Audit events could happen in a network namespace outside of a task context due to packets received from the net that trigger an auditing rule prior to being associated with a running task. The network namespace could be in use by multiple containers by association to the tasks in that network namespace. We still want a way to attribute these events to any potential containers. Keep a list per network namespace to track these audit container identifiiers. Add/increment the audit container identifier on: - initial setting of the audit container identifier via /proc - clone/fork call that inherits an audit container identifier - unshare call that inherits an audit container identifier - setns call that inherits an audit container identifier Delete/decrement the audit container identifier on: - an inherited audit container identifier dropped when child set - process exit - unshare call that drops a net namespace - setns call that drops a net namespace See: https://github.com/linux-audit/audit-kernel/issues/92 See: https://github.com/linux-audit/audit-testsuite/issues/64 See: https://github.com/linux-audit/audit-kernel/wiki/RFE-Audit-Container-ID Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx> --- include/linux/audit.h | 19 ++++++++++++ kernel/audit.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++-- kernel/nsproxy.c | 4 +++ 3 files changed, 106 insertions(+), 3 deletions(-) diff --git a/include/linux/audit.h b/include/linux/audit.h index fa19fa408931..70255c2dfb9f 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -27,6 +27,7 @@ #include <linux/ptrace.h> #include <linux/namei.h> /* LOOKUP_* */ #include <uapi/linux/audit.h> +#include <linux/refcount.h> #define AUDIT_INO_UNSET ((unsigned long)-1) #define AUDIT_DEV_UNSET ((dev_t)-1) @@ -99,6 +100,13 @@ struct audit_task_info { extern struct audit_task_info init_struct_audit; +struct audit_contid { + struct list_head list; + u64 id; + refcount_t refcount; + struct rcu_head rcu; +}; + extern int is_audit_feature_set(int which); extern int __init audit_register_class(int class, unsigned *list); @@ -202,6 +210,10 @@ static inline u64 audit_get_contid(struct task_struct *tsk) } extern void audit_log_contid(struct audit_context *context, u64 contid); +extern void audit_netns_contid_add(struct net *net, u64 contid); +extern void audit_netns_contid_del(struct net *net, u64 contid); +extern void audit_switch_task_namespaces(struct nsproxy *ns, + struct task_struct *p); extern u32 audit_enabled; #else /* CONFIG_AUDIT */ @@ -271,6 +283,13 @@ static inline u64 audit_get_contid(struct task_struct *tsk) static inline void audit_log_contid(struct audit_context *context, u64 contid) { } +static inline void audit_netns_contid_add(struct net *net, u64 contid) +{ } +static inline void audit_netns_contid_del(struct net *net, u64 contid) +{ } +static inline void audit_switch_task_namespaces(struct nsproxy *ns, + struct task_struct *p) +{ } #define audit_enabled AUDIT_OFF #endif /* CONFIG_AUDIT */ diff --git a/kernel/audit.c b/kernel/audit.c index cf448599ef34..7fa3194f5342 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -72,6 +72,7 @@ #include <linux/freezer.h> #include <linux/pid_namespace.h> #include <net/netns/generic.h> +#include <net/net_namespace.h> #include "audit.h" @@ -99,9 +100,13 @@ /** * struct audit_net - audit private network namespace data * @sk: communication socket + * @contid_list: audit container identifier list + * @contid_list_lock audit container identifier list lock */ struct audit_net { struct sock *sk; + struct list_head contid_list; + spinlock_t contid_list_lock; }; /** @@ -275,8 +280,11 @@ struct audit_task_info init_struct_audit = { void audit_free(struct task_struct *tsk) { struct audit_task_info *info = tsk->audit; + struct nsproxy *ns = tsk->nsproxy; audit_free_syscall(tsk); + if (ns) + audit_netns_contid_del(ns->net_ns, audit_get_contid(tsk)); /* Freeing the audit_task_info struct must be performed after * audit_log_exit() due to need for loginuid and sessionid. */ @@ -376,6 +384,73 @@ static struct sock *audit_get_sk(const struct net *net) return aunet->sk; } +void audit_netns_contid_add(struct net *net, u64 contid) +{ + struct audit_net *aunet = net_generic(net, audit_net_id); + struct list_head *contid_list = &aunet->contid_list; + struct audit_contid *cont; + + if (!audit_contid_valid(contid)) + return; + if (!aunet) + return; + spin_lock(&aunet->contid_list_lock); + if (!list_empty(contid_list)) + list_for_each_entry_rcu(cont, contid_list, list) + if (cont->id == contid) { + refcount_inc(&cont->refcount); + goto out; + } + cont = kmalloc(sizeof(struct audit_contid), GFP_ATOMIC); + if (cont) { + INIT_LIST_HEAD(&cont->list); + cont->id = contid; + refcount_set(&cont->refcount, 1); + list_add_rcu(&cont->list, contid_list); + } +out: + spin_unlock(&aunet->contid_list_lock); +} + +void audit_netns_contid_del(struct net *net, u64 contid) +{ + struct audit_net *aunet; + struct list_head *contid_list; + struct audit_contid *cont = NULL; + + if (!net) + return; + if (!audit_contid_valid(contid)) + return; + aunet = net_generic(net, audit_net_id); + if (!aunet) + return; + contid_list = &aunet->contid_list; + spin_lock(&aunet->contid_list_lock); + if (!list_empty(contid_list)) + list_for_each_entry_rcu(cont, contid_list, list) + if (cont->id == contid) { + if (refcount_dec_and_test(&cont->refcount)) { + list_del_rcu(&cont->list); + kfree_rcu(cont, rcu); + } + break; + } + spin_unlock(&aunet->contid_list_lock); +} + +void audit_switch_task_namespaces(struct nsproxy *ns, struct task_struct *p) +{ + u64 contid = audit_get_contid(p); + struct nsproxy *new = p->nsproxy; + + if (!audit_contid_valid(contid)) + return; + audit_netns_contid_del(ns->net_ns, contid); + if (new) + audit_netns_contid_add(new->net_ns, contid); +} + void audit_panic(const char *message) { switch (audit_failure) { @@ -1619,7 +1694,6 @@ static int __net_init audit_net_init(struct net *net) .flags = NL_CFG_F_NONROOT_RECV, .groups = AUDIT_NLGRP_MAX, }; - struct audit_net *aunet = net_generic(net, audit_net_id); aunet->sk = netlink_kernel_create(net, NETLINK_AUDIT, &cfg); @@ -1628,7 +1702,8 @@ static int __net_init audit_net_init(struct net *net) return -ENOMEM; } aunet->sk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT; - + INIT_LIST_HEAD(&aunet->contid_list); + spin_lock_init(&aunet->contid_list_lock); return 0; } @@ -2380,6 +2455,7 @@ int audit_set_contid(struct task_struct *task, u64 contid) uid_t uid; struct tty_struct *tty; char comm[sizeof(current->comm)]; + struct net *net = task->nsproxy->net_ns; task_lock(task); /* Can't set if audit disabled */ @@ -2401,8 +2477,12 @@ int audit_set_contid(struct task_struct *task, u64 contid) else if (!(thread_group_leader(task) && thread_group_empty(task))) rc = -EALREADY; read_unlock(&tasklist_lock); - if (!rc) + if (!rc) { + if (audit_contid_valid(oldcontid)) + audit_netns_contid_del(net, oldcontid); task->audit->contid = contid; + audit_netns_contid_add(net, contid); + } task_unlock(task); if (!audit_enabled) diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c index f6c5d330059a..718b1201ae70 100644 --- a/kernel/nsproxy.c +++ b/kernel/nsproxy.c @@ -27,6 +27,7 @@ #include <linux/syscalls.h> #include <linux/cgroup.h> #include <linux/perf_event.h> +#include <linux/audit.h> static struct kmem_cache *nsproxy_cachep; @@ -140,6 +141,7 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk) struct nsproxy *old_ns = tsk->nsproxy; struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns); struct nsproxy *new_ns; + u64 contid = audit_get_contid(tsk); if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | CLONE_NEWPID | CLONE_NEWNET | @@ -167,6 +169,7 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk) return PTR_ERR(new_ns); tsk->nsproxy = new_ns; + audit_netns_contid_add(new_ns->net_ns, contid); return 0; } @@ -224,6 +227,7 @@ void switch_task_namespaces(struct task_struct *p, struct nsproxy *new) ns = p->nsproxy; p->nsproxy = new; task_unlock(p); + audit_switch_task_namespaces(ns, p); if (ns && atomic_dec_and_test(&ns->count)) free_nsproxy(ns); -- 1.8.3.1
