[PATCH RFC 7/8] audit: report namespace information along with USER events

[Eric W. Biederman]

Aristeu Rozanski <arozansk at redhat.com> writes:

> For userspace generated events, include a record with the namespace
> procfs inode numbers the process belongs to. This allows to track down
> and filter audit messages by userspace.

I am not comfortable with using the inode numbers this way.  It does not
pass the test of can I migrate a container and still have this work
test.  Any kind of kernel assigned name for namespaces fails that test.

I also don't like that you don't include the procfs device number.  An
inode number means nothing without knowing which filesystem you are
referring to.

It may never happen but I reserve the right to have the inode numbers
for namespaces to show up differently in different instances of procfs.

Beyond that I think this usage is possibly buggy by using two audit
records for one event.

> Signed-off-by: Aristeu Rozanski <arozansk at redhat.com>
> ---
>  include/uapi/linux/audit.h |    1 +
>  kernel/audit.c             |   51 +++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 51 insertions(+), 1 deletions(-)
>
> diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> index 9f096f1..3ec3ccb 100644
> --- a/include/uapi/linux/audit.h
> +++ b/include/uapi/linux/audit.h
> @@ -106,6 +106,7 @@
>  #define AUDIT_NETFILTER_PKT	1324	/* Packets traversing netfilter chains */
>  #define AUDIT_NETFILTER_CFG	1325	/* Netfilter chain modifications */
>  #define AUDIT_SECCOMP		1326	/* Secure Computing event */
> +#define AUDIT_USER_NAMESPACE	1327	/* Information about process' namespaces */
>  
>  #define AUDIT_AVC		1400	/* SE Linux avc denial or grant */
>  #define AUDIT_SELINUX_ERR	1401	/* Internal SE Linux Errors */
> diff --git a/kernel/audit.c b/kernel/audit.c
> index 58db117..b17f9c0 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -62,6 +62,11 @@
>  #include <linux/freezer.h>
>  #include <linux/tty.h>
>  #include <linux/pid_namespace.h>
> +#include <linux/ipc_namespace.h>
> +#include <linux/mnt_namespace.h>
> +#include <linux/utsname.h>
> +#include <linux/user_namespace.h>
> +#include <net/net_namespace.h>
>  
>  #include "audit.h"
>  
> @@ -641,6 +646,49 @@ static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type,
>  	return rc;
>  }
>  
> +#ifdef CONFIG_NAMESPACES
> +static int audit_log_namespaces(struct task_struct *tsk,
> +				struct sk_buff *skb)
> +{
> +	struct audit_context *ctx = tsk->audit_context;
> +	struct audit_buffer *ab;
> +
> +	if (!audit_enabled)
> +		return 0;
> +
> +	ab = audit_log_start(ctx, GFP_KERNEL, AUDIT_USER_NAMESPACE);
> +	if (unlikely(!ab))
> +		return -ENOMEM;
> +
> +	audit_log_format(ab, "mnt=%u", mntns_get_inum(tsk));
> +#ifdef CONFIG_NET_NS
> +	audit_log_format(ab, " net=%u", netns_get_inum(tsk));
> +#endif
> +#ifdef CONFIG_UTS_NS
> +	audit_log_format(ab, " uts=%u", utsns_get_inum(tsk));
> +#endif
> +#ifdef CONFIG_IPC_NS
> +	audit_log_format(ab, " ipc=%u", ipcns_get_inum(tsk));
> +#endif
> +#ifdef CONFIG_PID_NS
> +	audit_log_format(ab, " pid=%u", pidns_get_inum(tsk));
> +#endif
> +#ifdef CONFIG_USER_NS
> +	audit_log_format(ab, " user=%u", userns_get_inum(tsk));
> +#endif  
> +	audit_set_pid(ab, NETLINK_CB(skb).portid);
> +	audit_log_end(ab);
> +
> +	return 0;
> +}
> +#else
> +static inline int audit_log_namespaces(struct task_struct *tsk,
> +				       struct sk_buff *skb)
> +{
> +	return 0;
> +}
> +#endif
> +
>  static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
>  {
>  	u32			seq, sid;
> @@ -741,7 +789,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
>  			}
>  			audit_log_common_recv_msg(&ab, msg_type,
>  						  loginuid, sessionid, sid,
> -						  NULL);
> +						  current->audit_context);
>  
>  			if (msg_type != AUDIT_USER_TTY)
>  				audit_log_format(ab, " msg='%.1024s'",
> @@ -758,6 +806,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
>  			}
>  			audit_set_pid(ab, NETLINK_CB(skb).portid);
>  			audit_log_end(ab);
> +			audit_log_namespaces(current, skb);
>  		}
>  		break;
>  	case AUDIT_ADD: