From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Moore Subject: Re: [PATCH 2/2] Add a netlink attribute INET_DIAG_SECCTX Date: Wed, 31 Aug 2011 17:18:47 -0400 Message-ID: <2593215.lUI7et83Qv@sifl> References: <1314779777-12669-1-git-send-email-rongqing.li@windriver.com> <1314779777-12669-3-git-send-email-rongqing.li@windriver.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: netdev@vger.kernel.org, selinux@tycho.nsa.gov, linux-security-module@vger.kernel.org To: rongqing.li@windriver.com Return-path: Received: from mail-wy0-f174.google.com ([74.125.82.174]:62837 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752604Ab1HaVSx (ORCPT ); Wed, 31 Aug 2011 17:18:53 -0400 In-Reply-To: <1314779777-12669-3-git-send-email-rongqing.li@windriver.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wednesday, August 31, 2011 04:36:17 PM rongqing.li@windriver.com wrote: > From: Roy.Li > > Add a new netlink attribute INET_DIAG_SECCTX to dump the security > context of TCP sockets. You'll have to forgive me, I'm not familiar with the netlink code used by netstat and friends, but is there anyway to report back the security context of UDP sockets? Or does the code below handle that already? In general, AF_INET and AF_INET6 sockets, regardless of any upper level protocols, have security contexts associated with them and it would be nice to see them in netstat. > diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c > index 389a2e6..1faf752 100644 > --- a/net/ipv4/inet_diag.c > +++ b/net/ipv4/inet_diag.c > @@ -34,6 +34,8 @@ > > #include > > +#define MAX_SECCTX_LEN 128 I'll echo Stephen's concerns that this is too small. A MCS/MLS system with a moderate number of categories could bump into this limit without too much difficulty. > struct inet_diag_entry { > @@ -108,6 +110,25 @@ static int inet_csk_diag_fill(struct sock *sk, > icsk->icsk_ca_ops->name); > } > > + if (ext & (1 << (INET_DIAG_SECCTX - 1))) { > + u32 ctxlen = 0; > + void *secctx; > + int error; > + > + error = security_sk_getsecctx(sk, &secctx, &ctxlen); > + > + if (!error && ctxlen) { > + if (ctxlen < MAX_SECCTX_LEN) { > + strcpy(INET_DIAG_PUT(skb, INET_DIAG_SECCTX, > + ctxlen + 1), secctx); > + } else { > + strcpy(INET_DIAG_PUT(skb, INET_DIAG_SECCTX, > + 2), "-"); Is the "-" string a special value already interpreted by the userspace tools? If not, you might consider using a string that would indicate an out-of-space condition occurred; at first glance I thought the "-" string indicated no context. > + } > + security_release_secctx(secctx, ctxlen); > + } > + } > + > r->idiag_family = sk->sk_family; > r->idiag_state = sk->sk_state; > r->idiag_timer = 0; > @@ -246,7 +267,7 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff > *skb, static int inet_diag_get_exact(struct sk_buff *in_skb, > const struct nlmsghdr *nlh) > { > - int err; > + int err, len; > struct sock *sk; > struct inet_diag_req *req = NLMSG_DATA(nlh); > struct sk_buff *rep; > @@ -293,10 +314,17 @@ static int inet_diag_get_exact(struct sk_buff *in_skb, > goto out; > > err = -ENOMEM; > - rep = alloc_skb(NLMSG_SPACE((sizeof(struct inet_diag_msg) + > - sizeof(struct inet_diag_meminfo) + > - handler->idiag_info_size + 64)), > - GFP_KERNEL); > + len = sizeof(struct inet_diag_msg) + 64; > + > + len += (req->idiag_ext & (1 << (INET_DIAG_MEMINFO - 1))) ? > + sizeof(struct inet_diag_meminfo) : 0; > + len += (req->idiag_ext & (1 << (INET_DIAG_INFO - 1))) ? > + handler->idiag_info_size : 0; > + len += (req->idiag_ext & (1 << (INET_DIAG_SECCTX - 1))) ? > + MAX_SECCTX_LEN : 0; > + > + rep = alloc_skb(NLMSG_SPACE(len), GFP_KERNEL); How much of a problem would it be if you just allocated an entire page (or 4k in the case of huge pages) and used that? Is memory usage a concern here? -- paul moore www.paul-moore.com