| Message ID | 20220208225350.1331628-3-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | f0202b8ca48cef152d4cdf775f39be6d3b372e1e |
| Headers | show |
| Series | fortify: Add Clang support | expand |
On Tue, Feb 8, 2022 at 2:53 PM Kees Cook <keescook@chromium.org> wrote: > > In order to gain greater visibility to type information when using > __builtin_object_size(), Clang has a function attribute "pass_object_size" > that will make size information available for marked arguments in > a function by way of implicit additional function arguments that are > then wired up the __builtin_object_size(). > > This is needed to implement FORTIFY_SOURCE in Clang, as a workaround > to Clang's __builtin_object_size() having limited visibility[1] into types > across function calls (even inlines). > > This attribute has an additional benefit that it can be used even on > non-inline functions to gain argument size information. > > [1] https://github.com/llvm/llvm-project/issues/53516 Thanks for the patch! Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > > Cc: Nick Desaulniers <ndesaulniers@google.com> > Cc: Nathan Chancellor <nathan@kernel.org> > Cc: llvm@lists.linux.dev > Reviewed-by: Miguel Ojeda <ojeda@kernel.org> > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > include/linux/compiler_attributes.h | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h > index 37e260020221..d0c503772061 100644 > --- a/include/linux/compiler_attributes.h > +++ b/include/linux/compiler_attributes.h > @@ -263,6 +263,20 @@ > */ > #define __packed __attribute__((__packed__)) > > +/* > + * Note: the "type" argument should match any __builtin_object_size(p, type) usage. > + * > + * Optional: not supported by gcc. > + * Optional: not supported by icc. > + * > + * clang: https://clang.llvm.org/docs/AttributeReference.html#pass-object-size-pass-dynamic-object-size > + */ > +#if __has_attribute(__pass_object_size__) > +# define __pass_object_size(type) __attribute__((__pass_object_size__(type))) > +#else > +# define __pass_object_size(type) > +#endif > + > /* > * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute > */ > -- > 2.30.2 > >
diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index 37e260020221..d0c503772061 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -263,6 +263,20 @@ */ #define __packed __attribute__((__packed__)) +/* + * Note: the "type" argument should match any __builtin_object_size(p, type) usage. + * + * Optional: not supported by gcc. + * Optional: not supported by icc. + * + * clang: https://clang.llvm.org/docs/AttributeReference.html#pass-object-size-pass-dynamic-object-size + */ +#if __has_attribute(__pass_object_size__) +# define __pass_object_size(type) __attribute__((__pass_object_size__(type))) +#else +# define __pass_object_size(type) +#endif + /* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute */