Re: [PATCH ghak90 (was ghak32) V4 08/10] audit: add support for containerid to network namespaces

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 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(a)redhat.com&gt; --- include/linux/audit.h | 17 ++++++++++ kernel/audit.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++ kernel/auditsc.c | 8 ++++- kernel/nsproxy.c | 4 +++ 4 files changed, 114 insertions(+), 1 deletion(-)

@@ -308,6 +312,86 @@ static struct sock *audit_get_sk(const struct net *net) return aunet->sk; } +/** + * audit_get_netns_contid_list - Return the audit container ID list for the given network namespace + * @net: the destination network namespace + * + * Description: + * Returns the list pointer if valid, NULL otherwise. The caller must ensure + * that a reference is held for the network namespace while the sock is in use. + */ +struct list_head *audit_get_netns_contid_list(const struct net *net) +{ + struct audit_net *aunet = net_generic(net, audit_net_id); + + return &aunet->contid_list; +} + +spinlock_t *audit_get_netns_contid_list_lock(const struct net *net) +{ + struct audit_net *aunet = net_generic(net, audit_net_id); + + return &aunet->contid_list_lock; +}

+void audit_netns_contid_add(struct net *net, u64 contid) +{ + spinlock_t *lock = audit_get_netns_contid_list_lock(net); + struct list_head *contid_list = audit_get_netns_contid_list(net); + struct audit_contid *cont; + + if (!audit_contid_valid(contid)) + return; + spin_lock(lock); + if (!list_empty(contid_list)) + list_for_each_entry(cont, contid_list, list) + if (cont->id == contid) { + refcount_inc(&cont->refcount); + goto out; + } + cont = kmalloc(sizeof(struct audit_contid), GFP_KERNEL); + if (cont) { + INIT_LIST_HEAD(&cont->list); + cont->id = contid; + refcount_set(&cont->refcount, 1); + list_add(&cont->list, contid_list); + } +out: + spin_unlock(lock); +} + +void audit_netns_contid_del(struct net *net, u64 contid) +{ + spinlock_t *lock = audit_get_netns_contid_list_lock(net); + struct list_head *contid_list = audit_get_netns_contid_list(net); + struct audit_contid *cont = NULL; + + if (!audit_contid_valid(contid)) + return; + spin_lock(lock); + if (!list_empty(contid_list)) + list_for_each_entry(cont, contid_list, list) + if (cont->id == contid) { + list_del(&cont->list); + if (refcount_dec_and_test(&cont->refcount)) + kfree(cont); + break; + } + spin_unlock(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) { @@ -1547,6 +1631,8 @@ 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; } diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 610c6869..fdf3f68 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -75,6 +75,7 @@ #include <linux/uaccess.h> #include <linux/fsnotify_backend.h> #include <uapi/linux/limits.h> +#include <net/net_namespace.h> #include "audit.h" @@ -2165,6 +2166,7 @@ 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 */ @@ -2186,8 +2188,12 @@ 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 f6c5d33..718b120 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);