forked from Minki/linux
da362b09e4
Andrew Vagin <avagin@parallels.com> writes:
> #define _GNU_SOURCE
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <fcntl.h>
> #include <sched.h>
> #include <unistd.h>
> #include <sys/mount.h>
>
> int main(int argc, char **argv)
> {
> int fd;
>
> fd = open("/proc/self/ns/mnt", O_RDONLY);
> if (fd < 0)
> return 1;
> while (1) {
> if (umount2("/", MNT_DETACH) ||
> setns(fd, CLONE_NEWNS))
> break;
> }
>
> return 0;
> }
>
> root@ubuntu:/home/avagin# gcc -Wall nsenter.c -o nsenter
> root@ubuntu:/home/avagin# strace ./nsenter
> execve("./nsenter", ["./nsenter"], [/* 22 vars */]) = 0
> ...
> open("/proc/self/ns/mnt", O_RDONLY) = 3
> umount("/", MNT_DETACH) = 0
> setns(3, 131072) = 0
> umount("/", MNT_DETACH
>
causes:
> [ 260.548301] ------------[ cut here ]------------
> [ 260.550941] kernel BUG at /build/buildd/linux-3.13.0/fs/pnode.c:372!
> [ 260.552068] invalid opcode: 0000 [#1] SMP
> [ 260.552068] Modules linked in: xt_CHECKSUM iptable_mangle xt_tcpudp xt_addrtype xt_conntrack ipt_MASQUERADE iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack bridge stp llc dm_thin_pool dm_persistent_data dm_bufio dm_bio_prison iptable_filter ip_tables x_tables crct10dif_pclmul crc32_pclmul ghash_clmulni_intel binfmt_misc nfsd auth_rpcgss nfs_acl aesni_intel nfs lockd aes_x86_64 sunrpc fscache lrw gf128mul glue_helper ablk_helper cryptd serio_raw ppdev parport_pc lp parport btrfs xor raid6_pq libcrc32c psmouse floppy
> [ 260.552068] CPU: 0 PID: 1723 Comm: nsenter Not tainted 3.13.0-30-generic #55-Ubuntu
> [ 260.552068] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> [ 260.552068] task: ffff8800376097f0 ti: ffff880074824000 task.ti: ffff880074824000
> [ 260.552068] RIP: 0010:[<ffffffff811e9483>] [<ffffffff811e9483>] propagate_umount+0x123/0x130
> [ 260.552068] RSP: 0018:ffff880074825e98 EFLAGS: 00010246
> [ 260.552068] RAX: ffff88007c741140 RBX: 0000000000000002 RCX: ffff88007c741190
> [ 260.552068] RDX: ffff88007c741190 RSI: ffff880074825ec0 RDI: ffff880074825ec0
> [ 260.552068] RBP: ffff880074825eb0 R08: 00000000000172e0 R09: ffff88007fc172e0
> [ 260.552068] R10: ffffffff811cc642 R11: ffffea0001d59000 R12: ffff88007c741140
> [ 260.552068] R13: ffff88007c741140 R14: ffff88007c741140 R15: 0000000000000000
> [ 260.552068] FS: 00007fd5c7e41740(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000
> [ 260.552068] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 260.552068] CR2: 00007fd5c7968050 CR3: 0000000070124000 CR4: 00000000000406f0
> [ 260.552068] Stack:
> [ 260.552068] 0000000000000002 0000000000000002 ffff88007c631000 ffff880074825ed8
> [ 260.552068] ffffffff811dcfac ffff88007c741140 0000000000000002 ffff88007c741160
> [ 260.552068] ffff880074825f38 ffffffff811dd12b ffffffff811cc642 0000000075640000
> [ 260.552068] Call Trace:
> [ 260.552068] [<ffffffff811dcfac>] umount_tree+0x20c/0x260
> [ 260.552068] [<ffffffff811dd12b>] do_umount+0x12b/0x300
> [ 260.552068] [<ffffffff811cc642>] ? final_putname+0x22/0x50
> [ 260.552068] [<ffffffff811cc849>] ? putname+0x29/0x40
> [ 260.552068] [<ffffffff811dd88c>] SyS_umount+0xdc/0x100
> [ 260.552068] [<ffffffff8172aeff>] tracesys+0xe1/0xe6
> [ 260.552068] Code: 89 50 08 48 8b 50 08 48 89 02 49 89 45 08 e9 72 ff ff ff 0f 1f 44 00 00 4c 89 e6 4c 89 e7 e8 f5 f6 ff ff 48 89 c3 e9 39 ff ff ff <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 66 66 66 66 90 55 b8 01
> [ 260.552068] RIP [<ffffffff811e9483>] propagate_umount+0x123/0x130
> [ 260.552068] RSP <ffff880074825e98>
> [ 260.611451] ---[ end trace 11c33d85f1d4c652 ]--
Which in practice is totally uninteresting. Only the global root user can
do it, and it is just a stupid thing to do.
However that is no excuse to allow a silly way to oops the kernel.
We can avoid this silly problem by setting MNT_LOCKED on the rootfs
mount point and thus avoid needing any special cases in the unmount
code.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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| .. | ||
| 9p | ||
| adfs | ||
| affs | ||
| afs | ||
| autofs4 | ||
| befs | ||
| bfs | ||
| btrfs | ||
| cachefiles | ||
| ceph | ||
| cifs | ||
| coda | ||
| configfs | ||
| cramfs | ||
| debugfs | ||
| devpts | ||
| dlm | ||
| ecryptfs | ||
| efivarfs | ||
| efs | ||
| exofs | ||
| exportfs | ||
| ext2 | ||
| ext3 | ||
| ext4 | ||
| f2fs | ||
| fat | ||
| freevxfs | ||
| fscache | ||
| fuse | ||
| gfs2 | ||
| hfs | ||
| hfsplus | ||
| hostfs | ||
| hpfs | ||
| hppfs | ||
| hugetlbfs | ||
| isofs | ||
| jbd | ||
| jbd2 | ||
| jffs2 | ||
| jfs | ||
| kernfs | ||
| lockd | ||
| logfs | ||
| minix | ||
| ncpfs | ||
| nfs | ||
| nfs_common | ||
| nfsd | ||
| nilfs2 | ||
| nls | ||
| notify | ||
| ntfs | ||
| ocfs2 | ||
| omfs | ||
| openpromfs | ||
| overlayfs | ||
| proc | ||
| pstore | ||
| qnx4 | ||
| qnx6 | ||
| quota | ||
| ramfs | ||
| reiserfs | ||
| romfs | ||
| squashfs | ||
| sysfs | ||
| sysv | ||
| ubifs | ||
| udf | ||
| ufs | ||
| xfs | ||
| aio.c | ||
| anon_inodes.c | ||
| attr.c | ||
| bad_inode.c | ||
| binfmt_aout.c | ||
| binfmt_elf_fdpic.c | ||
| binfmt_elf.c | ||
| binfmt_em86.c | ||
| binfmt_flat.c | ||
| binfmt_misc.c | ||
| binfmt_script.c | ||
| binfmt_som.c | ||
| block_dev.c | ||
| buffer.c | ||
| char_dev.c | ||
| compat_binfmt_elf.c | ||
| compat_ioctl.c | ||
| compat.c | ||
| coredump.c | ||
| dcache.c | ||
| dcookies.c | ||
| direct-io.c | ||
| drop_caches.c | ||
| eventfd.c | ||
| eventpoll.c | ||
| exec.c | ||
| fcntl.c | ||
| fhandle.c | ||
| file_table.c | ||
| file.c | ||
| filesystems.c | ||
| fs_pin.c | ||
| fs_struct.c | ||
| fs-writeback.c | ||
| inode.c | ||
| internal.h | ||
| ioctl.c | ||
| Kconfig | ||
| Kconfig.binfmt | ||
| libfs.c | ||
| locks.c | ||
| Makefile | ||
| mbcache.c | ||
| mount.h | ||
| mpage.c | ||
| namei.c | ||
| namespace.c | ||
| no-block.c | ||
| open.c | ||
| pipe.c | ||
| pnode.c | ||
| pnode.h | ||
| posix_acl.c | ||
| proc_namespace.c | ||
| read_write.c | ||
| readdir.c | ||
| select.c | ||
| seq_file.c | ||
| signalfd.c | ||
| splice.c | ||
| stack.c | ||
| stat.c | ||
| statfs.c | ||
| super.c | ||
| sync.c | ||
| timerfd.c | ||
| utimes.c | ||
| xattr.c | ||