xnu-4570.61.1.tar.gz

[apple/xnu.git] / bsd / vfs / vfs_cprotect.c

diff --git a/bsd/vfs/vfs_cprotect.c b/bsd/vfs/vfs_cprotect.c
index d286796231f7ac75ab77e44c92c9fcb2a7ed7504..ff53ee1a3c516d90d16d33c45c89c97b327a41cc 100644 (file)
--- a/bsd/vfs/vfs_cprotect.c
+++ b/bsd/vfs/vfs_cprotect.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 Apple Inc. All rights reserved.
+ * Copyright (c) 2015-2018 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  *
@@ -89,14 +89,40 @@ size_t cpx_sizex(const struct cpx *cpx)
 cpx_t cpx_alloc(size_t key_len)
 {
        cpx_t cpx;
-
+       
+#if TARGET_OS_OSX
+       /* 
+        * Macs only use 1 key per volume, so force it into its own page.
+        * This way, we can write-protect as needed.
+        */
+       size_t cpsize = cpx_size (key_len);
+       if (cpsize < PAGE_SIZE) {
+               MALLOC(cpx, cpx_t, PAGE_SIZE, M_TEMP, M_WAITOK);
+       }
+       else {
+               panic ("cpx_size too large ! (%lu)", cpsize);
+       }
+#else
        MALLOC(cpx, cpx_t, cpx_size(key_len), M_TEMP, M_WAITOK);
-
+#endif
        cpx_init(cpx, key_len);
 
        return cpx;
 }
 
+/* this is really a void function */
+void cpx_writeprotect (cpx_t cpx) 
+{
+#if TARGET_OS_OSX
+       void *cpxstart = (void*)cpx;
+       void *cpxend = (void*)((uint8_t*)cpx + PAGE_SIZE);
+       vm_map_protect (kernel_map, cpxstart, cpxend, (VM_PROT_READ), FALSE);
+#else
+       (void) cpx;
+#endif
+       return;
+}
+
 #if DEBUG
 static const uint32_t cpx_magic1 = 0x7b787063;         // cpx{
 static const uint32_t cpx_magic2 = 0x7870637d;         // }cpx
@@ -104,10 +130,19 @@ static const uint32_t cpx_magic2 = 0x7870637d;            // }cpx
 
 void cpx_free(cpx_t cpx)
 {
+
 #if DEBUG
        assert(cpx->cpx_magic1 == cpx_magic1);
        assert(*PTR_ADD(uint32_t *, cpx, cpx_sizex(cpx) - 4) == cpx_magic2);
 #endif
+       
+#if TARGET_OS_OSX
+       /* unprotect the page before bzeroing */
+       void *cpxstart = (void*)cpx;
+       void *cpxend = (void*)((uint8_t*)cpx + PAGE_SIZE);
+       vm_map_protect (kernel_map, cpxstart, cpxend, (VM_PROT_DEFAULT), FALSE);
+#endif
+
        bzero(cpx->cpx_cached_key, cpx->cpx_max_key_len);
        FREE(cpx, M_TEMP);
 }