kernel: usercopy functions

kernel-src/sys/syscalls/linkat.c

@@ -2,27 +2,38 @@
 #include <kernel/alloc.h>
 
 
-syscallret_t syscall_linkat(context_t *, int olddirfd, const char *uoldpath, int newdirfd, const char *unewpath, int flags, int type) {
+syscallret_t syscall_linkat(context_t *, int olddirfd, char *uoldpath, int newdirfd, char *unewpath, int flags, int type) {
 	syscallret_t ret = {
 		.ret = -1
 	};
 
-	char *oldpath = alloc(strlen(uoldpath) + 1);
+	size_t oldpathlen;
+	size_t newpathlen;
+
+	if (usercopy_strlen(uoldpath, &oldpathlen) || usercopy_strlen(unewpath, &newpathlen)) {
+		ret.errno = EFAULT;
+		return ret;
+	}
+
+	char *oldpath = alloc(oldpathlen + 1);
 	if (oldpath == NULL) {
 		ret.errno = ENOMEM;
 		return ret;
 	}
 
-	char *newpath = alloc(strlen(unewpath) + 1);
+	char *newpath = alloc(newpathlen + 1);
 	if (newpath == NULL) {
 		free(oldpath);
 		ret.errno = ENOMEM;
 		return ret;
 	}
 
-	// TODO safe strcopy
-	strcpy(oldpath, uoldpath);
-	strcpy(newpath, unewpath);
+	if (usercopy_fromuser(oldpath, uoldpath, oldpathlen) || usercopy_fromuser(newpath, unewpath, newpathlen)) {
+		ret.errno = EFAULT;
+		free(newpath);
+		free(oldpath);
+		return ret;
+	}
 
 	vnode_t *olddirnode = NULL;
 	file_t *oldfile = NULL;