Christophe Leroy <christophe.le...@csgroup.eu> writes:
> In the same spirit as commit fb05121fd6a2 ("signal: Add
> unsafe_get_compat_sigset()"), implement an 'unsafe' version of
> copy_siginfo_to_user() in order to use it within user access blocks.
>
> For that, also add an 'unsafe' version of clear_user().
Looking at your use cases you need the 32bit compat version of this
as well.
The 32bit compat version is too complicated to become a macro, so I
don't think you can make this work correctly for the 32bit compat case.
Probably-Not-by: "Eric W. Biederman" <ebied...@xmission.com>
Eric
> Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
> ---
> include/linux/signal.h | 15 +++++++++++++++
> include/linux/uaccess.h | 1 +
> kernel/signal.c | 5 -----
> 3 files changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/signal.h b/include/linux/signal.h
> index 3454c7ff0778..659bd43daf10 100644
> --- a/include/linux/signal.h
> +++ b/include/linux/signal.h
> @@ -35,6 +35,21 @@ static inline void copy_siginfo_to_external(siginfo_t *to,
> int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from);
> int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user
> *from);
>
> +static __always_inline char __user *si_expansion(const siginfo_t __user
> *info)
> +{
> + return ((char __user *)info) + sizeof(struct kernel_siginfo);
> +}
> +
> +#define unsafe_copy_siginfo_to_user(to, from, label) do { \
> + siginfo_t __user *__ucs_to = to; \
> + const kernel_siginfo_t *__ucs_from = from; \
> + char __user *__ucs_expansion = si_expansion(__ucs_to); \
> + \
> + unsafe_copy_to_user(__ucs_to, __ucs_from, \
> + sizeof(struct kernel_siginfo), label); \
> + unsafe_clear_user(__ucs_expansion, SI_EXPANSION_SIZE, label); \
> +} while (0)
> +
> enum siginfo_layout {
> SIL_KILL,
> SIL_TIMER,
> diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
> index c05e903cef02..37073caac474 100644
> --- a/include/linux/uaccess.h
> +++ b/include/linux/uaccess.h
> @@ -398,6 +398,7 @@ long strnlen_user_nofault(const void __user *unsafe_addr,
> long count);
> #define unsafe_put_user(x,p,e) unsafe_op_wrap(__put_user(x,p),e)
> #define unsafe_copy_to_user(d,s,l,e) unsafe_op_wrap(__copy_to_user(d,s,l),e)
> #define unsafe_copy_from_user(d,s,l,e)
> unsafe_op_wrap(__copy_from_user(d,s,l),e)
> +#define unsafe_clear_user(d, l, e) unsafe_op_wrap(__clear_user(d, l), e)
> static inline unsigned long user_access_save(void) { return 0UL; }
> static inline void user_access_restore(unsigned long flags) { }
> #endif
> diff --git a/kernel/signal.c b/kernel/signal.c
> index a3229add4455..83b5971e4304 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -3261,11 +3261,6 @@ enum siginfo_layout siginfo_layout(unsigned sig, int
> si_code)
> return layout;
> }
>
> -static inline char __user *si_expansion(const siginfo_t __user *info)
> -{
> - return ((char __user *)info) + sizeof(struct kernel_siginfo);
> -}
> -
> int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
> {
> char __user *expansion = si_expansion(to);
