[07/10] libbtrfsutil: relax the privileges of subvolume_info()

Message ID	4412561bf224e10c32bd9851f9281f291f7d3879.1542181521.git.osandov@fb.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-btrfs-owner@kernel.org> From: Omar Sandoval <osandov@osandov.com> To: linux-btrfs@vger.kernel.org Cc: kernel-team@fb.com, Misono Tomohiro <misono.tomohiro@jp.fujitsu.com> Subject: [PATCH 07/10] libbtrfsutil: relax the privileges of subvolume_info() Date: Tue, 13 Nov 2018 23:47:02 -0800 Message-Id: <4412561bf224e10c32bd9851f9281f291f7d3879.1542181521.git.osandov@fb.com> In-Reply-To: <cover.1542181521.git.osandov@fb.com> References: <cover.1542181521.git.osandov@fb.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk
Series	btrfs-progs: my libbtrfsutil patch queue \| expand [00/10] btrfs-progs: my libbtrfsutil patch queue [01/10] libbtrfsutil: use top=0 as default for SubvolumeIterator() [02/10] libbtrfsutil: change async parameters to async_ in Python bindings [03/10] libbtrfsutil: document qgroup_inherit parameter in Python bindings [04/10] libbtrfsutil: use SubvolumeIterator as context manager in tests [05/10] libbtrfsutil: add test helpers for dropping privileges [06/10] libbtrfsutil: allow tests to create multiple Btrfs instances [07/10] libbtrfsutil: relax the privileges of subvolume_info() [08/10] libbtrfsutil: relax the privileges of subvolume iterator [09/10] libbtrfsutil: bump version to 1.1.0 [10/10] libbtrfsutil: document API in README

diff --git a/libbtrfsutil/btrfsutil.h b/libbtrfsutil/btrfsutil.h index 6d655f49..c1925007 100644 --- a/libbtrfsutil/btrfsutil.h +++ b/libbtrfsutil/btrfsutil.h @@ -63,6 +63,7 @@ enum btrfs_util_error { BTRFS_UTIL_ERROR_SYNC_FAILED, BTRFS_UTIL_ERROR_START_SYNC_FAILED, BTRFS_UTIL_ERROR_WAIT_SYNC_FAILED, + BTRFS_UTIL_ERROR_GET_SUBVOL_INFO_FAILED, }; /** @@ -266,7 +267,8 @@ struct btrfs_util_subvolume_info { * to check whether the subvolume exists; %BTRFS_UTIL_ERROR_SUBVOLUME_NOT_FOUND * will be returned if it does not. * - * This requires appropriate privilege (CAP_SYS_ADMIN). + * This requires appropriate privilege (CAP_SYS_ADMIN) unless @id is zero and + * the kernel supports BTRFS_IOC_GET_SUBVOL_INFO (kernel >= 4.18). * * Return: %BTRFS_UTIL_OK on success, non-zero error code on failure. */ diff --git a/libbtrfsutil/errors.c b/libbtrfsutil/errors.c index 634edc65..cf968b03 100644 --- a/libbtrfsutil/errors.c +++ b/libbtrfsutil/errors.c @@ -45,6 +45,8 @@ static const char * const error_messages[] = { [BTRFS_UTIL_ERROR_SYNC_FAILED] = "Could not sync filesystem", [BTRFS_UTIL_ERROR_START_SYNC_FAILED] = "Could not start filesystem sync", [BTRFS_UTIL_ERROR_WAIT_SYNC_FAILED] = "Could not wait for filesystem sync", + [BTRFS_UTIL_ERROR_GET_SUBVOL_INFO_FAILED] = + "Could not get subvolume information with BTRFS_IOC_GET_SUBVOL_INFO", }; PUBLIC const char *btrfs_util_strerror(enum btrfs_util_error err) diff --git a/libbtrfsutil/python/tests/test_subvolume.py b/libbtrfsutil/python/tests/test_subvolume.py index 4049b08e..55ebf34d 100644 --- a/libbtrfsutil/python/tests/test_subvolume.py +++ b/libbtrfsutil/python/tests/test_subvolume.py @@ -23,7 +23,12 @@ from pathlib import PurePath import traceback import btrfsutil -from tests import BtrfsTestCase, HAVE_PATH_LIKE +from tests import ( + BtrfsTestCase, + drop_privs, + HAVE_PATH_LIKE, + skipUnlessHaveNobody, +) class TestSubvolume(BtrfsTestCase): @@ -87,7 +92,7 @@ class TestSubvolume(BtrfsTestCase): finally: os.chdir(pwd) - def test_subvolume_info(self): + def _test_subvolume_info(self, subvol, snapshot): for arg in self.path_or_fd(self.mountpoint): with self.subTest(type=type(arg)): info = btrfsutil.subvolume_info(arg) @@ -100,7 +105,7 @@ class TestSubvolume(BtrfsTestCase): self.assertEqual(info.parent_uuid, bytes(16)) self.assertEqual(info.received_uuid, bytes(16)) self.assertNotEqual(info.generation, 0) - self.assertEqual(info.ctransid, 0) + self.assertGreaterEqual(info.ctransid, 0) self.assertEqual(info.otransid, 0) self.assertEqual(info.stransid, 0) self.assertEqual(info.rtransid, 0) @@ -109,9 +114,6 @@ class TestSubvolume(BtrfsTestCase): self.assertEqual(info.stime, 0) self.assertEqual(info.rtime, 0) - subvol = os.path.join(self.mountpoint, 'subvol') - btrfsutil.create_subvolume(subvol) - info = btrfsutil.subvolume_info(subvol) self.assertEqual(info.id, 256) self.assertEqual(info.parent_id, 5) @@ -132,19 +134,43 @@ class TestSubvolume(BtrfsTestCase): self.assertEqual(info.rtime, 0) subvol_uuid = info.uuid - snapshot = os.path.join(self.mountpoint, 'snapshot') - btrfsutil.create_snapshot(subvol, snapshot) info = btrfsutil.subvolume_info(snapshot) self.assertEqual(info.parent_uuid, subvol_uuid) # TODO: test received_uuid, stransid, rtransid, stime, and rtime + def test_subvolume_info(self): + subvol = os.path.join(self.mountpoint, 'subvol') + btrfsutil.create_subvolume(subvol) + snapshot = os.path.join(self.mountpoint, 'snapshot') + btrfsutil.create_snapshot(subvol, snapshot) + + self._test_subvolume_info(subvol, snapshot) + for arg in self.path_or_fd(self.mountpoint): with self.subTest(type=type(arg)): with self.assertRaises(btrfsutil.BtrfsUtilError) as e: # BTRFS_EXTENT_TREE_OBJECTID btrfsutil.subvolume_info(arg, 2) + self.assertEqual(e.exception.btrfsutilerror, + btrfsutil.ERROR_SUBVOLUME_NOT_FOUND) + + @skipUnlessHaveNobody + def test_subvolume_info_unprivileged(self): + subvol = os.path.join(self.mountpoint, 'subvol') + btrfsutil.create_subvolume(subvol) + snapshot = os.path.join(self.mountpoint, 'snapshot') + btrfsutil.create_snapshot(subvol, snapshot) + + with drop_privs(): + try: + self._test_subvolume_info(subvol, snapshot) + except OSError as e: + if e.errno == errno.ENOTTY: + self.skipTest('BTRFS_IOC_GET_SUBVOL_INFO is not available') + else: + raise def test_read_only(self): for arg in self.path_or_fd(self.mountpoint): diff --git a/libbtrfsutil/subvolume.c b/libbtrfsutil/subvolume.c index 0d7ef5bf..69654db4 100644 --- a/libbtrfsutil/subvolume.c +++ b/libbtrfsutil/subvolume.c @@ -31,6 +31,11 @@ #include "btrfsutil_internal.h" +static bool is_root(void) +{ + return geteuid() == 0; +} + /* * This intentionally duplicates btrfs_util_is_subvolume_fd() instead of opening * a file descriptor and calling it, because fstat() and fstatfs() don't accept @@ -295,8 +300,8 @@ PUBLIC enum btrfs_util_error btrfs_util_subvolume_info(const char *path, return err; } -static enum btrfs_util_error get_subvolume_info_root(int fd, uint64_t id, - struct btrfs_util_subvolume_info *subvol) +static enum btrfs_util_error get_subvolume_info_privileged(int fd, uint64_t id, + struct btrfs_util_subvolume_info *subvol) { struct btrfs_ioctl_search_args search = { .key = { @@ -383,6 +388,45 @@ static enum btrfs_util_error get_subvolume_info_root(int fd, uint64_t id, return BTRFS_UTIL_OK; } +static enum btrfs_util_error get_subvolume_info_unprivileged(int fd, + struct btrfs_util_subvolume_info *subvol) +{ + struct btrfs_ioctl_get_subvol_info_args info; + int ret; + + ret = ioctl(fd, BTRFS_IOC_GET_SUBVOL_INFO, &info); + if (ret == -1) + return BTRFS_UTIL_ERROR_GET_SUBVOL_INFO_FAILED; + + subvol->id = info.treeid; + subvol->parent_id = info.parent_id; + subvol->dir_id = info.dirid; + subvol->flags = info.flags; + subvol->generation = info.generation; + + memcpy(subvol->uuid, info.uuid, sizeof(subvol->uuid)); + memcpy(subvol->parent_uuid, info.parent_uuid, + sizeof(subvol->parent_uuid)); + memcpy(subvol->received_uuid, info.received_uuid, + sizeof(subvol->received_uuid)); + + subvol->ctransid = info.ctransid; + subvol->otransid = info.otransid; + subvol->stransid = info.stransid; + subvol->rtransid = info.rtransid; + + subvol->ctime.tv_sec = info.ctime.sec; + subvol->ctime.tv_nsec = info.ctime.nsec; + subvol->otime.tv_sec = info.otime.sec; + subvol->otime.tv_nsec = info.otime.nsec; + subvol->stime.tv_sec = info.stime.sec; + subvol->stime.tv_nsec = info.stime.nsec; + subvol->rtime.tv_sec = info.rtime.sec; + subvol->rtime.tv_nsec = info.rtime.nsec; + + return BTRFS_UTIL_OK; +} + PUBLIC enum btrfs_util_error btrfs_util_subvolume_info_fd(int fd, uint64_t id, struct btrfs_util_subvolume_info *subvol) { @@ -393,6 +437,9 @@ PUBLIC enum btrfs_util_error btrfs_util_subvolume_info_fd(int fd, uint64_t id, if (err) return err; + if (!is_root()) + return get_subvolume_info_unprivileged(fd, subvol); + err = btrfs_util_subvolume_id_fd(fd, &id); if (err) return err; @@ -404,7 +451,7 @@ PUBLIC enum btrfs_util_error btrfs_util_subvolume_info_fd(int fd, uint64_t id, return BTRFS_UTIL_ERROR_SUBVOLUME_NOT_FOUND; } - return get_subvolume_info_root(fd, id, subvol); + return get_subvolume_info_privileged(fd, id, subvol); } PUBLIC enum btrfs_util_error btrfs_util_get_subvolume_read_only_fd(int fd,

[07/10] libbtrfsutil: relax the privileges of subvolume_info()

Commit Message

Patch