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-rw-r--r--net/netlink/policy.c308
1 files changed, 308 insertions, 0 deletions
diff --git a/net/netlink/policy.c b/net/netlink/policy.c
new file mode 100644
index 000000000000..f6491853c797
--- /dev/null
+++ b/net/netlink/policy.c
@@ -0,0 +1,308 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * NETLINK Policy advertisement to userspace
+ *
+ * Authors: Johannes Berg <johannes@sipsolutions.net>
+ *
+ * Copyright 2019 Intel Corporation
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <net/netlink.h>
+
+#define INITIAL_POLICIES_ALLOC 10
+
+struct nl_policy_dump {
+ unsigned int policy_idx;
+ unsigned int attr_idx;
+ unsigned int n_alloc;
+ struct {
+ const struct nla_policy *policy;
+ unsigned int maxtype;
+ } policies[];
+};
+
+static int add_policy(struct nl_policy_dump **statep,
+ const struct nla_policy *policy,
+ unsigned int maxtype)
+{
+ struct nl_policy_dump *state = *statep;
+ unsigned int n_alloc, i;
+
+ if (!policy || !maxtype)
+ return 0;
+
+ for (i = 0; i < state->n_alloc; i++) {
+ if (state->policies[i].policy == policy)
+ return 0;
+
+ if (!state->policies[i].policy) {
+ state->policies[i].policy = policy;
+ state->policies[i].maxtype = maxtype;
+ return 0;
+ }
+ }
+
+ n_alloc = state->n_alloc + INITIAL_POLICIES_ALLOC;
+ state = krealloc(state, struct_size(state, policies, n_alloc),
+ GFP_KERNEL);
+ if (!state)
+ return -ENOMEM;
+
+ state->policies[state->n_alloc].policy = policy;
+ state->policies[state->n_alloc].maxtype = maxtype;
+ state->n_alloc = n_alloc;
+ *statep = state;
+
+ return 0;
+}
+
+static unsigned int get_policy_idx(struct nl_policy_dump *state,
+ const struct nla_policy *policy)
+{
+ unsigned int i;
+
+ for (i = 0; i < state->n_alloc; i++) {
+ if (state->policies[i].policy == policy)
+ return i;
+ }
+
+ WARN_ON_ONCE(1);
+ return -1;
+}
+
+int netlink_policy_dump_start(const struct nla_policy *policy,
+ unsigned int maxtype,
+ unsigned long *_state)
+{
+ struct nl_policy_dump *state;
+ unsigned int policy_idx;
+ int err;
+
+ /* also returns 0 if "*_state" is our ERR_PTR() end marker */
+ if (*_state)
+ return 0;
+
+ /*
+ * 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 -ENOMEM;
+ state->n_alloc = INITIAL_POLICIES_ALLOC;
+
+ err = add_policy(&state, policy, maxtype);
+ if (err)
+ return err;
+
+ for (policy_idx = 0;
+ policy_idx < state->n_alloc && state->policies[policy_idx].policy;
+ policy_idx++) {
+ const struct nla_policy *policy;
+ unsigned int type;
+
+ policy = state->policies[policy_idx].policy;
+
+ for (type = 0;
+ type <= state->policies[policy_idx].maxtype;
+ type++) {
+ switch (policy[type].type) {
+ case NLA_NESTED:
+ case NLA_NESTED_ARRAY:
+ err = add_policy(&state,
+ policy[type].nested_policy,
+ policy[type].len);
+ if (err)
+ return err;
+ break;
+ default:
+ break;
+ }
+ }
+ }
+
+ *_state = (unsigned long)state;
+
+ return 0;
+}
+
+static bool netlink_policy_dump_finished(struct nl_policy_dump *state)
+{
+ return state->policy_idx >= state->n_alloc ||
+ !state->policies[state->policy_idx].policy;
+}
+
+bool netlink_policy_dump_loop(unsigned long *_state)
+{
+ struct nl_policy_dump *state = (void *)*_state;
+
+ if (IS_ERR(state))
+ return false;
+
+ if (netlink_policy_dump_finished(state)) {
+ kfree(state);
+ /* store end marker instead of freed state */
+ *_state = (unsigned long)ERR_PTR(-ENOENT);
+ return false;
+ }
+
+ return true;
+}
+
+int netlink_policy_dump_write(struct sk_buff *skb, unsigned long _state)
+{
+ struct nl_policy_dump *state = (void *)_state;
+ const struct nla_policy *pt;
+ struct nlattr *policy, *attr;
+ enum netlink_attribute_type type;
+ bool again;
+
+send_attribute:
+ again = false;
+
+ pt = &state->policies[state->policy_idx].policy[state->attr_idx];
+
+ policy = nla_nest_start(skb, state->policy_idx);
+ if (!policy)
+ return -ENOBUFS;
+
+ attr = nla_nest_start(skb, state->attr_idx);
+ if (!attr)
+ goto nla_put_failure;
+
+ switch (pt->type) {
+ default:
+ case NLA_UNSPEC:
+ case NLA_REJECT:
+ /* skip - use NLA_MIN_LEN to advertise such */
+ nla_nest_cancel(skb, policy);
+ again = true;
+ goto next;
+ case NLA_NESTED:
+ type = NL_ATTR_TYPE_NESTED;
+ /* fall through */
+ case NLA_NESTED_ARRAY:
+ if (pt->type == NLA_NESTED_ARRAY)
+ type = NL_ATTR_TYPE_NESTED_ARRAY;
+ if (pt->nested_policy && pt->len &&
+ (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_IDX,
+ get_policy_idx(state, pt->nested_policy)) ||
+ nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_MAXTYPE,
+ pt->len)))
+ goto nla_put_failure;
+ break;
+ case NLA_U8:
+ case NLA_U16:
+ case NLA_U32:
+ case NLA_U64:
+ case NLA_MSECS: {
+ struct netlink_range_validation range;
+
+ if (pt->type == NLA_U8)
+ type = NL_ATTR_TYPE_U8;
+ else if (pt->type == NLA_U16)
+ type = NL_ATTR_TYPE_U16;
+ else if (pt->type == NLA_U32)
+ type = NL_ATTR_TYPE_U32;
+ else
+ type = NL_ATTR_TYPE_U64;
+
+ nla_get_range_unsigned(pt, &range);
+
+ if (nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MIN_VALUE_U,
+ range.min, NL_POLICY_TYPE_ATTR_PAD) ||
+ nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MAX_VALUE_U,
+ range.max, NL_POLICY_TYPE_ATTR_PAD))
+ goto nla_put_failure;
+ break;
+ }
+ case NLA_S8:
+ case NLA_S16:
+ case NLA_S32:
+ case NLA_S64: {
+ struct netlink_range_validation_signed range;
+
+ if (pt->type == NLA_S8)
+ type = NL_ATTR_TYPE_S8;
+ else if (pt->type == NLA_S16)
+ type = NL_ATTR_TYPE_S16;
+ else if (pt->type == NLA_S32)
+ type = NL_ATTR_TYPE_S32;
+ else
+ type = NL_ATTR_TYPE_S64;
+
+ nla_get_range_signed(pt, &range);
+
+ if (nla_put_s64(skb, NL_POLICY_TYPE_ATTR_MIN_VALUE_S,
+ range.min, NL_POLICY_TYPE_ATTR_PAD) ||
+ nla_put_s64(skb, NL_POLICY_TYPE_ATTR_MAX_VALUE_S,
+ range.max, NL_POLICY_TYPE_ATTR_PAD))
+ goto nla_put_failure;
+ break;
+ }
+ case NLA_BITFIELD32:
+ type = NL_ATTR_TYPE_BITFIELD32;
+ if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_BITFIELD32_MASK,
+ pt->bitfield32_valid))
+ goto nla_put_failure;
+ break;
+ case NLA_EXACT_LEN:
+ type = NL_ATTR_TYPE_BINARY;
+ if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MIN_LENGTH, pt->len) ||
+ nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MAX_LENGTH, pt->len))
+ goto nla_put_failure;
+ break;
+ case NLA_STRING:
+ case NLA_NUL_STRING:
+ case NLA_BINARY:
+ if (pt->type == NLA_STRING)
+ type = NL_ATTR_TYPE_STRING;
+ else if (pt->type == NLA_NUL_STRING)
+ type = NL_ATTR_TYPE_NUL_STRING;
+ else
+ type = NL_ATTR_TYPE_BINARY;
+ if (pt->len && nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MAX_LENGTH,
+ pt->len))
+ goto nla_put_failure;
+ break;
+ case NLA_MIN_LEN:
+ type = NL_ATTR_TYPE_BINARY;
+ if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MIN_LENGTH, pt->len))
+ goto nla_put_failure;
+ break;
+ case NLA_FLAG:
+ type = NL_ATTR_TYPE_FLAG;
+ break;
+ }
+
+ if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_TYPE, type))
+ goto nla_put_failure;
+
+ /* finish and move state to next attribute */
+ nla_nest_end(skb, attr);
+ nla_nest_end(skb, policy);
+
+next:
+ state->attr_idx += 1;
+ if (state->attr_idx > state->policies[state->policy_idx].maxtype) {
+ state->attr_idx = 0;
+ state->policy_idx++;
+ }
+
+ if (again) {
+ if (netlink_policy_dump_finished(state))
+ return -ENODATA;
+ goto send_attribute;
+ }
+
+ return 0;
+
+nla_put_failure:
+ nla_nest_cancel(skb, policy);
+ return -ENOBUFS;
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.