auth: filesystem unlink action check + add parent vnode to auth_filesystem_check

kernel-src/fs/devfs.c

@@ -191,7 +191,7 @@ int devfs_munmap(vnode_t *node, void *addr, uintmax_t offset, int flags, cred_t
 }
 
 int devfs_access(vnode_t *vnode, mode_t mode, cred_t *cred) {
-	return auth_filesystem_check(cred, auth_filesystem_convertaccess(mode), vnode) ? EACCES : 0;
+	return auth_filesystem_check(cred, auth_filesystem_convertaccess(mode), vnode, NULL) ? EACCES : 0;
 }
 
 int devfs_isatty(vnode_t *node) {

kernel-src/fs/ext2.c

@@ -1243,7 +1243,7 @@ static int ext2_getdents(vnode_t *vnode, dent_t *buffer, size_t count, uintmax_t
 }
 
 static int ext2_access(vnode_t *vnode, mode_t mode, cred_t *cred) {
-	return auth_filesystem_check(cred, auth_filesystem_convertaccess(mode), vnode) ? EACCES : 0;
+	return auth_filesystem_check(cred, auth_filesystem_convertaccess(mode), vnode, NULL) ? EACCES : 0;
 }
 
 static int ext2_readlink(vnode_t *vnode, char **link, cred_t *cred) {

kernel-src/fs/tmpfs.c

@@ -238,7 +238,7 @@ static int tmpfs_write(vnode_t *node, void *buffer, size_t size, uintmax_t offse
 }
 
 static int tmpfs_access(vnode_t *vnode, mode_t mode, cred_t *cred) {
-	return auth_filesystem_check(cred, auth_filesystem_convertaccess(mode), vnode) ? EACCES : 0;
+	return auth_filesystem_check(cred, auth_filesystem_convertaccess(mode), vnode, NULL) ? EACCES : 0;
 }
 
 static int tmpfs_unlink(vnode_t *node, vnode_t *child, char *name, cred_t *cred) {

kernel-src/fs/vfs.c

@@ -85,7 +85,7 @@ int vfs_mount(vnode_t *backing, vnode_t *pathref, char *path, char *name, void *
 	if (err)
 		return err;
 
-	err = auth_filesystem_check(getcred(), AUTH_ACTIONS_FILESYSTEM_MOUNT, mounton);
+	err = auth_filesystem_check(getcred(), AUTH_ACTIONS_FILESYSTEM_MOUNT, mounton, NULL);
 	if (err) {
 		// locked by vfs_lookup
 		VOP_UNLOCK(mounton);
@@ -487,22 +487,15 @@ int vfs_unlink(vnode_t *ref, char *path) {
 		goto cleanup;
 	}
 
-	// TODO auth check
-	if (0) {
-		// locked by VOP_LOOKUP
-		VOP_UNLOCK(child);
-		// locked by vfs_lookup, unlocked by VOP_LOOKUP if component is ".."
-		if (!isdotdot)
-			VOP_UNLOCK(parent);
-		VOP_RELEASE(child);
-		VOP_RELEASE(parent);
-		return err;
-	}
+	err = auth_filesystem_check(getcred(), AUTH_ACTIONS_FILESYSTEM_UNLINK, child, parent) ? EACCES : 0;
+	if (err)
+		goto cleanup_release;
 
 	err = VOP_UNLINK(parent, child, component, getcred());
+	cleanup_release:
 	// locked by VOP_LOOKUP
 	VOP_UNLOCK(child);
-		// locked by vfs_lookup, unlocked by VOP_LOOKUP if component is ".."
+	// locked by vfs_lookup, unlocked by VOP_LOOKUP if component is ".."
 	if (!isdotdot)
 		VOP_UNLOCK(parent);
 
@@ -570,7 +563,6 @@ int vfs_rename(vnode_t *srcref, char *srcpath, vnode_t *dstref, char *dstpath, i
 	if (src != dst)
 		VOP_LOCK(src); // lock it again for the rename if they arent the same
 
-	// TODO auth check
 	if (0)
 		goto cleanup_child;
 

kernel-src/include/kernel/auth.h

@@ -25,6 +25,7 @@
 #define AUTH_ACTIONS_FILESYSTEM_READ 	4
 #define AUTH_ACTIONS_FILESYSTEM_SETATTR 8
 #define AUTH_ACTIONS_FILESYSTEM_MOUNT 	16
+#define AUTH_ACTIONS_FILESYSTEM_UNLINK	32
 
 #define AUTH_ACTIONS_CRED_SETRESUID	1
 #define AUTH_ACTIONS_CRED_SETRESGID	2
@@ -44,8 +45,8 @@ typedef struct {
 void auth_registerlistener(int scope, authlistener_t listener);
 int auth_check(int scope, cred_t *cred, int actions, void *arg0, void *arg1, void *arg2);
 
-static inline int auth_filesystem_check(cred_t *cred, int actions, vnode_t *vnode) {
-	return auth_check(AUTH_SCOPE_FILESYSTEM, cred, actions, vnode, NULL, NULL);
+static inline int auth_filesystem_check(cred_t *cred, int actions, vnode_t *vnode, vnode_t *dirvnode) {
+	return auth_check(AUTH_SCOPE_FILESYSTEM, cred, actions, vnode, dirvnode, NULL);
 }
 
 static inline int auth_system_check(cred_t *cred, int actions) {

kernel-src/sys/defaultauth.c

@@ -10,10 +10,15 @@
 
 static int filesystem(cred_t *cred, int actions, void *arg0, void *arg1, void *arg2) {
 	vnode_t *vnode = arg0; // expected locked
+	vnode_t *dirvnode = arg1; // expected locked
 
 	vattr_t attr;
 	VOP_GETATTR(vnode, &attr, NULL);
 
+	vattr_t dirattr;
+	if (dirvnode)
+		VOP_GETATTR(dirvnode, &dirattr, NULL);
+
 	int weight = 0;
 	if (actions & AUTH_ACTIONS_FILESYSTEM_WRITE) {
 		if (CRED_IS_ESU(cred))
@@ -77,8 +82,43 @@ static int filesystem(cred_t *cred, int actions, void *arg0, void *arg1, void *a
 			weight += 1;
 		else
 			return AUTH_DECISION_DENY;
+
+		DONE_CHECK(actions);
 	}
 
+	if (actions & AUTH_ACTIONS_FILESYSTEM_UNLINK) {
+		__assert(dirvnode);
+
+		bool dosticky = false;
+		if (CRED_IS_ESU(cred)) {
+			dosticky = false;
+			weight += 1;
+		} else if (dirattr.uid == cred->euid && (dirattr.mode & V_ATTR_MODE_USER_WRITE)) {
+			dosticky = true;
+		} else if (dirattr.uid != cred->euid && dirattr.gid == cred->egid && (dirattr.mode & V_ATTR_MODE_GROUP_WRITE)) {
+			dosticky = true;
+		} else if (dirattr.uid != cred->euid && dirattr.gid != cred->egid && (dirattr.mode & V_ATTR_MODE_OTHERS_WRITE)) {
+			dosticky = true;
+		} else {
+			return AUTH_DECISION_DENY;
+		}
+
+		if (dosticky && (dirattr.mode & V_ATTR_MODE_STICKY)) {
+			// sticky directory, file can only be unlinked if:
+			// - user requesting deletion is root (already checked for)
+			// OR
+			// - user requesting deletion has write access (already checked for) AND
+			// - 	effective user requesting deletion is owner of directory
+			// 	OR
+			// - 	effective user requesting deletion is owner of file
+			if (dirattr.uid == cred->euid || attr.uid == cred->euid)
+				weight += 1;
+			else
+				return AUTH_DECISION_DENY;
+		}
+
+		DONE_CHECK(actions);
+	}
 
 	done:
 	return weight ? AUTH_DECISION_ALLOW : AUTH_DECISION_DEFER;

kernel-src/sys/syscalls/chmod.c

@@ -10,7 +10,7 @@ static int dochmod(vnode_t *node, mode_t mode) {
 	vattr_t attr;
 	cred_t *cred = &_cpu()->thread->proc->cred;
 
-	int e = auth_filesystem_check(cred, AUTH_ACTIONS_FILESYSTEM_SETATTR, node);
+	int e = auth_filesystem_check(cred, AUTH_ACTIONS_FILESYSTEM_SETATTR, node, NULL);
 	if (e)
 		return e;
 

kernel-src/sys/syscalls/fchownat.c

@@ -50,7 +50,7 @@ syscallret_t syscall_fchownat(context_t *, int fd, char *upath, uid_t owner, gid
 			goto cleanup;
 	}
 
-	ret.errno = auth_filesystem_check(&_cpu()->thread->proc->cred, AUTH_ACTIONS_FILESYSTEM_SETATTR, node);
+	ret.errno = auth_filesystem_check(&_cpu()->thread->proc->cred, AUTH_ACTIONS_FILESYSTEM_SETATTR, node, NULL);
 	if (ret.errno) {
 		VOP_UNLOCK(node);
 		goto cleanup;

kernel-src/sys/syscalls/utime.c

@@ -71,7 +71,7 @@ syscallret_t syscall_utimensat(context_t *, int fd, char *upath, timespec_t uts[
 	attr.atime = ts[0];
 	attr.mtime = ts[1];
 
-	ret.errno = auth_filesystem_check(&_cpu()->thread->proc->cred, AUTH_ACTIONS_FILESYSTEM_SETATTR, node);
+	ret.errno = auth_filesystem_check(&_cpu()->thread->proc->cred, AUTH_ACTIONS_FILESYSTEM_SETATTR, node, NULL);
 	if (ret.errno) {
 		if (uts == NULL)
 			ret.errno = VOP_ACCESS(node, V_ACCESS_WRITE, &_cpu()->thread->proc->cred);