Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit aad82892 authored by Seth Forshee's avatar Seth Forshee Committed by Eric W. Biederman
Browse files

selinux: Add support for unprivileged mounts from user namespaces 



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: default avatarSeth Forshee <seth.forshee@canonical.com>
Acked-by: default avatarStephen Smalley <sds@tycho.nsa.gov>
Acked-by: default avatarJames Morris <james.l.morris@oracle.com>
Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
parent 809c02e0

security/selinux/hooks.c

+23 −0
Original line number Original line Diff line number Diff line
@@ -830,6 +830,28 @@ static int selinux_set_mnt_opts(struct super_block *sb, 
			goto out;

			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. */

	/* sets the context of the superblock for the fs being mounted. */

	if (fscontext_sid) {

	if (fscontext_sid) {

		rc = may_context_mount_sb_relabel(fscontext_sid, sbsec, cred);

		rc = may_context_mount_sb_relabel(fscontext_sid, sbsec, cred);
@@ -898,6 +920,7 @@ static int selinux_set_mnt_opts(struct super_block *sb, 
		sbsec->def_sid = defcontext_sid;

		sbsec->def_sid = defcontext_sid;

	}

	}





out_set_opts:

	rc = sb_finish_set_opts(sb);

	rc = sb_finish_set_opts(sb);

out:

out:

	mutex_unlock(&sbsec->lock);

	mutex_unlock(&sbsec->lock);