diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index 11917f747cb401be5b7dc8ab788fa5d0d4e8e47c..dfa4c860ccefd1af49a3fff7a0a0328db295c647 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/kernel/audit.c b/kernel/audit.c index 223cb746f141fe7d19381e34d07cf1b92dae14f2..d272cc11dff4488e72f4660859696857d8eed2c5 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -423,6 +423,35 @@ static void kauditd_send_skb(struct sk_buff *skb) consume_skb(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; + + /* + * 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 * @@ -1090,6 +1119,8 @@ 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); @@ -1911,10 +1942,10 @@ void audit_log_link_denied(const char *operation, struct path *link) * 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) { @@ -1924,6 +1955,18 @@ 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) {