From 877ce7c1b3afd69a9b1caeb1b9964c992641f52a Mon Sep 17 00:00:00 2001 From: Catherine Zhang Date: Thu, 29 Jun 2006 12:27:47 -0700 Subject: [AF_UNIX]: Datagram getpeersec This patch implements an API whereby an application can determine the label of its peer's Unix datagram sockets via the auxiliary data mechanism of recvmsg. Patch purpose: This patch enables a security-aware application to retrieve the security context of the peer of a Unix datagram socket. The application can then use this security context to determine the security context for processing on behalf of the peer who sent the packet. Patch design and implementation: The design and implementation is very similar to the UDP case for INET sockets. Basically we build upon the existing Unix domain socket API for retrieving user credentials. Linux offers the API for obtaining user credentials via ancillary messages (i.e., out of band/control messages that are bundled together with a normal message). To retrieve the security context, the application first indicates to the kernel such desire by setting the SO_PASSSEC option via getsockopt. Then the application retrieves the security context using the auxiliary data mechanism. An example server application for Unix datagram socket should look like this: toggle = 1; toggle_len = sizeof(toggle); setsockopt(sockfd, SOL_SOCKET, SO_PASSSEC, &toggle, &toggle_len); recvmsg(sockfd, &msg_hdr, 0); if (msg_hdr.msg_controllen > sizeof(struct cmsghdr)) { cmsg_hdr = CMSG_FIRSTHDR(&msg_hdr); if (cmsg_hdr->cmsg_len <= CMSG_LEN(sizeof(scontext)) && cmsg_hdr->cmsg_level == SOL_SOCKET && cmsg_hdr->cmsg_type == SCM_SECURITY) { memcpy(&scontext, CMSG_DATA(cmsg_hdr), sizeof(scontext)); } } sock_setsockopt is enhanced with a new socket option SOCK_PASSSEC to allow a server socket to receive security context of the peer. Testing: We have tested the patch by setting up Unix datagram client and server applications. We verified that the server can retrieve the security context using the auxiliary data mechanism of recvmsg. Signed-off-by: Catherine Zhang Acked-by: Acked-by: James Morris Signed-off-by: David S. Miller --- include/asm-s390/socket.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/asm-s390') diff --git a/include/asm-s390/socket.h b/include/asm-s390/socket.h index 15a5298c874..1778a49a74c 100644 --- a/include/asm-s390/socket.h +++ b/include/asm-s390/socket.h @@ -56,5 +56,6 @@ #define SO_ACCEPTCONN 30 #define SO_PEERSEC 31 +#define SO_PASSSEC 34 #endif /* _ASM_SOCKET_H */ -- cgit v1.2.3