[PATCH 00/10] Convert signal32 to user read access by block

[PATCH 00/10] Convert signal32 to user read access by block

[Christophe Leroy]

Similarly to the work done earlier with writes, this series
converts signal32 to using user_read_access_begin/end and
unsafe_get_user() and friends.

Applies on to of the signal64 series, ie on merge-test (ca6e327fefb2)

Christophe Leroy (10):
  signal: Add unsafe_get_compat_sigset()
  powerpc/uaccess: Also perform 64 bits copies in
    unsafe_copy_from_user() on ppc32
  powerpc/signal: Add unsafe_copy_ck{fpr/vsx}_from_user
  powerpc/signal32: Rename save_user_regs_unsafe() and
    save_general_regs_unsafe()
  powerpc/signal32: Remove ifdefery in middle of if/else in sigreturn()
  powerpc/signal32: Perform access_ok() inside restore_user_regs()
  powerpc/signal32: Reorder user reads in restore_tm_user_regs()
  powerpc/signal32: Convert restore_[tm]_user_regs() to user access
    block
  powerpc/signal32: Convert do_setcontext[_tm]() to user access block
  powerpc/signal32: Simplify logging in sigreturn()

 arch/powerpc/include/asm/ptrace.h  |   2 +-
 arch/powerpc/include/asm/uaccess.h |   6 +-
 arch/powerpc/kernel/signal.h       |  22 +++
 arch/powerpc/kernel/signal_32.c    | 251 ++++++++++++++++-------------
 include/linux/compat.h             |  35 ++++
 include/linux/uaccess.h            |   1 +
 6 files changed, 205 insertions(+), 112 deletions(-)

-- 
2.25.0

[PATCH 01/10] signal: Add unsafe_get_compat_sigset()

[Christophe Leroy]

In the same way as commit 14026b94ccfe ("signal: Add
unsafe_put_compat_sigset()"), this time add
unsafe_get_compat_sigset() macro which is the 'unsafe'
version of get_compat_sigset()

For the bigendian, use unsafe_get_user() directly
to avoid intermediate copy through the stack.

For the littleendian, use a straight unsafe_copy_from_user().

This commit adds the generic fallback for unsafe_copy_from_user().
Architectures wanting to use unsafe_get_compat_sigset() have to
make sure they have their own unsafe_copy_from_user().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 include/linux/compat.h  | 35 +++++++++++++++++++++++++++++++++++
 include/linux/uaccess.h |  1 +
 2 files changed, 36 insertions(+)

diff --git a/include/linux/compat.h b/include/linux/compat.h
index 6e65be753603..5112c3e35782 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -465,6 +465,34 @@ put_compat_sigset(compat_sigset_t __user *compat, const sigset_t *set,
 		unsafe_put_user(__s->sig[0], &__c->sig[0], label);	\
 	}								\
 } while (0)
+
+#define unsafe_get_compat_sigset(set, compat, label) do {		\
+	const compat_sigset_t __user *__c = compat;			\
+	compat_sigset_word hi, lo;					\
+	sigset_t *__s = set;						\
+									\
+	switch (_NSIG_WORDS) {						\
+	case 4:								\
+		unsafe_get_user(lo, &__c->sig[7], label);		\
+		unsafe_get_user(hi, &__c->sig[6], label);		\
+		__s->sig[3] = hi | (((long)lo) << 32);			\
+		fallthrough;						\
+	case 3:								\
+		unsafe_get_user(lo, &__c->sig[5], label);		\
+		unsafe_get_user(hi, &__c->sig[4], label);		\
+		__s->sig[2] = hi | (((long)lo) << 32);			\
+		fallthrough;						\
+	case 2:								\
+		unsafe_get_user(lo, &__c->sig[3], label);		\
+		unsafe_get_user(hi, &__c->sig[2], label);		\
+		__s->sig[1] = hi | (((long)lo) << 32);			\
+		fallthrough;						\
+	case 1:								\
+		unsafe_get_user(lo, &__c->sig[1], label);		\
+		unsafe_get_user(hi, &__c->sig[0], label);		\
+		__s->sig[0] = hi | (((long)lo) << 32);			\
+	}								\
+} while (0)
 #else
 #define unsafe_put_compat_sigset(compat, set, label) do {		\
 	compat_sigset_t __user *__c = compat;				\
@@ -472,6 +500,13 @@ put_compat_sigset(compat_sigset_t __user *compat, const sigset_t *set,
 									\
 	unsafe_copy_to_user(__c, __s, sizeof(*__c), label);		\
 } while (0)
+
+#define unsafe_get_compat_sigset(set, compat, label) do {		\
+	const compat_sigset_t __user *__c = compat;			\
+	sigset_t *__s = set;						\
+									\
+	unsafe_copy_from_user(__s, __c, sizeof(*__c), label);		\
+} while (0)
 #endif
 
 extern int compat_ptrace_request(struct task_struct *child,
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index c7c6e8b8344d..c05e903cef02 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -397,6 +397,7 @@ long strnlen_user_nofault(const void __user *unsafe_addr, long count);
 #define unsafe_get_user(x,p,e) unsafe_op_wrap(__get_user(x,p),e)
 #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)
 static inline unsigned long user_access_save(void) { return 0UL; }
 static inline void user_access_restore(unsigned long flags) { }
 #endif
-- 
2.25.0

Re: [PATCH 00/10] Convert signal32 to user read access by block

[Michael Ellerman]

On Fri, 19 Mar 2021 11:06:49 +0000 (UTC), Christophe Leroy wrote:
> Similarly to the work done earlier with writes, this series
> converts signal32 to using user_read_access_begin/end and
> unsafe_get_user() and friends.
> 
> Applies on to of the signal64 series, ie on merge-test (ca6e327fefb2)
> 
> Christophe Leroy (10):
>   signal: Add unsafe_get_compat_sigset()
>   powerpc/uaccess: Also perform 64 bits copies in
>     unsafe_copy_from_user() on ppc32
>   powerpc/signal: Add unsafe_copy_ck{fpr/vsx}_from_user
>   powerpc/signal32: Rename save_user_regs_unsafe() and
>     save_general_regs_unsafe()
>   powerpc/signal32: Remove ifdefery in middle of if/else in sigreturn()
>   powerpc/signal32: Perform access_ok() inside restore_user_regs()
>   powerpc/signal32: Reorder user reads in restore_tm_user_regs()
>   powerpc/signal32: Convert restore_[tm]_user_regs() to user access
>     block
>   powerpc/signal32: Convert do_setcontext[_tm]() to user access block
>   powerpc/signal32: Simplify logging in sigreturn()
> 
> [...]

Applied to powerpc/next.

[01/10] signal: Add unsafe_get_compat_sigset()
        https://git.kernel.org/powerpc/c/fb05121fd6a20f0830ff2a4420c51af6ca4ac6e7
[02/10] powerpc/uaccess: Also perform 64 bits copies in unsafe_copy_from_user() on ppc32
        https://git.kernel.org/powerpc/c/c1cc1570bc8d94f288060f262f11be8f7672578c
[03/10] powerpc/signal: Add unsafe_copy_ck{fpr/vsx}_from_user
        https://git.kernel.org/powerpc/c/7c11f8893a76ac4e86c07f4b57371d5fa593627f
[04/10] powerpc/signal32: Rename save_user_regs_unsafe() and save_general_regs_unsafe()
        https://git.kernel.org/powerpc/c/f918a81e209f24acb45cd935bcfb78d2c024f6a1
[05/10] powerpc/signal32: Remove ifdefery in middle of if/else in sigreturn()
        https://git.kernel.org/powerpc/c/ca9e1605cdd9473a0eb4d6da238d2524be12591a
[06/10] powerpc/signal32: Perform access_ok() inside restore_user_regs()
        https://git.kernel.org/powerpc/c/362471b3192e4184fff5fedee1ea20bdf637a0c8
[07/10] powerpc/signal32: Reorder user reads in restore_tm_user_regs()
        https://git.kernel.org/powerpc/c/036fc2cb1dc2245c2ea7d2f03c7af80417b6310c
[08/10] powerpc/signal32: Convert restore_[tm]_user_regs() to user access block
        https://git.kernel.org/powerpc/c/627b72bee84d6652e0af26617e71ce2b3c18fcd5
[09/10] powerpc/signal32: Convert do_setcontext[_tm]() to user access block
        https://git.kernel.org/powerpc/c/887f3ceb51cd34109ac17bfc98695162e299e657
[10/10] powerpc/signal32: Simplify logging in sigreturn()
        https://git.kernel.org/powerpc/c/c7393a71eb1abdda7e3a3ef798bae60de11540ec

cheers