Create a new libsubid

Closes #154

Currently this has three functions: one which returns the
list of subuid ranges for a user, one returning the subgids,
and one which frees the ranges lists.

I might be mistaken about what -disable-man means;  some of
the code suggests it means just don't re-generate them, but
not totally ignore them.  But that doesn't seem to really work,
so let's just ignore man/ when -disable-man.

Remove --disable-shared.  I'm not sure why it was there, but it stems
from long, long ago, and I suspect it comes from some ancient
toolchain bug.

Create a tests/run_some, a shorter version of run_all.  I'll
slowly add tests to this as I verify they work, then I can
work on fixing the once which don't.

Also, don't touch man/ if not -enable-man.

Changelog:
	Apr 22: change the subid list api as recomended by Dan Walsh.
	Apr 23: implement get_subid_owner
	Apr 24: implement range add/release
	Apr 25: finish tests and rebase
	May 10: make @owner const

Signed-off-by: Serge Hallyn <serge@hallyn.com>

libsubid/Makefile.am

@@ -0,0 +1,25 @@
+lib_LTLIBRARIES = libsubid.la
+libsubid_la_LDFLAGS = -Wl,-soname,libsubid.so.@LIBSUBID_ABI@ \
+	-shared -version-info @LIBSUBID_ABI_MAJOR@
+libsubid_la_SOURCES = api.c
+
+MISCLIBS = \
+	$(LIBAUDIT) \
+	$(LIBSELINUX) \
+	$(LIBSEMANAGE) \
+	$(LIBCRYPT_NOPAM) \
+	$(LIBSKEY) \
+	$(LIBMD) \
+	$(LIBECONF) \
+	$(LIBCRYPT) \
+	$(LIBTCB)
+
+libsubid_la_LIBADD = \
+	$(top_srcdir)/lib/libshadow.la \
+	$(top_srcdir)/libmisc/libmisc.a \
+	$(MISCLIBS)
+
+AM_CPPFLAGS = \
+	-I${top_srcdir}/lib \
+	-I${top_srcdir}/libmisc \
+	-DLOCALEDIR=\"$(datadir)/locale\"

libsubid/api.c

@@ -0,0 +1,231 @@
+/*
+ * Copyright (c) 2020 Serge Hallyn
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the copyright holders or contributors may not be used to
+ *    endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <config.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <pwd.h>
+#include <stdbool.h>
+#include "subordinateio.h"
+#include "idmapping.h"
+#include "api.h"
+
+static struct subordinate_range **get_subid_ranges(const char *owner, enum subid_type id_type)
+{
+	struct subordinate_range **ranges = NULL;
+
+	switch (id_type) {
+	case ID_TYPE_UID:
+		if (!sub_uid_open(O_RDONLY)) {
+			return NULL;
+		}
+		break;
+	case ID_TYPE_GID:
+		if (!sub_gid_open(O_RDONLY)) {
+			return NULL;
+		}
+		break;
+	default:
+		return NULL;
+	}
+
+	ranges = list_owner_ranges(owner, id_type);
+
+	if (id_type == ID_TYPE_UID)
+		sub_uid_close();
+	else
+		sub_gid_close();
+
+	return ranges;
+}
+
+struct subordinate_range **get_subuid_ranges(const char *owner)
+{
+	return get_subid_ranges(owner, ID_TYPE_UID);
+}
+
+struct subordinate_range **get_subgid_ranges(const char *owner)
+{
+	return get_subid_ranges(owner, ID_TYPE_GID);
+}
+
+void subid_free_ranges(struct subordinate_range **ranges)
+{
+	return free_subordinate_ranges(ranges);
+}
+
+int get_subid_owner(unsigned long id, uid_t **owner, enum subid_type id_type)
+{
+	int ret = -1;
+
+	switch (id_type) {
+	case ID_TYPE_UID:
+		if (!sub_uid_open(O_RDONLY)) {
+			return -1;
+		}
+		break;
+	case ID_TYPE_GID:
+		if (!sub_gid_open(O_RDONLY)) {
+			return -1;
+		}
+		break;
+	default:
+		return -1;
+	}
+
+	ret = find_subid_owners(id, owner, id_type);
+
+	if (id_type == ID_TYPE_UID)
+		sub_uid_close();
+	else
+		sub_gid_close();
+
+	return ret;
+}
+
+int get_subuid_owners(uid_t uid, uid_t **owner)
+{
+	return get_subid_owner((unsigned long)uid, owner, ID_TYPE_UID);
+}
+
+int get_subgid_owners(gid_t gid, uid_t **owner)
+{
+	return get_subid_owner((unsigned long)gid, owner, ID_TYPE_GID);
+}
+
+bool grant_subid_range(struct subordinate_range *range, bool reuse,
+		       enum subid_type id_type)
+{
+	bool ret;
+
+	switch (id_type) {
+	case ID_TYPE_UID:
+		if (!sub_uid_lock()) {
+			printf("Failed loging subuids (errno %d)\n", errno);
+			return false;
+		}
+		if (!sub_uid_open(O_CREAT | O_RDWR)) {
+			printf("Failed opening subuids (errno %d)\n", errno);
+			sub_uid_unlock();
+			return false;
+		}
+		break;
+	case ID_TYPE_GID:
+		if (!sub_gid_lock()) {
+			printf("Failed loging subgids (errno %d)\n", errno);
+			return false;
+		}
+		if (!sub_gid_open(O_CREAT | O_RDWR)) {
+			printf("Failed opening subgids (errno %d)\n", errno);
+			sub_gid_unlock();
+			return false;
+		}
+		break;
+	default:
+		return false;
+	}
+
+	ret = new_subid_range(range, id_type, reuse);
+
+	if (id_type == ID_TYPE_UID) {
+		sub_uid_close();
+		sub_uid_unlock();
+	} else {
+		sub_gid_close();
+		sub_gid_unlock();
+	}
+
+	return ret;
+}
+
+bool grant_subuid_range(struct subordinate_range *range, bool reuse)
+{
+	return grant_subid_range(range, reuse, ID_TYPE_UID);
+}
+
+bool grant_subgid_range(struct subordinate_range *range, bool reuse)
+{
+	return grant_subid_range(range, reuse, ID_TYPE_GID);
+}
+
+bool free_subid_range(struct subordinate_range *range, enum subid_type id_type)
+{
+	bool ret;
+
+	switch (id_type) {
+	case ID_TYPE_UID:
+		if (!sub_uid_lock()) {
+			printf("Failed loging subuids (errno %d)\n", errno);
+			return false;
+		}
+		if (!sub_uid_open(O_CREAT | O_RDWR)) {
+			printf("Failed opening subuids (errno %d)\n", errno);
+			sub_uid_unlock();
+			return false;
+		}
+		break;
+	case ID_TYPE_GID:
+		if (!sub_gid_lock()) {
+			printf("Failed loging subgids (errno %d)\n", errno);
+			return false;
+		}
+		if (!sub_gid_open(O_CREAT | O_RDWR)) {
+			printf("Failed opening subgids (errno %d)\n", errno);
+			sub_gid_unlock();
+			return false;
+		}
+		break;
+	default:
+		return false;
+	}
+
+	ret = release_subid_range(range, id_type);
+
+	if (id_type == ID_TYPE_UID) {
+		sub_uid_close();
+		sub_uid_unlock();
+	} else {
+		sub_gid_close();
+		sub_gid_unlock();
+	}
+
+	return ret;
+}
+
+bool free_subuid_range(struct subordinate_range *range)
+{
+	return free_subid_range(range, ID_TYPE_UID);
+}
+
+bool free_subgid_range(struct subordinate_range *range)
+{
+	return free_subid_range(range, ID_TYPE_GID);
+}

libsubid/api.h

@@ -0,0 +1,17 @@
+#include "subid.h"
+#include <stdbool.h>
+
+struct subordinate_range **get_subuid_ranges(const char *owner);
+struct subordinate_range **get_subgid_ranges(const char *owner);
+void subid_free_ranges(struct subordinate_range **ranges);
+
+int get_subuid_owners(uid_t uid, uid_t **owner);
+int get_subgid_owners(uid_t uid, uid_t **owner);
+
+/* range should be pre-allocated with owner and count filled in, start is
+ * ignored, can be 0 */
+bool grant_subuid_range(struct subordinate_range *range, bool reuse);
+bool grant_subgid_range(struct subordinate_range *range, bool reuse);
+
+bool free_subuid_range(struct subordinate_range *range);
+bool free_subgid_range(struct subordinate_range *range);

libsubid/subid.h

@@ -0,0 +1,17 @@
+#include <sys/types.h>
+
+#ifndef SUBID_RANGE_DEFINED
+#define SUBID_RANGE_DEFINED 1
+struct subordinate_range {
+	const char *owner;
+	unsigned long start;
+	unsigned long count;
+};
+
+enum subid_type {
+	ID_TYPE_UID = 1,
+	ID_TYPE_GID = 2
+};
+
+#define SUBID_NFIELDS 3
+#endif