path: root/security
diff options
authorCatherine Zhang <cxzhang@watson.ibm.com>2006-06-29 12:27:47 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2006-06-29 16:58:06 -0700
commit877ce7c1b3afd69a9b1caeb1b9964c992641f52a (patch)
tree740c6c0d4a2858af53c09c4635cadf06833536c1 /security
parentd6b4991ad5d1a9840e12db507be1a6593def01fe (diff)
[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 <cxzhang@watson.ibm.com> Acked-by: Acked-by: James Morris <jmorris@namei.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'security')
1 files changed, 8 insertions, 3 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index b6c378dd4f1..b85afcf3852 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -69,6 +69,7 @@
#include <linux/sysctl.h>
#include <linux/audit.h>
#include <linux/string.h>
+#include <linux/selinux.h>
#include "avc.h"
#include "objsec.h"
@@ -3420,7 +3421,13 @@ out:
static int selinux_socket_getpeersec_dgram(struct sk_buff *skb, char **secdata, u32 *seclen)
int err = 0;
- u32 peer_sid = selinux_socket_getpeer_dgram(skb);
+ u32 peer_sid;
+ if (skb->sk->sk_family == PF_UNIX)
+ selinux_get_inode_sid(SOCK_INODE(skb->sk->sk_socket),
+ &peer_sid);
+ else
+ peer_sid = selinux_socket_getpeer_dgram(skb);
if (peer_sid == SECSID_NULL)
return -EINVAL;
@@ -3432,8 +3439,6 @@ static int selinux_socket_getpeersec_dgram(struct sk_buff *skb, char **secdata,
return 0;
static int selinux_sk_alloc_security(struct sock *sk, int family, gfp_t priority)
return sk_alloc_security(sk, family, priority);