From 0b4d3452b8b4a5309b4445b900e3cec022cca95a Mon Sep 17 00:00:00 2001 From: Scott Mayhew Date: Mon, 5 Jun 2017 11:45:04 -0400 Subject: security/selinux: allow security_sb_clone_mnt_opts to enable/disable native labeling behavior 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. Resolves: https://github.com/SELinuxProject/selinux-kernel/issues/35 Signed-off-by: Scott Mayhew Reviewed-by: Stephen Smalley Tested-by: Stephen Smalley Signed-off-by: Paul Moore --- include/linux/lsm_hooks.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/linux/lsm_hooks.h') diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 68d91e423bca..3cc9d77c7527 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -1409,7 +1409,9 @@ 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, -- cgit v1.2.3