Re: [RFC PATCH 1/5] security: Add support for SCTP security hooks
From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Date: 2017-10-31 16:42:00
Also in:
linux-sctp, linux-security-module, selinux
On Tue, Oct 17, 2017 at 03:02:47PM +0100, Richard Haines wrote:
quoted hunk ↗ jump to hunk
The SCTP security hooks are explained in: Documentation/security/LSM-sctp.txt Signed-off-by: Richard Haines <redacted> --- Documentation/security/LSM-sctp.txt | 212 ++++++++++++++++++++++++++++++++++++ include/linux/lsm_hooks.h | 37 +++++++ include/linux/security.h | 27 +++++ security/security.c | 23 ++++ 4 files changed, 299 insertions(+) create mode 100644 Documentation/security/LSM-sctp.txtdiff --git a/Documentation/security/LSM-sctp.txt b/Documentation/security/LSM-sctp.txt new file mode 100644 index 0000000..30fe9b5 --- /dev/null +++ b/Documentation/security/LSM-sctp.txt@@ -0,0 +1,212 @@ + SCTP LSM Support + ================== + +For security module support, three sctp specific hooks have been implemented: + security_sctp_assoc_request() + security_sctp_bind_connect() + security_sctp_sk_clone() + +Also the following security hook has been utilised: + security_inet_conn_established() + +The usage of these hooks are described below with the SELinux implementation +described in Documentation/security/SELinux-sctp.txt + + +security_sctp_assoc_request() +------------------------------ +This new hook has been added to net/sctp/sm_statefuns.c where it passes the +@ep and @chunk->skb (the association INIT or INIT ACK 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. + @sctp_cid - set to sctp packet type (SCTP_CID_INIT or SCTP_CID_INIT_ACK). + +The security module performs the following operations: + 1) 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. + + 2) If not the first association, validate the @ep->base.sk peer_sid against + the @skb peer sid to determine whether the association should be allowed + or denied. + + 3) If @sctp_cid = SCTP_CID_INIT, then set the sctp @ep sid to socket's sid + (from ep->base.sk) with MLS portion taken from @skb peer sid. This will + only 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. + + To support this hook include/net/sctp/structs.h "struct sctp_endpoint" + has been updated with the following: + + /* Security identifiers from incoming (INIT). These are set by + * security_sctp_assoc_request(). These will only be used by + * SCTP TCP type sockets and peeled off connections as they + * cause a new socket to be generated. security_sctp_sk_clone() + * will then plug these into the new socket. + */ + u32 secid; + u32 peer_secid; + + +security_sctp_bind_connect() +----------------------------- +This new hook has been added to net/sctp/socket.c and net/sctp/sm_make_chunk.c. +It passes one or more ipv4/ipv6 addresses to the security module for +validation based on the @optname that will result in either a bind or connect +service as shown in the permission check tables below. +Returns 0 on success, error on failure. + + @sk - Pointer to sock structure. + @optname - Name of the option to validate. + @address - One or more ipv4 / ipv6 addresses. + @addrlen - The total length of address(s). This is calculated on each + ipv4 or ipv6 address using sizeof(struct sockaddr_in) or + sizeof(struct sockaddr_in6). + + ------------------------------------------------------------------ + | BIND Type 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 Type 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 | + ------------------------------------------------------------------ + +A summary of the @optname entries is as follows: + + SCTP_SOCKOPT_BINDX_ADD - Allows additional bind addresses to be + associated after (optionally) calling + bind(3). + sctp_bindx(3) adds a set of bind + addresses on a socket.
Nit, indentation issue above.