprintf(stderr, "stackleak: missing current_stack_pointer in %s()\n", + DECL_NAME_POINTER(current_function_decl)); + } return NULL_TREE; } @@ -366,6 +373,7 @@ static bool remove_stack_tracking_gasm(void) */ static unsigned int stackleak_cleanup_execute(void) { + const char *fn = DECL_NAME_POINTER(current_function_decl); bool removed = false; /* @@ -376,11 +384,17 @@ static unsigned int stackleak_cleanup_execute(void) * For more info see gcc commit 7072df0aae0c59ae437e. * Let's leave such functions instrumented. */ - if (cfun->calls_alloca) + if (cfun->calls_alloca) { + if (verbose) + fprintf(stderr, "stackleak: instrument %s() old\n", fn); return 0; + } - if (large_stack_frame()) + if (large_stack_frame()) { + if (verbose) + fprintf(stderr, "stackleak: instrument %s()\n", fn); return 0; + } if (lookup_attribute_spec(get_identifier("no_caller_saved_registers"))) removed = remove_stack_tracking_gasm(); @@ -506,9 +520,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, /* Parse the plugin arguments */ for (i = 0; i < argc; i++) { - if (!strcmp(argv[i].key, "disable")) - return 0; - if (!strcmp(argv[i].key, "track-min-size")) { if (!argv[i].value) { error(G_("no value supplied for option '-fplugin-arg-%s-%s'"), @@ -531,6 +542,10 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, if (!strcmp(argv[i].value, "x86")) build_for_x86 = true; + } else if (!strcmp(argv[i].key, "disable")) { + disable = true; + } else if (!strcmp(argv[i].key, "verbose")) { + verbose = true; } else { error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key); @@ -538,6 +553,12 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, } } + if (disable) { + if (verbose) + fprintf(stderr, "stackleak: disabled for this translation unit\n"); + return 0; + } + /* Give the information about the plugin */ register_callback(plugin_name, PLUGIN_INFO, NULL, &stackleak_plugin_info); From patchwork Thu Jun 4 13:49:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Popov X-Patchwork-Id: 11588023 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EF487739 for ; Thu, 4 Jun 2020 13:51:32 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 5E44420772 for ; Thu, 4 Jun 2020 13:51:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5E44420772 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18923-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 9971 invoked by uid 550); 4 Jun 2020 13:51:19 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; 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Thu, 04 Jun 2020 06:51:06 -0700 (PDT) From: Alexander Popov To: Kees Cook , Emese Revfy , Miguel Ojeda , Masahiro Yamada , Michal Marek , Andrew Morton , Masahiro Yamada , Thiago Jung Bauermann , Luis Chamberlain , Jessica Yu , Sven Schnelle , Iurii Zaikin , Catalin Marinas , Will Deacon , Vincenzo Frascino , Thomas Gleixner , Peter Collingbourne , Naohiro Aota , Alexander Monakov , Mathias Krause , PaX Team , Brad Spengler , Laura Abbott , Florian Weimer , Alexander Popov , kernel-hardening@lists.openwall.com, linux-kbuild@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, gcc@gcc.gnu.org Cc: notify@kernel.org Subject: [PATCH 4/5] gcc-plugins/stackleak: Don't instrument itself Date: Thu, 4 Jun 2020 16:49:56 +0300 Message-Id: <20200604134957.505389-5-alex.popov@linux.com> X-Mailer: git-send-email 2.25.2 In-Reply-To: <20200604134957.505389-1-alex.popov@linux.com> References: <20200604134957.505389-1-alex.popov@linux.com> MIME-Version: 1.0 There is no need to try instrumenting functions in kernel/stackleak.c. Otherwise that can cause issues if the cleanup pass of stackleak gcc plugin is disabled. Signed-off-by: Alexander Popov Acked-by: Kees Cook --- kernel/Makefile | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/Makefile b/kernel/Makefile index 4cb4130ced32..d372134ac9ec 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -118,6 +118,7 @@ obj-$(CONFIG_RSEQ) += rseq.o obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o +CFLAGS_stackleak.o += $(DISABLE_STACKLEAK_PLUGIN) obj-$(CONFIG_GCC_PLUGIN_STACKLEAK) += stackleak.o KASAN_SANITIZE_stackleak.o := n KCOV_INSTRUMENT_stackleak.o := n From patchwork Thu Jun 4 13:49:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Popov X-Patchwork-Id: 11588027 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 140D2739 for ; Thu, 4 Jun 2020 13:51:44 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 7986B20772 for ; Thu, 4 Jun 2020 13:51:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7986B20772 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18924-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 11431 invoked by uid 550); 4 Jun 2020 13:51:25 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 11378 invoked from network); 4 Jun 2020 13:51:24 -0000 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=b54SpJMSTOd6h+DBnk1Lku3f1oWBTa5w9a5vkJqB3fA=; b=YshXXe+fxWo4APPkrDVywSroRNbLLfT04UvRmD+l3UVKrbRO68KkcWpqgzqXtK0ZyE TWeXY0MC4+IoJ0O0xt8s+GcowBIqvr+w9P7rf5IZ36R33ASFxVQ1I1Sl/UIqW8s/Y/jb GDJIvp0gJ13yoo4uSz9V5JFgZ3XgPWGl86ciaw7xd8t2FwUfz8cBYjcJufseyyUzuxhb aCobmH2/rzv6i3yLoi+4AJIBFEy5MDrHKMXZcrKPGnoF8/3PzRoV1l2riC640yk5YNgJ q6WnZeCINJmzTYbE/D8A/DNXIFC7rzEJUk93Vqv468wRQCv9eYJM58pIPvmmf1/RlDIf unQQ== X-Gm-Message-State: AOAM533PWzGabnsDOCNVWQo1+I3Y+3xKLafmYBdiwQBEe0C/ayYMbev6 uPWIqhNa+B0f+Xnb5NUzg4E= X-Google-Smtp-Source: ABdhPJwJN+QU/v5qwJyKhHL0R8cAYtbe3PO9Gpb/m6COOlcWqK5m8q5guhRTY5qY7edIDaq2chb7lg== X-Received: by 2002:a2e:9dd8:: with SMTP id x24mr2410838ljj.304.1591278673307; Thu, 04 Jun 2020 06:51:13 -0700 (PDT) From: Alexander Popov To: Kees Cook , Emese Revfy , Miguel Ojeda , Masahiro Yamada , Michal Marek , Andrew Morton , Masahiro Yamada , Thiago Jung Bauermann , Luis Chamberlain , Jessica Yu , Sven Schnelle , Iurii Zaikin , Catalin Marinas , Will Deacon , Vincenzo Frascino , Thomas Gleixner , Peter Collingbourne , Naohiro Aota , Alexander Monakov , Mathias Krause , PaX Team , Brad Spengler , Laura Abbott , Florian Weimer , Alexander Popov , kernel-hardening@lists.openwall.com, linux-kbuild@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, gcc@gcc.gnu.org Cc: notify@kernel.org Subject: [PATCH 5/5] gcc-plugins/stackleak: Don't instrument vgettimeofday.c in arm64 VDSO Date: Thu, 4 Jun 2020 16:49:57 +0300 Message-Id: <20200604134957.505389-6-alex.popov@linux.com> X-Mailer: git-send-email 2.25.2 In-Reply-To: <20200604134957.505389-1-alex.popov@linux.com> References: <20200604134957.505389-1-alex.popov@linux.com> MIME-Version: 1.0 Don't try instrumenting functions in arch/arm64/kernel/vdso/vgettimeofday.c. Otherwise that can cause issues if the cleanup pass of stackleak gcc plugin is disabled. Signed-off-by: Alexander Popov --- arch/arm64/kernel/vdso/Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile index 3862cad2410c..9b84cafbd2da 100644 --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile @@ -32,7 +32,8 @@ UBSAN_SANITIZE := n OBJECT_FILES_NON_STANDARD := y KCOV_INSTRUMENT := n -CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny -fasynchronous-unwind-tables +CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny -fasynchronous-unwind-tables \ + $(DISABLE_STACKLEAK_PLUGIN) ifneq ($(c-gettimeofday-y),) CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)