Re: [PATCH] security/selinux: allow security_sb_clone_mnt_opts to enable/disable native labeling behavior

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On Thu, 2017-06-01 at 14:08 -0400, Stephen Smalley wrote:
> On Thu, 2017-06-01 at 10:55 -0400, Scott Mayhew wrote:
> > On Thu, 01 Jun 2017, Scott Mayhew wrote:
> > 
> > > When an NFSv4 client performs a mount operation, it first mounts
> > > the
> > > NFSv4 root and then does path walk to the exported path and
> > > performs a
> > > submount on that, cloning the security mount options from the
> > > root's
> > > superblock to the submount's superblock in the process.
> > > 
> > > Unless the NFS server has an explicit fsid=0 export with the
> > > "security_label" option, the NFSv4 root superblock will not have
> > > SBLABEL_MNT set, and neither will the submount superblock after
> > > cloning
> > > the security mount options.  As a result, setxattr's of security
> > > labels
> > > over NFSv4.2 will fail.  In a similar fashion, NFSv4.2 mounts
> > > mounted
> > > with the context= mount option will not show the correct labels
> > > because
> > > the nfs_server->caps flags of the cloned superblock will still
> > > have
> > > NFS_CAP_SECURITY_LABEL set.
> > > 
> > > Allowing the NFSv4 client to enable or disable
> > > SECURITY_LSM_NATIVE_LABELS
> > > behavior will ensure that the SBLABEL_MNT flag has the correct
> > > value
> > > when the client traverses from an exported path without the
> > > "security_label" option to one with the "security_label" option
> > > and
> > > vice versa.  Similarly, checking to see if
> > > SECURITY_LSM_NATIVE_LABELS is
> > > set upon return from security_sb_clone_mnt_opts() and clearing
> > > NFS_CAP_SECURITY_LABEL if necessary will allow the correct labels
> > > to
> > > be displayed for NFSv4.2 mounts mounted with the context= mount
> > > option.
> > > 
> > > Signed-off-by: Scott Mayhew <smayhew@xxxxxxxxxx>
> > > ---
> > >  fs/nfs/super.c            | 18 +++++++++++++++++-
> > >  include/linux/lsm_hooks.h |  4 +++-
> > >  include/linux/security.h  |  8 ++++++--
> > >  security/security.c       |  7 +++++--
> > >  security/selinux/hooks.c  | 43
> > > ++++++++++++++++++++++++++++++++++++++-----
> > >  5 files changed, 69 insertions(+), 11 deletions(-)
> > 
> > With this patch, the behavior and flags fields of the
> > superblock_security_struct
> > and the nfs_server->caps all have the correct values when crossing
> > from an
> > export without the "security_label" option to one with the
> > "security_label"
> > option and vice versa.
> > 
> > Here /export/export1 and /export/export1/export2/export3 have the
> > "security_label" option; /export and /export/export1/export2 do
> > not:
> > 
> > [root@rhel7u4 ~]# exportfs -v
> > /export       	<world>(rw,sync,wdelay,hide,no_subtree_check,
> > se
> > c=sys,secure,no_root_squash,no_all_squash)
> > /export/export1
> > 		<world>(rw,sync,wdelay,hide,no_subtree_check,security_l
> > abel,sec=sys,secure,no_root_squash,no_all_squash)
> > /export/export1/export2
> > 		<world>(rw,sync,wdelay,hide,no_subtree_check,sec=sys,se
> > cure,no_root_squash,no_all_squash)
> > /export/export1/export2/export3
> > 		<world>(rw,sync,wdelay,hide,no_subtree_check,security_l
> > abel,sec=sys,secure,no_root_squash,no_all_squash)
> > 
> > 
> > [root@fedora25 ~]# mount -o v4.2 rhel7u4:/export /mnt/t
> > [root@fedora25 ~]# ls -lZ /mnt/t
> > total 8
> > drwxr-xr-x. 4 root root system_u:object_r:nfs_t:s0 4096 May 30
> > 14:09
> > export1
> 
> Shouldn't this be the label of export1 from the server, since export1
> is exported with security_label?

BTW, I don't think your patch introduces this bug (assuming it is a
bug), so this isn't an obstacle to your patch proceeding, but unless I
misunderstand, it is another bug that needs to be fixed (in this case,
with the initialization of the root inode label for a NFS mount).

> 
> > -rw-r--r--. 1 root root system_u:object_r:nfs_t:s0    0 May 30
> > 14:09
> > file1
> > -rw-r--r--. 1 root root system_u:object_r:nfs_t:s0    0 May 30
> > 14:09
> > file2
> > -rw-r--r--. 1 root root system_u:object_r:nfs_t:s0    0 May 30
> > 14:09
> > file3
> > drwxrwxrwx. 3 root root system_u:object_r:nfs_t:s0   22 Apr 21
> > 12:58
> > scratch
> > drwxrwxrwx. 7 root root system_u:object_r:nfs_t:s0 4096 Apr 21
> > 12:55
> > test
> > [root@fedora25 ~]# ls -lZ /mnt/t/export1
> > total 20
> > drwxr-xr-x. 4 root root system_u:object_r:unlabeled_t:s0  4096 May
> > 30
> > 14:09 export2
> 
> Shouldn't this be system_u:object_r:nfs_t:s0, like the rest of
> export2?
> 
> > -rw-r--r--. 1 root root system_u:object_r:etc_t:s0           0 May
> > 30
> > 14:09 file1
> > -rw-r--r--. 1 root root system_u:object_r:bin_t:s0           0 May
> > 30
> > 14:09 file2
> > -rw-r--r--. 1 root root system_u:object_r:usr_t:s0           0 May
> > 30
> > 14:09 file3
> > drwx------. 2 root root system_u:object_r:unlabeled_t:s0 16384 May
> > 30
> > 14:02 lost+found
> > [root@fedora25 ~]# ls -lZ /mnt/t/export1/export2
> > total 20
> > drwxr-xr-x. 3 root root system_u:object_r:nfs_t:s0  4096 May 30
> > 14:08
> > export3
> 
> Shouldn't this be the label of export3 from the server, since it is
> exported with security_label?
> 
> > -rw-r--r--. 1 root root system_u:object_r:nfs_t:s0     0 May 30
> > 14:09
> > file1
> > -rw-r--r--. 1 root root system_u:object_r:nfs_t:s0     0 May 30
> > 14:09
> > file2
> > -rw-r--r--. 1 root root system_u:object_r:nfs_t:s0     0 May 30
> > 14:09
> > file3
> > drwx------. 2 root root system_u:object_r:nfs_t:s0 16384 May 30
> > 14:02
> > lost+found
> > [root@fedora25 ~]# ls -lZ /mnt/t/export1/export2/export3
> > total 16
> > -rw-r--r--. 1 root root system_u:object_r:etc_t:s0           0 May
> > 30
> > 14:08 file1
> > -rw-r--r--. 1 root root system_u:object_r:bin_t:s0           0 May
> > 30
> > 14:08 file2
> > -rw-r--r--. 1 root root system_u:object_r:usr_t:s0           0 May
> > 30
> > 14:08 file3
> > drwx------. 2 root root system_u:object_r:unlabeled_t:s0 16384 May
> > 30
> > 14:02 lost+found
> > 
> > I can do chcon on /mnt/t/export1 and /mnt/t/export1/export2/export3
> > but not /mnt/t or /mnt/t/export1/export2:
> > 
> > [root@fedora25 ~]# chcon -t usr_t /mnt/t/file1
> > chcon: failed to change context of '/mnt/t/file1' to
> > ‘system_u:object_r:usr_t:s0’: Operation not supported
> > [root@fedora25 ~]# chcon -t usr_t /mnt/t/export1/file1
> > [root@fedora25 ~]# chcon -t usr_t /mnt/t/export1/export2/file1
> > chcon: failed to change context of '/mnt/t/export1/export2/file1'
> > to
> > ‘system_u:object_r:usr_t:s0’: Operation not supported
> > [root@fedora25 ~]# chcon -t usr_t
> > /mnt/t/export1/export2/export3/file1
> > [root@fedora25 ~]# ls -lZ /mnt/t/file1
> > -rw-r--r--. 1 root root system_u:object_r:nfs_t:s0 0 May 30 14:09
> > /mnt/t/file1
> > [root@fedora25 ~]# ls -lZ /mnt/t/export1/file1
> > -rw-r--r--. 1 root root system_u:object_r:usr_t:s0 0 May 30 14:09
> > /mnt/t/export1/file1
> > [root@fedora25 ~]# ls -lZ /mnt/t/export1/export2/file1
> > -rw-r--r--. 1 root root system_u:object_r:nfs_t:s0 0 May 30 14:09
> > /mnt/t/export1/export2/file1
> > [root@fedora25 ~]# ls -lZ /mnt/t/export1/export2/export3/file1
> > -rw-r--r--. 1 root root system_u:object_r:usr_t:s0 0 May 30 14:08
> > /mnt/t/export1/export2/export3/file1
> > [root@fedora25 ~]# chcon -t etc_t /mnt/t/export1/file1
> > [root@fedora25 ~]# chcon -t etc_t
> > /mnt/t/export1/export2/export3/file1
> > 
> > /mnt/t/export1 and /mnt/t/export1/export2/export3 have the
> > "seclabel"
> > mount option; /mnt/t and /mnt/t/export1/export do not:
> > 
> > [root@fedora25 ~]# cat /proc/mounts
> > ...
> > rhel7u4:/export /mnt/t nfs4
> > rw,relatime,vers=4.2,rsize=131072,wsize=131072,namlen=255,hard,prot
> > o=
> > tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.122.236,l
> > oc
> > al_lock=none,addr=192.168.122.83 0 0
> > rhel7u4:/export/export1 /mnt/t/export1 nfs4
> > rw,seclabel,relatime,vers=4.2,rsize=131072,wsize=131072,namlen=255,
> > ha
> > rd,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.
> > 12
> > 2.236,local_lock=none,addr=192.168.122.83 0 0
> > rhel7u4:/export/export1/export2 /mnt/t/export1/export2 nfs4
> > rw,relatime,vers=4.2,rsize=131072,wsize=131072,namlen=255,hard,prot
> > o=
> > tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.122.236,l
> > oc
> > al_lock=none,addr=192.168.122.83 0 0
> > rhel7u4:/export/export1/export2/export3
> > /mnt/t/export1/export2/export3 nfs4
> > rw,seclabel,relatime,vers=4.2,rsize=131072,wsize=131072,namlen=255,
> > ha
> > rd,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.
> > 12
> > 2.236,local_lock=none,addr=192.168.122.83 0 0
> > 
> > The capabilities flags has NFS_CAP_SECURITY_LABEL set on
> > /mnt/t/export1 and
> > /mnt/t/export1/export2/export3; it is not set on /mnt/t and
> > /mnt/t/export1/export2:
> > 
> > [root@fedora25 ~]# egrep "rhel7u4|caps" /proc/self/mountstats
> > device rhel7u4:/export mounted on /mnt/t with fstype nfs4
> > statvers=1.1
> > 	caps:	caps=0x1fbffdf,wtmult=512,dtsize=32768,bsize=0,nam
> > len=255
> > device rhel7u4:/export/export1 mounted on /mnt/t/export1 with
> > fstype
> > nfs4 statvers=1.1
> > 	caps:	caps=0x1ffffdf,wtmult=512,dtsize=32768,bsize=0,nam
> > len=255
> > device rhel7u4:/export/export1/export2 mounted on
> > /mnt/t/export1/export2 with fstype nfs4 statvers=1.1
> > 	caps:	caps=0x1fbffdf,wtmult=512,dtsize=32768,bsize=0,nam
> > len=255
> > device rhel7u4:/export/export1/export2/export3 mounted on
> > /mnt/t/export1/export2/export3 with fstype nfs4 statvers=1.1
> > 	caps:	caps=0x1ffffdf,wtmult=512,dtsize=32768,bsize=0,nam
> > len=255
> > [root@fedora25 ~]# printf "%x\n" $(( 0x1fbffdf & (1<<18) ))
> > 0
> > [root@fedora25 ~]# printf "%x\n" $(( 0x1ffffdf & (1<<18) ))
> > 40000
> > [root@fedora25 ~]# 
> > 
> > The context= mount option now works correctly:
> > 
> > [root@fedora25 ~]# mount -o
> > v4.2,context="system_u:object_r:user_home_t:s0" rhel7u4:/export
> > /mnt/t
> > [root@fedora25 ~]# ls -lZ /mnt/t
> > total 8
> > drwxr-xr-x. 4 root root system_u:object_r:user_home_t:s0 4096 May
> > 30
> > 14:09 export1
> > -rw-r--r--. 1 root root system_u:object_r:user_home_t:s0    0 May
> > 30
> > 14:09 file1
> > -rw-r--r--. 1 root root system_u:object_r:user_home_t:s0    0 May
> > 30
> > 14:09 file2
> > -rw-r--r--. 1 root root system_u:object_r:user_home_t:s0    0 May
> > 30
> > 14:09 file3
> > drwxrwxrwx. 3 root root system_u:object_r:user_home_t:s0   22 Apr
> > 21
> > 12:58 scratch
> > drwxrwxrwx. 7 root root system_u:object_r:user_home_t:s0 4096 Apr
> > 21
> > 12:55 test
> > [root@fedora25 ~]# ls -lZ /mnt/t/export1
> > total 20
> > drwxr-xr-x. 4 root root system_u:object_r:user_home_t:s0  4096 May
> > 30
> > 14:09 export2
> > -rw-r--r--. 1 root root system_u:object_r:user_home_t:s0     0 May
> > 30
> > 14:09 file1
> > -rw-r--r--. 1 root root system_u:object_r:user_home_t:s0     0 May
> > 30
> > 14:09 file2
> > -rw-r--r--. 1 root root system_u:object_r:user_home_t:s0     0 May
> > 30
> > 14:09 file3
> > drwx------. 2 root root system_u:object_r:user_home_t:s0 16384 May
> > 30
> > 14:02 lost+found
> > [root@fedora25 ~]# ls -lZ /mnt/t/export1/export2
> > total 20
> > drwxr-xr-x. 3 root root system_u:object_r:user_home_t:s0  4096 May
> > 30
> > 14:08 export3
> > -rw-r--r--. 1 root root system_u:object_r:user_home_t:s0     0 May
> > 30
> > 14:09 file1
> > -rw-r--r--. 1 root root system_u:object_r:user_home_t:s0     0 May
> > 30
> > 14:09 file2
> > -rw-r--r--. 1 root root system_u:object_r:user_home_t:s0     0 May
> > 30
> > 14:09 file3
> > drwx------. 2 root root system_u:object_r:user_home_t:s0 16384 May
> > 30
> > 14:02 lost+found
> > [root@fedora25 ~]# ls -lZ /mnt/t/export1/export2/export3
> > total 16
> > -rw-r--r--. 1 root root system_u:object_r:user_home_t:s0     0 May
> > 30
> > 14:08 file1
> > -rw-r--r--. 1 root root system_u:object_r:user_home_t:s0     0 May
> > 30
> > 14:08 file2
> > -rw-r--r--. 1 root root system_u:object_r:user_home_t:s0     0 May
> > 30
> > 14:08 file3
> > drwx------. 2 root root system_u:object_r:user_home_t:s0 16384 May
> > 30
> > 14:02 lost+found
> > 
> > [root@fedora25 ~]# cat /proc/mounts
> > ...
> > rhel7u4:/export /mnt/t nfs4
> > rw,context=system_u:object_r:user_home_t:s0,relatime,vers=4.2,rsize
> > =1
> > 31072,wsize=131072,namlen=255,hard,proto=tcp,port=0,timeo=600,retra
> > ns
> > =2,sec=sys,clientaddr=192.168.122.236,local_lock=none,addr=192.168.
> > 12
> > 2.83 0 0
> > rhel7u4:/export/export1 /mnt/t/export1 nfs4
> > rw,context=system_u:object_r:user_home_t:s0,relatime,vers=4.2,rsize
> > =1
> > 31072,wsize=131072,namlen=255,hard,proto=tcp,port=0,timeo=600,retra
> > ns
> > =2,sec=sys,clientaddr=192.168.122.236,local_lock=none,addr=192.168.
> > 12
> > 2.83 0 0
> > rhel7u4:/export/export1/export2 /mnt/t/export1/export2 nfs4
> > rw,context=system_u:object_r:user_home_t:s0,relatime,vers=4.2,rsize
> > =1
> > 31072,wsize=131072,namlen=255,hard,proto=tcp,port=0,timeo=600,retra
> > ns
> > =2,sec=sys,clientaddr=192.168.122.236,local_lock=none,addr=192.168.
> > 12
> > 2.83 0 0
> > rhel7u4:/export/export1/export2/export3
> > /mnt/t/export1/export2/export3 nfs4
> > rw,context=system_u:object_r:user_home_t:s0,relatime,vers=4.2,rsize
> > =1
> > 31072,wsize=131072,namlen=255,hard,proto=tcp,port=0,timeo=600,retra
> > ns
> > =2,sec=sys,clientaddr=192.168.122.236,local_lock=none,addr=192.168.
> > 12
> > 2.83 0 0
> > 
> > [root@fedora25 ~]# egrep "rhel7u4|caps" /proc/self/mountstats
> > device rhel7u4:/export mounted on /mnt/t with fstype nfs4
> > statvers=1.1
> > 	caps:	caps=0x1fbffdf,wtmult=512,dtsize=32768,bsize=0,nam
> > len=255
> > device rhel7u4:/export/export1 mounted on /mnt/t/export1 with
> > fstype
> > nfs4 statvers=1.1
> > 	caps:	caps=0x1fbffdf,wtmult=512,dtsize=32768,bsize=0,nam
> > len=255
> > device rhel7u4:/export/export1/export2 mounted on
> > /mnt/t/export1/export2 with fstype nfs4 statvers=1.1
> > 	caps:	caps=0x1fbffdf,wtmult=512,dtsize=32768,bsize=0,nam
> > len=255
> > device rhel7u4:/export/export1/export2/export3 mounted on
> > /mnt/t/export1/export2/export3 with fstype nfs4 statvers=1.1
> > 	caps:	caps=0x1fbffdf,wtmult=512,dtsize=32768,bsize=0,nam
> > len=255
> > 
> > -Scott
> > 
> > > 
> > > diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> > > index 2f3822a..6a11535 100644
> > > --- a/fs/nfs/super.c
> > > +++ b/fs/nfs/super.c
> > > @@ -2544,10 +2544,26 @@ EXPORT_SYMBOL_GPL(nfs_set_sb_security);
> > >  int nfs_clone_sb_security(struct super_block *s, struct dentry
> > > *mntroot,
> > >  			  struct nfs_mount_info *mount_info)
> > >  {
> > > +	int error;
> > > +	unsigned long kflags = 0, kflags_out = 0;
> > > +
> > >  	/* clone any lsm security options from the parent to the
> > > new sb */
> > >  	if (d_inode(mntroot)->i_op != NFS_SB(s)->nfs_client-
> > > > rpc_ops->dir_inode_ops)
> > > 
> > >  		return -ESTALE;
> > > -	return security_sb_clone_mnt_opts(mount_info->cloned-
> > > >sb,
> > > s);
> > > +
> > > +	if (NFS_SB(s)->caps & NFS_CAP_SECURITY_LABEL)
> > > +		kflags |= SECURITY_LSM_NATIVE_LABELS;
> > > +
> > > +	error = security_sb_clone_mnt_opts(mount_info->cloned-
> > > >sb, 
> > > s, kflags, &kflags_out);
> > > +	if (error)
> > > +		goto err;
> > > +
> > > +	if (NFS_SB(s)->caps & NFS_CAP_SECURITY_LABEL &&
> > > +		!(kflags_out & SECURITY_LSM_NATIVE_LABELS))
> > > +		NFS_SB(s)->caps &= ~NFS_CAP_SECURITY_LABEL;
> > > +err:
> > > +	return error;
> > > +
> > >  }
> > >  EXPORT_SYMBOL_GPL(nfs_clone_sb_security);
> > >  
> > > diff --git a/include/linux/lsm_hooks.h
> > > b/include/linux/lsm_hooks.h
> > > index 080f34e..2f54bfb 100644
> > > --- a/include/linux/lsm_hooks.h
> > > +++ b/include/linux/lsm_hooks.h
> > > @@ -1388,7 +1388,9 @@ union security_list_options {
> > >  				unsigned long kern_flags,
> > >  				unsigned long *set_kern_flags);
> > >  	int (*sb_clone_mnt_opts)(const struct super_block
> > > *oldsb,
> > > -					struct super_block
> > > *newsb);
> > > +					struct super_block
> > > *newsb,
> > > +					unsigned long
> > > kern_flags,
> > > +					unsigned long
> > > *set_kern_flags);
> > >  	int (*sb_parse_opts_str)(char *options, struct
> > > security_mnt_opts *opts);
> > >  	int (*dentry_init_security)(struct dentry *dentry, int
> > > mode,
> > >  					const struct qstr *name,
> > > void **ctx,
> > > diff --git a/include/linux/security.h b/include/linux/security.h
> > > index af675b5..a55ae9c 100644
> > > --- a/include/linux/security.h
> > > +++ b/include/linux/security.h
> > > @@ -240,7 +240,9 @@ int security_sb_set_mnt_opts(struct
> > > super_block
> > > *sb,
> > >  				unsigned long kern_flags,
> > >  				unsigned long *set_kern_flags);
> > >  int security_sb_clone_mnt_opts(const struct super_block *oldsb,
> > > -				struct super_block *newsb);
> > > +				struct super_block *newsb,
> > > +				unsigned long kern_flags,
> > > +				unsigned long *set_kern_flags);
> > >  int security_sb_parse_opts_str(char *options, struct
> > > security_mnt_opts *opts);
> > >  int security_dentry_init_security(struct dentry *dentry, int
> > > mode,
> > >  					const struct qstr *name,
> > > void **ctx,
> > > @@ -581,7 +583,9 @@ static inline int
> > > security_sb_set_mnt_opts(struct super_block *sb,
> > >  }
> > >  
> > >  static inline int security_sb_clone_mnt_opts(const struct
> > > super_block *oldsb,
> > > -					      struct super_block
> > > *newsb)
> > > +					      struct super_block
> > > *newsb,
> > > +					      unsigned long
> > > kern_flags,
> > > +					      unsigned long
> > > *set_kern_flags)
> > >  {
> > >  	return 0;
> > >  }
> > > diff --git a/security/security.c b/security/security.c
> > > index b9fea39..7b70ea2 100644
> > > --- a/security/security.c
> > > +++ b/security/security.c
> > > @@ -380,9 +380,12 @@ int security_sb_set_mnt_opts(struct
> > > super_block *sb,
> > >  EXPORT_SYMBOL(security_sb_set_mnt_opts);
> > >  
> > >  int security_sb_clone_mnt_opts(const struct super_block *oldsb,
> > > -				struct super_block *newsb)
> > > +				struct super_block *newsb,
> > > +				unsigned long kern_flags,
> > > +				unsigned long *set_kern_flags)
> > >  {
> > > -	return call_int_hook(sb_clone_mnt_opts, 0, oldsb,
> > > newsb);
> > > +	return call_int_hook(sb_clone_mnt_opts, 0, oldsb, newsb,
> > > +				kern_flags, set_kern_flags);
> > >  }
> > >  EXPORT_SYMBOL(security_sb_clone_mnt_opts);
> > >  
> > > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> > > index e67a526..80d9acf 100644
> > > --- a/security/selinux/hooks.c
> > > +++ b/security/selinux/hooks.c
> > > @@ -529,8 +529,14 @@ static int sb_finish_set_opts(struct
> > > super_block *sb)
> > >  		       sb->s_id, sb->s_type->name);
> > >  
> > >  	sbsec->flags |= SE_SBINITIALIZED;
> > > +
> > > +	/* Explicitly set or clear SBLABEL_MNT.  It's not
> > > sufficient to simply
> > > +	   leave the flag untouched because sb_clone_mnt_opts
> > > might be handing
> > > +	   us a superblock that needs the flag to be cleared. */
> > >  	if (selinux_is_sblabel_mnt(sb))
> > >  		sbsec->flags |= SBLABEL_MNT;
> > > +	else
> > > +		sbsec->flags &= ~SBLABEL_MNT;
> > >  
> > >  	/* Initialize the root inode. */
> > >  	rc = inode_doinit_with_dentry(root_inode, root);
> > > @@ -963,8 +969,11 @@ static int selinux_cmp_sb_context(const
> > > struct
> > > super_block *oldsb,
> > >  }
> > >  
> > >  static int selinux_sb_clone_mnt_opts(const struct super_block
> > > *oldsb,
> > > -					struct super_block
> > > *newsb)
> > > +					struct super_block
> > > *newsb,
> > > +					unsigned long
> > > kern_flags,
> > > +					unsigned long
> > > *set_kern_flags)
> > >  {
> > > +	int rc = 0;
> > >  	const struct superblock_security_struct *oldsbsec =
> > > oldsb-
> > > > s_security;
> > > 
> > >  	struct superblock_security_struct *newsbsec = newsb-
> > > > s_security;
> > > 
> > >  
> > > @@ -977,14 +986,23 @@ static int selinux_sb_clone_mnt_opts(const
> > > struct super_block *oldsb,
> > >  	 * mount options.  thus we can safely deal with this
> > > superblock later
> > >  	 */
> > >  	if (!ss_initialized)
> > > -		return 0;
> > > +		goto out;
> > > +
> > > +	if (kern_flags && !set_kern_flags) {
> > > +		/* Specifying internal flags without providing a
> > > place to
> > > +		 * place the results is not allowed */
> > > +		rc = -EINVAL;
> > > +		goto out;
> > > +	}
> > >  
> > >  	/* how can we clone if the old one wasn't set up?? */
> > >  	BUG_ON(!(oldsbsec->flags & SE_SBINITIALIZED));
> > >  
> > >  	/* if fs is reusing a sb, make sure that the contexts
> > > match */
> > > -	if (newsbsec->flags & SE_SBINITIALIZED)
> > > -		return selinux_cmp_sb_context(oldsb, newsb);
> > > +	if (newsbsec->flags & SE_SBINITIALIZED) {
> > > +		rc = selinux_cmp_sb_context(oldsb, newsb);
> > > +		goto out;
> > > +	}
> > >  
> > >  	mutex_lock(&newsbsec->lock);
> > >  
> > > @@ -994,6 +1012,19 @@ static int selinux_sb_clone_mnt_opts(const
> > > struct super_block *oldsb,
> > >  	newsbsec->def_sid = oldsbsec->def_sid;
> > >  	newsbsec->behavior = oldsbsec->behavior;
> > >  
> > > +	if (newsbsec->behavior == SECURITY_FS_USE_NATIVE
> > > +			&& !(kern_flags &
> > > SECURITY_LSM_NATIVE_LABELS)
> > > +			&& !set_context) {
> > > +		rc = security_fs_use(newsb);
> > > +		if (rc)
> > > +			goto out_unlock;
> > > +	}
> > > +
> > > +	if (kern_flags & SECURITY_LSM_NATIVE_LABELS &&
> > > !set_context) {
> > > +		newsbsec->behavior = SECURITY_FS_USE_NATIVE;
> > > +		*set_kern_flags |= SECURITY_LSM_NATIVE_LABELS;
> > > +	}
> > > +
> > >  	if (set_context) {
> > >  		u32 sid = oldsbsec->mntpoint_sid;
> > >  
> > > @@ -1013,8 +1044,10 @@ static int selinux_sb_clone_mnt_opts(const
> > > struct super_block *oldsb,
> > >  	}
> > >  
> > >  	sb_finish_set_opts(newsb);
> > > +out_unlock:
> > >  	mutex_unlock(&newsbsec->lock);
> > > -	return 0;
> > > +out:
> > > +	return rc;
> > >  }
> > >  
> > >  static int selinux_parse_opts_str(char *options,
> > > -- 
> > > 2.9.3
> > > 
> > > --
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> > > nfs" in
> > > the body of a message to majordomo@xxxxxxxxxxxxxxx
> > > More majordomo info at  http://vger.kernel.org/majordomo-info.htm
> > > l
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