xnu-3248.60.10.tar.gz

[apple/xnu.git] / osfmk / mach / vm_param.h

diff --git a/osfmk/mach/vm_param.h b/osfmk/mach/vm_param.h
index afb040eeeb5f78fa98bfb1ac482e10458eb7df66..1fa361488256fe4209d6d53b7f706df179ccf640 100644 (file)
--- a/osfmk/mach/vm_param.h
+++ b/osfmk/mach/vm_param.h
@@ -245,30 +245,99 @@ extern vm_offset_t                vm_kernel_etext;
 extern vm_offset_t             vm_kernel_base;
 extern vm_offset_t             vm_kernel_top;
 extern vm_offset_t             vm_kernel_slide;
+extern vm_offset_t             vm_hib_base;
 extern vm_offset_t             vm_kernel_addrperm;
 
 extern vm_offset_t             vm_kext_base;
 extern vm_offset_t             vm_kext_top;
+extern vm_offset_t      vm_prelink_stext;
+extern vm_offset_t      vm_prelink_etext;
+extern vm_offset_t      vm_prelink_sinfo;
+extern vm_offset_t      vm_prelink_einfo;
+extern vm_offset_t      vm_slinkedit;
+extern vm_offset_t      vm_elinkedit;
 
 #define VM_KERNEL_IS_SLID(_o)                                                 \
                (((vm_offset_t)(_o) >= vm_kernel_base) &&                      \
-                ((vm_offset_t)(_o) <  vm_kernel_top))
-#define VM_KERNEL_IS_KEXT(_o)                                                  \
-                (((vm_offset_t)(_o) >= vm_kext_base) &&                        \
+                ((vm_offset_t)(_o) <=  vm_kernel_top))
+#define VM_KERNEL_IS_KEXT(_o)      \
+                (((vm_offset_t)(_o) >= vm_kext_base) &&   \
                  ((vm_offset_t)(_o) <  vm_kext_top))
+
+#define VM_KERNEL_IS_PRELINKTEXT(_o)        \
+        (((vm_offset_t)(_o) >= vm_prelink_stext) &&     \
+        ((vm_offset_t)(_o) <  vm_prelink_etext))
+
+#define VM_KERNEL_IS_PRELINKINFO(_o)        \
+    (((vm_offset_t)(_o) >= vm_prelink_sinfo) &&     \
+    ((vm_offset_t)(_o) <  vm_prelink_einfo))
+
+#define VM_KERNEL_IS_KEXT_LINKEDIT(_o)        \
+    (((vm_offset_t)(_o) >= vm_slinkedit) &&     \
+    ((vm_offset_t)(_o) <  vm_elinkedit))
+
+#define VM_KERNEL_SLIDE(_u)                                                   \
+               ((vm_offset_t)(_u) + vm_kernel_slide)
+
+/*
+ * The following macros are to be used when exposing kernel addresses to
+ * userspace via any of the various debug or info facilities that might exist
+ * (e.g. stackshot, proc_info syscall, etc.). It is important to understand
+ * the goal of each macro and choose the right one depending on what you are
+ * trying to do. Misuse of these macros can result in critical data leaks
+ * which in turn lead to all sorts of system vulnerabilities.
+ *
+ * Note that in general the ideal goal is to protect addresses from userspace
+ * in a way that is reversible assuming you know the permutation and/or slide.
+ *
+ * The macros are as follows:
+ * 
+ * VM_KERNEL_UNSLIDE:
+ *     Use this macro when you are exposing an address to userspace which is
+ *     a "static" kernel or kext address (i.e. coming from text or data
+ *     sections). These are the addresses which get "slid" via ASLR on kernel
+ *     or kext load, and it's precisely the slide value we are trying to
+ *     protect from userspace.
+ *
+ * VM_KERNEL_ADDRPERM:
+ *     Use this macro when you are exposing an address to userspace which is
+ *     coming from the kernel's "heap". Since these adresses are not "loaded"
+ *     from anywhere, there is no slide applied and we instead apply the
+ *     permutation value to obscure the address.
+ *
+ * VM_KERNEL_UNSLIDE_OR_ADDRPERM:
+ *     Use this macro when you are exposing an address to userspace that could
+ *     come from either kernel text/data *or* the heap. This is a rare case,
+ *     but one that does come up and must be handled correctly. If the argument
+ *     is known to be lower than any potential heap address, no transformation
+ *     is applied, to avoid revealing the operation on a constant.
+ *
+ * Nesting of these macros should be considered invalid.
+ */
 #define VM_KERNEL_UNSLIDE(_v)                                                 \
                ((VM_KERNEL_IS_SLID(_v) ||                                     \
-                 VM_KERNEL_IS_KEXT(_v)) ?                                     \
-                       (vm_offset_t)(_v) - vm_kernel_slide :                  \
+                 VM_KERNEL_IS_KEXT(_v) ||      \
+          VM_KERNEL_IS_PRELINKTEXT(_v) ||   \
+          VM_KERNEL_IS_PRELINKINFO(_v) ||   \
+          VM_KERNEL_IS_KEXT_LINKEDIT(_v)) ?      \
+                       (vm_offset_t)(_v) - vm_kernel_slide :    \
                        (vm_offset_t)(_v))
-#define VM_KERNEL_SLIDE(_u)                                                   \
-               ((vm_offset_t)(_u) + vm_kernel_slide)
 
-#define        VM_KERNEL_ADDRPERM(_v)                                                  \
-               (((vm_offset_t)(_v) == 0) ?                                     \
-                       (vm_offset_t)(0) :                                      \
+#define        VM_KERNEL_ADDRPERM(_v)                                                 \
+               (((vm_offset_t)(_v) == 0) ?                                    \
+                       (vm_offset_t)(0) :                                     \
                        (vm_offset_t)(_v) + vm_kernel_addrperm)
 
+#define VM_KERNEL_UNSLIDE_OR_PERM(_v)                                         \
+               ((VM_KERNEL_IS_SLID(_v) ||                                     \
+          VM_KERNEL_IS_KEXT(_v) ||      \
+          VM_KERNEL_IS_PRELINKTEXT(_v) ||   \
+          VM_KERNEL_IS_PRELINKINFO(_v) ||   \
+          VM_KERNEL_IS_KEXT_LINKEDIT(_v)) ?         \
+                       (vm_offset_t)(_v) - vm_kernel_slide :    \
+                ((vm_offset_t)(_v) >= VM_MIN_KERNEL_AND_KEXT_ADDRESS ? VM_KERNEL_ADDRPERM(_v) : (vm_offset_t)(_v)))
+       
+
 #endif /* XNU_KERNEL_PRIVATE */
 
 extern vm_size_t       page_size;