From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
ebiederm@xmission.com, hch@infradead.org
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4 3/5] signal: Add unsafe_copy_siginfo_to_user()
Date: Tue, 14 Sep 2021 16:31:25 +0200 [thread overview]
Message-ID: <4a31723d50fe14f95ece6ee29538db82e21751bf.1631629700.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <1718f38859d5366f82d5bef531f255cedf537b5d.1631629700.git.christophe.leroy@csgroup.eu>
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().
This commit adds the generic fallback for unsafe_clear_user().
Architectures wanting to use unsafe_copy_siginfo_to_user() within a
user_access_begin() section have to make sure they have their
own unsafe_clear_user().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v3: Added precision about unsafe_clear_user() in commit message.
---
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 3f96a6374e4f..70ea7e741427 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 952741f6d0f9..23f168730b7e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3324,11 +3324,6 @@ 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);
--
2.31.1
next prev parent reply other threads:[~2021-09-14 14:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-14 14:31 [PATCH v4 1/5] powerpc/signal64: Access function descriptor with user access block Christophe Leroy
2021-09-14 14:31 ` [PATCH v4 2/5] powerpc/signal: Include the new stack frame inside the " Christophe Leroy
2021-09-14 14:31 ` Christophe Leroy [this message]
2021-09-14 14:31 ` [PATCH v4 4/5] powerpc/uaccess: Add unsafe_clear_user() Christophe Leroy
2021-09-14 14:31 ` [PATCH v4 5/5] powerpc/signal: Use unsafe_copy_siginfo_to_user() Christophe Leroy
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