From ea2c36c5a99ddd71624d06ebe03294aa3acbee1a Mon Sep 17 00:00:00 2001
From: grischka <grischka>
Date: Sun, 5 Feb 2017 13:58:14 +0100
Subject: [PATCH] tccrun: 'selinux' mmap: use only one mapping

In the previous implementation, the rx mapping was never
used.  Therefor it is assumed that it is not needed.

With only one mapping there is no reason to use a real
/tmp/.xxxx file either as we can use an anonymous mapping.
---
 tccrun.c | 57 +++++++++++++++++++-------------------------------------
 1 file changed, 19 insertions(+), 38 deletions(-)

diff --git a/tccrun.c b/tccrun.c
index 7b533df..1fdea65 100644
--- a/tccrun.c
+++ b/tccrun.c
@@ -60,7 +60,7 @@ static void win64_del_function_table(void *);
 
 LIBTCCAPI int tcc_relocate(TCCState *s1, void *ptr)
 {
-    int size;  void *mem;
+    int size;
 
     if (TCC_RELOCATE_AUTO != ptr)
         return tcc_relocate_ex(s1, ptr);
@@ -70,35 +70,17 @@ LIBTCCAPI int tcc_relocate(TCCState *s1, void *ptr)
         return -1;
 
 #ifdef HAVE_SELINUX
-    {   /* Use mmap instead of malloc for Selinux.  Ref:
-           http://www.gnu.org/s/libc/manual/html_node/File-Size.html */
-
-        char tmpfname[] = "/tmp/.tccrunXXXXXX";
-        int fd = mkstemp (tmpfname);
-        void *wr_mem;
-
-        unlink (tmpfname);
-        ftruncate (fd, size);
-
-        wr_mem = mmap (NULL, size, PROT_READ|PROT_WRITE,
-            MAP_SHARED, fd, 0);
-        if (wr_mem == MAP_FAILED)
-            tcc_error("/tmp not writeable");
-        mem = mmap (NULL, size, PROT_READ|PROT_EXEC,
-            MAP_SHARED, fd, 0);
-        if (mem == MAP_FAILED)
-            tcc_error("/tmp not executable");
-
-        tcc_relocate_ex(s1, wr_mem);
-        dynarray_add(&s1->runtime_mem, &s1->nb_runtime_mem, (void*)(addr_t)size);
-        dynarray_add(&s1->runtime_mem, &s1->nb_runtime_mem, wr_mem);
-        dynarray_add(&s1->runtime_mem, &s1->nb_runtime_mem, mem);
-    }
+    /* Use mmap instead of malloc for Selinux. */
+    ptr = mmap (NULL, size, PROT_READ|PROT_WRITE,
+        MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    if (ptr == MAP_FAILED)
+        tcc_error("tccrun: could not map memory");
+    dynarray_add(&s1->runtime_mem, &s1->nb_runtime_mem, (void*)(addr_t)size);
 #else
-    mem = tcc_malloc(size);
-    tcc_relocate_ex(s1, mem); /* no more errors expected */
-    dynarray_add(&s1->runtime_mem, &s1->nb_runtime_mem, mem);
+    ptr = tcc_malloc(size);
 #endif
+    tcc_relocate_ex(s1, ptr); /* no more errors expected */
+    dynarray_add(&s1->runtime_mem, &s1->nb_runtime_mem, ptr);
     return 0;
 }
 
@@ -108,13 +90,12 @@ ST_FUNC void tcc_run_free(TCCState *s1)
 
     for (i = 0; i < s1->nb_runtime_mem; ++i) {
 #ifdef HAVE_SELINUX
-        int size = (int)(addr_t)s1->runtime_mem[i];
-        munmap(s1->runtime_mem[++i], size);
-        munmap(s1->runtime_mem[++i], size);
+        unsigned size = (unsigned)(addr_t)s1->runtime_mem[i++];
+        munmap(s1->runtime_mem[i], size);
 #else
-# ifdef _WIN64
+#ifdef _WIN64
         win64_del_function_table(*(void**)s1->runtime_mem[i]);
-# endif
+#endif
         tcc_free(s1->runtime_mem[i]);
 #endif
     }
@@ -264,19 +245,19 @@ static void set_pages_executable(void *ptr, unsigned long length)
     unsigned long old_protect;
     VirtualProtect(ptr, length, PAGE_EXECUTE_READWRITE, &old_protect);
 #else
+    void __clear_cache(void *beginning, void *end);
+    addr_t start, end;
 #ifndef PAGESIZE
 # define PAGESIZE 4096
 #endif
-    addr_t start, end;
     start = (addr_t)ptr & ~(PAGESIZE - 1);
     end = (addr_t)ptr + length;
     end = (end + PAGESIZE - 1) & ~(PAGESIZE - 1);
     if (mprotect((void *)start, end - start, PROT_READ | PROT_WRITE | PROT_EXEC))
         tcc_error("mprotect failed: did you mean to configure --with-selinux?");
-#if defined TCC_TARGET_ARM || defined TCC_TARGET_ARM64
-    { extern void __clear_cache(void *beginning, void *end);
-      __clear_cache(ptr, (char *)ptr + length); }
-#endif
+# if defined TCC_TARGET_ARM || defined TCC_TARGET_ARM64
+    __clear_cache(ptr, (char *)ptr + length);
+# endif
 #endif
 }