kernel: add a locking fix for netfilter hardware flow offloading

Protect the flow block cb list readers against concurrent updates

Reported-by: Chad Monroe <chad.monroe@smartrg.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/target/linux/generic/pending-5.10/706-netfilter-nf_flow_table-add-missing-locking.patch b/target/linux/generic/pending-5.10/706-netfilter-nf_flow_table-add-missing-locking.patch
new file mode 100644 (file)
index 0000000..b77d71c
--- /dev/null
+++ b/target/linux/generic/pending-5.10/706-netfilter-nf_flow_table-add-missing-locking.patch
@@ -0,0 +1,39 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 19 Nov 2022 18:48:42 +0100
+Subject: [PATCH] netfilter: nf_flow_table: add missing locking
+
+nf_flow_table_block_setup and the driver TC_SETUP_FT call can modify the flow
+block cb list while they are being traversed elsewhere, causing a crash.
+Add a write lock around the calls to protect readers
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/netfilter/nf_flow_table_offload.c
++++ b/net/netfilter/nf_flow_table_offload.c
+@@ -1015,6 +1015,7 @@ static int nf_flow_table_block_setup(str
+       struct flow_block_cb *block_cb, *next;
+       int err = 0;
+ 
++      down_write(&flowtable->flow_block_lock);
+       switch (cmd) {
+       case FLOW_BLOCK_BIND:
+               list_splice(&bo->cb_list, &flowtable->flow_block.cb_list);
+@@ -1029,6 +1030,7 @@ static int nf_flow_table_block_setup(str
+               WARN_ON_ONCE(1);
+               err = -EOPNOTSUPP;
+       }
++      up_write(&flowtable->flow_block_lock);
+ 
+       return err;
+ }
+@@ -1085,7 +1087,9 @@ static int nf_flow_table_offload_cmd(str
+ 
+       nf_flow_table_block_offload_init(bo, dev_net(dev), cmd, flowtable,
+                                        extack);
++      down_write(&flowtable->flow_block_lock);
+       err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_FT, bo);
++      up_write(&flowtable->flow_block_lock);
+       if (err < 0)
+               return err;
+ 

diff --git a/target/linux/generic/pending-5.15/701-netfilter-nf_flow_table-add-missing-locking.patch b/target/linux/generic/pending-5.15/701-netfilter-nf_flow_table-add-missing-locking.patch
new file mode 100644 (file)
index 0000000..9ff393a
--- /dev/null
+++ b/target/linux/generic/pending-5.15/701-netfilter-nf_flow_table-add-missing-locking.patch
@@ -0,0 +1,39 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 19 Nov 2022 18:48:42 +0100
+Subject: [PATCH] netfilter: nf_flow_table: add missing locking
+
+nf_flow_table_block_setup and the driver TC_SETUP_FT call can modify the flow
+block cb list while they are being traversed elsewhere, causing a crash.
+Add a write lock around the calls to protect readers
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/net/netfilter/nf_flow_table_offload.c
++++ b/net/netfilter/nf_flow_table_offload.c
+@@ -1074,6 +1074,7 @@ static int nf_flow_table_block_setup(str
+       struct flow_block_cb *block_cb, *next;
+       int err = 0;
+ 
++      down_write(&flowtable->flow_block_lock);
+       switch (cmd) {
+       case FLOW_BLOCK_BIND:
+               list_splice(&bo->cb_list, &flowtable->flow_block.cb_list);
+@@ -1088,6 +1089,7 @@ static int nf_flow_table_block_setup(str
+               WARN_ON_ONCE(1);
+               err = -EOPNOTSUPP;
+       }
++      up_write(&flowtable->flow_block_lock);
+ 
+       return err;
+ }
+@@ -1144,7 +1146,9 @@ static int nf_flow_table_offload_cmd(str
+ 
+       nf_flow_table_block_offload_init(bo, dev_net(dev), cmd, flowtable,
+                                        extack);
++      down_write(&flowtable->flow_block_lock);
+       err = dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_FT, bo);
++      up_write(&flowtable->flow_block_lock);
+       if (err < 0)
+               return err;
+