@@ -117,6 +117,7 @@ static __always_inline void allow_user_access(void __user *to, const void __user
return;
end = min(addr + size, TASK_SIZE);
+
current->thread.kuap = (addr & 0xf0000000) | ((((end - 1) >> 28) + 1) & 0xf);
kuap_update_sr(mfsrin(addr) & ~SR_KS, addr, end); /* Clear Ks */
}
@@ -127,15 +128,27 @@ static __always_inline void prevent_user_access(void __user *to, const void __us
u32 addr, end;
BUILD_BUG_ON(!__builtin_constant_p(dir));
- if (!(dir & KUAP_W))
- return;
- addr = (__force u32)to;
+ if (dir == KUAP_SELF) {
+ u32 kuap = current->thread.kuap;
- if (unlikely(addr >= TASK_SIZE || !size))
- return;
+ if (unlikely(!kuap))
+ return;
+
+ addr = kuap & 0xf0000000;
+ end = kuap << 28;
+ } else {
+ if (!(dir & KUAP_W))
+ return;
+
+ addr = (__force u32)to;
+
+ if (unlikely(addr >= TASK_SIZE || !size))
+ return;
+
+ end = min(addr + size, TASK_SIZE);
+ }
- end = min(addr + size, TASK_SIZE);
current->thread.kuap = 0;
kuap_update_sr(mfsrin(addr) | SR_KS, addr, end); /* set Ks */
}
@@ -5,6 +5,7 @@
#define KUAP_R 1
#define KUAP_W 2
#define KUAP_RW (KUAP_R | KUAP_W)
+#define KUAP_SELF 4
#ifdef CONFIG_PPC64
#include <asm/book3s/64/kup-radix.h>
In preparation of implementing user_access_begin and friends on powerpc, the book3s/32 version of prevent_user_access() need to be prepared for user_access_end(). user_access_end() doesn't provide the address and size which were passed to user_access_begin(), required by prevent_user_access() to know which segment to modify. The list of segments which where unprotected by allow_user_access() are available in current->kuap. But we don't want prevent_user_access() to read this all the time, especially everytime it is 0 (for instance because the access was not a write access). Implement a special direction case named KUAP_SELF. In this case only, the addr and end are retrieved from current->kuap. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- arch/powerpc/include/asm/book3s/32/kup.h | 25 ++++++++++++++++++------ arch/powerpc/include/asm/kup.h | 1 + 2 files changed, 20 insertions(+), 6 deletions(-)