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selftests: create detached mounts from detached mounts
Link: https://lore.kernel.org/r/20250221-brauner-open_tree-v1-7-dbcfcb98c676@kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
parent
c5c12f871a
commit
3f1724dd56
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@ -126,6 +126,26 @@
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#endif
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#endif
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#ifndef __NR_move_mount
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#if defined __alpha__
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#define __NR_move_mount 539
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#elif defined _MIPS_SIM
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#if _MIPS_SIM == _MIPS_SIM_ABI32 /* o32 */
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#define __NR_move_mount 4429
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#endif
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#if _MIPS_SIM == _MIPS_SIM_NABI32 /* n32 */
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#define __NR_move_mount 6429
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#endif
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#if _MIPS_SIM == _MIPS_SIM_ABI64 /* n64 */
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#define __NR_move_mount 5429
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#endif
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#elif defined __ia64__
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#define __NR_move_mount (428 + 1024)
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#else
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#define __NR_move_mount 429
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#endif
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#endif
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#ifndef MOUNT_ATTR_IDMAP
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#define MOUNT_ATTR_IDMAP 0x00100000
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#endif
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@ -157,6 +177,51 @@ static inline int sys_open_tree(int dfd, const char *filename, unsigned int flag
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return syscall(__NR_open_tree, dfd, filename, flags);
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}
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/* move_mount() flags */
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#ifndef MOVE_MOUNT_F_SYMLINKS
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#define MOVE_MOUNT_F_SYMLINKS 0x00000001 /* Follow symlinks on from path */
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#endif
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#ifndef MOVE_MOUNT_F_AUTOMOUNTS
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#define MOVE_MOUNT_F_AUTOMOUNTS 0x00000002 /* Follow automounts on from path */
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#endif
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#ifndef MOVE_MOUNT_F_EMPTY_PATH
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#define MOVE_MOUNT_F_EMPTY_PATH 0x00000004 /* Empty from path permitted */
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#endif
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#ifndef MOVE_MOUNT_T_SYMLINKS
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#define MOVE_MOUNT_T_SYMLINKS 0x00000010 /* Follow symlinks on to path */
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#endif
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#ifndef MOVE_MOUNT_T_AUTOMOUNTS
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#define MOVE_MOUNT_T_AUTOMOUNTS 0x00000020 /* Follow automounts on to path */
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#endif
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#ifndef MOVE_MOUNT_T_EMPTY_PATH
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#define MOVE_MOUNT_T_EMPTY_PATH 0x00000040 /* Empty to path permitted */
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#endif
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#ifndef MOVE_MOUNT_SET_GROUP
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#define MOVE_MOUNT_SET_GROUP 0x00000100 /* Set sharing group instead */
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#endif
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#ifndef MOVE_MOUNT_BENEATH
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#define MOVE_MOUNT_BENEATH 0x00000200 /* Mount beneath top mount */
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#endif
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#ifndef MOVE_MOUNT__MASK
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#define MOVE_MOUNT__MASK 0x00000377
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#endif
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static inline int sys_move_mount(int from_dfd, const char *from_pathname,
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int to_dfd, const char *to_pathname,
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unsigned int flags)
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{
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return syscall(__NR_move_mount, from_dfd, from_pathname, to_dfd,
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to_pathname, flags);
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}
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static ssize_t write_nointr(int fd, const void *buf, size_t count)
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{
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ssize_t ret;
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@ -397,6 +462,10 @@ FIXTURE_SETUP(mount_setattr)
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ASSERT_EQ(mkdir("/tmp/B/BB", 0777), 0);
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ASSERT_EQ(mkdir("/tmp/target1", 0777), 0);
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ASSERT_EQ(mkdir("/tmp/target2", 0777), 0);
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ASSERT_EQ(mount("testing", "/tmp/B/BB", "tmpfs", MS_NOATIME | MS_NODEV,
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"size=100000,mode=700"), 0);
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@ -1506,4 +1575,218 @@ TEST_F(mount_setattr, mount_attr_nosymfollow)
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ASSERT_EQ(close(fd), 0);
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}
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TEST_F(mount_setattr, open_tree_detached)
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{
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int fd_tree_base = -EBADF, fd_tree_subdir = -EBADF;
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struct statx stx;
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fd_tree_base = sys_open_tree(-EBADF, "/mnt",
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AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW |
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AT_RECURSIVE | OPEN_TREE_CLOEXEC |
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OPEN_TREE_CLONE);
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ASSERT_GE(fd_tree_base, 0);
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/*
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* /mnt testing tmpfs
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* |-/mnt/A testing tmpfs
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* | `-/mnt/A/AA testing tmpfs
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* | `-/mnt/A/AA/B testing tmpfs
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* | `-/mnt/A/AA/B/BB testing tmpfs
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* `-/mnt/B testing ramfs
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*/
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ASSERT_EQ(statx(fd_tree_base, "A", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_base, "A/AA", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_base, "A/AA/B", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_base, "A/AA/B/BB", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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fd_tree_subdir = sys_open_tree(fd_tree_base, "A/AA",
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AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW |
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AT_RECURSIVE | OPEN_TREE_CLOEXEC |
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OPEN_TREE_CLONE);
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ASSERT_GE(fd_tree_subdir, 0);
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/*
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* /AA testing tmpfs
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* `-/AA/B testing tmpfs
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* `-/AA/B/BB testing tmpfs
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*/
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ASSERT_EQ(statx(fd_tree_subdir, "B", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_subdir, "B/BB", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(move_mount(fd_tree_subdir, "", -EBADF, "/tmp/target1", MOVE_MOUNT_F_EMPTY_PATH), 0);
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/*
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* /tmp/target1 testing tmpfs
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* `-/tmp/target1/B testing tmpfs
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* `-/tmp/target1/B/BB testing tmpfs
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*/
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ASSERT_EQ(statx(-EBADF, "/tmp/target1", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(-EBADF, "/tmp/target1/B", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(-EBADF, "/tmp/target1/B/BB", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(move_mount(fd_tree_base, "", -EBADF, "/tmp/target2", MOVE_MOUNT_F_EMPTY_PATH), 0);
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/*
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* /tmp/target2 testing tmpfs
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* |-/tmp/target2/A testing tmpfs
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* | `-/tmp/target2/A/AA testing tmpfs
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* | `-/tmp/target2/A/AA/B testing tmpfs
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* | `-/tmp/target2/A/AA/B/BB testing tmpfs
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* `-/tmp/target2/B testing ramfs
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*/
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ASSERT_EQ(statx(-EBADF, "/tmp/target2", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(-EBADF, "/tmp/target2/A", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(-EBADF, "/tmp/target2/A/AA", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(-EBADF, "/tmp/target2/A/AA/B", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(-EBADF, "/tmp/target2/A/AA/B/BB", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(-EBADF, "/tmp/target2/B", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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EXPECT_EQ(close(fd_tree_base), 0);
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EXPECT_EQ(close(fd_tree_subdir), 0);
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}
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TEST_F(mount_setattr, open_tree_detached_fail)
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{
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int fd_tree_base = -EBADF, fd_tree_subdir = -EBADF;
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struct statx stx;
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fd_tree_base = sys_open_tree(-EBADF, "/mnt",
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AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW |
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AT_RECURSIVE | OPEN_TREE_CLOEXEC |
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OPEN_TREE_CLONE);
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ASSERT_GE(fd_tree_base, 0);
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/*
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* /mnt testing tmpfs
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* |-/mnt/A testing tmpfs
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* | `-/mnt/A/AA testing tmpfs
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* | `-/mnt/A/AA/B testing tmpfs
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* | `-/mnt/A/AA/B/BB testing tmpfs
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* `-/mnt/B testing ramfs
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*/
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ASSERT_EQ(statx(fd_tree_base, "A", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_base, "A/AA", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_base, "A/AA/B", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_base, "A/AA/B/BB", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(unshare(CLONE_NEWNS), 0);
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/*
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* The origin mount namespace of the anonymous mount namespace
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* of @fd_tree_base doesn't match the caller's mount namespace
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* anymore so creation of another detached mounts must fail.
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*/
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fd_tree_subdir = sys_open_tree(fd_tree_base, "A/AA",
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AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW |
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AT_RECURSIVE | OPEN_TREE_CLOEXEC |
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OPEN_TREE_CLONE);
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ASSERT_LT(fd_tree_subdir, 0);
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ASSERT_EQ(errno, EINVAL);
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}
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TEST_F(mount_setattr, open_tree_detached_fail2)
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{
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int fd_tree_base = -EBADF, fd_tree_subdir = -EBADF;
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struct statx stx;
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fd_tree_base = sys_open_tree(-EBADF, "/mnt",
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AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW |
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AT_RECURSIVE | OPEN_TREE_CLOEXEC |
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OPEN_TREE_CLONE);
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ASSERT_GE(fd_tree_base, 0);
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/*
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* /mnt testing tmpfs
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* |-/mnt/A testing tmpfs
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* | `-/mnt/A/AA testing tmpfs
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* | `-/mnt/A/AA/B testing tmpfs
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* | `-/mnt/A/AA/B/BB testing tmpfs
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* `-/mnt/B testing ramfs
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*/
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ASSERT_EQ(statx(fd_tree_base, "A", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_base, "A/AA", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_base, "A/AA/B", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_base, "A/AA/B/BB", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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EXPECT_EQ(create_and_enter_userns(), 0);
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/*
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* The caller entered a new user namespace. They will have
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* CAP_SYS_ADMIN in this user namespace. However, they're still
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* located in a mount namespace that is owned by an ancestor
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* user namespace in which they hold no privilege. Creating a
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* detached mount must thus fail.
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*/
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fd_tree_subdir = sys_open_tree(fd_tree_base, "A/AA",
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AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW |
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AT_RECURSIVE | OPEN_TREE_CLOEXEC |
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OPEN_TREE_CLONE);
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ASSERT_LT(fd_tree_subdir, 0);
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ASSERT_EQ(errno, EPERM);
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}
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TEST_F(mount_setattr, open_tree_detached_fail3)
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{
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int fd_tree_base = -EBADF, fd_tree_subdir = -EBADF;
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struct statx stx;
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fd_tree_base = sys_open_tree(-EBADF, "/mnt",
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AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW |
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AT_RECURSIVE | OPEN_TREE_CLOEXEC |
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OPEN_TREE_CLONE);
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ASSERT_GE(fd_tree_base, 0);
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/*
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* /mnt testing tmpfs
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* |-/mnt/A testing tmpfs
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* | `-/mnt/A/AA testing tmpfs
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* | `-/mnt/A/AA/B testing tmpfs
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* | `-/mnt/A/AA/B/BB testing tmpfs
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* `-/mnt/B testing ramfs
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*/
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ASSERT_EQ(statx(fd_tree_base, "A", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_base, "A/AA", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_base, "A/AA/B", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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ASSERT_EQ(statx(fd_tree_base, "A/AA/B/BB", 0, 0, &stx), 0);
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ASSERT_TRUE(stx.stx_attributes & STATX_ATTR_MOUNT_ROOT);
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EXPECT_EQ(prepare_unpriv_mountns(), 0);
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/*
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* The caller entered a new mount namespace. They will have
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* CAP_SYS_ADMIN in the owning user namespace of their mount
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* namespace.
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*
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* However, the origin mount namespace of the anonymous mount
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* namespace of @fd_tree_base doesn't match the caller's mount
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* namespace anymore so creation of another detached mounts must
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* fail.
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*/
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fd_tree_subdir = sys_open_tree(fd_tree_base, "A/AA",
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AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW |
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AT_RECURSIVE | OPEN_TREE_CLOEXEC |
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OPEN_TREE_CLONE);
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ASSERT_LT(fd_tree_subdir, 0);
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ASSERT_EQ(errno, EINVAL);
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}
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TEST_HARNESS_MAIN
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