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https://github.com/brain-hackers/linux-brain.git
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89d35528d1
Add a new socket option, NETLINK_DUMP_STRICT_CHK, that userspace can use via setsockopt to request strict checking of headers and attributes on dump requests. To get dump features such as kernel side filtering based on data in the header or attributes appended to the dump request, userspace must call setsockopt() for NETLINK_DUMP_STRICT_CHK and a non-zero value. Since the netlink sock and its flags are private to the af_netlink code, the strict checking flag is passed to dump handlers via a flag in the netlink_callback struct. For old userspace on new kernel there is no impact as all of the data checks in later patches are wrapped in a check on the new strict flag. For new userspace on old kernel, the setsockopt will fail and even if new userspace sets data in the headers and appended attributes the kernel will silently ignore it. Moving forward when the setsockopt succeeds, the new userspace on old kernel means the dump request can pass an attribute the kernel does not understand. The dump will then fail as the older kernel does not understand it. New userspace on new kernel setting the socket option gets the benefit of the improved data dump. Kernel side the NETLINK_DUMP_STRICT_CHK uapi is converted to a generic NETLINK_F_STRICT_CHK flag which can potentially be leveraged for tighter checking on the NEW, DEL, and SET commands. Signed-off-by: David Ahern <dsahern@gmail.com> Acked-by: Christian Brauner <christian@brauner.io> Signed-off-by: David S. Miller <davem@davemloft.net>
75 lines
1.8 KiB
C
75 lines
1.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _AF_NETLINK_H
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#define _AF_NETLINK_H
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#include <linux/rhashtable.h>
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#include <linux/atomic.h>
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#include <linux/workqueue.h>
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#include <net/sock.h>
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/* flags */
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#define NETLINK_F_KERNEL_SOCKET 0x1
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#define NETLINK_F_RECV_PKTINFO 0x2
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#define NETLINK_F_BROADCAST_SEND_ERROR 0x4
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#define NETLINK_F_RECV_NO_ENOBUFS 0x8
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#define NETLINK_F_LISTEN_ALL_NSID 0x10
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#define NETLINK_F_CAP_ACK 0x20
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#define NETLINK_F_EXT_ACK 0x40
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#define NETLINK_F_STRICT_CHK 0x80
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#define NLGRPSZ(x) (ALIGN(x, sizeof(unsigned long) * 8) / 8)
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#define NLGRPLONGS(x) (NLGRPSZ(x)/sizeof(unsigned long))
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struct netlink_sock {
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/* struct sock has to be the first member of netlink_sock */
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struct sock sk;
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u32 portid;
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u32 dst_portid;
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u32 dst_group;
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u32 flags;
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u32 subscriptions;
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u32 ngroups;
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unsigned long *groups;
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unsigned long state;
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size_t max_recvmsg_len;
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wait_queue_head_t wait;
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bool bound;
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bool cb_running;
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int dump_done_errno;
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struct netlink_callback cb;
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struct mutex *cb_mutex;
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struct mutex cb_def_mutex;
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void (*netlink_rcv)(struct sk_buff *skb);
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int (*netlink_bind)(struct net *net, int group);
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void (*netlink_unbind)(struct net *net, int group);
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struct module *module;
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struct rhash_head node;
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struct rcu_head rcu;
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struct work_struct work;
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};
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static inline struct netlink_sock *nlk_sk(struct sock *sk)
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{
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return container_of(sk, struct netlink_sock, sk);
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}
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struct netlink_table {
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struct rhashtable hash;
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struct hlist_head mc_list;
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struct listeners __rcu *listeners;
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unsigned int flags;
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unsigned int groups;
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struct mutex *cb_mutex;
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struct module *module;
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int (*bind)(struct net *net, int group);
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void (*unbind)(struct net *net, int group);
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bool (*compare)(struct net *net, struct sock *sock);
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int registered;
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};
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extern struct netlink_table *nl_table;
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extern rwlock_t nl_table_lock;
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#endif
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