Uploaded image for project: 'Lustre'
  1. Lustre
  2. LU-7002

mkfs.lustre mishandles SELinux context of temporary directory

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: Lustre 2.5.0, Lustre 2.7.0, Lustre 2.8.0
    • Fix Version/s: Lustre 2.9.0
    • Labels:
    • Severity:
      3
    • Rank (Obsolete):
      9223372036854775807

      Description

      After Shadow's patch for LU-2655 (see http://review.whamcloud.com/5135), in ldiskfs_write_ldd() if SELinux is enabled then the security context of the temporary mount point is appended to the mount options. Unfortunately this is done by appending the context to ldd_mount_opts and so it gets written into CONFIGS/mountdata.

      # lsb_release -d
      Description:	  CentOS Linux release 7.1.1503 (Core) 
      # git describe
      v2_7_57_0-60-g0addfa9
      # getenforce
      Enforcing
      # insmod ./ldiskfs/ldiskfs.ko 
      # dd if=/dev/zero of=/tmp/lustre-mdt1 bs=1K count=200000
      200000+0 records in
      200000+0 records out
      204800000 bytes (205 MB) copied, 1.40722 s, 146 MB/s
      # mkfs.lustre --fsname=lustre --mgs --mdt --index=0 /tmp/lustre-mdt1
      
         Permanent disk data:
      Target:     lustre:MDT0000
      Index:      0
      Lustre FS:  lustre
      Mount type: ldiskfs
      Flags:      0x65
                    (MDT MGS first_time update )
      Persistent mount opts: user_xattr,errors=remount-ro
      Parameters:
      
      checking for existing Lustre data: not found
      formatting backing filesystem ldiskfs on /dev/loop0
      	   target name  lustre:MDT0000
      	   4k blocks     0
      	   options        -I 512 -i 2048 -q -O dirdata,uninit_bg,^extents,dir_nlink,quota,huge_file,flex_bg -E lazy_journal_init -F
      mkfs_cmd = mke2fs -j -b 4096 -L lustre:MDT0000  -I 512 -i 2048 -q -O dirdata,uninit_bg,^extents,dir_nlink,quota,huge_file,flex_bg -E lazy_journal_init -F /dev/loop0
      Writing CONFIGS/mountdata
      # mount /tmp/lustre-mdt1 /mnt/mds1 -t ldiskfs -o loop
      # hexdump -C /mnt/mds1/CONFIGS/mountdata 
      00000000  01 00 d0 1d 00 00 00 00  00 00 00 00 00 00 00 00  |................|
      00000010  01 00 00 00 65 00 00 00  00 00 00 00 01 00 00 00  |....e...........|
      00000020  6c 75 73 74 72 65 00 00  00 00 00 00 00 00 00 00  |lustre..........|
      00000030  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
      *
      00000060  6c 75 73 74 72 65 3a 4d  44 54 30 30 30 30 00 00  |lustre:MDT0000..|
      00000070  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
      *
      00001000  75 73 65 72 5f 78 61 74  74 72 2c 65 72 72 6f 72  |user_xattr,error|
      00001010  73 3d 72 65 6d 6f 75 6e  74 2d 72 6f 2c 63 6f 6e  |s=remount-ro,con|
      00001020  74 65 78 74 3d 75 6e 63  6f 6e 66 69 6e 65 64 5f  |text=unconfined_|
      00001030  75 3a 6f 62 6a 65 63 74  5f 72 3a 75 73 65 72 5f  |u:object_r:user_|
      00001040  74 6d 70 5f 74 3a 73 30  00 00 00 00 00 00 00 00  |tmp_t:s0........|
      00001050  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
      *
      00003000
      # umount /mnt/mds1
      

      Then when the device is mounted as lustre mount.lustre tries to clear the LDD_F_UPDATE flag from CONFIGS/mountdata, so we call ldiskfs_write_ldd() again which appends the context to the new temporary directory to ldd_mount_opts and uses the result as the options to mount the target as ldiskfs. This fails since the context option can only be specified once.

      # LOAD=1 ./lustre/tests/llmount.sh
      Loading modules from /root/lustre-release/lustre
      ...
      # strace -f -o mount.strace -s 1024 mount /tmp/lustre-mdt1 /mnt/mds1 -t lustre -o loop
      mount.lustre: Unable to mount /dev/loop0: Invalid argument
      
      mount.lustre FATAL: failed to write local files: Invalid argument
      # awk '$2 ~ /^mount/' mount.strace
      8672  mount("/dev/loop0", "/tmp/mntACvy85", "ldiskfs", 0, "user_xattr,errors=remount-ro,context=unconfined_u:object_r:user_tmp_t:s0,context=unconfined_u:object_r:user_tmp_t:s0") = -1 EINVAL (Invalid argument)
      8672  mount("/dev/loop0", "/mnt/mds1", "lustre", MS_STRICTATIME, "osd=osd-ldiskfs,user_xattr,errors=remount-ro,context=unconfined_u:object_r:user_tmp_t:s0,mgs,update,svname=lustre-MDT0000,device=/dev/loop0") = 0
      

      mount.lustre does succeed but the LDD_F_UPDATE flag is never cleared.

      # mount
      ...
      /tmp/lustre-mdt1 on /mnt/mds1 type lustre (ro,seclabel)
      # umount /mnt/mds1
      # mount /tmp/lustre-mdt1 /mnt/mds1 -t lustre -o loop
      mount.lustre: Unable to mount /dev/loop0: Invalid argument
      
      mount.lustre FATAL: failed to write local files: Invalid argument
      # mount
      ...
      /tmp/lustre-mdt1 on /mnt/mds1 type lustre (ro,seclabel)
      

        Attachments

          Issue Links

            Activity

              People

              • Assignee:
                jhammond John Hammond
                Reporter:
                jhammond John Hammond
              • Votes:
                0 Vote for this issue
                Watchers:
                10 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved: