Messages in this thread | | | Subject | Re: [PATCH v2 3/5] signal: Add unsafe_copy_siginfo_to_user() | From | Christophe Leroy <> | Date | Fri, 3 Sep 2021 10:56:14 +0200 |
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Le 02/09/2021 à 20:43, Eric W. Biederman a écrit : > Christophe Leroy <christophe.leroy@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.
When looking into patch 5/5 that you nacked, I think you missed the fact that we keep using copy_siginfo_to_user32() as it for the 32 bit compat case.
> > Probably-Not-by: "Eric W. Biederman" <ebiederm@xmission.com> > > Eric > >> Signed-off-by: Christophe Leroy <christophe.leroy@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);
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