From: Nick Desaulniers <ndesaulniers@google.com> To: Sami Tolvanen <samitolvanen@google.com> Cc: Kees Cook <keescook@chromium.org>, Nathan Chancellor <nathan@kernel.org>, 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>, bpf <bpf@vger.kernel.org>, linux-hardening@vger.kernel.org, linux-arch <linux-arch@vger.kernel.org>, Linux ARM <linux-arm-kernel@lists.infradead.org>, Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>, PCI <linux-pci@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v2 02/17] cfi: add __cficanonical Date: Thu, 18 Mar 2021 10:49:50 -0700 [thread overview] Message-ID: <CAKwvOd=CfNmVT0RNsXw=vhTee40xpA-LjmyfagAQesS6VdAkXQ@mail.gmail.com> (raw) In-Reply-To: <20210318171111.706303-3-samitolvanen@google.com> On Thu, Mar 18, 2021 at 10:11 AM Sami Tolvanen <samitolvanen@google.com> wrote: > > With CONFIG_CFI_CLANG, the compiler replaces a function address taken > in C code with the address of a local jump table entry, which passes > runtime indirect call checks. However, the compiler won't replace > addresses taken in assembly code, which will result in a CFI failure > if we later jump to such an address in instrumented C code. The code > generated for the non-canonical jump table looks this: > > <noncanonical.cfi_jt>: /* In C, &noncanonical points here */ > jmp noncanonical > ... > <noncanonical>: /* function body */ > ... > > This change adds the __cficanonical attribute, which tells the > compiler to use a canonical jump table for the function instead. This > means the compiler will rename the actual function to <function>.cfi > and points the original symbol to the jump table entry instead: > > <canonical>: /* jump table entry */ > jmp canonical.cfi > ... > <canonical.cfi>: /* function body */ > ... > > As a result, the address taken in assembly, or other non-instrumented > code always points to the jump table and therefore, can be used for > indirect calls in instrumented code without tripping CFI checks. > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > Reviewed-by: Kees Cook <keescook@chromium.org> > Acked-by: Bjorn Helgaas <bhelgaas@google.com> # pci.h Irrelevant to this series, but I checked when the FN attr was first available in clang; clang-10. (That's the minimum supported version of clang for the kernel, and this series depends on LTO which depends on clang-12, so no additional guards are necessary). Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > --- > include/linux/compiler-clang.h | 1 + > include/linux/compiler_types.h | 4 ++++ > include/linux/init.h | 4 ++-- > include/linux/pci.h | 4 ++-- > 4 files changed, 9 insertions(+), 4 deletions(-) > > diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h > index 6de9d0c9377e..adbe76b203e2 100644 > --- a/include/linux/compiler-clang.h > +++ b/include/linux/compiler-clang.h > @@ -63,3 +63,4 @@ > #endif > > #define __nocfi __attribute__((__no_sanitize__("cfi"))) > +#define __cficanonical __attribute__((__cfi_canonical_jump_table__)) > diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h > index 796935a37e37..d29bda7f6ebd 100644 > --- a/include/linux/compiler_types.h > +++ b/include/linux/compiler_types.h > @@ -246,6 +246,10 @@ struct ftrace_likely_data { > # define __nocfi > #endif > > +#ifndef __cficanonical > +# define __cficanonical > +#endif > + > #ifndef asm_volatile_goto > #define asm_volatile_goto(x...) asm goto(x) > #endif > diff --git a/include/linux/init.h b/include/linux/init.h > index b3ea15348fbd..045ad1650ed1 100644 > --- a/include/linux/init.h > +++ b/include/linux/init.h > @@ -220,8 +220,8 @@ extern bool initcall_debug; > __initcall_name(initstub, __iid, id) > > #define __define_initcall_stub(__stub, fn) \ > - int __init __stub(void); \ > - int __init __stub(void) \ > + int __init __cficanonical __stub(void); \ > + int __init __cficanonical __stub(void) \ > { \ > return fn(); \ > } \ > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 86c799c97b77..39684b72db91 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -1944,8 +1944,8 @@ enum pci_fixup_pass { > #ifdef CONFIG_LTO_CLANG > #define __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > class_shift, hook, stub) \ > - void stub(struct pci_dev *dev); \ > - void stub(struct pci_dev *dev) \ > + void __cficanonical stub(struct pci_dev *dev); \ > + void __cficanonical stub(struct pci_dev *dev) \ > { \ > hook(dev); \ > } \ > -- > 2.31.0.291.g576ba9dcdaf-goog > -- Thanks, ~Nick Desaulniers
WARNING: multiple messages have this Message-ID (diff)
From: Nick Desaulniers <ndesaulniers@google.com> To: Sami Tolvanen <samitolvanen@google.com> Cc: Kees Cook <keescook@chromium.org>, Nathan Chancellor <nathan@kernel.org>, 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>, bpf <bpf@vger.kernel.org>, linux-hardening@vger.kernel.org, linux-arch <linux-arch@vger.kernel.org>, Linux ARM <linux-arm-kernel@lists.infradead.org>, Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>, PCI <linux-pci@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v2 02/17] cfi: add __cficanonical Date: Thu, 18 Mar 2021 10:49:50 -0700 [thread overview] Message-ID: <CAKwvOd=CfNmVT0RNsXw=vhTee40xpA-LjmyfagAQesS6VdAkXQ@mail.gmail.com> (raw) In-Reply-To: <20210318171111.706303-3-samitolvanen@google.com> On Thu, Mar 18, 2021 at 10:11 AM Sami Tolvanen <samitolvanen@google.com> wrote: > > With CONFIG_CFI_CLANG, the compiler replaces a function address taken > in C code with the address of a local jump table entry, which passes > runtime indirect call checks. However, the compiler won't replace > addresses taken in assembly code, which will result in a CFI failure > if we later jump to such an address in instrumented C code. The code > generated for the non-canonical jump table looks this: > > <noncanonical.cfi_jt>: /* In C, &noncanonical points here */ > jmp noncanonical > ... > <noncanonical>: /* function body */ > ... > > This change adds the __cficanonical attribute, which tells the > compiler to use a canonical jump table for the function instead. This > means the compiler will rename the actual function to <function>.cfi > and points the original symbol to the jump table entry instead: > > <canonical>: /* jump table entry */ > jmp canonical.cfi > ... > <canonical.cfi>: /* function body */ > ... > > As a result, the address taken in assembly, or other non-instrumented > code always points to the jump table and therefore, can be used for > indirect calls in instrumented code without tripping CFI checks. > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > Reviewed-by: Kees Cook <keescook@chromium.org> > Acked-by: Bjorn Helgaas <bhelgaas@google.com> # pci.h Irrelevant to this series, but I checked when the FN attr was first available in clang; clang-10. (That's the minimum supported version of clang for the kernel, and this series depends on LTO which depends on clang-12, so no additional guards are necessary). Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > --- > include/linux/compiler-clang.h | 1 + > include/linux/compiler_types.h | 4 ++++ > include/linux/init.h | 4 ++-- > include/linux/pci.h | 4 ++-- > 4 files changed, 9 insertions(+), 4 deletions(-) > > diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h > index 6de9d0c9377e..adbe76b203e2 100644 > --- a/include/linux/compiler-clang.h > +++ b/include/linux/compiler-clang.h > @@ -63,3 +63,4 @@ > #endif > > #define __nocfi __attribute__((__no_sanitize__("cfi"))) > +#define __cficanonical __attribute__((__cfi_canonical_jump_table__)) > diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h > index 796935a37e37..d29bda7f6ebd 100644 > --- a/include/linux/compiler_types.h > +++ b/include/linux/compiler_types.h > @@ -246,6 +246,10 @@ struct ftrace_likely_data { > # define __nocfi > #endif > > +#ifndef __cficanonical > +# define __cficanonical > +#endif > + > #ifndef asm_volatile_goto > #define asm_volatile_goto(x...) asm goto(x) > #endif > diff --git a/include/linux/init.h b/include/linux/init.h > index b3ea15348fbd..045ad1650ed1 100644 > --- a/include/linux/init.h > +++ b/include/linux/init.h > @@ -220,8 +220,8 @@ extern bool initcall_debug; > __initcall_name(initstub, __iid, id) > > #define __define_initcall_stub(__stub, fn) \ > - int __init __stub(void); \ > - int __init __stub(void) \ > + int __init __cficanonical __stub(void); \ > + int __init __cficanonical __stub(void) \ > { \ > return fn(); \ > } \ > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 86c799c97b77..39684b72db91 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -1944,8 +1944,8 @@ enum pci_fixup_pass { > #ifdef CONFIG_LTO_CLANG > #define __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > class_shift, hook, stub) \ > - void stub(struct pci_dev *dev); \ > - void stub(struct pci_dev *dev) \ > + void __cficanonical stub(struct pci_dev *dev); \ > + void __cficanonical stub(struct pci_dev *dev) \ > { \ > hook(dev); \ > } \ > -- > 2.31.0.291.g576ba9dcdaf-goog > -- Thanks, ~Nick Desaulniers _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-03-18 17:51 UTC|newest] Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-03-18 17:10 [PATCH v2 00/17] Add support for Clang CFI Sami Tolvanen 2021-03-18 17:10 ` Sami Tolvanen 2021-03-18 17:10 ` [PATCH v2 01/17] add " Sami Tolvanen 2021-03-18 17:10 ` Sami Tolvanen 2021-03-18 22:29 ` Peter Zijlstra 2021-03-18 22:29 ` Peter Zijlstra 2021-03-18 23:48 ` Sami Tolvanen 2021-03-18 23:48 ` Sami Tolvanen 2021-03-19 12:26 ` Peter Zijlstra 2021-03-19 12:26 ` Peter Zijlstra 2021-03-19 13:52 ` Paul E. McKenney 2021-03-19 13:52 ` Paul E. McKenney 2021-03-19 16:17 ` Sami Tolvanen 2021-03-19 16:17 ` Sami Tolvanen 2021-03-19 17:03 ` Paul E. McKenney 2021-03-19 17:03 ` Paul E. McKenney 2021-03-18 17:10 ` [PATCH v2 02/17] cfi: add __cficanonical Sami Tolvanen 2021-03-18 17:10 ` Sami Tolvanen 2021-03-18 17:49 ` Nick Desaulniers [this message] 2021-03-18 17:49 ` Nick Desaulniers 2021-03-18 17:10 ` [PATCH v2 03/17] mm: add generic __va_function and __pa_function macros Sami Tolvanen 2021-03-18 17:10 ` Sami Tolvanen 2021-03-18 17:10 ` [PATCH v2 04/17] module: ensure __cfi_check alignment Sami Tolvanen 2021-03-18 17:10 ` Sami Tolvanen 2021-03-18 19:27 ` Nick Desaulniers 2021-03-18 19:27 ` Nick Desaulniers 2021-03-18 21:43 ` Sami Tolvanen 2021-03-18 21:43 ` Sami Tolvanen 2021-03-18 17:10 ` [PATCH v2 05/17] workqueue: use WARN_ON_FUNCTION_MISMATCH Sami Tolvanen 2021-03-18 17:10 ` Sami Tolvanen 2021-03-18 18:50 ` Nick Desaulniers 2021-03-18 18:50 ` Nick Desaulniers 2021-03-18 21:38 ` Sami Tolvanen 2021-03-18 21:38 ` Sami Tolvanen 2021-03-18 17:11 ` [PATCH v2 06/17] kthread: " Sami Tolvanen 2021-03-18 17:11 ` Sami Tolvanen 2021-03-18 17:11 ` [PATCH v2 07/17] kallsyms: strip ThinLTO hashes from static functions Sami Tolvanen 2021-03-18 17:11 ` Sami Tolvanen 2021-03-18 19:00 ` Nick Desaulniers 2021-03-18 19:00 ` Nick Desaulniers 2021-03-18 21:41 ` Sami Tolvanen 2021-03-18 21:41 ` Sami Tolvanen 2021-03-18 17:11 ` [PATCH v2 08/17] bpf: disable CFI in dispatcher functions Sami Tolvanen 2021-03-18 17:11 ` Sami Tolvanen 2021-03-18 17:11 ` [PATCH v2 09/17] lib/list_sort: fix function type mismatches Sami Tolvanen 2021-03-18 17:11 ` Sami Tolvanen 2021-03-18 18:31 ` Nick Desaulniers 2021-03-18 18:31 ` Nick Desaulniers 2021-03-18 21:31 ` Sami Tolvanen 2021-03-18 21:31 ` Sami Tolvanen 2021-03-18 17:11 ` [PATCH v2 10/17] lkdtm: use __va_function Sami Tolvanen 2021-03-18 17:11 ` Sami Tolvanen 2021-03-18 18:43 ` Nick Desaulniers 2021-03-18 18:43 ` Nick Desaulniers 2021-03-18 18:45 ` Nick Desaulniers 2021-03-18 18:45 ` Nick Desaulniers 2021-03-18 17:11 ` [PATCH v2 11/17] psci: use __pa_function for cpu_resume Sami Tolvanen 2021-03-18 17:11 ` Sami Tolvanen 2021-03-18 17:11 ` [PATCH v2 12/17] arm64: implement __va_function Sami Tolvanen 2021-03-18 17:11 ` Sami Tolvanen 2021-03-18 17:11 ` [PATCH v2 13/17] arm64: use __pa_function Sami Tolvanen 2021-03-18 17:11 ` Sami Tolvanen 2021-03-18 17:11 ` [PATCH v2 14/17] arm64: add __nocfi to functions that jump to a physical address Sami Tolvanen 2021-03-18 17:11 ` Sami Tolvanen 2021-03-18 17:11 ` [PATCH v2 15/17] arm64: add __nocfi to __apply_alternatives Sami Tolvanen 2021-03-18 17:11 ` Sami Tolvanen 2021-03-18 17:11 ` [PATCH v2 16/17] KVM: arm64: Disable CFI for nVHE Sami Tolvanen 2021-03-18 17:11 ` Sami Tolvanen 2021-03-18 17:11 ` [PATCH v2 17/17] arm64: allow CONFIG_CFI_CLANG to be selected Sami Tolvanen 2021-03-18 17:11 ` Sami Tolvanen
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