Currently, creating a batman-adv interface in an unprivileged LXD container and attaching secondary interfaces to it with "ip" or "batctl" works fine. However all batctl debug and configuration commands fail:
root@container:~# batctl originators Error received: Operation not permitted root@container:~# batctl orig_interval 1000 root@container:~# batctl orig_interval 2000 root@container:~# batctl orig_interval 1000
To fix this change the generic netlink permissions from GENL_ADMIN_PERM to GENL_UNS_ADMIN_PERM. This way a batman-adv interface is fully maintainable as root from within a user namespace, from an unprivileged container.
All except one batman-adv netlink setting are per interface and do not leak information or change settings from the host system and are therefore save to retrieve or modify as root from within an unprivileged container.
"batctl routing_algo" / BATADV_CMD_GET_ROUTING_ALGOS is the only exception: It provides the batman-adv kernel module wide default routing algorithm. However it is read-only from netlink and an unprivileged container is still not allowed to modify /sys/module/batman_adv/parameters/routing_algo. Instead it is advised to use the newly introduced "batctl if create routing_algo RA_NAME" / IFLA_BATADV_ALGO_NAME to set the routing algorithm on interface creation, which already works fine in an unprivileged container.
Cc: Tycho Andersen tycho@tycho.pizza Signed-off-by: Linus Lüssing linus.luessing@c0d3.blue ---
Changelog v3: * adding compatibility code for Linux < 4.6
Changelog v2: * updating Tycho Andersen's email in Cc as @canonical.com returned an "Undelivered Mail Returned to Sender"
Cc'ing Tycho Andersen as he introduced the GENL_UNS_ADMIN_PERM in the following commit:
4a92602aa1cd ("openvswitch: allow management from inside user namespaces")
compat-include/uapi/linux/genetlink.h | 22 ++++++++++++++++++++ net/batman-adv/netlink.c | 30 +++++++++++++-------------- 2 files changed, 37 insertions(+), 15 deletions(-) create mode 100644 compat-include/uapi/linux/genetlink.h
diff --git a/compat-include/uapi/linux/genetlink.h b/compat-include/uapi/linux/genetlink.h new file mode 100644 index 00000000..5fd58e22 --- /dev/null +++ b/compat-include/uapi/linux/genetlink.h @@ -0,0 +1,22 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) B.A.T.M.A.N. contributors: + * + * Marek Lindner, Simon Wunderlich + * + * This file contains macros for maintaining compatibility with older versions + * of the Linux kernel. + */ + +#ifndef _NET_BATMAN_ADV_COMPAT_UAPI_LINUX_GENETLINK_H_ +#define _NET_BATMAN_ADV_COMPAT_UAPI_LINUX_GENETLINK_H_ + +#include <linux/version.h> +#include_next <uapi/linux/genetlink.h> + +#if LINUX_VERSION_IS_LESS(4, 6, 0) + +#define GENL_UNS_ADMIN_PERM GENL_ADMIN_PERM + +#endif /* LINUX_VERSION_IS_LESS(4, 6, 0) */ + +#endif /* _NET_BATMAN_ADV_COMPAT_UAPI_LINUX_GENETLINK_H_ */ diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c index 29276284..00875e1d 100644 --- a/net/batman-adv/netlink.c +++ b/net/batman-adv/netlink.c @@ -1368,21 +1368,21 @@ static const struct genl_small_ops batadv_netlink_ops[] = { { .cmd = BATADV_CMD_TP_METER, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .doit = batadv_netlink_tp_meter_start, .internal_flags = BATADV_FLAG_NEED_MESH, }, { .cmd = BATADV_CMD_TP_METER_CANCEL, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .doit = batadv_netlink_tp_meter_cancel, .internal_flags = BATADV_FLAG_NEED_MESH, }, { .cmd = BATADV_CMD_GET_ROUTING_ALGOS, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .dumpit = batadv_algo_dump, }, { @@ -1397,68 +1397,68 @@ static const struct genl_small_ops batadv_netlink_ops[] = { { .cmd = BATADV_CMD_GET_TRANSTABLE_LOCAL, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .dumpit = batadv_tt_local_dump, }, { .cmd = BATADV_CMD_GET_TRANSTABLE_GLOBAL, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .dumpit = batadv_tt_global_dump, }, { .cmd = BATADV_CMD_GET_ORIGINATORS, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .dumpit = batadv_orig_dump, }, { .cmd = BATADV_CMD_GET_NEIGHBORS, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .dumpit = batadv_hardif_neigh_dump, }, { .cmd = BATADV_CMD_GET_GATEWAYS, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .dumpit = batadv_gw_dump, }, { .cmd = BATADV_CMD_GET_BLA_CLAIM, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .dumpit = batadv_bla_claim_dump, }, { .cmd = BATADV_CMD_GET_BLA_BACKBONE, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .dumpit = batadv_bla_backbone_dump, }, { .cmd = BATADV_CMD_GET_DAT_CACHE, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .dumpit = batadv_dat_cache_dump, }, { .cmd = BATADV_CMD_GET_MCAST_FLAGS, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .dumpit = batadv_mcast_flags_dump, }, { .cmd = BATADV_CMD_SET_MESH, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .doit = batadv_netlink_set_mesh, .internal_flags = BATADV_FLAG_NEED_MESH, }, { .cmd = BATADV_CMD_SET_HARDIF, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .doit = batadv_netlink_set_hardif, .internal_flags = BATADV_FLAG_NEED_MESH | BATADV_FLAG_NEED_HARDIF, @@ -1474,7 +1474,7 @@ static const struct genl_small_ops batadv_netlink_ops[] = { { .cmd = BATADV_CMD_SET_VLAN, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, - .flags = GENL_ADMIN_PERM, + .flags = GENL_UNS_ADMIN_PERM, .doit = batadv_netlink_set_vlan, .internal_flags = BATADV_FLAG_NEED_MESH | BATADV_FLAG_NEED_VLAN,