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    Subject[073/115] SELinux: do not compute transition labels on mountpoint labeled filesystems
    2.6.32-longterm review patch.  If anyone has any objections, please let us know.


    From: Eric Paris <>

    commit 415103f9932d45f7927f4b17e3a9a13834cdb9a1 upstream.

    selinux_inode_init_security computes transitions sids even for filesystems
    that use mount point labeling. It shouldn't do that. It should just use
    the mount point label always and no matter what.

    This causes 2 problems. 1) it makes file creation slower than it needs to be
    since we calculate the transition sid and 2) it allows files to be created
    with a different label than the mount point!

    # id -Z
    # sesearch --type --class file --source sysadm_t --target tmp_t
    Found 1 semantic te rules:
    type_transition sysadm_t tmp_t : file user_tmp_t;

    # mount -o loop,context="system_u:object_r:tmp_t:s0" /tmp/fs /mnt/tmp

    # ls -lZ /mnt/tmp
    drwx------. root root system_u:object_r:tmp_t:s0 lost+found
    # touch /mnt/tmp/file1
    # ls -lZ /mnt/tmp
    -rw-r--r--. root root staff_u:object_r:user_tmp_t:s0 file1
    drwx------. root root system_u:object_r:tmp_t:s0 lost+found

    Whoops, we have a mount point labeled filesystem tmp_t with a user_tmp_t
    labeled file!

    Signed-off-by: Eric Paris <>
    Reviewed-by: Reviewed-by: James Morris <>
    Signed-off-by: Greg Kroah-Hartman <>

    security/selinux/hooks.c | 5 ++++-
    1 file changed, 4 insertions(+), 1 deletion(-)

    --- a/security/selinux/hooks.c
    +++ b/security/selinux/hooks.c
    @@ -2601,7 +2601,10 @@ static int selinux_inode_init_security(s
    sid = tsec->sid;
    newsid = tsec->create_sid;

    - if (!newsid || !(sbsec->flags & SE_SBLABELSUPP)) {
    + if ((sbsec->flags & SE_SBINITIALIZED) &&
    + (sbsec->behavior == SECURITY_FS_USE_MNTPOINT))
    + newsid = sbsec->mntpoint_sid;
    + else if (!newsid || !(sbsec->flags & SE_SBLABELSUPP)) {
    rc = security_transition_sid(sid, dsec->sid,

     \ /
      Last update: 2011-02-16 03:05    [W:0.023 / U:125.980 seconds]
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