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apparmor: Allow filtering based on secmark policy

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Add support for dropping or accepting packets based on their secmark
tags.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
Matthew Garrett 2018-05-24 13:27:47 -07:00 committed by John Johansen
parent 9caafbe2b4
commit ab9f211508
2 changed files with 177 additions and 1 deletions
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112
security/apparmor/lsm.c
View File

@ -23,6 +23,8 @@
#include <linux/sysctl.h>
#include <linux/audit.h>
#include <linux/user_namespace.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <net/sock.h>
#include "include/apparmor.h"
@ -1030,7 +1032,13 @@ static int apparmor_socket_shutdown(struct socket *sock, int how)
*/
static int apparmor_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
{
return 0;
struct aa_sk_ctx *ctx = SK_CTX(sk);
if (!skb->secmark)
return 0;
return apparmor_secmark_check(ctx->label, OP_RECVMSG, AA_MAY_RECEIVE,
skb->secmark, sk);
}
@ -1126,6 +1134,18 @@ static void apparmor_sock_graft(struct sock *sk, struct socket *parent)
ctx->label = aa_get_current_label();
}
static int apparmor_inet_conn_request(struct sock *sk, struct sk_buff *skb,
struct request_sock *req)
{
struct aa_sk_ctx *ctx = SK_CTX(sk);
if (!skb->secmark)
return 0;
return apparmor_secmark_check(ctx->label, OP_CONNECT, AA_MAY_CONNECT,
skb->secmark, sk);
}
static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(ptrace_access_check, apparmor_ptrace_access_check),
LSM_HOOK_INIT(ptrace_traceme, apparmor_ptrace_traceme),
@ -1183,6 +1203,7 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(socket_getpeersec_dgram,
apparmor_socket_getpeersec_dgram),
LSM_HOOK_INIT(sock_graft, apparmor_sock_graft),
LSM_HOOK_INIT(inet_conn_request, apparmor_inet_conn_request),
LSM_HOOK_INIT(cred_alloc_blank, apparmor_cred_alloc_blank),
LSM_HOOK_INIT(cred_free, apparmor_cred_free),
@ -1538,6 +1559,95 @@ static inline int apparmor_init_sysctl(void)
}
#endif /* CONFIG_SYSCTL */
static unsigned int apparmor_ip_postroute(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
struct aa_sk_ctx *ctx;
struct sock *sk;
if (!skb->secmark)
return NF_ACCEPT;
sk = skb_to_full_sk(skb);
if (sk == NULL)
return NF_ACCEPT;
ctx = SK_CTX(sk);
if (!apparmor_secmark_check(ctx->label, OP_SENDMSG, AA_MAY_SEND,
skb->secmark, sk))
return NF_ACCEPT;
return NF_DROP_ERR(-ECONNREFUSED);
}
static unsigned int apparmor_ipv4_postroute(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
return apparmor_ip_postroute(priv, skb, state);
}
static unsigned int apparmor_ipv6_postroute(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
return apparmor_ip_postroute(priv, skb, state);
}
static const struct nf_hook_ops apparmor_nf_ops[] = {
{
.hook = apparmor_ipv4_postroute,
.pf = NFPROTO_IPV4,
.hooknum = NF_INET_POST_ROUTING,
.priority = NF_IP_PRI_SELINUX_FIRST,
},
#if IS_ENABLED(CONFIG_IPV6)
{
.hook = apparmor_ipv6_postroute,
.pf = NFPROTO_IPV6,
.hooknum = NF_INET_POST_ROUTING,
.priority = NF_IP6_PRI_SELINUX_FIRST,
},
#endif
};
static int __net_init apparmor_nf_register(struct net *net)
{
int ret;
ret = nf_register_net_hooks(net, apparmor_nf_ops,
ARRAY_SIZE(apparmor_nf_ops));
return ret;
}
static void __net_exit apparmor_nf_unregister(struct net *net)
{
nf_unregister_net_hooks(net, apparmor_nf_ops,
ARRAY_SIZE(apparmor_nf_ops));
}
static struct pernet_operations apparmor_net_ops = {
.init = apparmor_nf_register,
.exit = apparmor_nf_unregister,
};
static int __init apparmor_nf_ip_init(void)
{
int err;
if (!apparmor_enabled)
return 0;
err = register_pernet_subsys(&apparmor_net_ops);
if (err)
panic("Apparmor: register_pernet_subsys: error %d\n", err);
return 0;
}
__initcall(apparmor_nf_ip_init);
static int __init apparmor_init(void)
{
int error;

66
security/apparmor/net.c
View File

@ -18,6 +18,7 @@
#include "include/label.h"
#include "include/net.h"
#include "include/policy.h"
#include "include/secid.h"
#include "net_names.h"
@ -188,3 +189,68 @@ int aa_sock_file_perm(struct aa_label *label, const char *op, u32 request,
return aa_label_sk_perm(label, op, request, sock->sk);
}
static int apparmor_secmark_init(struct aa_secmark *secmark)
{
struct aa_label *label;
if (secmark->label[0] == '*') {
secmark->secid = AA_SECID_WILDCARD;
return 0;
}
label = aa_label_strn_parse(&root_ns->unconfined->label,
secmark->label, strlen(secmark->label),
GFP_ATOMIC, false, false);
if (IS_ERR(label))
return PTR_ERR(label);
secmark->secid = label->secid;
return 0;
}
static int aa_secmark_perm(struct aa_profile *profile, u32 request, u32 secid,
struct common_audit_data *sa, struct sock *sk)
{
int i, ret;
struct aa_perms perms = { };
if (profile->secmark_count == 0)
return 0;
for (i = 0; i < profile->secmark_count; i++) {
if (!profile->secmark[i].secid) {
ret = apparmor_secmark_init(&profile->secmark[i]);
if (ret)
return ret;
}
if (profile->secmark[i].secid == secid ||
profile->secmark[i].secid == AA_SECID_WILDCARD) {
if (profile->secmark[i].deny)
perms.deny = ALL_PERMS_MASK;
else
perms.allow = ALL_PERMS_MASK;
if (profile->secmark[i].audit)
perms.audit = ALL_PERMS_MASK;
}
}
aa_apply_modes_to_perms(profile, &perms);
return aa_check_perms(profile, &perms, request, sa, audit_net_cb);
}
int apparmor_secmark_check(struct aa_label *label, char *op, u32 request,
u32 secid, struct sock *sk)
{
struct aa_profile *profile;
DEFINE_AUDIT_SK(sa, op, sk);
return fn_for_each_confined(label, profile,
aa_secmark_perm(profile, request, secid,
&sa, sk));
}