cred: setting and getting ids

kernel-src/arch/x86-64/syscall.asm

@@ -78,6 +78,10 @@ extern syscall_ppoll
 extern syscall_pread
 extern syscall_pwrite
 extern syscall_mknodat
+extern syscall_getresuid
+extern syscall_getresgid
+extern syscall_setresuid
+extern syscall_setresgid
 syscalltab:
 dq syscall_print
 dq syscall_mmap
@@ -158,7 +162,11 @@ dq syscall_ppoll
 dq syscall_pread
 dq syscall_pwrite
 dq syscall_mknodat
-syscallcount equ 79
+dq syscall_getresuid
+dq syscall_getresgid
+dq syscall_setresuid
+dq syscall_setresgid
+syscallcount equ 83
 section .text
 global arch_syscall_entry
 ; on entry:

kernel-src/arch/x86-64/syscalllog.c

@@ -5,7 +5,7 @@
 
 #ifdef SYSCALL_LOGGING
 
-#define SYSCALL_COUNT 79
+#define SYSCALL_COUNT 83
 #define LOGSTR(x) arch_e9_puts(x)
 
 static char *name[] = {
@@ -87,7 +87,11 @@ static char *name[] = {
 	"ppoll",
 	"pread",
 	"pwrite",
-	"mknodat"
+	"mknodat",
+	"getresuid",
+	"getresgid",
+	"setresuid",
+	"setresgid"
 };
 
 static char *args[] = {
@@ -169,7 +173,11 @@ static char *args[] = {
 	"fds %p nfds %d timeout %p sigmask %p", // ppoll
 	"fd %d buffer %p count %lu offset %lu\n", // pread
 	"fd %d buffer %p count %lu offset %lu\n", // pwrite
-	"dirfd %d path %s mode %o dev %x\n" // mknodat
+	"dirfd %d path %s mode %o dev %x\n", // mknodat
+	"uidp %p euidp %p suidp %p", // getresuid
+	"gidp %p egidp %p sgidp %p", // getresgid
+	"uid %d euid %d suid %d", // setresuid
+	"gid %d egid %d sgid %d" // setresgid
 };
 
 #endif

kernel-src/include/kernel/cred.h

@@ -0,0 +1,21 @@
+#ifndef _CRED_H
+#define _CRED_H
+
+#define CRED_PERM_SUPERUSER (1l << 63)
+
+#include <stdint.h>
+
+typedef struct {
+	int uid, euid, suid;
+	int gid, egid, sgid;
+
+	uintmax_t allow;
+	uintmax_t deny;
+} cred_t;
+
+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);
+
+#endif

kernel-src/sys/cred.c

@@ -0,0 +1,40 @@
+#include <kernel/cred.h>
+#include <errno.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))
+		return EINVAL;
+
+	// TODO do permission check to see if its possible
+
+	cred->uid = uid;
+	cred->euid = euid;
+	cred->suid = suid;
+
+	return 0;
+}
+
+int cred_setgids(cred_t *cred, int gid, int egid, int sgid) {
+	if (gid < -1 || egid < -1 || sgid < -1 || (gid == -1 && egid == -1 && sgid == -1))
+		return EINVAL;
+
+	// TODO do permission check to see if its possible
+
+	cred->gid = gid;
+	cred->egid = egid;
+	cred->sgid = sgid;
+
+	return 0;
+}
+
+void cred_getuids(cred_t *cred, int *uidp, int *euidp, int *suidp) {
+	*uidp = cred->uid;
+	*euidp = cred->euid;
+	*suidp = cred->suid;
+}
+
+void cred_getgids(cred_t *cred, int *gidp, int *egidp, int *sgidp) {
+	*gidp = cred->gid;
+	*egidp = cred->egid;
+	*sgidp = cred->sgid;
+}

kernel-src/sys/syscalls/fork.c

@@ -44,6 +44,7 @@ syscallret_t syscall_fork(context_t *ctx) {
 	MUTEX_RELEASE(&proc->mutex);
 
 	nproc->umask = _cpu()->thread->proc->umask;
+	nproc->cred = _cpu()->thread->proc->cred;
 	nproc->root = sched_getroot();
 	nproc->cwd = sched_getcwd();
 	nproc->threadlist = nthread;

kernel-src/sys/syscalls/getresgid.c

@@ -0,0 +1,29 @@
+#include <kernel/abi.h>
+#include <kernel/syscalls.h>
+#include <kernel/cred.h>
+
+syscallret_t syscall_getresgid(context_t *, gid_t *gidp, gid_t *egidp, gid_t *sgidp) {
+	syscallret_t ret = {
+		.ret = -1
+	};
+
+	int gid, egid, sgid;
+	cred_getgids(&_cpu()->thread->proc->cred, &gid, &egid, &sgid);
+
+	ret.errno = usercopy_touser(gidp, &gid, sizeof(gid));
+	if (ret.errno)
+		goto leave;
+
+	ret.errno = usercopy_touser(egidp, &egid, sizeof(egid));
+	if (ret.errno)
+		goto leave;
+
+	ret.errno = usercopy_touser(sgidp, &sgid, sizeof(sgid));
+	if (ret.errno)
+		goto leave;
+
+	ret.ret = 0;
+
+	leave:
+	return ret;
+}

kernel-src/sys/syscalls/getresuid.c

@@ -0,0 +1,29 @@
+#include <kernel/abi.h>
+#include <kernel/syscalls.h>
+#include <kernel/cred.h>
+
+syscallret_t syscall_getresuid(context_t *, uid_t *uidp, uid_t *euidp, uid_t *suidp) {
+	syscallret_t ret = {
+		.ret = -1
+	};
+
+	int uid, euid, suid;
+	cred_getuids(&_cpu()->thread->proc->cred, &uid, &euid, &suid);
+
+	ret.errno = usercopy_touser(uidp, &uid, sizeof(uid));
+	if (ret.errno)
+		goto leave;
+
+	ret.errno = usercopy_touser(euidp, &euid, sizeof(euid));
+	if (ret.errno)
+		goto leave;
+
+	ret.errno = usercopy_touser(suidp, &suid, sizeof(suid));
+	if (ret.errno)
+		goto leave;
+
+	ret.ret = 0;
+
+	leave:
+	return ret;
+}

kernel-src/sys/syscalls/setresgid.c

@@ -0,0 +1,12 @@
+#include <kernel/abi.h>
+#include <kernel/syscalls.h>
+#include <kernel/cred.h>
+
+syscallret_t syscall_setresgid(context_t *, gid_t gid, gid_t egid, gid_t sgid) {
+	syscallret_t ret;
+
+	ret.errno = cred_setgids(&_cpu()->thread->proc->cred, gid, egid, sgid);
+	ret.ret = ret.errno ? -1 : 0;
+
+	return ret;
+}

kernel-src/sys/syscalls/setresuid.c

@@ -0,0 +1,12 @@
+#include <kernel/abi.h>
+#include <kernel/syscalls.h>
+#include <kernel/cred.h>
+
+syscallret_t syscall_setresuid(context_t *, uid_t uid, uid_t euid, uid_t suid) {
+	syscallret_t ret;
+
+	ret.errno = cred_setuids(&_cpu()->thread->proc->cred, uid, euid, suid);
+	ret.ret = ret.errno ? -1 : 0;
+
+	return ret;
+}