Fix busybox-like symlink and argv[0] usage with qemu

This change passes the unmapped executable to qemu and
relies on qemu open()ing it, correct mapping will take
place at that time instead of the normal execve().

Signed-off-by: Lauri Leukkunen <lle@rahina.org>

1 files changed, 17 insertions, 9 deletions

diff --git a/preload/sb_exec.c b/preload/sb_exec.c
index e537f3d..46e5877 100644
--- a/preload/sb_exec.c
+++ b/preload/sb_exec.c
@@ -54,7 +54,8 @@ static int elem_count(char **elems)
 	return count;
 }
 
-int run_cputransparency(char *file, char **argv, char *const *envp)
+int run_cputransparency(char *orig_file, char *file, char **argv,
+			char *const *envp)
 {
 	char *cputransp_bin, *target_root;
 	char *basec, *bname;
@@ -76,10 +77,10 @@ int run_cputransparency(char *file, char **argv, char *const *envp)
 
 	if (strstr(bname, "qemu")) {
 		free(basec);
-		return run_qemu(cputransp_bin, file, argv, envp);
+		return run_qemu(cputransp_bin, orig_file, file, argv, envp);
 	} else if (strstr(bname, "sbrsh")) {
 		free(basec);
-		return run_sbrsh(cputransp_bin, target_root, file, argv, envp);
+		return run_sbrsh(cputransp_bin, orig_file, target_root, file, argv, envp);
 	}
 
 	free(basec);
@@ -87,12 +88,14 @@ int run_cputransparency(char *file, char **argv, char *const *envp)
 	return -1;
 }
 
-int run_sbrsh(char *sbrsh_bin, char *target_root, char *file, char **argv, char *const *envp)
+int run_sbrsh(char *sbrsh_bin, char *target_root, char *orig_file, char *file,
+		char **argv, char *const *envp)
 {
 	return -1;
 }
 
-int run_qemu(char *qemu_bin, char *file, char **argv, char *const *envp)
+int run_qemu(char *qemu_bin, char *orig_file,char *file,
+		char **argv, char *const *envp)
 {
 	char **my_argv, **p;
 	int i = 0;
@@ -104,14 +107,18 @@ int run_qemu(char *qemu_bin, char *file, char **argv, char *const *envp)
 	my_argv[i++] = "-L";
 
 	my_argv[i++] = "/";
-	my_argv[i++] = file;
+	my_argv[i++] = orig_file; /* we're passing the unmapped file
+				   * here, it works because qemu will
+				   * do open() on it, and that gets
+				   * mapped again.
+				   */
 	for (p=&argv[1]; *p; p++) {
 		my_argv[i++] = *p;
 	}
 
 	my_argv[i] = NULL;
 
-	return sb_next_execve(my_argv[0], my_argv, envp);
+	return sb_next_execve(qemu_bin, my_argv, envp);
 }
 
 int run_app(char *file, char **argv, char *const *envp)
@@ -295,7 +302,8 @@ static char const* const*drop_preload(char *const oldenv[])
 }
 
 
-int do_exec(const char *file, char *const *argv, char *const *envp)
+int do_exec(const char *orig_file, const char *file,
+		char *const *argv, char *const *envp)
 {
 	char **my_envp, **my_argv, **p;
 	char *binaryname, *tmp, *my_file;
@@ -400,7 +408,7 @@ int do_exec(const char *file, char *const *argv, char *const *envp)
 		case BIN_HOST:
 			return run_app((char *)my_file, (char **)my_argv, my_envp);
 		case BIN_TARGET:
-			return run_cputransparency(my_file, (char **)my_argv, my_envp);
+			return run_cputransparency((char *)orig_file, my_file, (char **)my_argv, my_envp);
 		case BIN_NONE:
 		case BIN_UNKNOWN:
 			DBGOUT("unknown\n");