execve: SUID and SGID

kernel-src/include/kernel/cred.h

@@ -17,5 +17,6 @@ int cred_setuids(cred_t *cred, int uid, int euid, int suid);
 int cred_setgids(cred_t *cred, int uid, int euid, int suid);
 void cred_getuids(cred_t *cred, int *uidp, int *euidp, int *suidp);
 void cred_getgids(cred_t *cred, int *gidp, int *egidp, int *sgidp);
+void cred_doexec(cred_t *cred, int suid, int sgid);
 
 #endif

kernel-src/sys/cred.c

@@ -1,5 +1,6 @@
 #include <kernel/cred.h>
 #include <errno.h>
+#include <logging.h>
 
 int cred_setuids(cred_t *cred, int uid, int euid, int suid) {
 	if (uid < -1 || euid < -1 || suid < -1 || (uid == -1 && euid == -1 && suid == -1))
@@ -27,6 +28,17 @@ int cred_setgids(cred_t *cred, int gid, int egid, int sgid) {
 	return 0;
 }
 
+void cred_doexec(cred_t *cred, int suid, int sgid) {
+	if (suid > -1)
+		cred->euid = suid;
+
+	if (sgid > -1)
+		cred->egid = sgid;
+
+	cred->suid = cred->euid;
+	cred->sgid = cred->egid;
+}
+
 void cred_getuids(cred_t *cred, int *uidp, int *euidp, int *suidp) {
 	*uidp = cred->uid;
 	*euidp = cred->euid;

kernel-src/sys/syscalls/execve.c

@@ -262,6 +262,11 @@ static syscallret_t execve(context_t *context, char *upath, char *uargv[], char
 		goto error;
 	}
 
+	vattr_t vattr;
+	ret.errno = VOP_GETATTR(node, &vattr, NULL);
+	if (ret.errno)
+		goto error;
+
 	ret.ret = 0;
 
 	sched_stopotherthreads();
@@ -281,6 +286,17 @@ static syscallret_t execve(context_t *context, char *upath, char *uargv[], char
 	CTX_SP(context) = (uint64_t)stack;
 	CTX_IP(context) = (uint64_t)entry;
 
+	int suid = -1;
+	int sgid = -1;
+
+	if (vattr.mode & V_ATTR_MODE_SUID)
+		suid = vattr.uid;
+
+	if (vattr.mode & V_ATTR_MODE_SGID)
+		sgid = vattr.gid;
+
+	cred_doexec(&_cpu()->thread->proc->cred, suid, sgid);
+
 	error:
 	free(path);
 	if (argv)