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From: Sami Tolvanen <samitolvanen@google.com>
To: Kees Cook <keescook@chromium.org>
Cc: Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Will Deacon <will@kernel.org>, Jessica Yu <jeyu@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>, Tejun Heo <tj@kernel.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Christoph Hellwig <hch@infradead.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	bpf@vger.kernel.org, linux-hardening@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kbuild@vger.kernel.org, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
	Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH v5 10/18] lkdtm: use function_nocfi
Date: Thu,  1 Apr 2021 16:32:08 -0700	[thread overview]
Message-ID: <20210401233216.2540591-11-samitolvanen@google.com> (raw)
In-Reply-To: <20210401233216.2540591-1-samitolvanen@google.com>

To ensure we take the actual address of a function in kernel text,
use function_nocfi. Otherwise, with CONFIG_CFI_CLANG, the compiler
replaces the address with a pointer to the CFI jump table, which is
actually in the module when compiled with CONFIG_LKDTM=m.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
---
 drivers/misc/lkdtm/usercopy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c
index 109e8d4302c1..15d220ef35a5 100644
--- a/drivers/misc/lkdtm/usercopy.c
+++ b/drivers/misc/lkdtm/usercopy.c
@@ -314,7 +314,7 @@ void lkdtm_USERCOPY_KERNEL(void)
 
 	pr_info("attempting bad copy_to_user from kernel text: %px\n",
 		vm_mmap);
-	if (copy_to_user((void __user *)user_addr, vm_mmap,
+	if (copy_to_user((void __user *)user_addr, function_nocfi(vm_mmap),
 			 unconst + PAGE_SIZE)) {
 		pr_warn("copy_to_user failed, but lacked Oops\n");
 		goto free_user;
-- 
2.31.0.208.g409f899ff0-goog


WARNING: multiple messages have this Message-ID (diff)
From: Sami Tolvanen <samitolvanen@google.com>
To: Kees Cook <keescook@chromium.org>
Cc: Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	 Masahiro Yamada <masahiroy@kernel.org>,
	Will Deacon <will@kernel.org>, Jessica Yu <jeyu@kernel.org>,
	 Arnd Bergmann <arnd@arndb.de>, Tejun Heo <tj@kernel.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	 Christoph Hellwig <hch@infradead.org>,
	Peter Zijlstra <peterz@infradead.org>,
	 Sedat Dilek <sedat.dilek@gmail.com>,
	Mark Rutland <mark.rutland@arm.com>,
	 Catalin Marinas <catalin.marinas@arm.com>,
	bpf@vger.kernel.org,  linux-hardening@vger.kernel.org,
	linux-arch@vger.kernel.org,
	 linux-arm-kernel@lists.infradead.org,
	linux-kbuild@vger.kernel.org,  linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	 clang-built-linux@googlegroups.com,
	Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH v5 10/18] lkdtm: use function_nocfi
Date: Thu,  1 Apr 2021 16:32:08 -0700	[thread overview]
Message-ID: <20210401233216.2540591-11-samitolvanen@google.com> (raw)
In-Reply-To: <20210401233216.2540591-1-samitolvanen@google.com>

To ensure we take the actual address of a function in kernel text,
use function_nocfi. Otherwise, with CONFIG_CFI_CLANG, the compiler
replaces the address with a pointer to the CFI jump table, which is
actually in the module when compiled with CONFIG_LKDTM=m.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
---
 drivers/misc/lkdtm/usercopy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c
index 109e8d4302c1..15d220ef35a5 100644
--- a/drivers/misc/lkdtm/usercopy.c
+++ b/drivers/misc/lkdtm/usercopy.c
@@ -314,7 +314,7 @@ void lkdtm_USERCOPY_KERNEL(void)
 
 	pr_info("attempting bad copy_to_user from kernel text: %px\n",
 		vm_mmap);
-	if (copy_to_user((void __user *)user_addr, vm_mmap,
+	if (copy_to_user((void __user *)user_addr, function_nocfi(vm_mmap),
 			 unconst + PAGE_SIZE)) {
 		pr_warn("copy_to_user failed, but lacked Oops\n");
 		goto free_user;
-- 
2.31.0.208.g409f899ff0-goog


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  parent reply	other threads:[~2021-04-01 23:33 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-01 23:31 [PATCH v5 00/18] Add support for Clang CFI Sami Tolvanen
2021-04-01 23:31 ` Sami Tolvanen
2021-04-01 23:31 ` [PATCH v5 01/18] add " Sami Tolvanen
2021-04-01 23:31   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 02/18] cfi: add __cficanonical Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 03/18] mm: add generic function_nocfi macro Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-02  6:37   ` Christoph Hellwig
2021-04-02  6:37     ` Christoph Hellwig
2021-04-06 11:27   ` Mark Rutland
2021-04-06 11:27     ` Mark Rutland
2021-04-01 23:32 ` [PATCH v5 04/18] module: ensure __cfi_check alignment Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 05/18] workqueue: use WARN_ON_FUNCTION_MISMATCH Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 06/18] kthread: " Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 07/18] kallsyms: strip ThinLTO hashes from static functions Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 08/18] bpf: disable CFI in dispatcher functions Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 09/18] treewide: Change list_sort to use const pointers Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` Sami Tolvanen [this message]
2021-04-01 23:32   ` [PATCH v5 10/18] lkdtm: use function_nocfi Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 11/18] psci: use function_nocfi for cpu_resume Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-06 11:27   ` Mark Rutland
2021-04-06 11:27     ` Mark Rutland
2021-04-01 23:32 ` [PATCH v5 12/18] arm64: implement function_nocfi Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-06 11:36   ` Mark Rutland
2021-04-06 11:36     ` Mark Rutland
2021-04-06 17:02     ` Sami Tolvanen
2021-04-06 17:02       ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 13/18] arm64: use function_nocfi with __pa_symbol Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-06 11:41   ` Mark Rutland
2021-04-06 11:41     ` Mark Rutland
2021-04-01 23:32 ` [PATCH v5 14/18] arm64: add __nocfi to functions that jump to a physical address Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-06 11:53   ` Mark Rutland
2021-04-06 11:53     ` Mark Rutland
2021-04-06 12:59     ` Ard Biesheuvel
2021-04-06 12:59       ` Ard Biesheuvel
2021-04-06 17:43     ` Sami Tolvanen
2021-04-06 17:43       ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 15/18] arm64: add __nocfi to __apply_alternatives Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 16/18] arm64: ftrace: use function_nocfi for ftrace_call Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-06 11:58   ` Mark Rutland
2021-04-06 11:58     ` Mark Rutland
2021-04-01 23:32 ` [PATCH v5 17/18] KVM: arm64: Disable CFI for nVHE Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 18/18] arm64: allow CONFIG_CFI_CLANG to be selected Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-02 19:58 ` [PATCH v5 00/18] Add support for Clang CFI Nathan Chancellor
2021-04-02 19:58   ` Nathan Chancellor

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