Date: Sun, 26 Mar 2023 08:53:30 GMT From: "Alexander V. Chernikov" <melifaro@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 04f75b980293 - main - netlink: allow netlink sockets in non-vnet jails. Message-ID: <202303260853.32Q8rUSo039414@gitrepo.freebsd.org>
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The branch main has been updated by melifaro: URL: https://cgit.FreeBSD.org/src/commit/?id=04f75b980293d517558990a7fda6900445edcac6 commit 04f75b980293d517558990a7fda6900445edcac6 Author: Alexander V. Chernikov <melifaro@FreeBSD.org> AuthorDate: 2023-03-26 08:42:51 +0000 Commit: Alexander V. Chernikov <melifaro@FreeBSD.org> CommitDate: 2023-03-26 08:44:09 +0000 netlink: allow netlink sockets in non-vnet jails. This change allow to open Netlink sockets in the non-vnet jails, even for unpriviledged processes. The security model largely follows the existing one. To be more specific: * by default, every `NETLINK_ROUTE` command is **NOT** allowed in non-VNET jail UNLESS `RTNL_F_ALLOW_NONVNET_JAIL` flag is specified in the command handler. * All notifications are **disabled** for non-vnet jails (requests to subscribe for the notifications are ignored). This will change to be more fine-grained model once the first netlink provider requiring this gets committed. * Listing interfaces (RTM_GETLINK) is **allowed** w/o limits (**including** interfaces w/o any addresses attached to the jail). The value of this is questionable, but it follows the existing approach. * Listing ARP/NDP neighbours is **forbidden**. This is a **change** from the current approach - currently we list static ARP/ND entries belonging to the addresses attached to the jail. * Listing interface addresses is **allowed**, but the addresses are filtered to match only ones attached to the jail. * Listing routes is **allowed**, but the routes are filtered to provide only host routes matching the addresses attached to the jail. * By default, every `NETLINK_GENERIC` command is **allowed** in non-VNET jail (as sub-families may be unrelated to network at all). It is the goal of the family author to implement the restriction if necessary. Differential Revision: https://reviews.freebsd.org/D39206 MFC after: 1 month --- sys/kern/kern_jail.c | 1 + sys/netlink/netlink_ctl.h | 1 + sys/netlink/netlink_domain.c | 12 ++++++++++++ sys/netlink/netlink_generic.c | 1 + sys/netlink/netlink_route.c | 5 +++++ sys/netlink/netlink_var.h | 1 + sys/netlink/route/iface.c | 8 +++++++- sys/netlink/route/route_var.h | 3 ++- sys/netlink/route/rt.c | 6 ++++++ 9 files changed, 36 insertions(+), 2 deletions(-) diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c index 7b57e5bb9d61..0558c7d9b7fe 100644 --- a/sys/kern/kern_jail.c +++ b/sys/kern/kern_jail.c @@ -3440,6 +3440,7 @@ prison_check_af(struct ucred *cred, int af) #endif case AF_LOCAL: case AF_ROUTE: + case AF_NETLINK: break; default: if (!(pr->pr_allow & PR_ALLOW_SOCKET_AF)) diff --git a/sys/netlink/netlink_ctl.h b/sys/netlink/netlink_ctl.h index 8cd29cf56d10..9369194151af 100644 --- a/sys/netlink/netlink_ctl.h +++ b/sys/netlink/netlink_ctl.h @@ -81,6 +81,7 @@ bool netlink_unregister_proto(int proto); bool nl_has_listeners(int netlink_family, uint32_t groups_mask); bool nlp_has_priv(struct nlpcb *nlp, int priv); struct ucred *nlp_get_cred(struct nlpcb *nlp); +bool nlp_unconstrained_vnet(const struct nlpcb *nlp); /* netlink_generic.c */ struct genl_cmd { diff --git a/sys/netlink/netlink_domain.c b/sys/netlink/netlink_domain.c index 2704974173b4..24ca9de877f0 100644 --- a/sys/netlink/netlink_domain.c +++ b/sys/netlink/netlink_domain.c @@ -36,6 +36,7 @@ #include <sys/lock.h> #include <sys/rmlock.h> #include <sys/domain.h> +#include <sys/jail.h> #include <sys/mbuf.h> #include <sys/protosw.h> #include <sys/proc.h> @@ -111,6 +112,10 @@ nl_add_group_locked(struct nlpcb *nlp, unsigned int group_id) MPASS(group_id <= NLP_MAX_GROUPS); --group_id; + /* TODO: add family handler callback */ + if (!nlp_unconstrained_vnet(nlp)) + return; + nlp->nl_groups[group_id / 64] |= (uint64_t)1 << (group_id % 64); } @@ -212,6 +217,12 @@ nlp_has_priv(struct nlpcb *nlp, int priv) return (priv_check_cred(nlp->nl_cred, priv) == 0); } +bool +nlp_unconstrained_vnet(const struct nlpcb *nlp) +{ + return (nlp->nl_unconstrained_vnet); +} + struct ucred * nlp_get_cred(struct nlpcb *nlp) { @@ -308,6 +319,7 @@ nl_pru_attach(struct socket *so, int proto, struct thread *td) nlp->nl_process_id = curproc->p_pid; nlp->nl_linux = is_linux; nlp->nl_active = true; + nlp->nl_unconstrained_vnet = !jailed_without_vnet(so->so_cred); NLP_LOCK_INIT(nlp); refcount_init(&nlp->nl_refcount, 1); nl_init_io(nlp); diff --git a/sys/netlink/netlink_generic.c b/sys/netlink/netlink_generic.c index d4022c2c2a75..a2bd624f99d9 100644 --- a/sys/netlink/netlink_generic.c +++ b/sys/netlink/netlink_generic.c @@ -31,6 +31,7 @@ __FBSDID("$FreeBSD$"); #include <sys/ck.h> #include <sys/epoch.h> #include <sys/kernel.h> +#include <sys/jail.h> #include <sys/lock.h> #include <sys/malloc.h> #include <sys/priv.h> diff --git a/sys/netlink/netlink_route.c b/sys/netlink/netlink_route.c index 037fd2170c66..ce0c0eb36dbc 100644 --- a/sys/netlink/netlink_route.c +++ b/sys/netlink/netlink_route.c @@ -93,6 +93,11 @@ rtnl_handle_message(struct nlmsghdr *hdr, struct nl_pstate *npt) } else if (cmd->priv != 0) NLP_LOG(LOG_DEBUG3, nlp, "priv %d check passed for msg %s", cmd->priv, cmd->name); + if (!nlp_unconstrained_vnet(nlp) && (cmd->flags & RTNL_F_ALLOW_NONVNET_JAIL) == 0) { + NLP_LOG(LOG_DEBUG2, nlp, "jail check failed for msg %s", cmd->name); + return (EPERM); + } + bool need_epoch = !(cmd->flags & RTNL_F_NOEPOCH); if (need_epoch) diff --git a/sys/netlink/netlink_var.h b/sys/netlink/netlink_var.h index ed19008248e9..0114306885cf 100644 --- a/sys/netlink/netlink_var.h +++ b/sys/netlink/netlink_var.h @@ -61,6 +61,7 @@ struct nlpcb { bool nl_task_pending; bool nl_tx_blocked; /* No new requests accepted */ bool nl_linux; /* true if running under compat */ + bool nl_unconstrained_vnet; /* true if running under VNET jail (or without jail) */ struct nl_io_queue rx_queue; struct nl_io_queue tx_queue; struct taskqueue *nl_taskqueue; diff --git a/sys/netlink/route/iface.c b/sys/netlink/route/iface.c index 6704acd1624f..18eab05576b7 100644 --- a/sys/netlink/route/iface.c +++ b/sys/netlink/route/iface.c @@ -32,6 +32,7 @@ __FBSDID("$FreeBSD$"); #include <sys/types.h> #include <sys/eventhandler.h> #include <sys/kernel.h> +#include <sys/jail.h> #include <sys/malloc.h> #include <sys/socket.h> #include <sys/sockio.h> @@ -61,6 +62,7 @@ struct netlink_walkargs { struct nl_writer *nw; struct nlmsghdr hdr; struct nlpcb *so; + struct ucred *cred; uint32_t fibnum; int family; int error; @@ -833,6 +835,8 @@ dump_iface_addrs(struct netlink_walkargs *wa, struct ifnet *ifp) continue; if (ifa->ifa_addr->sa_family == AF_LINK) continue; + if (prison_if(wa->cred, ifa->ifa_addr) != 0) + continue; wa->count++; if (!dump_iface_addr(wa->nw, ifp, ifa, &wa->hdr)) return (ENOMEM); @@ -856,6 +860,7 @@ rtnl_handle_getaddr(struct nlmsghdr *hdr, struct nlpcb *nlp, struct nl_pstate *n struct netlink_walkargs wa = { .so = nlp, .nw = npt->nw, + .cred = nlp_get_cred(nlp), .family = attrs.ifa_family, .hdr.nlmsg_pid = hdr->nlmsg_pid, .hdr.nlmsg_seq = hdr->nlmsg_seq, @@ -977,7 +982,7 @@ static const struct rtnl_cmd_handler cmd_handlers[] = { .cmd = NL_RTM_GETLINK, .name = "RTM_GETLINK", .cb = &rtnl_handle_getlink, - .flags = RTNL_F_NOEPOCH, + .flags = RTNL_F_NOEPOCH | RTNL_F_ALLOW_NONVNET_JAIL, }, { .cmd = NL_RTM_DELLINK, @@ -997,6 +1002,7 @@ static const struct rtnl_cmd_handler cmd_handlers[] = { .cmd = NL_RTM_GETADDR, .name = "RTM_GETADDR", .cb = &rtnl_handle_getaddr, + .flags = RTNL_F_ALLOW_NONVNET_JAIL, }, { .cmd = NL_RTM_NEWADDR, diff --git a/sys/netlink/route/route_var.h b/sys/netlink/route/route_var.h index f3b1d7d929a5..a11857b14a1f 100644 --- a/sys/netlink/route/route_var.h +++ b/sys/netlink/route/route_var.h @@ -48,7 +48,8 @@ struct rtnl_cmd_handler { int flags; }; -#define RTNL_F_NOEPOCH 0x01 +#define RTNL_F_NOEPOCH 0x01 /* Do not enter epoch when handling command */ +#define RTNL_F_ALLOW_NONVNET_JAIL 0x02 /* Allow command execution inside non-VNET jail */ bool rtnl_register_messages(const struct rtnl_cmd_handler *handlers, int count); diff --git a/sys/netlink/route/rt.c b/sys/netlink/route/rt.c index badd8d937be2..ef52dbf4edd6 100644 --- a/sys/netlink/route/rt.c +++ b/sys/netlink/route/rt.c @@ -513,6 +513,8 @@ dump_rtentry(struct rtentry *rt, void *_arg) wa->count++; if (wa->error != 0) return (0); + if (!rt_is_exportable(rt, nlp_get_cred(wa->nlp))) + return (0); wa->dumped++; rt_get_rnd(rt, &wa->rnd); @@ -606,6 +608,9 @@ handle_rtm_getroute(struct nlpcb *nlp, struct nl_parsed_route *attrs, RIB_RUNLOCK(rnh); + if (!rt_is_exportable(rt, nlp_get_cred(nlp))) + return (ESRCH); + IF_DEBUG_LEVEL(LOG_DEBUG2) { char rtbuf[NHOP_PRINT_BUFSIZE] __unused, nhbuf[NHOP_PRINT_BUFSIZE] __unused; FIB_LOG(LOG_DEBUG2, fibnum, family, "getroute completed: got %s for %s", @@ -1026,6 +1031,7 @@ static const struct rtnl_cmd_handler cmd_handlers[] = { .cmd = NL_RTM_GETROUTE, .name = "RTM_GETROUTE", .cb = &rtnl_handle_getroute, + .flags = RTNL_F_ALLOW_NONVNET_JAIL, }, { .cmd = NL_RTM_DELROUTE,
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