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-rw-r--r--include/linux/netlink.h3
-rw-r--r--include/uapi/linux/audit.h8
-rw-r--r--include/uapi/linux/capability.h7
-rw-r--r--kernel/audit.c64
-rw-r--r--net/netfilter/nfnetlink.c10
-rw-r--r--net/netlink/af_netlink.c70
-rw-r--r--net/netlink/af_netlink.h6
-rw-r--r--security/selinux/include/classmap.h2
8 files changed, 135 insertions, 35 deletions
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index aad8eeaf416d..5146ce066498 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -45,7 +45,8 @@ struct netlink_kernel_cfg {
unsigned int flags;
void (*input)(struct sk_buff *skb);
struct mutex *cb_mutex;
- void (*bind)(int group);
+ int (*bind)(int group);
+ void (*unbind)(int group);
bool (*compare)(struct net *net, struct sock *sk);
};
diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index 11917f747cb4..dfa4c860ccef 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -373,6 +373,14 @@ enum {
*/
#define AUDIT_MESSAGE_TEXT_MAX 8560
+/* Multicast Netlink socket groups (default up to 32) */
+enum audit_nlgrps {
+ AUDIT_NLGRP_NONE, /* Group 0 not used */
+ AUDIT_NLGRP_READLOG, /* "best effort" read only socket */
+ __AUDIT_NLGRP_MAX
+};
+#define AUDIT_NLGRP_MAX (__AUDIT_NLGRP_MAX - 1)
+
struct audit_status {
__u32 mask; /* Bit mask for valid entries */
__u32 enabled; /* 1 = enabled, 0 = disabled */
diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h
index 154dd6d3c8fe..12c37a197d24 100644
--- a/include/uapi/linux/capability.h
+++ b/include/uapi/linux/capability.h
@@ -347,7 +347,12 @@ struct vfs_cap_data {
#define CAP_BLOCK_SUSPEND 36
-#define CAP_LAST_CAP CAP_BLOCK_SUSPEND
+/* Allow reading the audit log via multicast netlink socket */
+
+#define CAP_AUDIT_READ 37
+
+
+#define CAP_LAST_CAP CAP_AUDIT_READ
#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
diff --git a/kernel/audit.c b/kernel/audit.c
index 7c2893602d06..33531d72e4a2 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -424,6 +424,38 @@ static void kauditd_send_skb(struct sk_buff *skb)
}
/*
+ * kauditd_send_multicast_skb - send the skb to multicast userspace listeners
+ *
+ * This function doesn't consume an skb as might be expected since it has to
+ * copy it anyways.
+ */
+static void kauditd_send_multicast_skb(struct sk_buff *skb)
+{
+ struct sk_buff *copy;
+ struct audit_net *aunet = net_generic(&init_net, audit_net_id);
+ struct sock *sock = aunet->nlsk;
+
+ if (!netlink_has_listeners(sock, AUDIT_NLGRP_READLOG))
+ return;
+
+ /*
+ * The seemingly wasteful skb_copy() rather than bumping the refcount
+ * using skb_get() is necessary because non-standard mods are made to
+ * the skb by the original kaudit unicast socket send routine. The
+ * existing auditd daemon assumes this breakage. Fixing this would
+ * require co-ordinating a change in the established protocol between
+ * the kaudit kernel subsystem and the auditd userspace code. There is
+ * no reason for new multicast clients to continue with this
+ * non-compliance.
+ */
+ copy = skb_copy(skb, GFP_KERNEL);
+ if (!copy)
+ return;
+
+ nlmsg_multicast(sock, copy, 0, AUDIT_NLGRP_READLOG, GFP_KERNEL);
+}
+
+/*
* flush_hold_queue - empty the hold queue if auditd appears
*
* If auditd just started, drain the queue of messages already
@@ -1076,10 +1108,22 @@ static void audit_receive(struct sk_buff *skb)
mutex_unlock(&audit_cmd_mutex);
}
+/* Run custom bind function on netlink socket group connect or bind requests. */
+static int audit_bind(int group)
+{
+ if (!capable(CAP_AUDIT_READ))
+ return -EPERM;
+
+ return 0;
+}
+
static int __net_init audit_net_init(struct net *net)
{
struct netlink_kernel_cfg cfg = {
.input = audit_receive,
+ .bind = audit_bind,
+ .flags = NL_CFG_F_NONROOT_RECV,
+ .groups = AUDIT_NLGRP_MAX,
};
struct audit_net *aunet = net_generic(net, audit_net_id);
@@ -1901,10 +1945,10 @@ out:
* audit_log_end - end one audit record
* @ab: the audit_buffer
*
- * The netlink_* functions cannot be called inside an irq context, so
- * the audit buffer is placed on a queue and a tasklet is scheduled to
- * remove them from the queue outside the irq context. May be called in
- * any context.
+ * netlink_unicast() cannot be called inside an irq context because it blocks
+ * (last arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed
+ * on a queue and a tasklet is scheduled to remove them from the queue outside
+ * the irq context. May be called in any context.
*/
void audit_log_end(struct audit_buffer *ab)
{
@@ -1914,6 +1958,18 @@ void audit_log_end(struct audit_buffer *ab)
audit_log_lost("rate limit exceeded");
} else {
struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
+
+ kauditd_send_multicast_skb(ab->skb);
+
+ /*
+ * The original kaudit unicast socket sends up messages with
+ * nlmsg_len set to the payload length rather than the entire
+ * message length. This breaks the standard set by netlink.
+ * The existing auditd daemon assumes this breakage. Fixing
+ * this would require co-ordinating a change in the established
+ * protocol between the kaudit kernel subsystem and the auditd
+ * userspace code.
+ */
nlh->nlmsg_len = ab->skb->len - NLMSG_HDRLEN;
if (audit_pid) {
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index e8138da4c14f..6e42dcfad40a 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -400,19 +400,17 @@ static void nfnetlink_rcv(struct sk_buff *skb)
}
#ifdef CONFIG_MODULES
-static void nfnetlink_bind(int group)
+static int nfnetlink_bind(int group)
{
const struct nfnetlink_subsystem *ss;
int type = nfnl_group2type[group];
rcu_read_lock();
ss = nfnetlink_get_subsys(type);
- if (!ss) {
- rcu_read_unlock();
- request_module("nfnetlink-subsys-%d", type);
- return;
- }
rcu_read_unlock();
+ if (!ss)
+ request_module("nfnetlink-subsys-%d", type);
+ return 0;
}
#endif
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 894cda0206bb..92f4b6915e89 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1206,7 +1206,8 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
struct module *module = NULL;
struct mutex *cb_mutex;
struct netlink_sock *nlk;
- void (*bind)(int group);
+ int (*bind)(int group);
+ void (*unbind)(int group);
int err = 0;
sock->state = SS_UNCONNECTED;
@@ -1232,6 +1233,7 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
err = -EPROTONOSUPPORT;
cb_mutex = nl_table[protocol].cb_mutex;
bind = nl_table[protocol].bind;
+ unbind = nl_table[protocol].unbind;
netlink_unlock_table();
if (err < 0)
@@ -1248,6 +1250,7 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
nlk = nlk_sk(sock->sk);
nlk->module = module;
nlk->netlink_bind = bind;
+ nlk->netlink_unbind = unbind;
out:
return err;
@@ -1301,6 +1304,7 @@ static int netlink_release(struct socket *sock)
kfree_rcu(old, rcu);
nl_table[sk->sk_protocol].module = NULL;
nl_table[sk->sk_protocol].bind = NULL;
+ nl_table[sk->sk_protocol].unbind = NULL;
nl_table[sk->sk_protocol].flags = 0;
nl_table[sk->sk_protocol].registered = 0;
}
@@ -1411,6 +1415,19 @@ static int netlink_realloc_groups(struct sock *sk)
return err;
}
+static void netlink_unbind(int group, long unsigned int groups,
+ struct netlink_sock *nlk)
+{
+ int undo;
+
+ if (!nlk->netlink_unbind)
+ return;
+
+ for (undo = 0; undo < group; undo++)
+ if (test_bit(group, &groups))
+ nlk->netlink_unbind(undo);
+}
+
static int netlink_bind(struct socket *sock, struct sockaddr *addr,
int addr_len)
{
@@ -1419,6 +1436,7 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
struct netlink_sock *nlk = nlk_sk(sk);
struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
int err;
+ long unsigned int groups = nladdr->nl_groups;
if (addr_len < sizeof(struct sockaddr_nl))
return -EINVAL;
@@ -1427,7 +1445,7 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
return -EINVAL;
/* Only superuser is allowed to listen multicasts */
- if (nladdr->nl_groups) {
+ if (groups) {
if (!netlink_capable(sock, NL_CFG_F_NONROOT_RECV))
return -EPERM;
err = netlink_realloc_groups(sk);
@@ -1435,37 +1453,45 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
return err;
}
- if (nlk->portid) {
+ if (nlk->portid)
if (nladdr->nl_pid != nlk->portid)
return -EINVAL;
- } else {
+
+ if (nlk->netlink_bind && groups) {
+ int group;
+
+ for (group = 0; group < nlk->ngroups; group++) {
+ if (!test_bit(group, &groups))
+ continue;
+ err = nlk->netlink_bind(group);
+ if (!err)
+ continue;
+ netlink_unbind(group, groups, nlk);
+ return err;
+ }
+ }
+
+ if (!nlk->portid) {
err = nladdr->nl_pid ?
netlink_insert(sk, net, nladdr->nl_pid) :
netlink_autobind(sock);
- if (err)
+ if (err) {
+ netlink_unbind(nlk->ngroups - 1, groups, nlk);
return err;
+ }
}
- if (!nladdr->nl_groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
+ if (!groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
return 0;
netlink_table_grab();
netlink_update_subscriptions(sk, nlk->subscriptions +
- hweight32(nladdr->nl_groups) -
+ hweight32(groups) -
hweight32(nlk->groups[0]));
- nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | nladdr->nl_groups;
+ nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | groups;
netlink_update_listeners(sk);
netlink_table_ungrab();
- if (nlk->netlink_bind && nlk->groups[0]) {
- int i;
-
- for (i = 0; i < nlk->ngroups; i++) {
- if (test_bit(i, nlk->groups))
- nlk->netlink_bind(i);
- }
- }
-
return 0;
}
@@ -2103,13 +2129,17 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
return err;
if (!val || val - 1 >= nlk->ngroups)
return -EINVAL;
+ if (optname == NETLINK_ADD_MEMBERSHIP && nlk->netlink_bind) {
+ err = nlk->netlink_bind(val);
+ if (err)
+ return err;
+ }
netlink_table_grab();
netlink_update_socket_mc(nlk, val,
optname == NETLINK_ADD_MEMBERSHIP);
netlink_table_ungrab();
-
- if (nlk->netlink_bind)
- nlk->netlink_bind(val);
+ if (optname == NETLINK_DROP_MEMBERSHIP && nlk->netlink_unbind)
+ nlk->netlink_unbind(val);
err = 0;
break;
diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h
index ed13a790b00e..0b59d441f5b6 100644
--- a/net/netlink/af_netlink.h
+++ b/net/netlink/af_netlink.h
@@ -38,7 +38,8 @@ struct netlink_sock {
struct mutex *cb_mutex;
struct mutex cb_def_mutex;
void (*netlink_rcv)(struct sk_buff *skb);
- void (*netlink_bind)(int group);
+ int (*netlink_bind)(int group);
+ void (*netlink_unbind)(int group);
struct module *module;
#ifdef CONFIG_NETLINK_MMAP
struct mutex pg_vec_lock;
@@ -74,7 +75,8 @@ struct netlink_table {
unsigned int groups;
struct mutex *cb_mutex;
struct module *module;
- void (*bind)(int group);
+ int (*bind)(int group);
+ void (*unbind)(int group);
bool (*compare)(struct net *net, struct sock *sock);
int registered;
};
diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
index 14d04e63b1f0..be491a74c1ed 100644
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -147,7 +147,7 @@ struct security_class_mapping secclass_map[] = {
{ "peer", { "recv", NULL } },
{ "capability2",
{ "mac_override", "mac_admin", "syslog", "wake_alarm", "block_suspend",
- NULL } },
+ "audit_read", NULL } },
{ "kernel_service", { "use_as_override", "create_files_as", NULL } },
{ "tun_socket",
{ COMMON_SOCK_PERMS, "attach_queue", NULL } },
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.