[Cryptech-Commits] [core/novena_eim] 01/01: add mmap for eim peeking and poking

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paul at psgd.org pushed a commit to branch master
in repository core/novena_eim.

commit 62c914ca659dc7201a70113ac76c4a5582351f0c
Author: Paul Selkirk <paul at psgd.org>
Date:   Thu Nov 6 16:41:16 2014 -0500

    add mmap for eim peeking and poking
---
 src/sw/mmap.c | 130 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 130 insertions(+)

diff --git a/src/sw/mmap.c b/src/sw/mmap.c
new file mode 100644
index 0000000..6157947
--- /dev/null
+++ b/src/sw/mmap.c
@@ -0,0 +1,130 @@
+/* adapted from https://github.com/bunnie/novena-gpbb-example/blob/master/novena-gpbb.c */
+
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <time.h>
+#include <sys/ioctl.h>
+#include <arpa/inet.h>
+#include <ctype.h>
+
+static int fd = 0;
+static uint32_t *mem_32 = NULL;
+static uint16_t *mem_16 = NULL;
+static uint8_t  *mem_8  = NULL;
+static void *prev_mem_range = NULL;
+
+void map_mem(off_t offset)
+{
+    void *mem_range = (void *)(offset & ~0xFFFF);
+
+    if (mem_range == prev_mem_range)
+        return;
+
+    //fprintf(stderr, "New range detected.  Reopening at memory range %p\n", mem_range);
+    prev_mem_range = mem_range;
+
+    if (mem_32)
+        munmap((void *)mem_32, 0xFFFF);
+    if (fd)
+        close(fd);
+
+    fd = open("/dev/mem", O_RDWR);
+    if (fd < 0) {
+        perror("Unable to open /dev/mem");
+        fd = 0;
+        return;
+    }
+
+    mem_32 = (uint32_t *)mmap(NULL, 0xffff, PROT_READ | PROT_WRITE, MAP_SHARED, fd, offset&~0xFFFF);
+    if (mem_32 == MAP_FAILED) {
+        perror("Unable to mmap file");
+
+        if (close(fd) < 0)
+            perror("Also couldn't close file");
+
+        fd=0;
+        return;
+    }
+    mem_16 = (uint16_t *)mem_32;
+    mem_8  = (uint8_t *)mem_32;
+}
+
+uint32_t read_kernel_memory(off_t offset, size_t size)
+{
+  uint32_t result;
+
+  //fprintf(stderr, "read_kernel_memory(0x%04x, %d)\n", (unsigned int)offset, (int)size);
+  map_mem(offset);
+
+  off_t scaled_offset = (offset-(offset&~0xFFFF));
+  //fprintf(stderr, "Returning offset 0x%08x\n", scaled_offset);
+  if (size == 1)
+    result = mem_8[scaled_offset/sizeof(uint8_t)];
+  else if (size == 2)
+    result = mem_16[scaled_offset/sizeof(uint16_t)];
+  else
+    result = mem_32[scaled_offset/sizeof(uint32_t)];
+
+  return result;
+}
+
+uint32_t write_kernel_memory(off_t offset, uint32_t value, size_t size)
+{
+  uint32_t old_value = read_kernel_memory(offset, size);
+  off_t scaled_offset = (offset-(offset&~0xFFFF));
+  //printf("write_kernel_memory(%x, %x, %d)\n", (uint32_t)offset, value, size);
+  if (size == 1)
+    mem_8[scaled_offset/sizeof(uint8_t)]   = value;
+  else if (size == 2)
+    mem_16[scaled_offset/sizeof(uint16_t)] = value;
+  else
+    mem_32[scaled_offset/sizeof(uint32_t)] = value;
+  return old_value;
+}
+
+int
+main(int argc, char *argv[])
+{
+    off_t offset;
+    size_t length, size = 2;
+    int i, result;
+    unsigned long value;
+
+    if (argc < 4 || argc > 5) {
+	fprintf(stderr, "usage: %s r offset length [size]\n", argv[0]);
+	fprintf(stderr, "usage: %s w offset value [size]\n", argv[0]);
+	exit(EXIT_FAILURE);
+    }
+
+    offset = (off_t)strtoul(argv[2], NULL, 0);
+    if (argc > 4)
+	size = atoi(argv[4]);
+    if (argv[1][0] == 'r') {
+	length = atoi(argv[3]);
+	for (i = 0; i < length; i += size) {
+	    result = read_kernel_memory(offset + i, size);
+	    if (size == 1)
+		printf("%02x ", result & 0xff);
+	    else if (size == 2)
+		printf("%04x ", result & 0xffff);
+	    else if (size == 4)
+		printf("%08x ", result & 0xffffffff);
+	    else {
+		fprintf(stderr, "bad size %d\n", (int)size);
+		exit(EXIT_FAILURE);
+	    }
+	}
+	printf("\n");
+    }
+    else if (argv[1][0] == 'w') {
+	value = strtoul(argv[3], NULL, 0);
+	write_kernel_memory(offset, value, size);
+    }
+
+    exit(EXIT_SUCCESS);
+}