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Wed, 30 Oct 2024 17:32:35 +0800 From: Liu Jian To: , , , , , , , , , , , , , , CC: , Subject: [PATCH net v2] sunrpc: fix one UAF issue caused by sunrpc kernel tcp socket Date: Wed, 30 Oct 2024 17:49:53 +0800 Message-ID: <20241030094953.1921574-1-liujian56@huawei.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemg200003.china.huawei.com (7.202.181.30) BUG: KASAN: slab-use-after-free in tcp_write_timer_handler+0x156/0x3e0 Read of size 1 at addr ffff888111f322cd by task swapper/0/0 CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.12.0-rc4-dirty #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 Call Trace: dump_stack_lvl+0x68/0xa0 print_address_description.constprop.0+0x2c/0x3d0 print_report+0xb4/0x270 kasan_report+0xbd/0xf0 tcp_write_timer_handler+0x156/0x3e0 tcp_write_timer+0x66/0x170 call_timer_fn+0xfb/0x1d0 __run_timers+0x3f8/0x480 run_timer_softirq+0x9b/0x100 handle_softirqs+0x153/0x390 __irq_exit_rcu+0x103/0x120 irq_exit_rcu+0xe/0x20 sysvec_apic_timer_interrupt+0x76/0x90 asm_sysvec_apic_timer_interrupt+0x1a/0x20 RIP: 0010:default_idle+0xf/0x20 Code: 4c 01 c7 4c 29 c2 e9 72 ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 33 f8 25 00 fb f4 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 RSP: 0018:ffffffffa2007e28 EFLAGS: 00000242 RAX: 00000000000f3b31 RBX: 1ffffffff4400fc7 RCX: ffffffffa09c3196 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff9f00590f RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed102360835d R10: ffff88811b041aeb R11: 0000000000000001 R12: 0000000000000000 R13: ffffffffa202d7c0 R14: 0000000000000000 R15: 00000000000147d0 default_idle_call+0x6b/0xa0 cpuidle_idle_call+0x1af/0x1f0 do_idle+0xbc/0x130 cpu_startup_entry+0x33/0x40 rest_init+0x11f/0x210 start_kernel+0x39a/0x420 x86_64_start_reservations+0x18/0x30 x86_64_start_kernel+0x97/0xa0 common_startup_64+0x13e/0x141 Allocated by task 595: kasan_save_stack+0x24/0x50 kasan_save_track+0x14/0x30 __kasan_slab_alloc+0x87/0x90 kmem_cache_alloc_noprof+0x12b/0x3f0 copy_net_ns+0x94/0x380 create_new_namespaces+0x24c/0x500 unshare_nsproxy_namespaces+0x75/0xf0 ksys_unshare+0x24e/0x4f0 __x64_sys_unshare+0x1f/0x30 do_syscall_64+0x70/0x180 entry_SYSCALL_64_after_hwframe+0x76/0x7e Freed by task 100: kasan_save_stack+0x24/0x50 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x54/0x70 kmem_cache_free+0x156/0x5d0 cleanup_net+0x5d3/0x670 process_one_work+0x776/0xa90 worker_thread+0x2e2/0x560 kthread+0x1a8/0x1f0 ret_from_fork+0x34/0x60 ret_from_fork_asm+0x1a/0x30 Reproduction script: mkdir -p /mnt/nfsshare mkdir -p /mnt/nfs/netns_1 mkfs.ext4 /dev/sdb mount /dev/sdb /mnt/nfsshare systemctl restart nfs-server chmod 777 /mnt/nfsshare exportfs -i -o rw,no_root_squash *:/mnt/nfsshare ip netns add netns_1 ip link add name veth_1_peer type veth peer veth_1 ifconfig veth_1_peer 11.11.0.254 up ip link set veth_1 netns netns_1 ip netns exec netns_1 ifconfig veth_1 11.11.0.1 ip netns exec netns_1 /root/iptables -A OUTPUT -d 11.11.0.254 -p tcp \ --tcp-flags FIN FIN -j DROP (note: In my environment, a DESTROY_CLIENTID operation is always sent immediately, breaking the nfs tcp connection.) ip netns exec netns_1 timeout -s 9 300 mount -t nfs -o proto=tcp,vers=4.1 \ 11.11.0.254:/mnt/nfsshare /mnt/nfs/netns_1 ip netns del netns_1 The reason here is that the tcp socket in netns_1 (nfs side) has been shutdown and closed (done in xs_destroy), but the FIN message (with ack) is discarded, and the nfsd side keeps sending retransmission messages. As a result, when the tcp sock in netns_1 processes the received message, it sends the message (FIN message) in the sending queue, and the tcp timer is re-established. When the network namespace is deleted, the net structure accessed by tcp's timer handler function causes problems. To fix this problem: Add the sock_create_kern_getnet() helper function, add the get_net() operation for the kernel socket. Fixes: 26abe14379f8 ("net: Modify sk_alloc to not reference count the netns of kernel sockets.") Signed-off-by: Liu Jian --- v1: https://lore.kernel.org/all/20241024015543.568476-1-liujian56@huawei.com/ v1->v2: change to get netns reference count. include/linux/net.h | 1 + net/socket.c | 28 ++++++++++++++++++++++++++++ net/sunrpc/svcsock.c | 2 +- net/sunrpc/xprtsock.c | 2 +- 4 files changed, 31 insertions(+), 2 deletions(-) diff --git a/include/linux/net.h b/include/linux/net.h index b75bc534c1b3..58216da3b62c 100644 --- a/include/linux/net.h +++ b/include/linux/net.h @@ -255,6 +255,7 @@ int __sock_create(struct net *net, int family, int type, int proto, struct socket **res, int kern); int sock_create(int family, int type, int proto, struct socket **res); int sock_create_kern(struct net *net, int family, int type, int proto, struct socket **res); +int sock_create_kern_getnet(struct net *net, int family, int type, int proto, struct socket **res); int sock_create_lite(int family, int type, int proto, struct socket **res); struct socket *sock_alloc(void); void sock_release(struct socket *sock); diff --git a/net/socket.c b/net/socket.c index 042451f01c65..e64a02445b1a 100644 --- a/net/socket.c +++ b/net/socket.c @@ -1651,6 +1651,34 @@ int sock_create_kern(struct net *net, int family, int type, int protocol, struct } EXPORT_SYMBOL(sock_create_kern); +int sock_create_kern_getnet(struct net *net, int family, int type, int proto, struct socket **res) +{ + struct sock *sk; + int ret; + + if (!maybe_get_net(net)) + return -EINVAL; + + ret = sock_create_kern(net, family, type, proto, res); + if (ret < 0) { + put_net(net); + return ret; + } + + sk = (*res)->sk; + lock_sock(sk); + /* Update ns_tracker to current stack trace and refcounted tracker */ + __netns_tracker_free(net, &sk->ns_tracker, false); + + sk->sk_net_refcnt = 1; + netns_tracker_alloc(net, &sk->ns_tracker, GFP_KERNEL); + sock_inuse_add(net, 1); + release_sock(sk); + + return ret; +} +EXPORT_SYMBOL(sock_create_kern_getnet); + static struct socket *__sys_socket_create(int family, int type, int protocol) { struct socket *sock; diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c index 825ec5357691..6f272013fd9b 100644 --- a/net/sunrpc/svcsock.c +++ b/net/sunrpc/svcsock.c @@ -1526,7 +1526,7 @@ static struct svc_xprt *svc_create_socket(struct svc_serv *serv, return ERR_PTR(-EINVAL); } - error = __sock_create(net, family, type, protocol, &sock, 1); + error = sock_create_kern_getnet(net, family, type, protocol, &sock); if (error < 0) return ERR_PTR(error); diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 110749b85040..f7734ce5eec9 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -1925,7 +1925,7 @@ static struct socket *xs_create_sock(struct rpc_xprt *xprt, struct socket *sock; int err; - err = __sock_create(xprt->xprt_net, family, type, protocol, &sock, 1); + err = sock_create_kern_getnet(xprt->xprt_net, family, type, protocol, &sock); if (err < 0) { dprintk("RPC: can't create %d transport socket (%d).\n", protocol, -err);