Re: [PATCH 5/7] signal: Add unsafe_copy_siginfo_to_user()
Le 15/06/2021 à 09:21, Christoph Hellwig a écrit : On Tue, Jun 15, 2021 at 09:03:42AM +0200, Christophe Leroy wrote: Le 15/06/2021 ?? 08:52, Christoph Hellwig a ??crit??: On Tue, Jun 15, 2021 at 06:41:01AM +, Christophe Leroy wrote: + unsafe_copy_to_user(__ucs_to, __ucs_from, \ + sizeof(struct kernel_siginfo), label); \ + unsafe_clear_user(__ucs_expansion, SI_EXPANSION_SIZE, label); \ +} while (0) unsafe_clear_user does not exist at this point, and even your later patch only adds it for powerpc. You missed below chunck I guess: 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) That doesn't help with architectures that define user_access_begin but do not define unsafe_clear_user. (i.e. x86). Yes, the day they want to use unsafe_copy_siginfo_to_user() they'll have to implement unsafe_clear_user(). Until that day, they don't need unsafe_clear_user() and I'm sure the result would be disastrous if a poor powerpc guy like me was trying to implement some low level x86 code. Similar to unsafe_get_compat_sigset(), an arch wanting to use it has to implement unsafe_copy_from_user().
Re: [PATCH 5/7] signal: Add unsafe_copy_siginfo_to_user()
On Tue, Jun 15, 2021 at 09:03:42AM +0200, Christophe Leroy wrote: > > > Le 15/06/2021 ?? 08:52, Christoph Hellwig a ??crit??: > > On Tue, Jun 15, 2021 at 06:41:01AM +, Christophe Leroy wrote: > > > + unsafe_copy_to_user(__ucs_to, __ucs_from, \ > > > + sizeof(struct kernel_siginfo), label); \ > > > + unsafe_clear_user(__ucs_expansion, SI_EXPANSION_SIZE, label); \ > > > +} while (0) > > > > unsafe_clear_user does not exist at this point, and even your later > > patch only adds it for powerpc. > > > > You missed below chunck I guess: > > > 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) That doesn't help with architectures that define user_access_begin but do not define unsafe_clear_user. (i.e. x86).
Re: [PATCH 5/7] signal: Add unsafe_copy_siginfo_to_user()
Le 15/06/2021 à 08:52, Christoph Hellwig a écrit :
On Tue, Jun 15, 2021 at 06:41:01AM +, Christophe Leroy wrote:
+ unsafe_copy_to_user(__ucs_to, __ucs_from, \
+ sizeof(struct kernel_siginfo), label); \
+ unsafe_clear_user(__ucs_expansion, SI_EXPANSION_SIZE, label); \
+} while (0)
unsafe_clear_user does not exist at this point, and even your later
patch only adds it for powerpc.
You missed below chunck I guess:
> 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
Re: [PATCH 5/7] signal: Add unsafe_copy_siginfo_to_user()
On Tue, Jun 15, 2021 at 06:41:01AM +, Christophe Leroy wrote: > + unsafe_copy_to_user(__ucs_to, __ucs_from, \ > + sizeof(struct kernel_siginfo), label); \ > + unsafe_clear_user(__ucs_expansion, SI_EXPANSION_SIZE, label); \ > +} while (0) unsafe_clear_user does not exist at this point, and even your later patch only adds it for powerpc.
[PATCH 5/7] signal: Add unsafe_copy_siginfo_to_user()
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().
Signed-off-by: Christophe Leroy
---
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 201f88e3738b..beac7b5e4acc 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 f7c6ffcbd044..7a366331d2b7 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3286,11 +3286,6 @@ 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);
--
2.25.0
