On Tue, 2017-10-17 at 14:59 +0100, Richard Haines wrote:
> The SELinux SCTP implementation is explained in:
> Documentation/security/SELinux-sctp.txt
>
> Signed-off-by: Richard Haines <richard_c_hai...@btinternet.com>
> ---
> Documentation/security/SELinux-sctp.txt | 108 +++++++++++++
> security/selinux/hooks.c | 268
> ++++++++++++++++++++++++++++++--
> security/selinux/include/classmap.h | 3 +-
> security/selinux/include/netlabel.h | 9 +-
> security/selinux/include/objsec.h | 5 +
> security/selinux/netlabel.c | 52 ++++++-
> 6 files changed, 427 insertions(+), 18 deletions(-)
> create mode 100644 Documentation/security/SELinux-sctp.txt
>
> diff --git a/Documentation/security/SELinux-sctp.txt
> b/Documentation/security/SELinux-sctp.txt
> new file mode 100644
> index 0000000..32e0255
> --- /dev/null
> +++ b/Documentation/security/SELinux-sctp.txt
> @@ -0,0 +1,108 @@
> + SCTP SELinux Support
> + ======================
> +
> +Security Hooks
> +===============
> +
> +The Documentation/security/LSM-sctp.txt document describes how the
> following
> +sctp security hooks are utilised:
> + security_sctp_assoc_request()
> + security_sctp_bind_connect()
> + security_sctp_sk_clone()
> +
> + security_inet_conn_established()
> +
> +
> +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;
> +
> +The SELinux SCTP support adds the additional permissions that are
> explained
> +in the sections below:
> + association bindx connectx
> +
> +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 Bind, Connect and ASCONF Chunk Parameter Permission Checks
> +================================================================
> +The hook security_sctp_bind_connect() is called by SCTP to check
> permissions
> +required for ipv4/ipv6 addresses based on the @optname as follows:
> +
> + ------------------------------------------------------------------
> + | BINDX Permission Check |
> + | @optname | @address contains |
> + |----------------------------|-----------------------------------|
> + | SCTP_SOCKOPT_BINDX_ADD | One or more ipv4 / ipv6 addresses |
> + ------------------------------------------------------------------
> +
> + ------------------------------------------------------------------
> + | BIND Permission Checks |
> + | @optname | @address contains |
> + |----------------------------|-----------------------------------|
> + | SCTP_PRIMARY_ADDR | Single ipv4 or ipv6 address |
> + | SCTP_SET_PEER_PRIMARY_ADDR | Single ipv4 or ipv6 address |
> + ------------------------------------------------------------------
> +
> + ------------------------------------------------------------------
> + | CONNECTX Permission Check |
> + | @optname | @address contains |
> + |----------------------------|-----------------------------------|
> + | SCTP_SOCKOPT_CONNECTX | One or more ipv4 / ipv6 addresses |
> + ------------------------------------------------------------------
> +
> + ------------------------------------------------------------------
> + | CONNECT Permission Checks |
> + | @optname | @address contains |
> + |----------------------------|-----------------------------------|
> + | SCTP_SENDMSG_CONNECT | Single ipv4 or ipv6 address |
> + | SCTP_PARAM_ADD_IP | One or more ipv4 / ipv6 addresses |
> + | SCTP_PARAM_SET_PRIMARY | Single ipv4 or ipv6 address |
> + ------------------------------------------------------------------
> +
> +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 supports multiple endpoints with multi-homing on a
> single socket
> + it is recommended that peer labels are consistent.
> +
> + 3) getpeercon(3) may be used by userspace to retrieve the sockets
> peer
> + context.
> +
> + 4) If using NetLabel be aware 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/b
> log/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 rfc3554 - 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 33fd061..c3e9600 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 */
> @@ -4119,6 +4121,23 @@ 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;
> }
> @@ -4192,6 +4211,19 @@ 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;
> @@ -4381,6 +4413,10 @@ 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;
> +
What prevents this from interleaving with selinux_sctp_assoc_request()
accesses to sctp_assoc_state?
> err = selinux_netlbl_socket_post_create(sock->sk,
> family);
> }
>
> @@ -4401,11 +4437,7 @@ 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;
> @@ -4417,7 +4449,13 @@ 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 (family == PF_INET || address->sa_family ==
> AF_INET) {
> if (addrlen < sizeof(struct sockaddr_in)) {
> err = -EINVAL;
> goto out;
> @@ -4471,6 +4509,10 @@ 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;
> @@ -4485,7 +4527,7 @@ 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 (family == PF_INET || address->sa_family ==
> AF_INET)
> ad.u.net->v4info.saddr = addr4-
> >sin_addr.s_addr;
> else
> ad.u.net->v6info.saddr = addr6->sin6_addr;
> @@ -4510,10 +4552,12 @@ 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;
> @@ -4521,7 +4565,14 @@ 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 (sk->sk_family == PF_INET ||
> + address->sa_family ==
> AF_INET) {
> addr4 = (struct sockaddr_in *)address;
> if (addrlen < sizeof(struct sockaddr_in))
> return -EINVAL;
> @@ -4534,11 +4585,21 @@ static int selinux_socket_connect(struct
> socket *sock, struct sockaddr *address,
> }
>
> err = sel_netport_sid(sk->sk_protocol, snum, &sid);
> +
> if (err)
> goto out;
>
> - 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;
> @@ -4815,7 +4876,8 @@ 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;
> @@ -4928,6 +4990,183 @@ static void selinux_sock_graft(struct sock
> *sk, struct socket *parent)
> sksec->sclass = isec->sclass;
> }
>
> +/* Called whenever SCTP receives an INIT or INIT_ACK chunk */
> +static int selinux_sctp_assoc_request(struct sctp_endpoint *ep,
> + struct sk_buff *skb,
> + int sctp_cid)
> +{
> + 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;
> +
> + 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;
> + }
> +
> + if (sctp_cid == SCTP_CID_INIT) {
> + /* Have INIT when incoming connect(2),
> sctp_connectx(3)
> + * or sctp_sendmsg(3) (with no association already
> present),
> + * so 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);
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * 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;
> +
> + switch (optname) {
> + case SCTP_SOCKOPT_BINDX_ADD:
> + err = sock_has_perm(sk, SCTP_SOCKET__BINDX);
> + break;
> + case SCTP_SOCKOPT_CONNECTX:
> + err = sock_has_perm(sk, SCTP_SOCKET__CONNECTX);
> + break;
> + /* These need SOCKET__BIND or SOCKET__CONNECT permissions
> that will
> + * be checked later.
> + */
> + case SCTP_PRIMARY_ADDR:
> + case SCTP_SET_PEER_PRIMARY_ADDR:
> + case SCTP_PARAM_SET_PRIMARY:
> + case SCTP_PARAM_ADD_IP:
> + case SCTP_SENDMSG_CONNECT:
> + break;
> + default:
> + err = -EINVAL;
> + }
> + if (err)
> + return err;
> +
> + /* 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(sock, addr,
> len);
> + 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;
> + newsksec->nlbl_state = sksec->nlbl_state;
> +}
> +
> static int selinux_inet_conn_request(struct sock *sk, struct sk_buff
> *skb,
> struct request_sock *req)
> {
> @@ -6416,6 +6655,9 @@ 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 b9fe343..b4b10da 100644
> --- a/security/selinux/include/classmap.h
> +++ b/security/selinux/include/classmap.h
> @@ -173,7 +173,8 @@ struct security_class_mapping secclass_map[] = {
> { COMMON_CAP2_PERMS, NULL } },
> { "sctp_socket",
> { COMMON_SOCK_PERMS,
> - "node_bind", NULL } },
> + "node_bind", "name_connect", "association", "bindx",
> + "connectx", 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..835a0d6 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"
> @@ -53,7 +54,8 @@ 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);
> int selinux_netlbl_socket_post_create(struct sock *sk, u16 family);
> @@ -114,6 +116,11 @@ 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)
> {
> diff --git a/security/selinux/include/objsec.h
> b/security/selinux/include/objsec.h
> index 6ebc61e..660f270 100644
> --- a/security/selinux/include/objsec.h
> +++ b/security/selinux/include/objsec.h
> @@ -130,6 +130,11 @@ 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..7d5aa15 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);
> @@ -271,6 +272,41 @@ int selinux_netlbl_skbuff_setsid(struct sk_buff
> *skb,
> }
>
> /**
> + * 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;
> +
> + 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;
> +
> + rc = netlbl_sctp_setattr(ep->base.sk, skb, &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
> *
> @@ -481,7 +517,7 @@ int selinux_netlbl_socket_setsockopt(struct
> socket *sock,
> */
> int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr
> *addr)
> {
> - int rc;
> + int rc, already_owned_by_user = 0;
> struct sk_security_struct *sksec = sk->sk_security;
> struct netlbl_lsm_secattr *secattr;
>
> @@ -489,7 +525,16 @@ int selinux_netlbl_socket_connect(struct sock
> *sk, struct sockaddr *addr)
> sksec->nlbl_state != NLBL_CONNLABELED)
> return 0;
>
> - lock_sock(sk);
> + /* Note: When called via connect(2) this happens before the
> socket
> + * protocol layer connect operation and @sk is not locked,
> HOWEVER,
> + * when called by the SCTP protocol layer via
> sctp_connectx(3),
> + * sctp_sendmsg(3) or sendmsg(2), @sk is locked. Therefore
> check if
> + * @sk owned already.
> + */
> + if (sock_owned_by_user(sk) && sksec->sclass ==
> SECCLASS_SCTP_SOCKET)
> + already_owned_by_user = 1;
> + else
> + lock_sock(sk);
Conditional locking is generally considered harmful. I'd split the
cases for the different callers, and use a common helper for both.
>
> /* 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
> @@ -510,6 +555,7 @@ int selinux_netlbl_socket_connect(struct sock
> *sk, struct sockaddr *addr)
> sksec->nlbl_state = NLBL_CONNLABELED;
>
> socket_connect_return:
> - release_sock(sk);
> + if (!already_owned_by_user)
> + release_sock(sk);
> return rc;
> }
