From: Sami Tolvanen <samitolvanen@google.com>
To: x86@kernel.org
Cc: Kees Cook <keescook@chromium.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Sedat Dilek <sedat.dilek@gmail.com>,
linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
clang-built-linux@googlegroups.com,
Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH v3 10/16] x86/extable: Mark handlers __cficanonical
Date: Tue, 14 Sep 2021 12:10:39 -0700 [thread overview]
Message-ID: <20210914191045.2234020-11-samitolvanen@google.com> (raw)
In-Reply-To: <20210914191045.2234020-1-samitolvanen@google.com>
Exception tables are populated in assembly code, but the handlers are
called in fixup_exception, which trips indirect call checking with
CONFIG_CFI_CLANG. Mark the handlers __cficanonical to allow addresses
taken in assembly to pass CFI checking.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
arch/x86/mm/extable.c | 64 ++++++++++++++++++++++++-------------------
1 file changed, 36 insertions(+), 28 deletions(-)
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index e1664e9f969c..d16912dcbb4e 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -24,16 +24,18 @@ ex_fixup_handler(const struct exception_table_entry *x)
return (ex_handler_t)((unsigned long)&x->handler + x->handler);
}
-__visible bool ex_handler_default(const struct exception_table_entry *fixup,
- struct pt_regs *regs, int trapnr,
- unsigned long error_code,
- unsigned long fault_addr)
+__visible __cficanonical
+bool ex_handler_default(const struct exception_table_entry *fixup,
+ struct pt_regs *regs, int trapnr,
+ unsigned long error_code,
+ unsigned long fault_addr)
{
regs->ip = ex_fixup_addr(fixup);
return true;
}
EXPORT_SYMBOL(ex_handler_default);
+__visible __cficanonical
__visible bool ex_handler_fault(const struct exception_table_entry *fixup,
struct pt_regs *regs, int trapnr,
unsigned long error_code,
@@ -55,10 +57,11 @@ EXPORT_SYMBOL_GPL(ex_handler_fault);
* of vulnerability by restoring from the initial state (essentially, zeroing
* out all the FPU registers) if we can't restore from the task's FPU state.
*/
-__visible bool ex_handler_fprestore(const struct exception_table_entry *fixup,
- struct pt_regs *regs, int trapnr,
- unsigned long error_code,
- unsigned long fault_addr)
+__visible __cficanonical
+bool ex_handler_fprestore(const struct exception_table_entry *fixup,
+ struct pt_regs *regs, int trapnr,
+ unsigned long error_code,
+ unsigned long fault_addr)
{
regs->ip = ex_fixup_addr(fixup);
@@ -70,10 +73,11 @@ __visible bool ex_handler_fprestore(const struct exception_table_entry *fixup,
}
EXPORT_SYMBOL_GPL(ex_handler_fprestore);
-__visible bool ex_handler_uaccess(const struct exception_table_entry *fixup,
- struct pt_regs *regs, int trapnr,
- unsigned long error_code,
- unsigned long fault_addr)
+__visible __cficanonical
+bool ex_handler_uaccess(const struct exception_table_entry *fixup,
+ struct pt_regs *regs, int trapnr,
+ unsigned long error_code,
+ unsigned long fault_addr)
{
WARN_ONCE(trapnr == X86_TRAP_GP, "General protection fault in user access. Non-canonical address?");
regs->ip = ex_fixup_addr(fixup);
@@ -81,10 +85,11 @@ __visible bool ex_handler_uaccess(const struct exception_table_entry *fixup,
}
EXPORT_SYMBOL(ex_handler_uaccess);
-__visible bool ex_handler_copy(const struct exception_table_entry *fixup,
- struct pt_regs *regs, int trapnr,
- unsigned long error_code,
- unsigned long fault_addr)
+__visible __cficanonical
+bool ex_handler_copy(const struct exception_table_entry *fixup,
+ struct pt_regs *regs, int trapnr,
+ unsigned long error_code,
+ unsigned long fault_addr)
{
WARN_ONCE(trapnr == X86_TRAP_GP, "General protection fault in user access. Non-canonical address?");
regs->ip = ex_fixup_addr(fixup);
@@ -93,10 +98,11 @@ __visible bool ex_handler_copy(const struct exception_table_entry *fixup,
}
EXPORT_SYMBOL(ex_handler_copy);
-__visible bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup,
- struct pt_regs *regs, int trapnr,
- unsigned long error_code,
- unsigned long fault_addr)
+__visible __cficanonical
+bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup,
+ struct pt_regs *regs, int trapnr,
+ unsigned long error_code,
+ unsigned long fault_addr)
{
if (pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pS)\n",
(unsigned int)regs->cx, regs->ip, (void *)regs->ip))
@@ -110,10 +116,11 @@ __visible bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup
}
EXPORT_SYMBOL(ex_handler_rdmsr_unsafe);
-__visible bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup,
- struct pt_regs *regs, int trapnr,
- unsigned long error_code,
- unsigned long fault_addr)
+__visible __cficanonical
+bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup,
+ struct pt_regs *regs, int trapnr,
+ unsigned long error_code,
+ unsigned long fault_addr)
{
if (pr_warn_once("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pS)\n",
(unsigned int)regs->cx, (unsigned int)regs->dx,
@@ -126,10 +133,11 @@ __visible bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup
}
EXPORT_SYMBOL(ex_handler_wrmsr_unsafe);
-__visible bool ex_handler_clear_fs(const struct exception_table_entry *fixup,
- struct pt_regs *regs, int trapnr,
- unsigned long error_code,
- unsigned long fault_addr)
+__visible __cficanonical
+bool ex_handler_clear_fs(const struct exception_table_entry *fixup,
+ struct pt_regs *regs, int trapnr,
+ unsigned long error_code,
+ unsigned long fault_addr)
{
if (static_cpu_has(X86_BUG_NULL_SEG))
asm volatile ("mov %0, %%fs" : : "rm" (__USER_DS));
--
2.33.0.309.g3052b89438-goog
next prev parent reply other threads:[~2021-09-14 19:11 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-14 19:10 [PATCH v3 00/16] x86: Add support for Clang CFI Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 01/16] objtool: Add CONFIG_CFI_CLANG support Sami Tolvanen
2021-09-14 19:29 ` Nick Desaulniers
2021-09-14 21:01 ` Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 02/16] objtool: Add ASM_STACK_FRAME_NON_STANDARD Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 03/16] linkage: Add DECLARE_ASM_FUNC_SYMBOL Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 04/16] cfi: Add DEFINE_CFI_IMMEDIATE_RETURN_STUB Sami Tolvanen
2021-09-14 19:36 ` Nick Desaulniers
2021-09-14 20:32 ` Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 05/16] tracepoint: Exclude tp_stub_func from CFI checking Sami Tolvanen
2021-09-14 19:39 ` Nick Desaulniers
2021-09-14 19:10 ` [PATCH v3 06/16] ftrace: Use an opaque type for functions not callable from C Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 07/16] lkdtm: Disable UNSET_SMEP with CFI Sami Tolvanen
2021-09-14 19:30 ` Kees Cook
2021-09-14 19:10 ` [PATCH v3 08/16] lkdtm: Use an opaque type for lkdtm_rodata_do_nothing Sami Tolvanen
2021-09-14 19:32 ` Kees Cook
2021-09-14 19:10 ` [PATCH v3 09/16] x86: Use an opaque type for functions not callable from C Sami Tolvanen
2021-09-14 19:33 ` Kees Cook
2021-09-14 19:10 ` Sami Tolvanen [this message]
2021-09-14 19:37 ` [PATCH v3 10/16] x86/extable: Mark handlers __cficanonical Kees Cook
2021-09-14 20:38 ` Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 11/16] x86/purgatory: Disable CFI Sami Tolvanen
2021-09-14 20:02 ` Nick Desaulniers
2021-09-14 20:30 ` Sami Tolvanen
2021-09-14 22:31 ` Nick Desaulniers
2021-09-15 6:24 ` Kees Cook
2021-09-14 19:10 ` [PATCH v3 12/16] x86, relocs: Ignore __typeid__ relocations Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 13/16] x86, module: " Sami Tolvanen
2021-09-14 19:10 ` [PATCH v3 14/16] x86, cpu: Use LTO for cpu.c with CFI Sami Tolvanen
2021-09-14 19:44 ` Kees Cook
2021-09-14 19:46 ` Nick Desaulniers
2021-09-14 19:10 ` [PATCH v3 15/16] x86, kprobes: Fix optprobe_template_func type mismatch Sami Tolvanen
2021-09-14 19:40 ` Kees Cook
2021-09-14 19:10 ` [PATCH v3 16/16] x86, build: Allow CONFIG_CFI_CLANG to be selected Sami Tolvanen
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