| Message ID | 20250106180137.1861472-1-kuba@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] netdev: prevent accessing NAPI instances from another namespace | expand |
On 1/6/2025 10:01 AM, Jakub Kicinski wrote: > The NAPI IDs were not fully exposed to user space prior to the netlink > API, so they were never namespaced. The netlink API must ensure that > at the very least NAPI instance belongs to the same netns as the owner > of the genl sock. > > napi_by_id() can become static now, but it needs to move because of > dev_get_by_napi_id(). > > Cc: stable@vger.kernel.org > Fixes: 1287c1ae0fc2 ("netdev-genl: Support setting per-NAPI config values") > Fixes: 27f91aaf49b3 ("netdev-genl: Add netlink framework functions for napi") > Signed-off-by: Jakub Kicinski <kuba@kernel.org> Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Jakub Kicinski wrote: > The NAPI IDs were not fully exposed to user space prior to the netlink > API, so they were never namespaced. The netlink API must ensure that > at the very least NAPI instance belongs to the same netns as the owner > of the genl sock. > > napi_by_id() can become static now, but it needs to move because of > dev_get_by_napi_id(). > > Cc: stable@vger.kernel.org > Fixes: 1287c1ae0fc2 ("netdev-genl: Support setting per-NAPI config values") > Fixes: 27f91aaf49b3 ("netdev-genl: Add netlink framework functions for napi") > Signed-off-by: Jakub Kicinski <kuba@kernel.org> > --- > Splitting this into fix per-version is a bit tricky, because we need > to replace the napi_by_id() helper with a better one. I'll send the > stable versions manually. > > CC: jdamato@fastly.com > CC: almasrymina@google.com > CC: amritha.nambiar@intel.com > CC: sridhar.samudrala@intel.com > --- > net/core/dev.c | 43 +++++++++++++++++++++++++++++------------- > net/core/dev.h | 3 ++- > net/core/netdev-genl.c | 6 ++---- > 3 files changed, 34 insertions(+), 18 deletions(-) > > diff --git a/net/core/dev.c b/net/core/dev.c > index 7c63d97b13c1..e001df4cb486 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -753,6 +753,36 @@ int dev_fill_forward_path(const struct net_device *dev, const u8 *daddr, > } > EXPORT_SYMBOL_GPL(dev_fill_forward_path); > > +/* must be called under rcu_read_lock(), as we dont take a reference */ > +static struct napi_struct *napi_by_id(unsigned int napi_id) > +{ > + unsigned int hash = napi_id % HASH_SIZE(napi_hash); > + struct napi_struct *napi; > + > + hlist_for_each_entry_rcu(napi, &napi_hash[hash], napi_hash_node) > + if (napi->napi_id == napi_id) > + return napi; > + > + return NULL; > +} > + > +/* must be called under rcu_read_lock(), as we dont take a reference */ Instead of function comments, invariant checks in code? Like in dev_get_by_napi_id: WARN_ON_ONCE(!rcu_read_lock_held());
On Tue, 07 Jan 2025 08:10:36 -0500 Willem de Bruijn wrote: > > +/* must be called under rcu_read_lock(), as we dont take a reference */ > > Instead of function comments, invariant checks in code? > > Like in dev_get_by_napi_id: > > WARN_ON_ONCE(!rcu_read_lock_held()); Can I do it as a follow up? Adding the warning to napi_by_id() reveals that napi_hash_add() currently walks the list without holding the RCU lock :)
Jakub Kicinski wrote: > On Tue, 07 Jan 2025 08:10:36 -0500 Willem de Bruijn wrote: > > > +/* must be called under rcu_read_lock(), as we dont take a reference */ > > > > Instead of function comments, invariant checks in code? > > > > Like in dev_get_by_napi_id: > > > > WARN_ON_ONCE(!rcu_read_lock_held()); > > Can I do it as a follow up? Adding the warning to napi_by_id() > reveals that napi_hash_add() currently walks the list without > holding the RCU lock :) Ah I should have noticed that :) Of course, or ignore in this case then.
diff --git a/net/core/dev.c b/net/core/dev.c index 7c63d97b13c1..e001df4cb486 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -753,6 +753,36 @@ int dev_fill_forward_path(const struct net_device *dev, const u8 *daddr, } EXPORT_SYMBOL_GPL(dev_fill_forward_path); +/* must be called under rcu_read_lock(), as we dont take a reference */ +static struct napi_struct *napi_by_id(unsigned int napi_id) +{ + unsigned int hash = napi_id % HASH_SIZE(napi_hash); + struct napi_struct *napi; + + hlist_for_each_entry_rcu(napi, &napi_hash[hash], napi_hash_node) + if (napi->napi_id == napi_id) + return napi; + + return NULL; +} + +/* must be called under rcu_read_lock(), as we dont take a reference */ +struct napi_struct *netdev_napi_by_id(struct net *net, unsigned int napi_id) +{ + struct napi_struct *napi; + + napi = napi_by_id(napi_id); + if (!napi) + return NULL; + + if (WARN_ON_ONCE(!napi->dev)) + return NULL; + if (!net_eq(net, dev_net(napi->dev))) + return NULL; + + return napi; +} + /** * __dev_get_by_name - find a device by its name * @net: the applicable net namespace @@ -6293,19 +6323,6 @@ bool napi_complete_done(struct napi_struct *n, int work_done) } EXPORT_SYMBOL(napi_complete_done); -/* must be called under rcu_read_lock(), as we dont take a reference */ -struct napi_struct *napi_by_id(unsigned int napi_id) -{ - unsigned int hash = napi_id % HASH_SIZE(napi_hash); - struct napi_struct *napi; - - hlist_for_each_entry_rcu(napi, &napi_hash[hash], napi_hash_node) - if (napi->napi_id == napi_id) - return napi; - - return NULL; -} - static void skb_defer_free_flush(struct softnet_data *sd) { struct sk_buff *skb, *next; diff --git a/net/core/dev.h b/net/core/dev.h index aa91eed55a40..08812a025a9b 100644 --- a/net/core/dev.h +++ b/net/core/dev.h @@ -22,6 +22,8 @@ struct sd_flow_limit { extern int netdev_flow_limit_table_len; +struct napi_struct *netdev_napi_by_id(struct net *net, unsigned int napi_id); + #ifdef CONFIG_PROC_FS int __init dev_proc_init(void); #else @@ -269,7 +271,6 @@ void xdp_do_check_flushed(struct napi_struct *napi); static inline void xdp_do_check_flushed(struct napi_struct *napi) { } #endif -struct napi_struct *napi_by_id(unsigned int napi_id); void kick_defer_list_purge(struct softnet_data *sd, unsigned int cpu); #define XMIT_RECURSION_LIMIT 8 diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c index 125b660004d3..a3bdaf075b6b 100644 --- a/net/core/netdev-genl.c +++ b/net/core/netdev-genl.c @@ -167,8 +167,6 @@ netdev_nl_napi_fill_one(struct sk_buff *rsp, struct napi_struct *napi, void *hdr; pid_t pid; - if (WARN_ON_ONCE(!napi->dev)) - return -EINVAL; if (!(napi->dev->flags & IFF_UP)) return 0; @@ -234,7 +232,7 @@ int netdev_nl_napi_get_doit(struct sk_buff *skb, struct genl_info *info) rtnl_lock(); rcu_read_lock(); - napi = napi_by_id(napi_id); + napi = netdev_napi_by_id(genl_info_net(info), napi_id); if (napi) { err = netdev_nl_napi_fill_one(rsp, napi, info); } else { @@ -355,7 +353,7 @@ int netdev_nl_napi_set_doit(struct sk_buff *skb, struct genl_info *info) rtnl_lock(); rcu_read_lock(); - napi = napi_by_id(napi_id); + napi = netdev_napi_by_id(genl_info_net(info), napi_id); if (napi) { err = netdev_nl_napi_set_config(napi, info); } else {
The NAPI IDs were not fully exposed to user space prior to the netlink API, so they were never namespaced. The netlink API must ensure that at the very least NAPI instance belongs to the same netns as the owner of the genl sock. napi_by_id() can become static now, but it needs to move because of dev_get_by_napi_id(). Cc: stable@vger.kernel.org Fixes: 1287c1ae0fc2 ("netdev-genl: Support setting per-NAPI config values") Fixes: 27f91aaf49b3 ("netdev-genl: Add netlink framework functions for napi") Signed-off-by: Jakub Kicinski <kuba@kernel.org> --- Splitting this into fix per-version is a bit tricky, because we need to replace the napi_by_id() helper with a better one. I'll send the stable versions manually. CC: jdamato@fastly.com CC: almasrymina@google.com CC: amritha.nambiar@intel.com CC: sridhar.samudrala@intel.com --- net/core/dev.c | 43 +++++++++++++++++++++++++++++------------- net/core/dev.h | 3 ++- net/core/netdev-genl.c | 6 ++---- 3 files changed, 34 insertions(+), 18 deletions(-)