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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id 25sm316356pfp.76.2019.06.26.16.16.18 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 26 Jun 2019 16:16:18 -0700 (PDT) Date: Wed, 26 Jun 2019 16:16:17 -0700 From: Kees Cook To: Casey Schaufler Cc: casey.schaufler@intel.com, jmorris@namei.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp, paul@paul-moore.com, sds@tycho.nsa.gov Subject: Re: [PATCH v4 20/23] LSM: security_secid_to_secctx in netlink netfilter Message-ID: <201906261616.FB14505D9@keescook> References: <20190626192234.11725-1-casey@schaufler-ca.com> <20190626192234.11725-21-casey@schaufler-ca.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190626192234.11725-21-casey@schaufler-ca.com> Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Wed, Jun 26, 2019 at 12:22:31PM -0700, Casey Schaufler wrote: > Change netlink netfilter interfaces to use lsmcontext > pointers, and remove scaffolding. > > Signed-off-by: Casey Schaufler Reviewed-by: Kees Cook -Kees > --- > net/netfilter/nfnetlink_queue.c | 32 +++++++++++++------------------- > 1 file changed, 13 insertions(+), 19 deletions(-) > > diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c > index 6da00c7add5b..69efb688383f 100644 > --- a/net/netfilter/nfnetlink_queue.c > +++ b/net/netfilter/nfnetlink_queue.c > @@ -305,12 +305,10 @@ static int nfqnl_put_sk_uidgid(struct sk_buff *skb, struct sock *sk) > return -1; > } > > -static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, char **secdata) > +static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, struct lsmcontext *context) > { > - u32 seclen = 0; > #if IS_ENABLED(CONFIG_NETWORK_SECMARK) > struct lsmblob blob; > - struct lsmcontext context; > > if (!skb || !sk_fullsock(skb->sk)) > return 0; > @@ -318,15 +316,16 @@ static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, char **secdata) > read_lock_bh(&skb->sk->sk_callback_lock); > > if (skb->secmark) { > + /* Any LSM might be looking for the secmark */ > lsmblob_init(&blob, skb->secmark); > - security_secid_to_secctx(&blob, &context); > - *secdata = context.context; > + security_secid_to_secctx(&blob, context); > } > > read_unlock_bh(&skb->sk->sk_callback_lock); > - seclen = context.len; > + return context->len; > +#else > + return 0; > #endif > - return seclen; > } > > static u32 nfqnl_get_bridge_size(struct nf_queue_entry *entry) > @@ -402,8 +401,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue, > enum ip_conntrack_info uninitialized_var(ctinfo); > struct nfnl_ct_hook *nfnl_ct; > bool csum_verify; > - struct lsmcontext scaff; /* scaffolding */ > - char *secdata = NULL; > + struct lsmcontext context; > u32 seclen = 0; > > size = nlmsg_total_size(sizeof(struct nfgenmsg)) > @@ -470,7 +468,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue, > } > > if ((queue->flags & NFQA_CFG_F_SECCTX) && entskb->sk) { > - seclen = nfqnl_get_sk_secctx(entskb, &secdata); > + seclen = nfqnl_get_sk_secctx(entskb, &context); > if (seclen) > size += nla_total_size(seclen); > } > @@ -605,7 +603,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue, > nfqnl_put_sk_uidgid(skb, entskb->sk) < 0) > goto nla_put_failure; > > - if (seclen && nla_put(skb, NFQA_SECCTX, seclen, secdata)) > + if (seclen && nla_put(skb, NFQA_SECCTX, context.len, context.context)) > goto nla_put_failure; > > if (ct && nfnl_ct->build(skb, ct, ctinfo, NFQA_CT, NFQA_CT_INFO) < 0) > @@ -633,10 +631,8 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue, > } > > nlh->nlmsg_len = skb->len; > - if (seclen) { > - lsmcontext_init(&scaff, secdata, seclen, 0); > - security_release_secctx(&scaff); > - } > + if (seclen) > + security_release_secctx(&context); > return skb; > > nla_put_failure: > @@ -644,10 +640,8 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue, > kfree_skb(skb); > net_err_ratelimited("nf_queue: error creating packet message\n"); > nlmsg_failure: > - if (seclen) { > - lsmcontext_init(&scaff, secdata, seclen, 0); > - security_release_secctx(&scaff); > - } > + if (seclen) > + security_release_secctx(&context); > return NULL; > } > > -- > 2.20.1 > -- Kees Cook