| Message ID | 1447778351-118699-6-git-send-email-seth.forshee@canonical.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Tue, 17 Nov 2015, Seth Forshee wrote: > Security labels from unprivileged mounts in user namespaces must > be ignored. Force superblocks from user namespaces whose labeling > behavior is to use xattrs to use mountpoint labeling instead. > For the mountpoint label, default to converting the current task > context into a form suitable for file objects, but also allow the > policy writer to specify a different label through policy > transition rules. > > Pieced together from code snippets provided by Stephen Smalley. > > Signed-off-by: Seth Forshee <seth.forshee@canonical.com> > Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Acked-by: James Morris <james.l.morris@oracle.com>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index de05207eb665..09be1dc21e58 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -756,6 +756,28 @@ static int selinux_set_mnt_opts(struct super_block *sb, goto out; } } + + /* + * If this is a user namespace mount, no contexts are allowed + * on the command line and security labels must be ignored. + */ + if (sb->s_user_ns != &init_user_ns) { + if (context_sid || fscontext_sid || rootcontext_sid || + defcontext_sid) { + rc = -EACCES; + goto out; + } + if (sbsec->behavior == SECURITY_FS_USE_XATTR) { + sbsec->behavior = SECURITY_FS_USE_MNTPOINT; + rc = security_transition_sid(current_sid(), current_sid(), + SECCLASS_FILE, NULL, + &sbsec->mntpoint_sid); + if (rc) + goto out; + } + goto out_set_opts; + } + /* sets the context of the superblock for the fs being mounted. */ if (fscontext_sid) { rc = may_context_mount_sb_relabel(fscontext_sid, sbsec, cred); @@ -824,6 +846,7 @@ static int selinux_set_mnt_opts(struct super_block *sb, sbsec->def_sid = defcontext_sid; } +out_set_opts: rc = sb_finish_set_opts(sb); out: mutex_unlock(&sbsec->lock);