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Message-ID: <CANiq72n6zK=sXn2j71bAEUUYwRse2dT9f8kLrYzncnPjN1XTow@mail.gmail.com> Date: Sat, 24 Sep 2022 12:06:31 +0200 From: Miguel Ojeda <miguel.ojeda.sandonis@...il.com> To: Kees Cook <keescook@...omium.org> Cc: Miguel Ojeda <ojeda@...nel.org>, Siddhesh Poyarekar <siddhesh@...plt.org>, Nick Desaulniers <ndesaulniers@...gle.com>, Nathan Chancellor <nathan@...nel.org>, Tom Rix <trix@...hat.com>, llvm@...ts.linux.dev, linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org Subject: Re: [PATCH] Compiler Attributes: Introduce __access_*() function attribute On Sat, Sep 24, 2022 at 1:54 AM Kees Cook <keescook@...omium.org> wrote: > > are specified. While it is legal to provide only the pointer argument > position and access type, design the kernel macros to require also the > bounds (element count) argument position: if a function has no bounds > argument, refactor the code to include one. Should this bit be included in the comment of the attribute? (since it is specific to the kernel) > These can be used multiple times. For example: > > __access_wo(2, 3) __access_ro(4, 5) > int copy_something(struct context *ctx, u32 *dst, size_t dst_count, > u8 *src, int src_len); > > (And if "dst" will also be read, it could use __access_rw(2, 3) instead.) Also maybe the example could be nice there too, since it uses the syntax for the kernel and you took the time to write it :) By the way, shouldn't `src` typically be `const u8 *`? Given it is an example, I would qualify it. > +#if __has_attribute(__access__) > +#define __access_rw(ptr, count) __attribute__((__access__(read_write, ptr, count))) > +#define __access_ro(ptr, count) __attribute__((__access__(read_only, ptr, count))) > +#define __access_wo(ptr, count) __attribute__((__access__(write_only, ptr, count))) > +#else > +#define __access_rw(ptr, count) > +#define __access_ro(ptr, count) > +#define __access_wo(ptr, count) > +#endif If you do a v2 for the above, please take the chance to indent with a single space after the `#` (like `# define`) for consistency. Thanks! Cheers, Miguel
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