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Date: Fri, 2 Oct 2020 11:09:42 +0200
From: Johannes Berg <johannes@...solutions.net>
To: netdev@...r.kernel.org
Cc: Jakub Kicinski <kuba@...nel.org>,
Johannes Berg <johannes.berg@...el.com>
Subject: [PATCH 3/5] netlink: rework policy dump to support multiple policies
From: Johannes Berg <johannes.berg@...el.com>
Rework the policy dump code a bit to support adding multiple
policies to a single dump, in order to e.g. support per-op
policies in generic netlink.
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
---
include/net/netlink.h | 62 +++++++++++++++++++++++++++++++++++++++--
net/netlink/genetlink.c | 6 ++--
net/netlink/policy.c | 57 +++++++++++++++++++++++++++++--------
3 files changed, 106 insertions(+), 19 deletions(-)
diff --git a/include/net/netlink.h b/include/net/netlink.h
index 4be0ad237e57..a929759a03f5 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -1937,12 +1937,68 @@ void nla_get_range_signed(const struct nla_policy *pt,
struct netlink_policy_dump_state;
-struct netlink_policy_dump_state *
-netlink_policy_dump_start(const struct nla_policy *policy,
- unsigned int maxtype);
+/**
+ * netlink_policy_dump_add_policy - add a policy to the dump
+ * @pstate: state to add to, may be reallocated, must be %NULL the first time
+ * @policy: the new policy to add to the dump
+ * @maxtype: the new policy's max attr type
+ *
+ * Returns: 0 on success, a negative error code otherwise.
+ *
+ * Call this to allocate a policy dump state, and to add policies to it. This
+ * should be called from the dump start() callback.
+ *
+ * Note: on failures, any previously allocated state is freed.
+ */
+int netlink_policy_dump_add_policy(struct netlink_policy_dump_state **pstate,
+ const struct nla_policy *policy,
+ unsigned int maxtype);
+
+/**
+ * netlink_policy_dump_get_policy_idx - retrieve policy index
+ * @state: the policy dump state
+ * @policy: the policy to find
+ * @maxattr: the policy's maxattr
+ *
+ * Returns: the index of the given policy in the dump state
+ *
+ * Call this to find a policy index when you've added multiple and e.g.
+ * need to tell userspace which command has which policy (by index).
+ *
+ * Note: this will WARN and return 0 if the policy isn't found, which
+ * means it wasn't added in the first place, which would be an
+ * internal consistency bug.
+ */
+int netlink_policy_dump_get_policy_idx(struct netlink_policy_dump_state *state,
+ const struct nla_policy *policy,
+ unsigned int maxtype);
+
+/**
+ * netlink_policy_dump_loop - dumping loop indicator
+ * @state: the policy dump state
+ *
+ * Returns: %true if the dump continues, %false otherwise
+ *
+ * Note: this frees the dump state when finishing
+ */
bool netlink_policy_dump_loop(struct netlink_policy_dump_state *state);
+
+/**
+ * netlink_policy_dump_write - write current policy dump attributes
+ * @skb: the message skb to write to
+ * @state: the policy dump state
+ *
+ * Returns: 0 on success, an error code otherwise
+ */
int netlink_policy_dump_write(struct sk_buff *skb,
struct netlink_policy_dump_state *state);
+
+/**
+ * netlink_policy_dump_free - free policy dump state
+ * @state: the policy dump state to free
+ *
+ * Call this from the done() method to ensure dump state is freed.
+ */
void netlink_policy_dump_free(struct netlink_policy_dump_state *state);
#endif
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 537472342781..42777749d4d8 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1164,10 +1164,8 @@ static int ctrl_dumppolicy_start(struct netlink_callback *cb)
if (!op.policy)
return -ENODATA;
- ctx->state = netlink_policy_dump_start(op.policy, op.maxattr);
- if (IS_ERR(ctx->state))
- return PTR_ERR(ctx->state);
- return 0;
+ return netlink_policy_dump_add_policy(&ctx->state, op.policy,
+ op.maxattr);
}
static int ctrl_dumppolicy(struct sk_buff *skb, struct netlink_callback *cb)
diff --git a/net/netlink/policy.c b/net/netlink/policy.c
index 7bc8f81ecc43..d930064cbaf3 100644
--- a/net/netlink/policy.c
+++ b/net/netlink/policy.c
@@ -77,28 +77,41 @@ static unsigned int get_policy_idx(struct netlink_policy_dump_state *state,
return -1;
}
-struct netlink_policy_dump_state *
-netlink_policy_dump_start(const struct nla_policy *policy,
- unsigned int maxtype)
+static struct netlink_policy_dump_state *alloc_state(void)
{
struct netlink_policy_dump_state *state;
+
+ state = kzalloc(struct_size(state, policies, INITIAL_POLICIES_ALLOC),
+ GFP_KERNEL);
+ if (!state)
+ return ERR_PTR(-ENOMEM);
+ state->n_alloc = INITIAL_POLICIES_ALLOC;
+
+ return state;
+}
+
+int netlink_policy_dump_add_policy(struct netlink_policy_dump_state **pstate,
+ const struct nla_policy *policy,
+ unsigned int maxtype)
+{
+ struct netlink_policy_dump_state *state = *pstate;
unsigned int policy_idx;
int err;
+ if (!state) {
+ state = alloc_state();
+ if (IS_ERR(state))
+ return PTR_ERR(state);
+ }
+
/*
* walk the policies and nested ones first, and build
* a linear list of them.
*/
- state = kzalloc(struct_size(state, policies, INITIAL_POLICIES_ALLOC),
- GFP_KERNEL);
- if (!state)
- return ERR_PTR(-ENOMEM);
- state->n_alloc = INITIAL_POLICIES_ALLOC;
-
err = add_policy(&state, policy, maxtype);
if (err)
- return ERR_PTR(err);
+ return err;
for (policy_idx = 0;
policy_idx < state->n_alloc && state->policies[policy_idx].policy;
@@ -118,7 +131,7 @@ netlink_policy_dump_start(const struct nla_policy *policy,
policy[type].nested_policy,
policy[type].len);
if (err)
- return ERR_PTR(err);
+ return err;
break;
default:
break;
@@ -126,7 +139,27 @@ netlink_policy_dump_start(const struct nla_policy *policy,
}
}
- return state;
+ *pstate = state;
+ return 0;
+}
+
+int netlink_policy_dump_get_policy_idx(struct netlink_policy_dump_state *state,
+ const struct nla_policy *policy,
+ unsigned int maxtype)
+{
+ unsigned int i;
+
+ if (WARN_ON(!policy || !maxtype))
+ return 0;
+
+ for (i = 0; i < state->n_alloc; i++) {
+ if (state->policies[i].policy == policy &&
+ state->policies[i].maxtype == maxtype)
+ return i;
+ }
+
+ WARN_ON(1);
+ return 0;
}
static bool
--
2.26.2
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