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114a61d8d9
[ Upstream commit1904fb9ebf] Netlink supports iterative dumping of data. It provides the families the following ops: - start - (optional) kicks off the dumping process - dump - actual dump helper, keeps getting called until it returns 0 - done - (optional) pairs with .start, can be used for cleanup The whole process is asynchronous and the repeated calls to .dump don't actually happen in a tight loop, but rather are triggered in response to recvmsg() on the socket. This gives the user full control over the dump, but also means that the user can close the socket without getting to the end of the dump. To make sure .start is always paired with .done we check if there is an ongoing dump before freeing the socket, and if so call .done. The complication is that sockets can get freed from BH and .done is allowed to sleep. So we use a workqueue to defer the call, when needed. Unfortunately this does not work correctly. What we defer is not the cleanup but rather releasing a reference on the socket. We have no guarantee that we own the last reference, if someone else holds the socket they may release it in BH and we're back to square one. The whole dance, however, appears to be unnecessary. Only the user can interact with dumps, so we can clean up when socket is closed. And close always happens in process context. Some async code may still access the socket after close, queue notification skbs to it etc. but no dumps can start, end or otherwise make progress. Delete the workqueue and flush the dump state directly from the release handler. Note that further cleanup is possible in -next, for instance we now always call .done before releasing the main module reference, so dump doesn't have to take a reference of its own. Reported-by: syzkaller <syzkaller@googlegroups.com> Fixes:ed5d7788a9("netlink: Do not schedule work from sk_destruct") Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20241106015235.2458807-1-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
72 lines
1.8 KiB
C
72 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 <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 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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};
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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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