* [Patch net 0/2] l2tp: fix race conditions in l2tp_tunnel_register() @ 2023-01-05 19:13 Cong Wang 2023-01-05 19:13 ` [Patch net 1/2] l2tp: convert l2tp_tunnel_list to idr Cong Wang 2023-01-05 19:13 ` [Patch net 2/2] l2tp: close all race conditions in l2tp_tunnel_register() Cong Wang 0 siblings, 2 replies; 11+ messages in thread From: Cong Wang @ 2023-01-05 19:13 UTC (permalink / raw) To: netdev; +Cc: g.nault, Cong Wang From: Cong Wang <cong.wang@bytedance.com> This patchset contains two patches, the first one is a preparation for the second one. Please find more details in each patch description. I have ran the l2tp test (https://github.com/katalix/l2tp-ktest), all test cases are passed. --- Cong Wang (2): l2tp: convert l2tp_tunnel_list to idr l2tp: close all race conditions in l2tp_tunnel_register() net/l2tp/l2tp_core.c | 116 +++++++++++++++++++++------------------- net/l2tp/l2tp_core.h | 3 +- net/l2tp/l2tp_netlink.c | 3 +- net/l2tp/l2tp_ppp.c | 3 +- 4 files changed, 68 insertions(+), 57 deletions(-) -- 2.34.1 ^ permalink raw reply [flat|nested] 11+ messages in thread
* [Patch net 1/2] l2tp: convert l2tp_tunnel_list to idr 2023-01-05 19:13 [Patch net 0/2] l2tp: fix race conditions in l2tp_tunnel_register() Cong Wang @ 2023-01-05 19:13 ` Cong Wang 2023-01-07 18:25 ` Saeed Mahameed 2023-01-07 19:48 ` Guillaume Nault 2023-01-05 19:13 ` [Patch net 2/2] l2tp: close all race conditions in l2tp_tunnel_register() Cong Wang 1 sibling, 2 replies; 11+ messages in thread From: Cong Wang @ 2023-01-05 19:13 UTC (permalink / raw) To: netdev; +Cc: g.nault, Cong Wang, Tetsuo Handa, Jakub Sitnicki, Eric Dumazet From: Cong Wang <cong.wang@bytedance.com> l2tp uses l2tp_tunnel_list to track all registered tunnels and to allocate tunnel ID's. IDR can do the same job. More importantly, with IDR we can hold the ID before a successful registration so that we don't need to worry about late error hanlding, it is not easy to rollback socket changes. This is a preparation for the following fix. Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Guillaume Nault <g.nault@alphalink.fr> Cc: Jakub Sitnicki <jakub@cloudflare.com> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Cong Wang <cong.wang@bytedance.com> --- net/l2tp/l2tp_core.c | 93 ++++++++++++++++++++++------------------- net/l2tp/l2tp_core.h | 3 +- net/l2tp/l2tp_netlink.c | 3 +- net/l2tp/l2tp_ppp.c | 3 +- 4 files changed, 57 insertions(+), 45 deletions(-) diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 9a1415fe3fa7..570249a91c6c 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -104,9 +104,9 @@ static struct workqueue_struct *l2tp_wq; /* per-net private data for this module */ static unsigned int l2tp_net_id; struct l2tp_net { - struct list_head l2tp_tunnel_list; - /* Lock for write access to l2tp_tunnel_list */ - spinlock_t l2tp_tunnel_list_lock; + /* Lock for write access to l2tp_tunnel_idr */ + spinlock_t l2tp_tunnel_idr_lock; + struct idr l2tp_tunnel_idr; struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2]; /* Lock for write access to l2tp_session_hlist */ spinlock_t l2tp_session_hlist_lock; @@ -208,13 +208,10 @@ struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) struct l2tp_tunnel *tunnel; rcu_read_lock_bh(); - list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { - if (tunnel->tunnel_id == tunnel_id && - refcount_inc_not_zero(&tunnel->ref_count)) { - rcu_read_unlock_bh(); - - return tunnel; - } + tunnel = idr_find(&pn->l2tp_tunnel_idr, tunnel_id); + if (tunnel && refcount_inc_not_zero(&tunnel->ref_count)) { + rcu_read_unlock_bh(); + return tunnel; } rcu_read_unlock_bh(); @@ -224,13 +221,14 @@ EXPORT_SYMBOL_GPL(l2tp_tunnel_get); struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth) { - const struct l2tp_net *pn = l2tp_pernet(net); + struct l2tp_net *pn = l2tp_pernet(net); + unsigned long tunnel_id, tmp; struct l2tp_tunnel *tunnel; int count = 0; rcu_read_lock_bh(); - list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { - if (++count > nth && + idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) { + if (tunnel && ++count > nth && refcount_inc_not_zero(&tunnel->ref_count)) { rcu_read_unlock_bh(); return tunnel; @@ -1234,7 +1232,6 @@ static void l2tp_tunnel_del_work(struct work_struct *work) del_work); struct sock *sk = tunnel->sock; struct socket *sock = sk->sk_socket; - struct l2tp_net *pn; l2tp_tunnel_closeall(tunnel); @@ -1248,12 +1245,7 @@ static void l2tp_tunnel_del_work(struct work_struct *work) } } - /* Remove the tunnel struct from the tunnel list */ - pn = l2tp_pernet(tunnel->l2tp_net); - spin_lock_bh(&pn->l2tp_tunnel_list_lock); - list_del_rcu(&tunnel->list); - spin_unlock_bh(&pn->l2tp_tunnel_list_lock); - + l2tp_tunnel_remove(tunnel); /* drop initial ref */ l2tp_tunnel_dec_refcount(tunnel); @@ -1386,16 +1378,37 @@ static int l2tp_tunnel_sock_create(struct net *net, static struct lock_class_key l2tp_socket_class; -int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, - struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp) +void l2tp_tunnel_remove(struct l2tp_tunnel *tunnel) +{ + struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); + + spin_lock_bh(&pn->l2tp_tunnel_idr_lock); + idr_remove(&pn->l2tp_tunnel_idr, tunnel->tunnel_id); + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); +} +EXPORT_SYMBOL_GPL(l2tp_tunnel_remove); + +int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, + u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, + struct l2tp_tunnel **tunnelp) { struct l2tp_tunnel *tunnel = NULL; int err; enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; + struct l2tp_net *pn = l2tp_pernet(net); if (cfg) encap = cfg->encap; + spin_lock_bh(&pn->l2tp_tunnel_idr_lock); + err = idr_alloc_u32(&pn->l2tp_tunnel_idr, NULL, &tunnel_id, tunnel_id, + GFP_ATOMIC); + if (err) { + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); + return err; + } + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); + tunnel = kzalloc(sizeof(*tunnel), GFP_KERNEL); if (!tunnel) { err = -ENOMEM; @@ -1412,6 +1425,7 @@ int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, tunnel->acpt_newsess = true; tunnel->encap = encap; + tunnel->l2tp_net = net; refcount_set(&tunnel->ref_count, 1); tunnel->fd = fd; @@ -1425,6 +1439,11 @@ int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, err: if (tunnelp) *tunnelp = tunnel; + if (err) { + spin_lock_bh(&pn->l2tp_tunnel_idr_lock); + idr_remove(&pn->l2tp_tunnel_idr, tunnel_id); + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); + } return err; } @@ -1455,7 +1474,6 @@ static int l2tp_validate_socket(const struct sock *sk, const struct net *net, int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, struct l2tp_tunnel_cfg *cfg) { - struct l2tp_tunnel *tunnel_walk; struct l2tp_net *pn; struct socket *sock; struct sock *sk; @@ -1481,23 +1499,14 @@ int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, rcu_assign_sk_user_data(sk, tunnel); write_unlock_bh(&sk->sk_callback_lock); - tunnel->l2tp_net = net; pn = l2tp_pernet(net); sock_hold(sk); tunnel->sock = sk; - spin_lock_bh(&pn->l2tp_tunnel_list_lock); - list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) { - if (tunnel_walk->tunnel_id == tunnel->tunnel_id) { - spin_unlock_bh(&pn->l2tp_tunnel_list_lock); - sock_put(sk); - ret = -EEXIST; - goto err_sock; - } - } - list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); - spin_unlock_bh(&pn->l2tp_tunnel_list_lock); + spin_lock_bh(&pn->l2tp_tunnel_idr_lock); + idr_replace(&pn->l2tp_tunnel_idr, tunnel, tunnel->tunnel_id); + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { struct udp_tunnel_sock_cfg udp_cfg = { @@ -1523,9 +1532,6 @@ int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, return 0; -err_sock: - write_lock_bh(&sk->sk_callback_lock); - rcu_assign_sk_user_data(sk, NULL); err_inval_sock: write_unlock_bh(&sk->sk_callback_lock); @@ -1647,8 +1653,8 @@ static __net_init int l2tp_init_net(struct net *net) struct l2tp_net *pn = net_generic(net, l2tp_net_id); int hash; - INIT_LIST_HEAD(&pn->l2tp_tunnel_list); - spin_lock_init(&pn->l2tp_tunnel_list_lock); + idr_init(&pn->l2tp_tunnel_idr); + spin_lock_init(&pn->l2tp_tunnel_idr_lock); for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); @@ -1662,11 +1668,13 @@ static __net_exit void l2tp_exit_net(struct net *net) { struct l2tp_net *pn = l2tp_pernet(net); struct l2tp_tunnel *tunnel = NULL; + unsigned long tunnel_id, tmp; int hash; rcu_read_lock_bh(); - list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { - l2tp_tunnel_delete(tunnel); + idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) { + if (tunnel) + l2tp_tunnel_delete(tunnel); } rcu_read_unlock_bh(); @@ -1676,6 +1684,7 @@ static __net_exit void l2tp_exit_net(struct net *net) for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash])); + idr_destroy(&pn->l2tp_tunnel_idr); } static struct pernet_operations l2tp_net_ops = { diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h index a88e070b431d..aec7e0611591 100644 --- a/net/l2tp/l2tp_core.h +++ b/net/l2tp/l2tp_core.h @@ -236,9 +236,10 @@ struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, * Creation of a new instance is a two-step process: create, then register. * Destruction is triggered using the *_delete functions, and completes asynchronously. */ -int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, +int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp); +void l2tp_tunnel_remove(struct l2tp_tunnel *tunnel); int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, struct l2tp_tunnel_cfg *cfg); void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel); diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c index a901fd14fe3b..6fcf36a8eafd 100644 --- a/net/l2tp/l2tp_netlink.c +++ b/net/l2tp/l2tp_netlink.c @@ -233,7 +233,7 @@ static int l2tp_nl_cmd_tunnel_create(struct sk_buff *skb, struct genl_info *info switch (cfg.encap) { case L2TP_ENCAPTYPE_UDP: case L2TP_ENCAPTYPE_IP: - ret = l2tp_tunnel_create(fd, proto_version, tunnel_id, + ret = l2tp_tunnel_create(net, fd, proto_version, tunnel_id, peer_tunnel_id, &cfg, &tunnel); break; } @@ -244,6 +244,7 @@ static int l2tp_nl_cmd_tunnel_create(struct sk_buff *skb, struct genl_info *info l2tp_tunnel_inc_refcount(tunnel); ret = l2tp_tunnel_register(tunnel, net, &cfg); if (ret < 0) { + l2tp_tunnel_remove(tunnel); kfree(tunnel); goto out; } diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c index db2e584c625e..813ada637485 100644 --- a/net/l2tp/l2tp_ppp.c +++ b/net/l2tp/l2tp_ppp.c @@ -711,7 +711,7 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr, goto end; } - error = l2tp_tunnel_create(info.fd, + error = l2tp_tunnel_create(sock_net(sk), info.fd, info.version, info.tunnel_id, info.peer_tunnel_id, &tcfg, @@ -723,6 +723,7 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr, error = l2tp_tunnel_register(tunnel, sock_net(sk), &tcfg); if (error < 0) { + l2tp_tunnel_remove(tunnel); kfree(tunnel); goto end; } -- 2.34.1 ^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [Patch net 1/2] l2tp: convert l2tp_tunnel_list to idr 2023-01-05 19:13 ` [Patch net 1/2] l2tp: convert l2tp_tunnel_list to idr Cong Wang @ 2023-01-07 18:25 ` Saeed Mahameed 2023-01-07 19:48 ` Cong Wang 2023-01-07 19:48 ` Guillaume Nault 1 sibling, 1 reply; 11+ messages in thread From: Saeed Mahameed @ 2023-01-07 18:25 UTC (permalink / raw) To: Cong Wang Cc: netdev, g.nault, Cong Wang, Tetsuo Handa, Jakub Sitnicki, Eric Dumazet On 05 Jan 11:13, Cong Wang wrote: >From: Cong Wang <cong.wang@bytedance.com> > >l2tp uses l2tp_tunnel_list to track all registered tunnels and >to allocate tunnel ID's. IDR can do the same job. > >More importantly, with IDR we can hold the ID before a successful >registration so that we don't need to worry about late error >hanlding, it is not easy to rollback socket changes. > >This is a preparation for the following fix. > >Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> >Cc: Guillaume Nault <g.nault@alphalink.fr> >Cc: Jakub Sitnicki <jakub@cloudflare.com> >Cc: Eric Dumazet <edumazet@google.com> >Signed-off-by: Cong Wang <cong.wang@bytedance.com> >--- > net/l2tp/l2tp_core.c | 93 ++++++++++++++++++++++------------------- > net/l2tp/l2tp_core.h | 3 +- > net/l2tp/l2tp_netlink.c | 3 +- > net/l2tp/l2tp_ppp.c | 3 +- > 4 files changed, 57 insertions(+), 45 deletions(-) > >diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c >index 9a1415fe3fa7..570249a91c6c 100644 >--- a/net/l2tp/l2tp_core.c >+++ b/net/l2tp/l2tp_core.c >@@ -104,9 +104,9 @@ static struct workqueue_struct *l2tp_wq; > /* per-net private data for this module */ > static unsigned int l2tp_net_id; > struct l2tp_net { >- struct list_head l2tp_tunnel_list; >- /* Lock for write access to l2tp_tunnel_list */ >- spinlock_t l2tp_tunnel_list_lock; >+ /* Lock for write access to l2tp_tunnel_idr */ >+ spinlock_t l2tp_tunnel_idr_lock; >+ struct idr l2tp_tunnel_idr; > struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2]; > /* Lock for write access to l2tp_session_hlist */ > spinlock_t l2tp_session_hlist_lock; >@@ -208,13 +208,10 @@ struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) > struct l2tp_tunnel *tunnel; > > rcu_read_lock_bh(); >- list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { >- if (tunnel->tunnel_id == tunnel_id && >- refcount_inc_not_zero(&tunnel->ref_count)) { >- rcu_read_unlock_bh(); >- >- return tunnel; >- } >+ tunnel = idr_find(&pn->l2tp_tunnel_idr, tunnel_id); >+ if (tunnel && refcount_inc_not_zero(&tunnel->ref_count)) { >+ rcu_read_unlock_bh(); >+ return tunnel; > } > rcu_read_unlock_bh(); > >@@ -224,13 +221,14 @@ EXPORT_SYMBOL_GPL(l2tp_tunnel_get); > > struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth) > { >- const struct l2tp_net *pn = l2tp_pernet(net); >+ struct l2tp_net *pn = l2tp_pernet(net); Any reason to remove the const keyword ? Other than that LGTM: Reviewed-by: Saeed Mahameed <saeed@kernel.org> ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Patch net 1/2] l2tp: convert l2tp_tunnel_list to idr 2023-01-07 18:25 ` Saeed Mahameed @ 2023-01-07 19:48 ` Cong Wang 0 siblings, 0 replies; 11+ messages in thread From: Cong Wang @ 2023-01-07 19:48 UTC (permalink / raw) To: Saeed Mahameed Cc: netdev, g.nault, Cong Wang, Tetsuo Handa, Jakub Sitnicki, Eric Dumazet On Sat, Jan 07, 2023 at 10:25:04AM -0800, Saeed Mahameed wrote: > On 05 Jan 11:13, Cong Wang wrote: > > From: Cong Wang <cong.wang@bytedance.com> > > > > l2tp uses l2tp_tunnel_list to track all registered tunnels and > > to allocate tunnel ID's. IDR can do the same job. > > > > More importantly, with IDR we can hold the ID before a successful > > registration so that we don't need to worry about late error > > hanlding, it is not easy to rollback socket changes. > > > > This is a preparation for the following fix. > > > > Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > > Cc: Guillaume Nault <g.nault@alphalink.fr> > > Cc: Jakub Sitnicki <jakub@cloudflare.com> > > Cc: Eric Dumazet <edumazet@google.com> > > Signed-off-by: Cong Wang <cong.wang@bytedance.com> > > --- > > net/l2tp/l2tp_core.c | 93 ++++++++++++++++++++++------------------- > > net/l2tp/l2tp_core.h | 3 +- > > net/l2tp/l2tp_netlink.c | 3 +- > > net/l2tp/l2tp_ppp.c | 3 +- > > 4 files changed, 57 insertions(+), 45 deletions(-) > > > > diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c > > index 9a1415fe3fa7..570249a91c6c 100644 > > --- a/net/l2tp/l2tp_core.c > > +++ b/net/l2tp/l2tp_core.c > > @@ -104,9 +104,9 @@ static struct workqueue_struct *l2tp_wq; > > /* per-net private data for this module */ > > static unsigned int l2tp_net_id; > > struct l2tp_net { > > - struct list_head l2tp_tunnel_list; > > - /* Lock for write access to l2tp_tunnel_list */ > > - spinlock_t l2tp_tunnel_list_lock; > > + /* Lock for write access to l2tp_tunnel_idr */ > > + spinlock_t l2tp_tunnel_idr_lock; > > + struct idr l2tp_tunnel_idr; > > struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2]; > > /* Lock for write access to l2tp_session_hlist */ > > spinlock_t l2tp_session_hlist_lock; > > @@ -208,13 +208,10 @@ struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) > > struct l2tp_tunnel *tunnel; > > > > rcu_read_lock_bh(); > > - list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { > > - if (tunnel->tunnel_id == tunnel_id && > > - refcount_inc_not_zero(&tunnel->ref_count)) { > > - rcu_read_unlock_bh(); > > - > > - return tunnel; > > - } > > + tunnel = idr_find(&pn->l2tp_tunnel_idr, tunnel_id); > > + if (tunnel && refcount_inc_not_zero(&tunnel->ref_count)) { > > + rcu_read_unlock_bh(); > > + return tunnel; > > } > > rcu_read_unlock_bh(); > > > > @@ -224,13 +221,14 @@ EXPORT_SYMBOL_GPL(l2tp_tunnel_get); > > > > struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth) > > { > > - const struct l2tp_net *pn = l2tp_pernet(net); > > + struct l2tp_net *pn = l2tp_pernet(net); > > Any reason to remove the const keyword ? Yes, GCC complained about discarding const in idr_for_each_entry_ul(). Thanks. ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Patch net 1/2] l2tp: convert l2tp_tunnel_list to idr 2023-01-05 19:13 ` [Patch net 1/2] l2tp: convert l2tp_tunnel_list to idr Cong Wang 2023-01-07 18:25 ` Saeed Mahameed @ 2023-01-07 19:48 ` Guillaume Nault 2023-01-09 9:55 ` Tom Parkin 2023-01-10 6:49 ` Cong Wang 1 sibling, 2 replies; 11+ messages in thread From: Guillaume Nault @ 2023-01-07 19:48 UTC (permalink / raw) To: Cong Wang Cc: netdev, g.nault, Cong Wang, Tetsuo Handa, Jakub Sitnicki, Eric Dumazet On Thu, Jan 05, 2023 at 11:13:38AM -0800, Cong Wang wrote: > +int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, > + u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, > + struct l2tp_tunnel **tunnelp) > { > struct l2tp_tunnel *tunnel = NULL; > int err; > enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; > + struct l2tp_net *pn = l2tp_pernet(net); > > if (cfg) > encap = cfg->encap; > > + spin_lock_bh(&pn->l2tp_tunnel_idr_lock); > + err = idr_alloc_u32(&pn->l2tp_tunnel_idr, NULL, &tunnel_id, tunnel_id, > + GFP_ATOMIC); > + if (err) { > + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); > + return err; > + } > + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); Why reserving the tunnel_id in l2tp_tunnel_create()? This function is supposed to just allocate a structure and pre-initialise some fields. The only cleanup required upon error after this call is to kfree() the new structure. So I can't see any reason to guarantee the id will be accepted by the future l2tp_tunnel_register() call. Looks like you could reserve the id at the beginning of l2tp_tunnel_register() instead. That'd avoid changing the API and thus the side effects on l2tp_{ppp,netlink}.c. Also we wouldn't need create l2tp_tunnel_remove(). ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Patch net 1/2] l2tp: convert l2tp_tunnel_list to idr 2023-01-07 19:48 ` Guillaume Nault @ 2023-01-09 9:55 ` Tom Parkin 2023-01-10 6:49 ` Cong Wang 1 sibling, 0 replies; 11+ messages in thread From: Tom Parkin @ 2023-01-09 9:55 UTC (permalink / raw) To: Guillaume Nault Cc: Cong Wang, netdev, g.nault, Cong Wang, Tetsuo Handa, Jakub Sitnicki, Eric Dumazet [-- Attachment #1: Type: text/plain, Size: 1549 bytes --] On Sat, Jan 07, 2023 at 20:48:51 +0100, Guillaume Nault wrote: > On Thu, Jan 05, 2023 at 11:13:38AM -0800, Cong Wang wrote: > > +int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, > > + u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, > > + struct l2tp_tunnel **tunnelp) > > { > > struct l2tp_tunnel *tunnel = NULL; > > int err; > > enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; > > + struct l2tp_net *pn = l2tp_pernet(net); > > > > if (cfg) > > encap = cfg->encap; > > > > + spin_lock_bh(&pn->l2tp_tunnel_idr_lock); > > + err = idr_alloc_u32(&pn->l2tp_tunnel_idr, NULL, &tunnel_id, tunnel_id, > > + GFP_ATOMIC); > > + if (err) { > > + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); > > + return err; > > + } > > + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); > > Why reserving the tunnel_id in l2tp_tunnel_create()? This function is > supposed to just allocate a structure and pre-initialise some fields. > The only cleanup required upon error after this call is to kfree() the > new structure. So I can't see any reason to guarantee the id will be > accepted by the future l2tp_tunnel_register() call. > > Looks like you could reserve the id at the beginning of > l2tp_tunnel_register() instead. That'd avoid changing the API and thus > the side effects on l2tp_{ppp,netlink}.c. Also we wouldn't need create > l2tp_tunnel_remove(). > FWIW I also think that'd make more sense, and leave callsites will less tidyup to do on behalf of l2tp_core. [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 488 bytes --] ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Patch net 1/2] l2tp: convert l2tp_tunnel_list to idr 2023-01-07 19:48 ` Guillaume Nault 2023-01-09 9:55 ` Tom Parkin @ 2023-01-10 6:49 ` Cong Wang 1 sibling, 0 replies; 11+ messages in thread From: Cong Wang @ 2023-01-10 6:49 UTC (permalink / raw) To: Guillaume Nault Cc: netdev, g.nault, Cong Wang, Tetsuo Handa, Jakub Sitnicki, Eric Dumazet On Sat, Jan 07, 2023 at 08:48:51PM +0100, Guillaume Nault wrote: > On Thu, Jan 05, 2023 at 11:13:38AM -0800, Cong Wang wrote: > > +int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, > > + u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, > > + struct l2tp_tunnel **tunnelp) > > { > > struct l2tp_tunnel *tunnel = NULL; > > int err; > > enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; > > + struct l2tp_net *pn = l2tp_pernet(net); > > > > if (cfg) > > encap = cfg->encap; > > > > + spin_lock_bh(&pn->l2tp_tunnel_idr_lock); > > + err = idr_alloc_u32(&pn->l2tp_tunnel_idr, NULL, &tunnel_id, tunnel_id, > > + GFP_ATOMIC); > > + if (err) { > > + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); > > + return err; > > + } > > + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); > > Why reserving the tunnel_id in l2tp_tunnel_create()? This function is > supposed to just allocate a structure and pre-initialise some fields. > The only cleanup required upon error after this call is to kfree() the > new structure. So I can't see any reason to guarantee the id will be > accepted by the future l2tp_tunnel_register() call. > > Looks like you could reserve the id at the beginning of > l2tp_tunnel_register() instead. That'd avoid changing the API and thus > the side effects on l2tp_{ppp,netlink}.c. Also we wouldn't need create > l2tp_tunnel_remove(). > The idr_replace() is guaranteed to succeed in terms of ID allocation. So either way could work, but I think you are right that the patch could be smaller if we do it in l2tp_tunnel_register(). Thanks. ^ permalink raw reply [flat|nested] 11+ messages in thread
* [Patch net 2/2] l2tp: close all race conditions in l2tp_tunnel_register() 2023-01-05 19:13 [Patch net 0/2] l2tp: fix race conditions in l2tp_tunnel_register() Cong Wang 2023-01-05 19:13 ` [Patch net 1/2] l2tp: convert l2tp_tunnel_list to idr Cong Wang @ 2023-01-05 19:13 ` Cong Wang 2023-01-07 18:41 ` Saeed Mahameed 1 sibling, 1 reply; 11+ messages in thread From: Cong Wang @ 2023-01-05 19:13 UTC (permalink / raw) To: netdev Cc: g.nault, Cong Wang, syzbot+52866e24647f9a23403f, syzbot+94cc2a66fc228b23f360, Tetsuo Handa, Jakub Sitnicki, Eric Dumazet From: Cong Wang <cong.wang@bytedance.com> The code in l2tp_tunnel_register() is racy in several ways: 1. It modifies the tunnel socket _after_ publishing it. 2. It calls setup_udp_tunnel_sock() on an existing socket without locking. 3. It changes sock lock class on fly, which triggers many syzbot reports. This patch amends all of them by moving socket initialization code before publishing and under sock lock. As suggested by Jakub, the l2tp lockdep class is not necessary as we can just switch to bh_lock_sock_nested(). Fixes: 37159ef2c1ae ("l2tp: fix a lockdep splat") Fixes: 6b9f34239b00 ("l2tp: fix races in tunnel creation") Reported-by: syzbot+52866e24647f9a23403f@syzkaller.appspotmail.com Reported-by: syzbot+94cc2a66fc228b23f360@syzkaller.appspotmail.com Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Guillaume Nault <g.nault@alphalink.fr> Cc: Jakub Sitnicki <jakub@cloudflare.com> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Cong Wang <cong.wang@bytedance.com> --- net/l2tp/l2tp_core.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 570249a91c6c..3cb5cbfd4399 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1041,7 +1041,7 @@ static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, uns IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED); nf_reset_ct(skb); - bh_lock_sock(sk); + bh_lock_sock_nested(sk); if (sock_owned_by_user(sk)) { kfree_skb(skb); ret = NET_XMIT_DROP; @@ -1376,8 +1376,6 @@ static int l2tp_tunnel_sock_create(struct net *net, return err; } -static struct lock_class_key l2tp_socket_class; - void l2tp_tunnel_remove(struct l2tp_tunnel *tunnel) { struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); @@ -1492,22 +1490,16 @@ int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, } sk = sock->sk; + lock_sock(sk); write_lock_bh(&sk->sk_callback_lock); ret = l2tp_validate_socket(sk, net, tunnel->encap); - if (ret < 0) + if (ret < 0) { + release_sock(sk); goto err_inval_sock; + } rcu_assign_sk_user_data(sk, tunnel); write_unlock_bh(&sk->sk_callback_lock); - pn = l2tp_pernet(net); - - sock_hold(sk); - tunnel->sock = sk; - - spin_lock_bh(&pn->l2tp_tunnel_idr_lock); - idr_replace(&pn->l2tp_tunnel_idr, tunnel, tunnel->tunnel_id); - spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); - if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { struct udp_tunnel_sock_cfg udp_cfg = { .sk_user_data = tunnel, @@ -1518,12 +1510,19 @@ int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, setup_udp_tunnel_sock(net, sock, &udp_cfg); } - tunnel->old_sk_destruct = sk->sk_destruct; sk->sk_destruct = &l2tp_tunnel_destruct; - lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, - "l2tp_sock"); sk->sk_allocation = GFP_ATOMIC; + release_sock(sk); + + pn = l2tp_pernet(net); + + sock_hold(sk); + tunnel->sock = sk; + + spin_lock_bh(&pn->l2tp_tunnel_idr_lock); + idr_replace(&pn->l2tp_tunnel_idr, tunnel, tunnel->tunnel_id); + spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); trace_register_tunnel(tunnel); -- 2.34.1 ^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [Patch net 2/2] l2tp: close all race conditions in l2tp_tunnel_register() 2023-01-05 19:13 ` [Patch net 2/2] l2tp: close all race conditions in l2tp_tunnel_register() Cong Wang @ 2023-01-07 18:41 ` Saeed Mahameed 2023-01-07 19:52 ` Cong Wang 0 siblings, 1 reply; 11+ messages in thread From: Saeed Mahameed @ 2023-01-07 18:41 UTC (permalink / raw) To: Cong Wang Cc: netdev, g.nault, Cong Wang, syzbot+52866e24647f9a23403f, syzbot+94cc2a66fc228b23f360, Tetsuo Handa, Jakub Sitnicki, Eric Dumazet On 05 Jan 11:13, Cong Wang wrote: >From: Cong Wang <cong.wang@bytedance.com> > >The code in l2tp_tunnel_register() is racy in several ways: > >1. It modifies the tunnel socket _after_ publishing it. > >2. It calls setup_udp_tunnel_sock() on an existing socket without > locking. > >3. It changes sock lock class on fly, which triggers many syzbot > reports. > >This patch amends all of them by moving socket initialization code >before publishing and under sock lock. As suggested by Jakub, the >l2tp lockdep class is not necessary as we can just switch to >bh_lock_sock_nested(). > >Fixes: 37159ef2c1ae ("l2tp: fix a lockdep splat") >Fixes: 6b9f34239b00 ("l2tp: fix races in tunnel creation") This patch relies on the previous one which doesn't include any tags. If you are interested in this making it to -stable then maybe you need to add those tags to the previous commit ? I am not really familiar with the issue and how socket locks should work here, but code wise LGTM. Reviewed-by: Saeed Mahameed <saeed@kernel.org> >Reported-by: syzbot+52866e24647f9a23403f@syzkaller.appspotmail.com >Reported-by: syzbot+94cc2a66fc228b23f360@syzkaller.appspotmail.com >Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> >Cc: Guillaume Nault <g.nault@alphalink.fr> >Cc: Jakub Sitnicki <jakub@cloudflare.com> >Cc: Eric Dumazet <edumazet@google.com> >Signed-off-by: Cong Wang <cong.wang@bytedance.com> ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Patch net 2/2] l2tp: close all race conditions in l2tp_tunnel_register() 2023-01-07 18:41 ` Saeed Mahameed @ 2023-01-07 19:52 ` Cong Wang 2023-01-10 1:36 ` Jakub Kicinski 0 siblings, 1 reply; 11+ messages in thread From: Cong Wang @ 2023-01-07 19:52 UTC (permalink / raw) To: Saeed Mahameed Cc: netdev, g.nault, Cong Wang, syzbot+52866e24647f9a23403f, syzbot+94cc2a66fc228b23f360, Tetsuo Handa, Jakub Sitnicki, Eric Dumazet On Sat, Jan 07, 2023 at 10:41:41AM -0800, Saeed Mahameed wrote: > On 05 Jan 11:13, Cong Wang wrote: > > From: Cong Wang <cong.wang@bytedance.com> > > > > The code in l2tp_tunnel_register() is racy in several ways: > > > > 1. It modifies the tunnel socket _after_ publishing it. > > > > 2. It calls setup_udp_tunnel_sock() on an existing socket without > > locking. > > > > 3. It changes sock lock class on fly, which triggers many syzbot > > reports. > > > > This patch amends all of them by moving socket initialization code > > before publishing and under sock lock. As suggested by Jakub, the > > l2tp lockdep class is not necessary as we can just switch to > > bh_lock_sock_nested(). > > > > Fixes: 37159ef2c1ae ("l2tp: fix a lockdep splat") > > Fixes: 6b9f34239b00 ("l2tp: fix races in tunnel creation") > > This patch relies on the previous one which doesn't include any tags. > If you are interested in this making it to -stable then maybe you need to > add those tags to the previous commit ? > But technically patch 1/2 does not fix anything alone, this is why I heisitate to add any Fixes tag to it. Since this is a patchset, I think maintainers can easily figure out this is a whole set. Thanks. ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [Patch net 2/2] l2tp: close all race conditions in l2tp_tunnel_register() 2023-01-07 19:52 ` Cong Wang @ 2023-01-10 1:36 ` Jakub Kicinski 0 siblings, 0 replies; 11+ messages in thread From: Jakub Kicinski @ 2023-01-10 1:36 UTC (permalink / raw) To: Cong Wang Cc: Saeed Mahameed, netdev, g.nault, Cong Wang, syzbot+52866e24647f9a23403f, syzbot+94cc2a66fc228b23f360, Tetsuo Handa, Jakub Sitnicki, Eric Dumazet On Sat, 7 Jan 2023 11:52:23 -0800 Cong Wang wrote: > But technically patch 1/2 does not fix anything alone, this is why I > heisitate to add any Fixes tag to it. > > Since this is a patchset, I think maintainers can easily figure out this > is a whole set. Yup, afaik prep patches don't need any extra tags if the dependency is pretty obvious (same series and fix does not apply without the prep). ^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2023-01-10 6:49 UTC | newest] Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2023-01-05 19:13 [Patch net 0/2] l2tp: fix race conditions in l2tp_tunnel_register() Cong Wang 2023-01-05 19:13 ` [Patch net 1/2] l2tp: convert l2tp_tunnel_list to idr Cong Wang 2023-01-07 18:25 ` Saeed Mahameed 2023-01-07 19:48 ` Cong Wang 2023-01-07 19:48 ` Guillaume Nault 2023-01-09 9:55 ` Tom Parkin 2023-01-10 6:49 ` Cong Wang 2023-01-05 19:13 ` [Patch net 2/2] l2tp: close all race conditions in l2tp_tunnel_register() Cong Wang 2023-01-07 18:41 ` Saeed Mahameed 2023-01-07 19:52 ` Cong Wang 2023-01-10 1:36 ` Jakub Kicinski
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