Gears Restructuring plus code injection preparation and template

[palacios.git] / gears / service_setup / inject_code_template.c

diff --git a/gears/service_setup/inject_code_template.c b/gears/service_setup/inject_code_template.c
new file mode 100644 (file)
index 0000000..c43fe68
--- /dev/null
+++ b/gears/service_setup/inject_code_template.c
@@ -0,0 +1,100 @@
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+
+/* 32-bit syscall numbers */
+#define __NR_exit          1
+#define __NR_fork          2
+#define __NR_write         4
+#define __NR_open          5
+#define __NR_close         6
+#define __NR_waitpid       7
+#define __NR_execve       11
+
+/* 32-bit system call conventions 
+ *
+ * eax = syscall nr
+ * ebx = arg 1
+ * ecx = arg 2
+ * edx = arg 3
+ * esi = arg 4
+ * edi = arg 5
+ * ebp = arg 6
+ */
+int _start() {
+
+    int FD, bytes_written, status, exec_ret;
+    int flags = O_RDWR|O_CREAT; 
+    int mode = S_IRUSR|S_IWUSR|S_IXUSR;
+    pid_t pid, ret;
+    char * env[1];
+
+    env[0] = 0;
+
+#include "generated.h"
+
+#ifdef DO_WRITE
+    /* open("FILENAME, O_RDWR | O_CREAT,  */
+    asm volatile ("pushl %%ebx; movl %2,%%ebx; int $0x80; popl %%ebx" 
+                : "=a" (FD)
+                : "0" (__NR_open), "r" (FILE_NAME), "c" (flags), "d" (mode)); 
+
+    if (!FD)
+        goto die;
+
+
+    /* write(FD, INJECT_FILE, FILE_LENGTH) */
+    asm volatile ("pushl %%ebx; movl %2,%%ebx; int $0x80; popl %%ebx" 
+                       : "=a" (bytes_written)
+                       : "0" (__NR_write), "r" (FD), "c" (inject_file), "d" (FILE_LENGTH));
+
+    if (!bytes_written)
+        goto die;
+
+
+    /* close(FD) */
+    asm volatile ("pushl %%ebx; movl %1,%%ebx; int $0x80; popl %%ebx" 
+                     : : "a" (__NR_close), "r" (FD));
+#endif 
+
+
+#ifdef DO_FORKEXEC
+    /* pid = fork() */
+    asm volatile ("int $0x80" : "=a" (pid) : "0" (__NR_fork));
+
+
+    if (pid < 0) {
+        goto die;
+    } else if (pid > 0) {
+
+        do {
+            /* ret = waitpid(pid, &status, 0) */
+            asm volatile ("pushl %%ebx; movl %2,%%ebx; int $0x80; popl %%ebx"
+                        : "=a" (ret)
+                        : "0" (__NR_waitpid), "r" (pid), "c" (&status), "d" (0));
+
+        } while (ret == -1);
+
+    } else {
+
+        /* execve("command", "arg0" , ..., "argN" , env) */
+        asm volatile ("pushl %%ebx; movl %2,%%ebx; int $0x80; popl %%ebx"
+                    : "=a" (exec_ret)
+                    : "0" (__NR_execve), "r" (CMD), "c" (args), "d" (env));
+        
+        if (exec_ret < 0)
+            /* exit(127) */
+            asm volatile ("pushl %%ebx; movl %1,%%ebx; int $0x80; popl %%ebx"
+                          : : "a" (__NR_exit), "r" (127));
+    }
+#endif
+
+    die:
+        /* hypercall(f001) <=> exit(0) */
+        asm volatile ("movl $0xf001, %eax");
+        asm volatile ("vmmcall");
+        /* exit(1) */
+        asm volatile ("pushl %%ebx; movl %1,%%ebx; int $0x80; popl %%ebx"
+                      : : "a" (__NR_exit), "r" (1));
+}