| Message ID | 20171230172035.15837-1-richard_c_haines@btinternet.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Sat, Dec 30, 2017 at 05:20:35PM +0000, Richard Haines wrote: > The SELinux SCTP implementation is explained in: > Documentation/security/SELinux-sctp.rst > > Signed-off-by: Richard Haines <richard_c_haines@btinternet.com> Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Thanks Richard. > --- > Documentation/security/SELinux-sctp.rst | 157 ++++++++++++++++++ > security/selinux/hooks.c | 280 +++++++++++++++++++++++++++++--- > security/selinux/include/classmap.h | 2 +- > security/selinux/include/netlabel.h | 21 ++- > security/selinux/include/objsec.h | 4 + > security/selinux/netlabel.c | 138 ++++++++++++++-- > 6 files changed, 570 insertions(+), 32 deletions(-) > create mode 100644 Documentation/security/SELinux-sctp.rst > > diff --git a/Documentation/security/SELinux-sctp.rst b/Documentation/security/SELinux-sctp.rst > new file mode 100644 > index 0000000..2f66bf3 > --- /dev/null > +++ b/Documentation/security/SELinux-sctp.rst > @@ -0,0 +1,157 @@ > +SCTP SELinux Support > +===================== > + > +Security Hooks > +=============== > + > +``Documentation/security/LSM-sctp.rst`` describes the following SCTP security > +hooks with the SELinux specifics expanded below:: > + > + security_sctp_assoc_request() > + security_sctp_bind_connect() > + security_sctp_sk_clone() > + security_inet_conn_established() > + > + > +security_sctp_assoc_request() > +----------------------------- > +Passes the ``@ep`` and ``@chunk->skb`` of the association INIT packet to the > +security module. Returns 0 on success, error on failure. > +:: > + > + @ep - pointer to sctp endpoint structure. > + @skb - pointer to skbuff of association packet. > + > +The security module performs the following operations: > + IF this is the first association on ``@ep->base.sk``, then set the peer > + sid to that in ``@skb``. This will ensure there is only one peer sid > + assigned to ``@ep->base.sk`` that may support multiple associations. > + > + ELSE validate the ``@ep->base.sk peer_sid`` against the ``@skb peer sid`` > + to determine whether the association should be allowed or denied. > + > + Set the sctp ``@ep sid`` to socket's sid (from ``ep->base.sk``) with > + MLS portion taken from ``@skb peer sid``. This will be used by SCTP > + TCP style sockets and peeled off connections as they cause a new socket > + to be generated. > + > + If IP security options are configured (CIPSO/CALIPSO), then the ip > + options are set on the socket. > + > + > +security_sctp_bind_connect() > +----------------------------- > +Checks permissions required for ipv4/ipv6 addresses based on the ``@optname`` > +as follows:: > + > + ------------------------------------------------------------------ > + | BIND Permission Checks | > + | @optname | @address contains | > + |----------------------------|-----------------------------------| > + | SCTP_SOCKOPT_BINDX_ADD | One or more ipv4 / ipv6 addresses | > + | SCTP_PRIMARY_ADDR | Single ipv4 or ipv6 address | > + | SCTP_SET_PEER_PRIMARY_ADDR | Single ipv4 or ipv6 address | > + ------------------------------------------------------------------ > + > + ------------------------------------------------------------------ > + | CONNECT Permission Checks | > + | @optname | @address contains | > + |----------------------------|-----------------------------------| > + | SCTP_SOCKOPT_CONNECTX | One or more ipv4 / ipv6 addresses | > + | SCTP_PARAM_ADD_IP | One or more ipv4 / ipv6 addresses | > + | SCTP_SENDMSG_CONNECT | Single ipv4 or ipv6 address | > + | SCTP_PARAM_SET_PRIMARY | Single ipv4 or ipv6 address | > + ------------------------------------------------------------------ > + > + > +``Documentation/security/LSM-sctp.rst`` gives a summary of the ``@optname`` > +entries and also describes ASCONF chunk processing when Dynamic Address > +Reconfiguration is enabled. > + > + > +security_sctp_sk_clone() > +------------------------- > +Called whenever a new socket is created by **accept**\(2) (i.e. a TCP style > +socket) or when a socket is 'peeled off' e.g userspace calls > +**sctp_peeloff**\(3). ``security_sctp_sk_clone()`` will set the new > +sockets sid and peer sid to that contained in the ``@ep sid`` and > +``@ep peer sid`` respectively. > +:: > + > + @ep - pointer to current sctp endpoint structure. > + @sk - pointer to current sock structure. > + @sk - pointer to new sock structure. > + > + > +security_inet_conn_established() > +--------------------------------- > +Called when a COOKIE ACK is received where it sets the connection's peer sid > +to that in ``@skb``:: > + > + @sk - pointer to sock structure. > + @skb - pointer to skbuff of the COOKIE ACK packet. > + > + > +Policy Statements > +================== > +The following class and permissions to support SCTP are available within the > +kernel:: > + > + class sctp_socket inherits socket { node_bind } > + > +whenever the following policy capability is enabled:: > + > + policycap extended_socket_class; > + > +SELinux SCTP support adds the ``name_connect`` permission for connecting > +to a specific port type and the ``association`` permission that is explained > +in the section below. > + > +If userspace tools have been updated, SCTP will support the ``portcon`` > +statement as shown in the following example:: > + > + portcon sctp 1024-1036 system_u:object_r:sctp_ports_t:s0 > + > + > +SCTP Peer Labeling > +=================== > +An SCTP socket will only have one peer label assigned to it. This will be > +assigned during the establishment of the first association. Once the peer > +label has been assigned, any new associations will have the ``association`` > +permission validated by checking the socket peer sid against the received > +packets peer sid to determine whether the association should be allowed or > +denied. > + > +NOTES: > + 1) If peer labeling is not enabled, then the peer context will always be > + ``SECINITSID_UNLABELED`` (``unlabeled_t`` in Reference Policy). > + > + 2) As SCTP can support more than one transport address per endpoint > + (multi-homing) on a single socket, it is possible to configure policy > + and NetLabel to provide different peer labels for each of these. As the > + socket peer label is determined by the first associations transport > + address, it is recommended that all peer labels are consistent. > + > + 3) **getpeercon**\(3) may be used by userspace to retrieve the sockets peer > + context. > + > + 4) While not SCTP specific, be aware when using NetLabel that if a label > + is assigned to a specific interface, and that interface 'goes down', > + then the NetLabel service will remove the entry. Therefore ensure that > + the network startup scripts call **netlabelctl**\(8) to set the required > + label (see **netlabel-config**\(8) helper script for details). > + > + 5) The NetLabel SCTP peer labeling rules apply as discussed in the following > + set of posts tagged "netlabel" at: http://www.paul-moore.com/blog/t. > + > + 6) CIPSO is only supported for IPv4 addressing: ``socket(AF_INET, ...)`` > + CALIPSO is only supported for IPv6 addressing: ``socket(AF_INET6, ...)`` > + > + Note the following when testing CIPSO/CALIPSO: > + a) CIPSO will send an ICMP packet if an SCTP packet cannot be > + delivered because of an invalid label. > + b) CALIPSO does not send an ICMP packet, just silently discards it. > + > + 7) IPSEC is not supported as RFC 3554 - sctp/ipsec support has not been > + implemented in userspace (**racoon**\(8) or **ipsec_pluto**\(8)), > + although the kernel supports SCTP/IPSEC. > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index f5d3047..24d6f39 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -67,6 +67,8 @@ > #include <linux/tcp.h> > #include <linux/udp.h> > #include <linux/dccp.h> > +#include <linux/sctp.h> > +#include <net/sctp/structs.h> > #include <linux/quota.h> > #include <linux/un.h> /* for Unix socket types */ > #include <net/af_unix.h> /* for Unix socket types */ > @@ -4126,6 +4128,23 @@ static int selinux_parse_skb_ipv4(struct sk_buff *skb, > break; > } > > +#if IS_ENABLED(CONFIG_IP_SCTP) > + case IPPROTO_SCTP: { > + struct sctphdr _sctph, *sh; > + > + if (ntohs(ih->frag_off) & IP_OFFSET) > + break; > + > + offset += ihlen; > + sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph); > + if (sh == NULL) > + break; > + > + ad->u.net->sport = sh->source; > + ad->u.net->dport = sh->dest; > + break; > + } > +#endif > default: > break; > } > @@ -4199,6 +4218,19 @@ static int selinux_parse_skb_ipv6(struct sk_buff *skb, > break; > } > > +#if IS_ENABLED(CONFIG_IP_SCTP) > + case IPPROTO_SCTP: { > + struct sctphdr _sctph, *sh; > + > + sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph); > + if (sh == NULL) > + break; > + > + ad->u.net->sport = sh->source; > + ad->u.net->dport = sh->dest; > + break; > + } > +#endif > /* includes fragments */ > default: > break; > @@ -4388,6 +4420,10 @@ static int selinux_socket_post_create(struct socket *sock, int family, > sksec = sock->sk->sk_security; > sksec->sclass = sclass; > sksec->sid = sid; > + /* Allows detection of the first association on this socket */ > + if (sksec->sclass == SECCLASS_SCTP_SOCKET) > + sksec->sctp_assoc_state = SCTP_ASSOC_UNSET; > + > err = selinux_netlbl_socket_post_create(sock->sk, family); > } > > @@ -4408,11 +4444,7 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in > if (err) > goto out; > > - /* > - * If PF_INET or PF_INET6, check name_bind permission for the port. > - * Multiple address binding for SCTP is not supported yet: we just > - * check the first address now. > - */ > + /* If PF_INET or PF_INET6, check name_bind permission for the port. */ > family = sk->sk_family; > if (family == PF_INET || family == PF_INET6) { > char *addrp; > @@ -4424,7 +4456,13 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in > unsigned short snum; > u32 sid, node_perm; > > - if (family == PF_INET) { > + /* > + * sctp_bindx(3) calls via selinux_sctp_bind_connect() > + * that validates multiple binding addresses. Because of this > + * need to check address->sa_family as it is possible to have > + * sk->sk_family = PF_INET6 with addr->sa_family = AF_INET. > + */ > + if (address->sa_family == AF_INET) { > if (addrlen < sizeof(struct sockaddr_in)) { > err = -EINVAL; > goto out; > @@ -4478,6 +4516,10 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in > node_perm = DCCP_SOCKET__NODE_BIND; > break; > > + case SECCLASS_SCTP_SOCKET: > + node_perm = SCTP_SOCKET__NODE_BIND; > + break; > + > default: > node_perm = RAWIP_SOCKET__NODE_BIND; > break; > @@ -4492,7 +4534,7 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in > ad.u.net->sport = htons(snum); > ad.u.net->family = family; > > - if (family == PF_INET) > + if (address->sa_family == AF_INET) > ad.u.net->v4info.saddr = addr4->sin_addr.s_addr; > else > ad.u.net->v6info.saddr = addr6->sin6_addr; > @@ -4506,7 +4548,11 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in > return err; > } > > -static int selinux_socket_connect(struct socket *sock, struct sockaddr *address, int addrlen) > +/* This supports connect(2) and SCTP connect services such as sctp_connectx(3) > + * and sctp_sendmsg(3) as described in Documentation/security/LSM-sctp.txt > + */ > +static int selinux_socket_connect_helper(struct socket *sock, > + struct sockaddr *address, int addrlen) > { > struct sock *sk = sock->sk; > struct sk_security_struct *sksec = sk->sk_security; > @@ -4517,10 +4563,12 @@ static int selinux_socket_connect(struct socket *sock, struct sockaddr *address, > return err; > > /* > - * If a TCP or DCCP socket, check name_connect permission for the port. > + * If a TCP, DCCP or SCTP socket, check name_connect permission > + * for the port. > */ > if (sksec->sclass == SECCLASS_TCP_SOCKET || > - sksec->sclass == SECCLASS_DCCP_SOCKET) { > + sksec->sclass == SECCLASS_DCCP_SOCKET || > + sksec->sclass == SECCLASS_SCTP_SOCKET) { > struct common_audit_data ad; > struct lsm_network_audit net = {0,}; > struct sockaddr_in *addr4 = NULL; > @@ -4528,7 +4576,12 @@ static int selinux_socket_connect(struct socket *sock, struct sockaddr *address, > unsigned short snum; > u32 sid, perm; > > - if (sk->sk_family == PF_INET) { > + /* sctp_connectx(3) calls via selinux_sctp_bind_connect() > + * that validates multiple connect addresses. Because of this > + * need to check address->sa_family as it is possible to have > + * sk->sk_family = PF_INET6 with addr->sa_family = AF_INET. > + */ > + if (address->sa_family == AF_INET) { > addr4 = (struct sockaddr_in *)address; > if (addrlen < sizeof(struct sockaddr_in)) > return -EINVAL; > @@ -4542,10 +4595,19 @@ static int selinux_socket_connect(struct socket *sock, struct sockaddr *address, > > err = sel_netport_sid(sk->sk_protocol, snum, &sid); > if (err) > - goto out; > + return err; > > - perm = (sksec->sclass == SECCLASS_TCP_SOCKET) ? > - TCP_SOCKET__NAME_CONNECT : DCCP_SOCKET__NAME_CONNECT; > + switch (sksec->sclass) { > + case SECCLASS_TCP_SOCKET: > + perm = TCP_SOCKET__NAME_CONNECT; > + break; > + case SECCLASS_DCCP_SOCKET: > + perm = DCCP_SOCKET__NAME_CONNECT; > + break; > + case SECCLASS_SCTP_SOCKET: > + perm = SCTP_SOCKET__NAME_CONNECT; > + break; > + } > > ad.type = LSM_AUDIT_DATA_NET; > ad.u.net = &net; > @@ -4553,13 +4615,24 @@ static int selinux_socket_connect(struct socket *sock, struct sockaddr *address, > ad.u.net->family = sk->sk_family; > err = avc_has_perm(sksec->sid, sid, sksec->sclass, perm, &ad); > if (err) > - goto out; > + return err; > } > > - err = selinux_netlbl_socket_connect(sk, address); > + return 0; > +} > > -out: > - return err; > +/* Supports connect(2), see comments in selinux_socket_connect_helper() */ > +static int selinux_socket_connect(struct socket *sock, > + struct sockaddr *address, int addrlen) > +{ > + int err; > + struct sock *sk = sock->sk; > + > + err = selinux_socket_connect_helper(sock, address, addrlen); > + if (err) > + return err; > + > + return selinux_netlbl_socket_connect(sk, address); > } > > static int selinux_socket_listen(struct socket *sock, int backlog) > @@ -4822,7 +4895,8 @@ static int selinux_socket_getpeersec_stream(struct socket *sock, char __user *op > u32 peer_sid = SECSID_NULL; > > if (sksec->sclass == SECCLASS_UNIX_STREAM_SOCKET || > - sksec->sclass == SECCLASS_TCP_SOCKET) > + sksec->sclass == SECCLASS_TCP_SOCKET || > + sksec->sclass == SECCLASS_SCTP_SOCKET) > peer_sid = sksec->peer_sid; > if (peer_sid == SECSID_NULL) > return -ENOPROTOOPT; > @@ -4935,6 +5009,171 @@ static void selinux_sock_graft(struct sock *sk, struct socket *parent) > sksec->sclass = isec->sclass; > } > > +/* Called whenever SCTP receives an INIT chunk. This happens when an incoming > + * connect(2), sctp_connectx(3) or sctp_sendmsg(3) (with no association > + * already present). > + */ > +static int selinux_sctp_assoc_request(struct sctp_endpoint *ep, > + struct sk_buff *skb) > +{ > + struct sk_security_struct *sksec = ep->base.sk->sk_security; > + struct common_audit_data ad; > + struct lsm_network_audit net = {0,}; > + u8 peerlbl_active; > + u32 peer_sid = SECINITSID_UNLABELED; > + u32 conn_sid; > + int err = 0; > + > + if (!selinux_policycap_extsockclass) > + return 0; > + > + peerlbl_active = selinux_peerlbl_enabled(); > + > + if (peerlbl_active) { > + /* This will return peer_sid = SECSID_NULL if there are > + * no peer labels, see security_net_peersid_resolve(). > + */ > + err = selinux_skb_peerlbl_sid(skb, ep->base.sk->sk_family, > + &peer_sid); > + if (err) > + return err; > + > + if (peer_sid == SECSID_NULL) > + peer_sid = SECINITSID_UNLABELED; > + } > + > + if (sksec->sctp_assoc_state == SCTP_ASSOC_UNSET) { > + sksec->sctp_assoc_state = SCTP_ASSOC_SET; > + > + /* Here as first association on socket. As the peer SID > + * was allowed by peer recv (and the netif/node checks), > + * then it is approved by policy and used as the primary > + * peer SID for getpeercon(3). > + */ > + sksec->peer_sid = peer_sid; > + } else if (sksec->peer_sid != peer_sid) { > + /* Other association peer SIDs are checked to enforce > + * consistency among the peer SIDs. > + */ > + ad.type = LSM_AUDIT_DATA_NET; > + ad.u.net = &net; > + ad.u.net->sk = ep->base.sk; > + err = avc_has_perm(sksec->peer_sid, peer_sid, sksec->sclass, > + SCTP_SOCKET__ASSOCIATION, &ad); > + if (err) > + return err; > + } > + > + /* Compute the MLS component for the connection and store > + * the information in ep. This will be used by SCTP TCP type > + * sockets and peeled off connections as they cause a new > + * socket to be generated. selinux_sctp_sk_clone() will then > + * plug this into the new socket. > + */ > + err = selinux_conn_sid(sksec->sid, peer_sid, &conn_sid); > + if (err) > + return err; > + > + ep->secid = conn_sid; > + ep->peer_secid = peer_sid; > + > + /* Set any NetLabel labels including CIPSO/CALIPSO options. */ > + return selinux_netlbl_sctp_assoc_request(ep, skb); > +} > + > +/* Check if sctp IPv4/IPv6 addresses are valid for binding or connecting > + * based on their @optname. > + */ > +static int selinux_sctp_bind_connect(struct sock *sk, int optname, > + struct sockaddr *address, > + int addrlen) > +{ > + int len, err = 0, walk_size = 0; > + void *addr_buf; > + struct sockaddr *addr; > + struct socket *sock; > + > + if (!selinux_policycap_extsockclass) > + return 0; > + > + /* Process one or more addresses that may be IPv4 or IPv6 */ > + sock = sk->sk_socket; > + addr_buf = address; > + > + while (walk_size < addrlen) { > + addr = addr_buf; > + switch (addr->sa_family) { > + case AF_INET: > + len = sizeof(struct sockaddr_in); > + break; > + case AF_INET6: > + len = sizeof(struct sockaddr_in6); > + break; > + default: > + return -EAFNOSUPPORT; > + } > + > + err = -EINVAL; > + switch (optname) { > + /* Bind checks */ > + case SCTP_PRIMARY_ADDR: > + case SCTP_SET_PEER_PRIMARY_ADDR: > + case SCTP_SOCKOPT_BINDX_ADD: > + err = selinux_socket_bind(sock, addr, len); > + break; > + /* Connect checks */ > + case SCTP_SOCKOPT_CONNECTX: > + case SCTP_PARAM_SET_PRIMARY: > + case SCTP_PARAM_ADD_IP: > + case SCTP_SENDMSG_CONNECT: > + err = selinux_socket_connect_helper(sock, addr, len); > + if (err) > + return err; > + > + /* As selinux_sctp_bind_connect() is called by the > + * SCTP protocol layer, the socket is already locked, > + * therefore selinux_netlbl_socket_connect_locked() is > + * is called here. The situations handled are: > + * sctp_connectx(3), sctp_sendmsg(3), sendmsg(2), > + * whenever a new IP address is added or when a new > + * primary address is selected. > + * Note that an SCTP connect(2) call happens before > + * the SCTP protocol layer and is handled via > + * selinux_socket_connect(). > + */ > + err = selinux_netlbl_socket_connect_locked(sk, addr); > + break; > + } > + > + if (err) > + return err; > + > + addr_buf += len; > + walk_size += len; > + } > + > + return 0; > +} > + > +/* Called whenever a new socket is created by accept(2) or sctp_peeloff(3). */ > +static void selinux_sctp_sk_clone(struct sctp_endpoint *ep, struct sock *sk, > + struct sock *newsk) > +{ > + struct sk_security_struct *sksec = sk->sk_security; > + struct sk_security_struct *newsksec = newsk->sk_security; > + > + /* If policy does not support SECCLASS_SCTP_SOCKET then call > + * the non-sctp clone version. > + */ > + if (!selinux_policycap_extsockclass) > + return selinux_sk_clone_security(sk, newsk); > + > + newsksec->sid = ep->secid; > + newsksec->peer_sid = ep->peer_secid; > + newsksec->sclass = sksec->sclass; > + selinux_netlbl_sctp_sk_clone(sk, newsk); > +} > + > static int selinux_inet_conn_request(struct sock *sk, struct sk_buff *skb, > struct request_sock *req) > { > @@ -6422,6 +6661,9 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { > LSM_HOOK_INIT(sk_clone_security, selinux_sk_clone_security), > LSM_HOOK_INIT(sk_getsecid, selinux_sk_getsecid), > LSM_HOOK_INIT(sock_graft, selinux_sock_graft), > + LSM_HOOK_INIT(sctp_assoc_request, selinux_sctp_assoc_request), > + LSM_HOOK_INIT(sctp_sk_clone, selinux_sctp_sk_clone), > + LSM_HOOK_INIT(sctp_bind_connect, selinux_sctp_bind_connect), > LSM_HOOK_INIT(inet_conn_request, selinux_inet_conn_request), > LSM_HOOK_INIT(inet_csk_clone, selinux_inet_csk_clone), > LSM_HOOK_INIT(inet_conn_established, selinux_inet_conn_established), > diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h > index cc35695..167c20a 100644 > --- a/security/selinux/include/classmap.h > +++ b/security/selinux/include/classmap.h > @@ -176,7 +176,7 @@ struct security_class_mapping secclass_map[] = { > { COMMON_CAP2_PERMS, NULL } }, > { "sctp_socket", > { COMMON_SOCK_PERMS, > - "node_bind", NULL } }, > + "node_bind", "name_connect", "association", NULL } }, > { "icmp_socket", > { COMMON_SOCK_PERMS, > "node_bind", NULL } }, > diff --git a/security/selinux/include/netlabel.h b/security/selinux/include/netlabel.h > index 75686d5..0fae720 100644 > --- a/security/selinux/include/netlabel.h > +++ b/security/selinux/include/netlabel.h > @@ -33,6 +33,7 @@ > #include <linux/skbuff.h> > #include <net/sock.h> > #include <net/request_sock.h> > +#include <net/sctp/structs.h> > > #include "avc.h" > #include "objsec.h" > @@ -53,9 +54,11 @@ int selinux_netlbl_skbuff_getsid(struct sk_buff *skb, > int selinux_netlbl_skbuff_setsid(struct sk_buff *skb, > u16 family, > u32 sid); > - > +int selinux_netlbl_sctp_assoc_request(struct sctp_endpoint *ep, > + struct sk_buff *skb); > int selinux_netlbl_inet_conn_request(struct request_sock *req, u16 family); > void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family); > +void selinux_netlbl_sctp_sk_clone(struct sock *sk, struct sock *newsk); > int selinux_netlbl_socket_post_create(struct sock *sk, u16 family); > int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec, > struct sk_buff *skb, > @@ -65,6 +68,8 @@ int selinux_netlbl_socket_setsockopt(struct socket *sock, > int level, > int optname); > int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr); > +int selinux_netlbl_socket_connect_locked(struct sock *sk, > + struct sockaddr *addr); > > #else > static inline void selinux_netlbl_cache_invalidate(void) > @@ -114,6 +119,11 @@ static inline int selinux_netlbl_conn_setsid(struct sock *sk, > return 0; > } > > +static inline int selinux_netlbl_sctp_assoc_request(struct sctp_endpoint *ep, > + struct sk_buff *skb) > +{ > + return 0; > +} > static inline int selinux_netlbl_inet_conn_request(struct request_sock *req, > u16 family) > { > @@ -123,6 +133,10 @@ static inline void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family) > { > return; > } > +static inline void selinux_netlbl_sctp_sk_clone(struct sock *sk, sock *newsk) > +{ > + return; > +} > static inline int selinux_netlbl_socket_post_create(struct sock *sk, > u16 family) > { > @@ -146,6 +160,11 @@ static inline int selinux_netlbl_socket_connect(struct sock *sk, > { > return 0; > } > +static inline int selinux_netlbl_socket_connect_locked(struct sock *sk, > + struct sockaddr *addr) > +{ > + return 0; > +} > #endif /* CONFIG_NETLABEL */ > > #endif > diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h > index 1649cd1..be145cf 100644 > --- a/security/selinux/include/objsec.h > +++ b/security/selinux/include/objsec.h > @@ -130,6 +130,10 @@ struct sk_security_struct { > u32 sid; /* SID of this object */ > u32 peer_sid; /* SID of peer */ > u16 sclass; /* sock security class */ > + enum { /* SCTP association state */ > + SCTP_ASSOC_UNSET = 0, > + SCTP_ASSOC_SET, > + } sctp_assoc_state; > }; > > struct tun_security_struct { > diff --git a/security/selinux/netlabel.c b/security/selinux/netlabel.c > index aaba667..0a566e3 100644 > --- a/security/selinux/netlabel.c > +++ b/security/selinux/netlabel.c > @@ -250,6 +250,7 @@ int selinux_netlbl_skbuff_setsid(struct sk_buff *skb, > sk = skb_to_full_sk(skb); > if (sk != NULL) { > struct sk_security_struct *sksec = sk->sk_security; > + > if (sksec->nlbl_state != NLBL_REQSKB) > return 0; > secattr = selinux_netlbl_sock_getattr(sk, sid); > @@ -270,6 +271,61 @@ int selinux_netlbl_skbuff_setsid(struct sk_buff *skb, > return rc; > } > > +/** > + * selinux_netlbl_sctp_assoc_request - Label an incoming sctp association. > + * @ep: incoming association endpoint. > + * @skb: the packet. > + * > + * Description: > + * A new incoming connection is represented by @ep, ...... > + * Returns zero on success, negative values on failure. > + * > + */ > +int selinux_netlbl_sctp_assoc_request(struct sctp_endpoint *ep, > + struct sk_buff *skb) > +{ > + int rc; > + struct netlbl_lsm_secattr secattr; > + struct sk_security_struct *sksec = ep->base.sk->sk_security; > + struct sockaddr *addr; > + struct sockaddr_in addr4; > +#if IS_ENABLED(CONFIG_IPV6) > + struct sockaddr_in6 addr6; > +#endif > + > + if (ep->base.sk->sk_family != PF_INET && > + ep->base.sk->sk_family != PF_INET6) > + return 0; > + > + netlbl_secattr_init(&secattr); > + rc = security_netlbl_sid_to_secattr(ep->secid, &secattr); > + if (rc != 0) > + goto assoc_request_return; > + > + /* Move skb hdr address info to a struct sockaddr and then call > + * netlbl_conn_setattr(). > + */ > + if (ip_hdr(skb)->version == 4) { > + addr4.sin_family = AF_INET; > + addr4.sin_addr.s_addr = ip_hdr(skb)->saddr; > + addr = (struct sockaddr *)&addr4; > +#if IS_ENABLED(CONFIG_IPV6) > + } else { > + addr6.sin6_family = AF_INET6; > + addr6.sin6_addr = ipv6_hdr(skb)->saddr; > + addr = (struct sockaddr *)&addr6; > +#endif > + } > + > + rc = netlbl_conn_setattr(ep->base.sk, addr, &secattr); > + if (rc == 0) > + sksec->nlbl_state = NLBL_LABELED; > + > +assoc_request_return: > + netlbl_secattr_destroy(&secattr); > + return rc; > +} > + > /** > * selinux_netlbl_inet_conn_request - Label an incoming stream connection > * @req: incoming connection request socket > @@ -319,6 +375,22 @@ void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family) > sksec->nlbl_state = NLBL_UNSET; > } > > +/** > + * selinux_netlbl_sctp_sk_clone - Copy state to the newly created sock > + * @sk: current sock > + * @newsk: the new sock > + * > + * Description: > + * Called whenever a new socket is created by accept(2) or sctp_peeloff(3). > + */ > +void selinux_netlbl_sctp_sk_clone(struct sock *sk, struct sock *newsk) > +{ > + struct sk_security_struct *sksec = sk->sk_security; > + struct sk_security_struct *newsksec = newsk->sk_security; > + > + newsksec->nlbl_state = sksec->nlbl_state; > +} > + > /** > * selinux_netlbl_socket_post_create - Label a socket using NetLabel > * @sock: the socket to label > @@ -470,7 +542,8 @@ int selinux_netlbl_socket_setsockopt(struct socket *sock, > } > > /** > - * selinux_netlbl_socket_connect - Label a client-side socket on connect > + * selinux_netlbl_socket_connect_helper - Help label a client-side socket on > + * connect > * @sk: the socket to label > * @addr: the destination address > * > @@ -479,18 +552,13 @@ int selinux_netlbl_socket_setsockopt(struct socket *sock, > * Returns zero values on success, negative values on failure. > * > */ > -int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr) > +static int selinux_netlbl_socket_connect_helper(struct sock *sk, > + struct sockaddr *addr) > { > int rc; > struct sk_security_struct *sksec = sk->sk_security; > struct netlbl_lsm_secattr *secattr; > > - if (sksec->nlbl_state != NLBL_REQSKB && > - sksec->nlbl_state != NLBL_CONNLABELED) > - return 0; > - > - lock_sock(sk); > - > /* connected sockets are allowed to disconnect when the address family > * is set to AF_UNSPEC, if that is what is happening we want to reset > * the socket */ > @@ -498,18 +566,66 @@ int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr) > netlbl_sock_delattr(sk); > sksec->nlbl_state = NLBL_REQSKB; > rc = 0; > - goto socket_connect_return; > + return rc; > } > secattr = selinux_netlbl_sock_genattr(sk); > if (secattr == NULL) { > rc = -ENOMEM; > - goto socket_connect_return; > + return rc; > } > rc = netlbl_conn_setattr(sk, addr, secattr); > if (rc == 0) > sksec->nlbl_state = NLBL_CONNLABELED; > > -socket_connect_return: > + return rc; > +} > + > +/** > + * selinux_netlbl_socket_connect - Label a client-side socket on connect > + * @sk: the socket to label > + * @addr: the destination address > + * > + * Description: > + * Attempt to label a connected socket with NetLabel using the given address. > + * Returns zero values on success, negative values on failure. > + * > + */ > +int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr) > +{ > + int rc; > + struct sk_security_struct *sksec = sk->sk_security; > + > + if (sksec->nlbl_state != NLBL_REQSKB && > + sksec->nlbl_state != NLBL_CONNLABELED) > + return 0; > + > + lock_sock(sk); > + rc = selinux_netlbl_socket_connect_helper(sk, addr); > release_sock(sk); > + > return rc; > } > + > +/** > + * selinux_netlbl_socket_connect_locked - Label a client-side socket on > + * connect > + * @sk: the socket to label > + * @addr: the destination address > + * > + * Description: > + * Attempt to label a connected socket that already has the socket locked > + * with NetLabel using the given address. > + * Returns zero values on success, negative values on failure. > + * > + */ > +int selinux_netlbl_socket_connect_locked(struct sock *sk, > + struct sockaddr *addr) > +{ > + struct sk_security_struct *sksec = sk->sk_security; > + > + if (sksec->nlbl_state != NLBL_REQSKB && > + sksec->nlbl_state != NLBL_CONNLABELED) > + return 0; > + > + return selinux_netlbl_socket_connect_helper(sk, addr); > +} > -- > 2.14.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-sctp" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
On Sat, Dec 30, 2017 at 12:20 PM, Richard Haines <richard_c_haines@btinternet.com> wrote: > The SELinux SCTP implementation is explained in: > Documentation/security/SELinux-sctp.rst > > Signed-off-by: Richard Haines <richard_c_haines@btinternet.com> > --- > Documentation/security/SELinux-sctp.rst | 157 ++++++++++++++++++ > security/selinux/hooks.c | 280 +++++++++++++++++++++++++++++--- > security/selinux/include/classmap.h | 2 +- > security/selinux/include/netlabel.h | 21 ++- > security/selinux/include/objsec.h | 4 + > security/selinux/netlabel.c | 138 ++++++++++++++-- > 6 files changed, 570 insertions(+), 32 deletions(-) > create mode 100644 Documentation/security/SELinux-sctp.rst ... > +/** > + * selinux_netlbl_socket_connect - Label a client-side socket on connect > + * @sk: the socket to label > + * @addr: the destination address > + * > + * Description: > + * Attempt to label a connected socket with NetLabel using the given address. > + * Returns zero values on success, negative values on failure. > + * > + */ > +int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr) > +{ > + int rc; > + struct sk_security_struct *sksec = sk->sk_security; > + > + if (sksec->nlbl_state != NLBL_REQSKB && > + sksec->nlbl_state != NLBL_CONNLABELED) > + return 0; > + > + lock_sock(sk); > + rc = selinux_netlbl_socket_connect_helper(sk, addr); > release_sock(sk); > + > return rc; > } > + > +/** > + * selinux_netlbl_socket_connect_locked - Label a client-side socket on > + * connect > + * @sk: the socket to label > + * @addr: the destination address > + * > + * Description: > + * Attempt to label a connected socket that already has the socket locked > + * with NetLabel using the given address. > + * Returns zero values on success, negative values on failure. > + * > + */ > +int selinux_netlbl_socket_connect_locked(struct sock *sk, > + struct sockaddr *addr) > +{ > + struct sk_security_struct *sksec = sk->sk_security; > + > + if (sksec->nlbl_state != NLBL_REQSKB && > + sksec->nlbl_state != NLBL_CONNLABELED) > + return 0; > + > + return selinux_netlbl_socket_connect_helper(sk, addr); > +} [Sorry for the review delay, the holidays and some associated travel made it hard to find some quiet time to look at the latest patches.] I probably should have been a bit more clear in my last comment, but what I had in mind was something like the following: int selinux_netlbl_socket_connect_locked(...) { if (sksec->nlbl_state ...) return 0; return selinux_netlbl_socket_connect_helper(); } int selinux_netlbl_socket_connect(...) { int rc; lock_sock(); rc = selinux_netlbl_socket_connect_locked(); release_sock(); return rc; } Yes, you do end up checking nlbl_state while the socket lock is held, but I believe the benefit of consolidating the code outweighs any additional overhead (I believe it would be "noise" anyway). Otherwise, this all looks good to me.
On Wed, 2018-01-10 at 11:37 -0500, Paul Moore wrote: > On Sat, Dec 30, 2017 at 12:20 PM, Richard Haines > <richard_c_haines@btinternet.com> wrote: > > The SELinux SCTP implementation is explained in: > > Documentation/security/SELinux-sctp.rst > > > > Signed-off-by: Richard Haines <richard_c_haines@btinternet.com> > > --- > > Documentation/security/SELinux-sctp.rst | 157 ++++++++++++++++++ > > security/selinux/hooks.c | 280 > > +++++++++++++++++++++++++++++--- > > security/selinux/include/classmap.h | 2 +- > > security/selinux/include/netlabel.h | 21 ++- > > security/selinux/include/objsec.h | 4 + > > security/selinux/netlabel.c | 138 ++++++++++++++-- > > 6 files changed, 570 insertions(+), 32 deletions(-) > > create mode 100644 Documentation/security/SELinux-sctp.rst > > ... > > > +/** > > + * selinux_netlbl_socket_connect - Label a client-side socket on > > connect > > + * @sk: the socket to label > > + * @addr: the destination address > > + * > > + * Description: > > + * Attempt to label a connected socket with NetLabel using the > > given address. > > + * Returns zero values on success, negative values on failure. > > + * > > + */ > > +int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr > > *addr) > > +{ > > + int rc; > > + struct sk_security_struct *sksec = sk->sk_security; > > + > > + if (sksec->nlbl_state != NLBL_REQSKB && > > + sksec->nlbl_state != NLBL_CONNLABELED) > > + return 0; > > + > > + lock_sock(sk); > > + rc = selinux_netlbl_socket_connect_helper(sk, addr); > > release_sock(sk); > > + > > return rc; > > } > > + > > +/** > > + * selinux_netlbl_socket_connect_locked - Label a client-side > > socket on > > + * connect > > + * @sk: the socket to label > > + * @addr: the destination address > > + * > > + * Description: > > + * Attempt to label a connected socket that already has the socket > > locked > > + * with NetLabel using the given address. > > + * Returns zero values on success, negative values on failure. > > + * > > + */ > > +int selinux_netlbl_socket_connect_locked(struct sock *sk, > > + struct sockaddr *addr) > > +{ > > + struct sk_security_struct *sksec = sk->sk_security; > > + > > + if (sksec->nlbl_state != NLBL_REQSKB && > > + sksec->nlbl_state != NLBL_CONNLABELED) > > + return 0; > > + > > + return selinux_netlbl_socket_connect_helper(sk, addr); > > +} > > [Sorry for the review delay, the holidays and some associated travel > made it hard to find some quiet time to look at the latest patches.] > > I probably should have been a bit more clear in my last comment, but > what I had in mind was something like the following: > > int selinux_netlbl_socket_connect_locked(...) > { > if (sksec->nlbl_state ...) > return 0; > > return selinux_netlbl_socket_connect_helper(); > } > > int selinux_netlbl_socket_connect(...) > { > int rc; > > lock_sock(); > rc = selinux_netlbl_socket_connect_locked(); > release_sock(); > > return rc; > } > > Yes, you do end up checking nlbl_state while the socket lock is held, > but I believe the benefit of consolidating the code outweighs any > additional overhead (I believe it would be "noise" anyway). Okay I'll send an updated [PATCH V5 4/4] tomorrow. > > Otherwise, this all looks good to me. >
diff --git a/Documentation/security/SELinux-sctp.rst b/Documentation/security/SELinux-sctp.rst new file mode 100644 index 0000000..2f66bf3 --- /dev/null +++ b/Documentation/security/SELinux-sctp.rst @@ -0,0 +1,157 @@ +SCTP SELinux Support +===================== + +Security Hooks +=============== + +``Documentation/security/LSM-sctp.rst`` describes the following SCTP security +hooks with the SELinux specifics expanded below:: + + security_sctp_assoc_request() + security_sctp_bind_connect() + security_sctp_sk_clone() + security_inet_conn_established() + + +security_sctp_assoc_request() +----------------------------- +Passes the ``@ep`` and ``@chunk->skb`` of the association INIT packet to the +security module. Returns 0 on success, error on failure. +:: + + @ep - pointer to sctp endpoint structure. + @skb - pointer to skbuff of association packet. + +The security module performs the following operations: + IF this is the first association on ``@ep->base.sk``, then set the peer + sid to that in ``@skb``. This will ensure there is only one peer sid + assigned to ``@ep->base.sk`` that may support multiple associations. + + ELSE validate the ``@ep->base.sk peer_sid`` against the ``@skb peer sid`` + to determine whether the association should be allowed or denied. + + Set the sctp ``@ep sid`` to socket's sid (from ``ep->base.sk``) with + MLS portion taken from ``@skb peer sid``. This will be used by SCTP + TCP style sockets and peeled off connections as they cause a new socket + to be generated. + + If IP security options are configured (CIPSO/CALIPSO), then the ip + options are set on the socket. + + +security_sctp_bind_connect() +----------------------------- +Checks permissions required for ipv4/ipv6 addresses based on the ``@optname`` +as follows:: + + ------------------------------------------------------------------ + | BIND Permission Checks | + | @optname | @address contains | + |----------------------------|-----------------------------------| + | SCTP_SOCKOPT_BINDX_ADD | One or more ipv4 / ipv6 addresses | + | SCTP_PRIMARY_ADDR | Single ipv4 or ipv6 address | + | SCTP_SET_PEER_PRIMARY_ADDR | Single ipv4 or ipv6 address | + ------------------------------------------------------------------ + + ------------------------------------------------------------------ + | CONNECT Permission Checks | + | @optname | @address contains | + |----------------------------|-----------------------------------| + | SCTP_SOCKOPT_CONNECTX | One or more ipv4 / ipv6 addresses | + | SCTP_PARAM_ADD_IP | One or more ipv4 / ipv6 addresses | + | SCTP_SENDMSG_CONNECT | Single ipv4 or ipv6 address | + | SCTP_PARAM_SET_PRIMARY | Single ipv4 or ipv6 address | + ------------------------------------------------------------------ + + +``Documentation/security/LSM-sctp.rst`` gives a summary of the ``@optname`` +entries and also describes ASCONF chunk processing when Dynamic Address +Reconfiguration is enabled. + + +security_sctp_sk_clone() +------------------------- +Called whenever a new socket is created by **accept**\(2) (i.e. a TCP style +socket) or when a socket is 'peeled off' e.g userspace calls +**sctp_peeloff**\(3). ``security_sctp_sk_clone()`` will set the new +sockets sid and peer sid to that contained in the ``@ep sid`` and +``@ep peer sid`` respectively. +:: + + @ep - pointer to current sctp endpoint structure. + @sk - pointer to current sock structure. + @sk - pointer to new sock structure. + + +security_inet_conn_established() +--------------------------------- +Called when a COOKIE ACK is received where it sets the connection's peer sid +to that in ``@skb``:: + + @sk - pointer to sock structure. + @skb - pointer to skbuff of the COOKIE ACK packet. + + +Policy Statements +================== +The following class and permissions to support SCTP are available within the +kernel:: + + class sctp_socket inherits socket { node_bind } + +whenever the following policy capability is enabled:: + + policycap extended_socket_class; + +SELinux SCTP support adds the ``name_connect`` permission for connecting +to a specific port type and the ``association`` permission that is explained +in the section below. + +If userspace tools have been updated, SCTP will support the ``portcon`` +statement as shown in the following example:: + + portcon sctp 1024-1036 system_u:object_r:sctp_ports_t:s0 + + +SCTP Peer Labeling +=================== +An SCTP socket will only have one peer label assigned to it. This will be +assigned during the establishment of the first association. Once the peer +label has been assigned, any new associations will have the ``association`` +permission validated by checking the socket peer sid against the received +packets peer sid to determine whether the association should be allowed or +denied. + +NOTES: + 1) If peer labeling is not enabled, then the peer context will always be + ``SECINITSID_UNLABELED`` (``unlabeled_t`` in Reference Policy). + + 2) As SCTP can support more than one transport address per endpoint + (multi-homing) on a single socket, it is possible to configure policy + and NetLabel to provide different peer labels for each of these. As the + socket peer label is determined by the first associations transport + address, it is recommended that all peer labels are consistent. + + 3) **getpeercon**\(3) may be used by userspace to retrieve the sockets peer + context. + + 4) While not SCTP specific, be aware when using NetLabel that if a label + is assigned to a specific interface, and that interface 'goes down', + then the NetLabel service will remove the entry. Therefore ensure that + the network startup scripts call **netlabelctl**\(8) to set the required + label (see **netlabel-config**\(8) helper script for details). + + 5) The NetLabel SCTP peer labeling rules apply as discussed in the following + set of posts tagged "netlabel" at: http://www.paul-moore.com/blog/t. + + 6) CIPSO is only supported for IPv4 addressing: ``socket(AF_INET, ...)`` + CALIPSO is only supported for IPv6 addressing: ``socket(AF_INET6, ...)`` + + Note the following when testing CIPSO/CALIPSO: + a) CIPSO will send an ICMP packet if an SCTP packet cannot be + delivered because of an invalid label. + b) CALIPSO does not send an ICMP packet, just silently discards it. + + 7) IPSEC is not supported as RFC 3554 - sctp/ipsec support has not been + implemented in userspace (**racoon**\(8) or **ipsec_pluto**\(8)), + although the kernel supports SCTP/IPSEC. diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index f5d3047..24d6f39 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -67,6 +67,8 @@ #include <linux/tcp.h> #include <linux/udp.h> #include <linux/dccp.h> +#include <linux/sctp.h> +#include <net/sctp/structs.h> #include <linux/quota.h> #include <linux/un.h> /* for Unix socket types */ #include <net/af_unix.h> /* for Unix socket types */ @@ -4126,6 +4128,23 @@ static int selinux_parse_skb_ipv4(struct sk_buff *skb, break; } +#if IS_ENABLED(CONFIG_IP_SCTP) + case IPPROTO_SCTP: { + struct sctphdr _sctph, *sh; + + if (ntohs(ih->frag_off) & IP_OFFSET) + break; + + offset += ihlen; + sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph); + if (sh == NULL) + break; + + ad->u.net->sport = sh->source; + ad->u.net->dport = sh->dest; + break; + } +#endif default: break; } @@ -4199,6 +4218,19 @@ static int selinux_parse_skb_ipv6(struct sk_buff *skb, break; } +#if IS_ENABLED(CONFIG_IP_SCTP) + case IPPROTO_SCTP: { + struct sctphdr _sctph, *sh; + + sh = skb_header_pointer(skb, offset, sizeof(_sctph), &_sctph); + if (sh == NULL) + break; + + ad->u.net->sport = sh->source; + ad->u.net->dport = sh->dest; + break; + } +#endif /* includes fragments */ default: break; @@ -4388,6 +4420,10 @@ static int selinux_socket_post_create(struct socket *sock, int family, sksec = sock->sk->sk_security; sksec->sclass = sclass; sksec->sid = sid; + /* Allows detection of the first association on this socket */ + if (sksec->sclass == SECCLASS_SCTP_SOCKET) + sksec->sctp_assoc_state = SCTP_ASSOC_UNSET; + err = selinux_netlbl_socket_post_create(sock->sk, family); } @@ -4408,11 +4444,7 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in if (err) goto out; - /* - * If PF_INET or PF_INET6, check name_bind permission for the port. - * Multiple address binding for SCTP is not supported yet: we just - * check the first address now. - */ + /* If PF_INET or PF_INET6, check name_bind permission for the port. */ family = sk->sk_family; if (family == PF_INET || family == PF_INET6) { char *addrp; @@ -4424,7 +4456,13 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in unsigned short snum; u32 sid, node_perm; - if (family == PF_INET) { + /* + * sctp_bindx(3) calls via selinux_sctp_bind_connect() + * that validates multiple binding addresses. Because of this + * need to check address->sa_family as it is possible to have + * sk->sk_family = PF_INET6 with addr->sa_family = AF_INET. + */ + if (address->sa_family == AF_INET) { if (addrlen < sizeof(struct sockaddr_in)) { err = -EINVAL; goto out; @@ -4478,6 +4516,10 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in node_perm = DCCP_SOCKET__NODE_BIND; break; + case SECCLASS_SCTP_SOCKET: + node_perm = SCTP_SOCKET__NODE_BIND; + break; + default: node_perm = RAWIP_SOCKET__NODE_BIND; break; @@ -4492,7 +4534,7 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in ad.u.net->sport = htons(snum); ad.u.net->family = family; - if (family == PF_INET) + if (address->sa_family == AF_INET) ad.u.net->v4info.saddr = addr4->sin_addr.s_addr; else ad.u.net->v6info.saddr = addr6->sin6_addr; @@ -4506,7 +4548,11 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in return err; } -static int selinux_socket_connect(struct socket *sock, struct sockaddr *address, int addrlen) +/* This supports connect(2) and SCTP connect services such as sctp_connectx(3) + * and sctp_sendmsg(3) as described in Documentation/security/LSM-sctp.txt + */ +static int selinux_socket_connect_helper(struct socket *sock, + struct sockaddr *address, int addrlen) { struct sock *sk = sock->sk; struct sk_security_struct *sksec = sk->sk_security; @@ -4517,10 +4563,12 @@ static int selinux_socket_connect(struct socket *sock, struct sockaddr *address, return err; /* - * If a TCP or DCCP socket, check name_connect permission for the port. + * If a TCP, DCCP or SCTP socket, check name_connect permission + * for the port. */ if (sksec->sclass == SECCLASS_TCP_SOCKET || - sksec->sclass == SECCLASS_DCCP_SOCKET) { + sksec->sclass == SECCLASS_DCCP_SOCKET || + sksec->sclass == SECCLASS_SCTP_SOCKET) { struct common_audit_data ad; struct lsm_network_audit net = {0,}; struct sockaddr_in *addr4 = NULL; @@ -4528,7 +4576,12 @@ static int selinux_socket_connect(struct socket *sock, struct sockaddr *address, unsigned short snum; u32 sid, perm; - if (sk->sk_family == PF_INET) { + /* sctp_connectx(3) calls via selinux_sctp_bind_connect() + * that validates multiple connect addresses. Because of this + * need to check address->sa_family as it is possible to have + * sk->sk_family = PF_INET6 with addr->sa_family = AF_INET. + */ + if (address->sa_family == AF_INET) { addr4 = (struct sockaddr_in *)address; if (addrlen < sizeof(struct sockaddr_in)) return -EINVAL; @@ -4542,10 +4595,19 @@ static int selinux_socket_connect(struct socket *sock, struct sockaddr *address, err = sel_netport_sid(sk->sk_protocol, snum, &sid); if (err) - goto out; + return err; - perm = (sksec->sclass == SECCLASS_TCP_SOCKET) ? - TCP_SOCKET__NAME_CONNECT : DCCP_SOCKET__NAME_CONNECT; + switch (sksec->sclass) { + case SECCLASS_TCP_SOCKET: + perm = TCP_SOCKET__NAME_CONNECT; + break; + case SECCLASS_DCCP_SOCKET: + perm = DCCP_SOCKET__NAME_CONNECT; + break; + case SECCLASS_SCTP_SOCKET: + perm = SCTP_SOCKET__NAME_CONNECT; + break; + } ad.type = LSM_AUDIT_DATA_NET; ad.u.net = &net; @@ -4553,13 +4615,24 @@ static int selinux_socket_connect(struct socket *sock, struct sockaddr *address, ad.u.net->family = sk->sk_family; err = avc_has_perm(sksec->sid, sid, sksec->sclass, perm, &ad); if (err) - goto out; + return err; } - err = selinux_netlbl_socket_connect(sk, address); + return 0; +} -out: - return err; +/* Supports connect(2), see comments in selinux_socket_connect_helper() */ +static int selinux_socket_connect(struct socket *sock, + struct sockaddr *address, int addrlen) +{ + int err; + struct sock *sk = sock->sk; + + err = selinux_socket_connect_helper(sock, address, addrlen); + if (err) + return err; + + return selinux_netlbl_socket_connect(sk, address); } static int selinux_socket_listen(struct socket *sock, int backlog) @@ -4822,7 +4895,8 @@ static int selinux_socket_getpeersec_stream(struct socket *sock, char __user *op u32 peer_sid = SECSID_NULL; if (sksec->sclass == SECCLASS_UNIX_STREAM_SOCKET || - sksec->sclass == SECCLASS_TCP_SOCKET) + sksec->sclass == SECCLASS_TCP_SOCKET || + sksec->sclass == SECCLASS_SCTP_SOCKET) peer_sid = sksec->peer_sid; if (peer_sid == SECSID_NULL) return -ENOPROTOOPT; @@ -4935,6 +5009,171 @@ static void selinux_sock_graft(struct sock *sk, struct socket *parent) sksec->sclass = isec->sclass; } +/* Called whenever SCTP receives an INIT chunk. This happens when an incoming + * connect(2), sctp_connectx(3) or sctp_sendmsg(3) (with no association + * already present). + */ +static int selinux_sctp_assoc_request(struct sctp_endpoint *ep, + struct sk_buff *skb) +{ + struct sk_security_struct *sksec = ep->base.sk->sk_security; + struct common_audit_data ad; + struct lsm_network_audit net = {0,}; + u8 peerlbl_active; + u32 peer_sid = SECINITSID_UNLABELED; + u32 conn_sid; + int err = 0; + + if (!selinux_policycap_extsockclass) + return 0; + + peerlbl_active = selinux_peerlbl_enabled(); + + if (peerlbl_active) { + /* This will return peer_sid = SECSID_NULL if there are + * no peer labels, see security_net_peersid_resolve(). + */ + err = selinux_skb_peerlbl_sid(skb, ep->base.sk->sk_family, + &peer_sid); + if (err) + return err; + + if (peer_sid == SECSID_NULL) + peer_sid = SECINITSID_UNLABELED; + } + + if (sksec->sctp_assoc_state == SCTP_ASSOC_UNSET) { + sksec->sctp_assoc_state = SCTP_ASSOC_SET; + + /* Here as first association on socket. As the peer SID + * was allowed by peer recv (and the netif/node checks), + * then it is approved by policy and used as the primary + * peer SID for getpeercon(3). + */ + sksec->peer_sid = peer_sid; + } else if (sksec->peer_sid != peer_sid) { + /* Other association peer SIDs are checked to enforce + * consistency among the peer SIDs. + */ + ad.type = LSM_AUDIT_DATA_NET; + ad.u.net = &net; + ad.u.net->sk = ep->base.sk; + err = avc_has_perm(sksec->peer_sid, peer_sid, sksec->sclass, + SCTP_SOCKET__ASSOCIATION, &ad); + if (err) + return err; + } + + /* Compute the MLS component for the connection and store + * the information in ep. This will be used by SCTP TCP type + * sockets and peeled off connections as they cause a new + * socket to be generated. selinux_sctp_sk_clone() will then + * plug this into the new socket. + */ + err = selinux_conn_sid(sksec->sid, peer_sid, &conn_sid); + if (err) + return err; + + ep->secid = conn_sid; + ep->peer_secid = peer_sid; + + /* Set any NetLabel labels including CIPSO/CALIPSO options. */ + return selinux_netlbl_sctp_assoc_request(ep, skb); +} + +/* Check if sctp IPv4/IPv6 addresses are valid for binding or connecting + * based on their @optname. + */ +static int selinux_sctp_bind_connect(struct sock *sk, int optname, + struct sockaddr *address, + int addrlen) +{ + int len, err = 0, walk_size = 0; + void *addr_buf; + struct sockaddr *addr; + struct socket *sock; + + if (!selinux_policycap_extsockclass) + return 0; + + /* Process one or more addresses that may be IPv4 or IPv6 */ + sock = sk->sk_socket; + addr_buf = address; + + while (walk_size < addrlen) { + addr = addr_buf; + switch (addr->sa_family) { + case AF_INET: + len = sizeof(struct sockaddr_in); + break; + case AF_INET6: + len = sizeof(struct sockaddr_in6); + break; + default: + return -EAFNOSUPPORT; + } + + err = -EINVAL; + switch (optname) { + /* Bind checks */ + case SCTP_PRIMARY_ADDR: + case SCTP_SET_PEER_PRIMARY_ADDR: + case SCTP_SOCKOPT_BINDX_ADD: + err = selinux_socket_bind(sock, addr, len); + break; + /* Connect checks */ + case SCTP_SOCKOPT_CONNECTX: + case SCTP_PARAM_SET_PRIMARY: + case SCTP_PARAM_ADD_IP: + case SCTP_SENDMSG_CONNECT: + err = selinux_socket_connect_helper(sock, addr, len); + if (err) + return err; + + /* As selinux_sctp_bind_connect() is called by the + * SCTP protocol layer, the socket is already locked, + * therefore selinux_netlbl_socket_connect_locked() is + * is called here. The situations handled are: + * sctp_connectx(3), sctp_sendmsg(3), sendmsg(2), + * whenever a new IP address is added or when a new + * primary address is selected. + * Note that an SCTP connect(2) call happens before + * the SCTP protocol layer and is handled via + * selinux_socket_connect(). + */ + err = selinux_netlbl_socket_connect_locked(sk, addr); + break; + } + + if (err) + return err; + + addr_buf += len; + walk_size += len; + } + + return 0; +} + +/* Called whenever a new socket is created by accept(2) or sctp_peeloff(3). */ +static void selinux_sctp_sk_clone(struct sctp_endpoint *ep, struct sock *sk, + struct sock *newsk) +{ + struct sk_security_struct *sksec = sk->sk_security; + struct sk_security_struct *newsksec = newsk->sk_security; + + /* If policy does not support SECCLASS_SCTP_SOCKET then call + * the non-sctp clone version. + */ + if (!selinux_policycap_extsockclass) + return selinux_sk_clone_security(sk, newsk); + + newsksec->sid = ep->secid; + newsksec->peer_sid = ep->peer_secid; + newsksec->sclass = sksec->sclass; + selinux_netlbl_sctp_sk_clone(sk, newsk); +} + static int selinux_inet_conn_request(struct sock *sk, struct sk_buff *skb, struct request_sock *req) { @@ -6422,6 +6661,9 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(sk_clone_security, selinux_sk_clone_security), LSM_HOOK_INIT(sk_getsecid, selinux_sk_getsecid), LSM_HOOK_INIT(sock_graft, selinux_sock_graft), + LSM_HOOK_INIT(sctp_assoc_request, selinux_sctp_assoc_request), + LSM_HOOK_INIT(sctp_sk_clone, selinux_sctp_sk_clone), + LSM_HOOK_INIT(sctp_bind_connect, selinux_sctp_bind_connect), LSM_HOOK_INIT(inet_conn_request, selinux_inet_conn_request), LSM_HOOK_INIT(inet_csk_clone, selinux_inet_csk_clone), LSM_HOOK_INIT(inet_conn_established, selinux_inet_conn_established), diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index cc35695..167c20a 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -176,7 +176,7 @@ struct security_class_mapping secclass_map[] = { { COMMON_CAP2_PERMS, NULL } }, { "sctp_socket", { COMMON_SOCK_PERMS, - "node_bind", NULL } }, + "node_bind", "name_connect", "association", NULL } }, { "icmp_socket", { COMMON_SOCK_PERMS, "node_bind", NULL } }, diff --git a/security/selinux/include/netlabel.h b/security/selinux/include/netlabel.h index 75686d5..0fae720 100644 --- a/security/selinux/include/netlabel.h +++ b/security/selinux/include/netlabel.h @@ -33,6 +33,7 @@ #include <linux/skbuff.h> #include <net/sock.h> #include <net/request_sock.h> +#include <net/sctp/structs.h> #include "avc.h" #include "objsec.h" @@ -53,9 +54,11 @@ int selinux_netlbl_skbuff_getsid(struct sk_buff *skb, int selinux_netlbl_skbuff_setsid(struct sk_buff *skb, u16 family, u32 sid); - +int selinux_netlbl_sctp_assoc_request(struct sctp_endpoint *ep, + struct sk_buff *skb); int selinux_netlbl_inet_conn_request(struct request_sock *req, u16 family); void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family); +void selinux_netlbl_sctp_sk_clone(struct sock *sk, struct sock *newsk); int selinux_netlbl_socket_post_create(struct sock *sk, u16 family); int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec, struct sk_buff *skb, @@ -65,6 +68,8 @@ int selinux_netlbl_socket_setsockopt(struct socket *sock, int level, int optname); int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr); +int selinux_netlbl_socket_connect_locked(struct sock *sk, + struct sockaddr *addr); #else static inline void selinux_netlbl_cache_invalidate(void) @@ -114,6 +119,11 @@ static inline int selinux_netlbl_conn_setsid(struct sock *sk, return 0; } +static inline int selinux_netlbl_sctp_assoc_request(struct sctp_endpoint *ep, + struct sk_buff *skb) +{ + return 0; +} static inline int selinux_netlbl_inet_conn_request(struct request_sock *req, u16 family) { @@ -123,6 +133,10 @@ static inline void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family) { return; } +static inline void selinux_netlbl_sctp_sk_clone(struct sock *sk, sock *newsk) +{ + return; +} static inline int selinux_netlbl_socket_post_create(struct sock *sk, u16 family) { @@ -146,6 +160,11 @@ static inline int selinux_netlbl_socket_connect(struct sock *sk, { return 0; } +static inline int selinux_netlbl_socket_connect_locked(struct sock *sk, + struct sockaddr *addr) +{ + return 0; +} #endif /* CONFIG_NETLABEL */ #endif diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h index 1649cd1..be145cf 100644 --- a/security/selinux/include/objsec.h +++ b/security/selinux/include/objsec.h @@ -130,6 +130,10 @@ struct sk_security_struct { u32 sid; /* SID of this object */ u32 peer_sid; /* SID of peer */ u16 sclass; /* sock security class */ + enum { /* SCTP association state */ + SCTP_ASSOC_UNSET = 0, + SCTP_ASSOC_SET, + } sctp_assoc_state; }; struct tun_security_struct { diff --git a/security/selinux/netlabel.c b/security/selinux/netlabel.c index aaba667..0a566e3 100644 --- a/security/selinux/netlabel.c +++ b/security/selinux/netlabel.c @@ -250,6 +250,7 @@ int selinux_netlbl_skbuff_setsid(struct sk_buff *skb, sk = skb_to_full_sk(skb); if (sk != NULL) { struct sk_security_struct *sksec = sk->sk_security; + if (sksec->nlbl_state != NLBL_REQSKB) return 0; secattr = selinux_netlbl_sock_getattr(sk, sid); @@ -270,6 +271,61 @@ int selinux_netlbl_skbuff_setsid(struct sk_buff *skb, return rc; } +/** + * selinux_netlbl_sctp_assoc_request - Label an incoming sctp association. + * @ep: incoming association endpoint. + * @skb: the packet. + * + * Description: + * A new incoming connection is represented by @ep, ...... + * Returns zero on success, negative values on failure. + * + */ +int selinux_netlbl_sctp_assoc_request(struct sctp_endpoint *ep, + struct sk_buff *skb) +{ + int rc; + struct netlbl_lsm_secattr secattr; + struct sk_security_struct *sksec = ep->base.sk->sk_security; + struct sockaddr *addr; + struct sockaddr_in addr4; +#if IS_ENABLED(CONFIG_IPV6) + struct sockaddr_in6 addr6; +#endif + + if (ep->base.sk->sk_family != PF_INET && + ep->base.sk->sk_family != PF_INET6) + return 0; + + netlbl_secattr_init(&secattr); + rc = security_netlbl_sid_to_secattr(ep->secid, &secattr); + if (rc != 0) + goto assoc_request_return; + + /* Move skb hdr address info to a struct sockaddr and then call + * netlbl_conn_setattr(). + */ + if (ip_hdr(skb)->version == 4) { + addr4.sin_family = AF_INET; + addr4.sin_addr.s_addr = ip_hdr(skb)->saddr; + addr = (struct sockaddr *)&addr4; +#if IS_ENABLED(CONFIG_IPV6) + } else { + addr6.sin6_family = AF_INET6; + addr6.sin6_addr = ipv6_hdr(skb)->saddr; + addr = (struct sockaddr *)&addr6; +#endif + } + + rc = netlbl_conn_setattr(ep->base.sk, addr, &secattr); + if (rc == 0) + sksec->nlbl_state = NLBL_LABELED; + +assoc_request_return: + netlbl_secattr_destroy(&secattr); + return rc; +} + /** * selinux_netlbl_inet_conn_request - Label an incoming stream connection * @req: incoming connection request socket @@ -319,6 +375,22 @@ void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family) sksec->nlbl_state = NLBL_UNSET; } +/** + * selinux_netlbl_sctp_sk_clone - Copy state to the newly created sock + * @sk: current sock + * @newsk: the new sock + * + * Description: + * Called whenever a new socket is created by accept(2) or sctp_peeloff(3). + */ +void selinux_netlbl_sctp_sk_clone(struct sock *sk, struct sock *newsk) +{ + struct sk_security_struct *sksec = sk->sk_security; + struct sk_security_struct *newsksec = newsk->sk_security; + + newsksec->nlbl_state = sksec->nlbl_state; +} + /** * selinux_netlbl_socket_post_create - Label a socket using NetLabel * @sock: the socket to label @@ -470,7 +542,8 @@ int selinux_netlbl_socket_setsockopt(struct socket *sock, } /** - * selinux_netlbl_socket_connect - Label a client-side socket on connect + * selinux_netlbl_socket_connect_helper - Help label a client-side socket on + * connect * @sk: the socket to label * @addr: the destination address * @@ -479,18 +552,13 @@ int selinux_netlbl_socket_setsockopt(struct socket *sock, * Returns zero values on success, negative values on failure. * */ -int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr) +static int selinux_netlbl_socket_connect_helper(struct sock *sk, + struct sockaddr *addr) { int rc; struct sk_security_struct *sksec = sk->sk_security; struct netlbl_lsm_secattr *secattr; - if (sksec->nlbl_state != NLBL_REQSKB && - sksec->nlbl_state != NLBL_CONNLABELED) - return 0; - - lock_sock(sk); - /* connected sockets are allowed to disconnect when the address family * is set to AF_UNSPEC, if that is what is happening we want to reset * the socket */ @@ -498,18 +566,66 @@ int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr) netlbl_sock_delattr(sk); sksec->nlbl_state = NLBL_REQSKB; rc = 0; - goto socket_connect_return; + return rc; } secattr = selinux_netlbl_sock_genattr(sk); if (secattr == NULL) { rc = -ENOMEM; - goto socket_connect_return; + return rc; } rc = netlbl_conn_setattr(sk, addr, secattr); if (rc == 0) sksec->nlbl_state = NLBL_CONNLABELED; -socket_connect_return: + return rc; +} + +/** + * selinux_netlbl_socket_connect - Label a client-side socket on connect + * @sk: the socket to label + * @addr: the destination address + * + * Description: + * Attempt to label a connected socket with NetLabel using the given address. + * Returns zero values on success, negative values on failure. + * + */ +int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr) +{ + int rc; + struct sk_security_struct *sksec = sk->sk_security; + + if (sksec->nlbl_state != NLBL_REQSKB && + sksec->nlbl_state != NLBL_CONNLABELED) + return 0; + + lock_sock(sk); + rc = selinux_netlbl_socket_connect_helper(sk, addr); release_sock(sk); + return rc; } + +/** + * selinux_netlbl_socket_connect_locked - Label a client-side socket on + * connect + * @sk: the socket to label + * @addr: the destination address + * + * Description: + * Attempt to label a connected socket that already has the socket locked + * with NetLabel using the given address. + * Returns zero values on success, negative values on failure. + * + */ +int selinux_netlbl_socket_connect_locked(struct sock *sk, + struct sockaddr *addr) +{ + struct sk_security_struct *sksec = sk->sk_security; + + if (sksec->nlbl_state != NLBL_REQSKB && + sksec->nlbl_state != NLBL_CONNLABELED) + return 0; + + return selinux_netlbl_socket_connect_helper(sk, addr); +}
The SELinux SCTP implementation is explained in: Documentation/security/SELinux-sctp.rst Signed-off-by: Richard Haines <richard_c_haines@btinternet.com> --- Documentation/security/SELinux-sctp.rst | 157 ++++++++++++++++++ security/selinux/hooks.c | 280 +++++++++++++++++++++++++++++--- security/selinux/include/classmap.h | 2 +- security/selinux/include/netlabel.h | 21 ++- security/selinux/include/objsec.h | 4 + security/selinux/netlabel.c | 138 ++++++++++++++-- 6 files changed, 570 insertions(+), 32 deletions(-) create mode 100644 Documentation/security/SELinux-sctp.rst