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? > -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,proto= > tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.122.236,loc > 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,proto= > tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.122.236,loc > 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,retrans > =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,retrans > =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,retrans > =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,retrans > =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 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux- > > nfs" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html