All of lore.kernel.org
 help / color / mirror / Atom feed
From: Sami Tolvanen <samitolvanen@google.com>
To: linux-kernel@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	 Peter Zijlstra <peterz@infradead.org>,
	x86@kernel.org,  Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	 Mark Rutland <mark.rutland@arm.com>,
	Nathan Chancellor <nathan@kernel.org>,
	 Nick Desaulniers <ndesaulniers@google.com>,
	Joao Moreira <joao@overdrivepizza.com>,
	 Sedat Dilek <sedat.dilek@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	 linux-hardening@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,  llvm@lists.linux.dev,
	Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH v5 17/22] objtool: Disable CFI warnings
Date: Thu,  8 Sep 2022 14:54:59 -0700	[thread overview]
Message-ID: <20220908215504.3686827-18-samitolvanen@google.com> (raw)
In-Reply-To: <20220908215504.3686827-1-samitolvanen@google.com>

The __cfi_ preambles contain a mov instruction that embeds the KCFI
type identifier in the following format:

  ; type preamble
  __cfi_function:
    mov <id>, %eax
  function:
    ...

While the preamble symbols are STT_FUNC and contain valid
instructions, they are never executed and always fall through. Skip
the warning for them.

.kcfi_traps sections point to CFI traps in text sections. Also skip
the warning about them referencing !ENDBR instructions.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index e55fdf952a3a..48e18737a2d1 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3316,6 +3316,10 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 		next_insn = next_insn_to_validate(file, insn);
 
 		if (func && insn->func && func != insn->func->pfunc) {
+			/* Ignore KCFI type preambles, which always fall through */
+			if (!strncmp(func->name, "__cfi_", 6))
+				return 0;
+
 			WARN("%s() falls through to next function %s()",
 			     func->name, insn->func->name);
 			return 1;
@@ -4113,7 +4117,8 @@ static int validate_ibt(struct objtool_file *file)
 		    !strcmp(sec->name, "__bug_table")			||
 		    !strcmp(sec->name, "__ex_table")			||
 		    !strcmp(sec->name, "__jump_table")			||
-		    !strcmp(sec->name, "__mcount_loc"))
+		    !strcmp(sec->name, "__mcount_loc")			||
+		    !strcmp(sec->name, ".kcfi_traps"))
 			continue;
 
 		list_for_each_entry(reloc, &sec->reloc->reloc_list, list)
-- 
2.37.2.789.g6183377224-goog


WARNING: multiple messages have this Message-ID (diff)
From: Sami Tolvanen <samitolvanen@google.com>
To: linux-kernel@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	 Peter Zijlstra <peterz@infradead.org>,
	x86@kernel.org,  Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	 Mark Rutland <mark.rutland@arm.com>,
	Nathan Chancellor <nathan@kernel.org>,
	 Nick Desaulniers <ndesaulniers@google.com>,
	Joao Moreira <joao@overdrivepizza.com>,
	 Sedat Dilek <sedat.dilek@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	 linux-hardening@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,  llvm@lists.linux.dev,
	Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH v5 17/22] objtool: Disable CFI warnings
Date: Thu,  8 Sep 2022 14:54:59 -0700	[thread overview]
Message-ID: <20220908215504.3686827-18-samitolvanen@google.com> (raw)
In-Reply-To: <20220908215504.3686827-1-samitolvanen@google.com>

The __cfi_ preambles contain a mov instruction that embeds the KCFI
type identifier in the following format:

  ; type preamble
  __cfi_function:
    mov <id>, %eax
  function:
    ...

While the preamble symbols are STT_FUNC and contain valid
instructions, they are never executed and always fall through. Skip
the warning for them.

.kcfi_traps sections point to CFI traps in text sections. Also skip
the warning about them referencing !ENDBR instructions.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index e55fdf952a3a..48e18737a2d1 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3316,6 +3316,10 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 		next_insn = next_insn_to_validate(file, insn);
 
 		if (func && insn->func && func != insn->func->pfunc) {
+			/* Ignore KCFI type preambles, which always fall through */
+			if (!strncmp(func->name, "__cfi_", 6))
+				return 0;
+
 			WARN("%s() falls through to next function %s()",
 			     func->name, insn->func->name);
 			return 1;
@@ -4113,7 +4117,8 @@ static int validate_ibt(struct objtool_file *file)
 		    !strcmp(sec->name, "__bug_table")			||
 		    !strcmp(sec->name, "__ex_table")			||
 		    !strcmp(sec->name, "__jump_table")			||
-		    !strcmp(sec->name, "__mcount_loc"))
+		    !strcmp(sec->name, "__mcount_loc")			||
+		    !strcmp(sec->name, ".kcfi_traps"))
 			continue;
 
 		list_for_each_entry(reloc, &sec->reloc->reloc_list, list)
-- 
2.37.2.789.g6183377224-goog


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2022-09-08 21:55 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-08 21:54 [PATCH v5 00/22] KCFI support Sami Tolvanen
2022-09-08 21:54 ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 01/22] treewide: Filter out CC_FLAGS_CFI Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 02/22] scripts/kallsyms: Ignore __kcfi_typeid_ Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 03/22] cfi: Remove CONFIG_CFI_CLANG_SHADOW Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 04/22] cfi: Drop __CFI_ADDRESSABLE Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 05/22] cfi: Switch to -fsanitize=kcfi Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 06/22] cfi: Add type helper macros Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 07/22] lkdtm: Emit an indirect call for CFI tests Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 08/22] psci: Fix the function type for psci_initcall_t Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 09/22] arm64: Add types to indirect called assembly functions Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 10/22] arm64: Add CFI error handling Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 11/22] arm64: Drop unneeded __nocfi attributes Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 12/22] init: Drop __nocfi from __init Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 13/22] treewide: Drop function_nocfi Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 14/22] treewide: Drop WARN_ON_FUNCTION_MISMATCH Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 15/22] treewide: Drop __cficanonical Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` [PATCH v5 16/22] objtool: Preserve special st_shndx indexes in elf_update_symbol Sami Tolvanen
2022-09-08 21:54   ` Sami Tolvanen
2022-09-08 21:54 ` Sami Tolvanen [this message]
2022-09-08 21:54   ` [PATCH v5 17/22] objtool: Disable CFI warnings Sami Tolvanen
2022-09-08 21:55 ` [PATCH v5 18/22] kallsyms: Drop CONFIG_CFI_CLANG workarounds Sami Tolvanen
2022-09-08 21:55   ` Sami Tolvanen
2022-09-08 21:55 ` [PATCH v5 19/22] x86/tools/relocs: Ignore __kcfi_typeid_ relocations Sami Tolvanen
2022-09-08 21:55   ` Sami Tolvanen
2022-09-08 21:55 ` [PATCH v5 20/22] x86: Add types to indirectly called assembly functions Sami Tolvanen
2022-09-08 21:55   ` Sami Tolvanen
2022-09-08 21:55 ` [PATCH v5 21/22] x86/purgatory: Disable CFI Sami Tolvanen
2022-09-08 21:55   ` Sami Tolvanen
2022-09-08 21:55 ` [PATCH v5 22/22] x86: Add support for CONFIG_CFI_CLANG Sami Tolvanen
2022-09-08 21:55   ` Sami Tolvanen
2022-09-26 12:39 ` [PATCH v5 00/22] KCFI support Peter Zijlstra
2022-09-26 12:39   ` Peter Zijlstra
2022-09-26 20:16   ` H.J. Lu
2022-09-26 20:16     ` H.J. Lu
2022-09-27  7:29     ` Peter Zijlstra
2022-09-27  7:29       ` Peter Zijlstra
2022-09-26 17:20 ` Kees Cook
2022-09-26 17:20   ` Kees Cook
2022-09-28  9:01   ` Sedat Dilek
2022-09-28  9:01     ` Sedat Dilek

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220908215504.3686827-18-samitolvanen@google.com \
    --to=samitolvanen@google.com \
    --cc=catalin.marinas@arm.com \
    --cc=joao@overdrivepizza.com \
    --cc=jpoimboe@redhat.com \
    --cc=keescook@chromium.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-hardening@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=llvm@lists.linux.dev \
    --cc=mark.rutland@arm.com \
    --cc=nathan@kernel.org \
    --cc=ndesaulniers@google.com \
    --cc=peterz@infradead.org \
    --cc=rostedt@goodmis.org \
    --cc=sedat.dilek@gmail.com \
    --cc=will@kernel.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.