Move ia2_get_pkey into libia2

We need to use ia2_get_pkey from outside the allocator library, so this change moves that function into libia2 where it can be shared for both.
immunant · Aug 1, 2023 · a22b75f · a22b75f
1 parent f9572c6
commit a22b75f
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Showing 6 changed files with 83 additions and 75 deletions.
diff --git a/external/chromium/src/base/allocator/partition_allocator/partition_bucket.cc b/external/chromium/src/base/allocator/partition_allocator/partition_bucket.cc
@@ -42,7 +42,7 @@
 #endif  // BUILDFLAG(STARSCAN)
 
 #include <sys/mman.h>
-#include <ia2_get_pkey.h>
+#include <ia2.h>
 
 namespace partition_alloc::internal {
 

diff --git a/libia2/ia2.c b/libia2/ia2.c
@@ -5,6 +5,74 @@
 
 #include "ia2.h"
 
+#ifdef LIBIA2_INSECURE
+size_t ia2_get_pkey() { return 0; }
+#else
+size_t ia2_get_pkey() {
+  uint32_t pkru;
+  __asm__("rdpkru" : "=a"(pkru) : "a"(0), "d"(0), "c"(0));
+  switch (pkru) {
+  case 0xFFFFFFFC: {
+    return 0;
+  }
+  case 0xFFFFFFF0: {
+    return 1;
+  }
+  case 0xFFFFFFCC: {
+    return 2;
+  }
+  case 0xFFFFFF3C: {
+    return 3;
+  }
+  case 0xFFFFFCFC: {
+    return 4;
+  }
+  case 0xFFFFF3FC: {
+    return 5;
+  }
+  case 0xFFFFCFFC: {
+    return 6;
+  }
+  case 0xFFFF3FFC: {
+    return 7;
+  }
+  case 0xFFFCFFFC: {
+    return 8;
+  }
+  case 0xFFF3FFFC: {
+    return 9;
+  }
+  case 0xFFCFFFFC: {
+    return 10;
+  }
+  case 0xFF3FFFFC: {
+    return 11;
+  }
+  case 0xFCFFFFFC: {
+    return 12;
+  }
+  case 0xF3FFFFFC: {
+    return 13;
+  }
+  case 0xCFFFFFFC: {
+    return 14;
+  }
+  case 0x3FFFFFFC: {
+    return 15;
+  }
+  // TODO: We currently treat any unexpected PKRU value as pkey 0 (the shared
+  // heap) for simplicity since glibc(?) initializes the PKRU to 0x55555554
+  // (usually). We don't set the PKRU until the first compartment transition, so
+  // let's default to using the shared heap before our first wrpkru. When we
+  // initialize the PKRU properly (see issue #95) we should probably abort when
+  // we see unexpected PKRU values.
+  default: {
+    return 0;
+  }
+  }
+}
+#endif // LIBIA2_INSECURE
+
 static const char *shared_sections[][2] = {
     {"__start_ia2_shared_data", "__stop_ia2_shared_data"},
 };

diff --git a/libia2/include/ia2.h b/libia2/include/ia2.h
@@ -100,6 +100,12 @@ static uint32_t ia2_get_pkru() {
 #define IA2_IGNORE_FIELD(decl) decl
 
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+size_t ia2_get_pkey();
+
 /// Protect pages in the given shared object
 ///
 /// \param info dynamic linker information for the current object
@@ -310,3 +316,7 @@ static int insecure_pkey_mprotect(void *ptr, size_t len, int prot, int pkey) {
     protect_tls();                                                             \
     init_stacks();                                                             \
   }
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/partition-alloc/CMakeLists.txt b/partition-alloc/CMakeLists.txt
@@ -57,6 +57,8 @@ add_library(partition-alloc SHARED
     src/allocator_shim.cc
     ${PA_SRCS})
 
+target_link_libraries(partition-alloc libia2)
+
 if(LIBIA2_INSECURE)
     target_compile_definitions(partition-alloc PUBLIC LIBIA2_INSECURE=1)
 endif()

diff --git a/partition-alloc/src/allocator_shim.cc b/partition-alloc/src/allocator_shim.cc
@@ -8,77 +8,7 @@
 #include "allocator_shim.h"
 #include "base/allocator/partition_allocator/partition_alloc.h"
 #include "base/allocator/partition_allocator/partition_root.h"
-#include <ia2_get_pkey.h>
-
-extern "C" {
-
-#ifdef LIBIA2_INSECURE
-size_t ia2_get_pkey() { return 0; }
-#else
-size_t ia2_get_pkey() {
-  uint32_t pkru;
-  __asm__("rdpkru" : "=a"(pkru) : "a"(0), "d"(0), "c"(0));
-  switch (pkru) {
-  case 0xFFFFFFFC: {
-    return 0;
-  }
-  case 0xFFFFFFF0: {
-    return 1;
-  }
-  case 0xFFFFFFCC: {
-    return 2;
-  }
-  case 0xFFFFFF3C: {
-    return 3;
-  }
-  case 0xFFFFFCFC: {
-    return 4;
-  }
-  case 0xFFFFF3FC: {
-    return 5;
-  }
-  case 0xFFFFCFFC: {
-    return 6;
-  }
-  case 0xFFFF3FFC: {
-    return 7;
-  }
-  case 0xFFFCFFFC: {
-    return 8;
-  }
-  case 0xFFF3FFFC: {
-    return 9;
-  }
-  case 0xFFCFFFFC: {
-    return 10;
-  }
-  case 0xFF3FFFFC: {
-    return 11;
-  }
-  case 0xFCFFFFFC: {
-    return 12;
-  }
-  case 0xF3FFFFFC: {
-    return 13;
-  }
-  case 0xCFFFFFFC: {
-    return 14;
-  }
-  case 0x3FFFFFFC: {
-    return 15;
-  }
-  // TODO: We currently treat any unexpected PKRU value as pkey 0 (the shared
-  // heap) for simplicity since glibc(?) initializes the PKRU to 0x55555554
-  // (usually). We don't set the PKRU until the first compartment transition, so
-  // let's default to using the shared heap before our first wrpkru. When we
-  // initialize the PKRU properly (see issue #95) we should probably abort when
-  // we see unexpected PKRU values.
-  default: {
-    return 0;
-  }
-  }
-}
-#endif // LIBIA2_INSECURE
+#include <ia2.h>
 
 using namespace partition_alloc::internal;
 using partition_alloc::PartitionOptions;
@@ -217,5 +147,3 @@ void *ShimCallocWithPkey(size_t num, size_t size, size_t pkey) {
     return ret;
   }
 }
-
-} // extern "C"
diff --git a/scripts/partition_alloc/partition_alloc.diff b/scripts/partition_alloc/partition_alloc.diff
@@ -7,7 +7,7 @@ index 6434ee54..c27030dd 100644
  #endif  // BUILDFLAG(STARSCAN)
 
 +#include <sys/mman.h>
-+#include <ia2_get_pkey.h>
++#include <ia2.h>
 +
  namespace partition_alloc::internal {