tipc: Fix missing RTNL lock protection during setting link properties
Currently when user changes link properties, TIPC first checks if user's command message contains media name or bearer name through tipc_media_find() or tipc_bearer_find() which is protected by RTNL lock. But when tipc_nl_compat_link_set() conducts the checking with the two functions, it doesn't hold RTNL lock at all, as a result, the following complaints were reported: audit: type=1400 audit(1514679888.244:9): avc: denied { write } for pid=3194 comm="syzkaller021477" path="socket:[11143]" dev="sockfs" ino=11143 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=1 Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> ============================= WARNING: suspicious RCU usage 4.15.0-rc5+ #152 Not tainted ----------------------------- net/tipc/bearer.c:177 suspicious rcu_dereference_protected() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 2 locks held by syzkaller021477/3194: #0: (cb_lock){++++}, at: [<00000000d20133ea>] genl_rcv+0x19/0x40 net/netlink/genetlink.c:634 #1: (genl_mutex){+.+.}, at: [<00000000fcc5d1bc>] genl_lock net/netlink/genetlink.c:33 [inline] #1: (genl_mutex){+.+.}, at: [<00000000fcc5d1bc>] genl_rcv_msg+0x115/0x140 net/netlink/genetlink.c:622 stack backtrace: CPU: 1 PID: 3194 Comm: syzkaller021477 Not tainted 4.15.0-rc5+ #152 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4585 tipc_bearer_find+0x2b4/0x3b0 net/tipc/bearer.c:177 tipc_nl_compat_link_set+0x329/0x9f0 net/tipc/netlink_compat.c:729 __tipc_nl_compat_doit net/tipc/netlink_compat.c:288 [inline] tipc_nl_compat_doit+0x15b/0x660 net/tipc/netlink_compat.c:335 tipc_nl_compat_handle net/tipc/netlink_compat.c:1119 [inline] tipc_nl_compat_recv+0x112f/0x18f0 net/tipc/netlink_compat.c:1201 genl_family_rcv_msg+0x7b7/0xfb0 net/netlink/genetlink.c:599 genl_rcv_msg+0xb2/0x140 net/netlink/genetlink.c:624 netlink_rcv_skb+0x21e/0x460 net/netlink/af_netlink.c:2408 genl_rcv+0x28/0x40 net/netlink/genetlink.c:635 netlink_unicast_kernel net/netlink/af_netlink.c:1275 [inline] netlink_unicast+0x4e8/0x6f0 net/netlink/af_netlink.c:1301 netlink_sendmsg+0xa4a/0xe60 net/netlink/af_netlink.c:1864 sock_sendmsg_nosec net/socket.c:636 [inline] sock_sendmsg+0xca/0x110 net/socket.c:646 sock_write_iter+0x31a/0x5d0 net/socket.c:915 call_write_iter include/linux/fs.h:1772 [inline] new_sync_write fs/read_write.c:469 [inline] __vfs_write+0x684/0x970 fs/read_write.c:482 vfs_write+0x189/0x510 fs/read_write.c:544 SYSC_write fs/read_write.c:589 [inline] SyS_write+0xef/0x220 fs/read_write.c:581 do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline] do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389 entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129 In order to correct the mistake, __tipc_nl_compat_doit() has been protected by RTNL lock, which means the whole operation of setting bearer/media properties is under RTNL protection. Signed-off-by: Ying Xue <ying.xue@windriver.com> Reported-by: syzbot <syzbot+6345fd433db009b29413@syzkaller.appspotmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -301,6 +301,7 @@ static int __tipc_nl_compat_doit(struct tipc_nl_compat_cmd_doit *cmd,
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memset(&info, 0, sizeof(info));
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info.attrs = attrbuf;
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rtnl_lock();
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err = (*cmd->transcode)(cmd, trans_buf, msg);
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if (err)
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goto doit_out;
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@ -315,6 +316,7 @@ static int __tipc_nl_compat_doit(struct tipc_nl_compat_cmd_doit *cmd,
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err = (*cmd->doit)(doit_buf, &info);
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doit_out:
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rtnl_unlock();
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kfree_skb(doit_buf);
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attrbuf_out:
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@ -723,13 +725,13 @@ static int tipc_nl_compat_link_set(struct tipc_nl_compat_cmd_doit *cmd,
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media = tipc_media_find(lc->name);
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if (media) {
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cmd->doit = &tipc_nl_media_set;
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cmd->doit = &__tipc_nl_media_set;
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return tipc_nl_compat_media_set(skb, msg);
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}
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bearer = tipc_bearer_find(msg->net, lc->name);
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if (bearer) {
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cmd->doit = &tipc_nl_bearer_set;
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cmd->doit = &__tipc_nl_bearer_set;
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return tipc_nl_compat_bearer_set(skb, msg);
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}
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@ -1090,12 +1092,12 @@ static int tipc_nl_compat_handle(struct tipc_nl_compat_msg *msg)
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return tipc_nl_compat_dumpit(&dump, msg);
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case TIPC_CMD_ENABLE_BEARER:
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msg->req_type = TIPC_TLV_BEARER_CONFIG;
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doit.doit = tipc_nl_bearer_enable;
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doit.doit = __tipc_nl_bearer_enable;
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doit.transcode = tipc_nl_compat_bearer_enable;
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return tipc_nl_compat_doit(&doit, msg);
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case TIPC_CMD_DISABLE_BEARER:
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msg->req_type = TIPC_TLV_BEARER_NAME;
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doit.doit = tipc_nl_bearer_disable;
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doit.doit = __tipc_nl_bearer_disable;
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doit.transcode = tipc_nl_compat_bearer_disable;
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return tipc_nl_compat_doit(&doit, msg);
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case TIPC_CMD_SHOW_LINK_STATS:
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@ -1149,12 +1151,12 @@ static int tipc_nl_compat_handle(struct tipc_nl_compat_msg *msg)
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return tipc_nl_compat_dumpit(&dump, msg);
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case TIPC_CMD_SET_NODE_ADDR:
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msg->req_type = TIPC_TLV_NET_ADDR;
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doit.doit = tipc_nl_net_set;
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doit.doit = __tipc_nl_net_set;
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doit.transcode = tipc_nl_compat_net_set;
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return tipc_nl_compat_doit(&doit, msg);
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case TIPC_CMD_SET_NETID:
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msg->req_type = TIPC_TLV_UNSIGNED;
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doit.doit = tipc_nl_net_set;
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doit.doit = __tipc_nl_net_set;
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doit.transcode = tipc_nl_compat_net_set;
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return tipc_nl_compat_doit(&doit, msg);
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case TIPC_CMD_GET_NETID:
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