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-rw-r--r--net/netlink/policy.c479
1 files changed, 479 insertions, 0 deletions
diff --git a/net/netlink/policy.c b/net/netlink/policy.c
new file mode 100644
index 000000000..87e3de0fd
--- /dev/null
+++ b/net/netlink/policy.c
@@ -0,0 +1,479 @@
+// 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 netlink_policy_dump_state {
+ 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 netlink_policy_dump_state **statep,
+ const struct nla_policy *policy,
+ unsigned int maxtype)
+{
+ struct netlink_policy_dump_state *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 &&
+ state->policies[i].maxtype == maxtype)
+ 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;
+
+ memset(&state->policies[state->n_alloc], 0,
+ flex_array_size(state, policies, n_alloc - state->n_alloc));
+
+ state->policies[state->n_alloc].policy = policy;
+ state->policies[state->n_alloc].maxtype = maxtype;
+ state->n_alloc = n_alloc;
+ *statep = state;
+
+ return 0;
+}
+
+/**
+ * netlink_policy_dump_get_policy_idx - retrieve policy index
+ * @state: the policy dump state
+ * @policy: the policy to find
+ * @maxtype: 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)
+{
+ 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 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;
+}
+
+/**
+ * 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)
+{
+ 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.
+ */
+
+ err = add_policy(&state, policy, maxtype);
+ if (err)
+ goto err_try_undo;
+
+ 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)
+ goto err_try_undo;
+ break;
+ default:
+ break;
+ }
+ }
+ }
+
+ *pstate = state;
+ return 0;
+
+err_try_undo:
+ /* Try to preserve reasonable unwind semantics - if we're starting from
+ * scratch clean up fully, otherwise record what we got and caller will.
+ */
+ if (!*pstate)
+ netlink_policy_dump_free(state);
+ else
+ *pstate = state;
+ return err;
+}
+
+static bool
+netlink_policy_dump_finished(struct netlink_policy_dump_state *state)
+{
+ return state->policy_idx >= state->n_alloc ||
+ !state->policies[state->policy_idx].policy;
+}
+
+/**
+ * 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)
+{
+ return !netlink_policy_dump_finished(state);
+}
+
+int netlink_policy_dump_attr_size_estimate(const struct nla_policy *pt)
+{
+ /* nested + type */
+ int common = 2 * nla_attr_size(sizeof(u32));
+
+ switch (pt->type) {
+ case NLA_UNSPEC:
+ case NLA_REJECT:
+ /* these actually don't need any space */
+ return 0;
+ case NLA_NESTED:
+ case NLA_NESTED_ARRAY:
+ /* common, policy idx, policy maxattr */
+ return common + 2 * nla_attr_size(sizeof(u32));
+ case NLA_U8:
+ case NLA_U16:
+ case NLA_U32:
+ case NLA_U64:
+ case NLA_MSECS:
+ case NLA_S8:
+ case NLA_S16:
+ case NLA_S32:
+ case NLA_S64:
+ /* maximum is common, u64 min/max with padding */
+ return common +
+ 2 * (nla_attr_size(0) + nla_attr_size(sizeof(u64)));
+ case NLA_BITFIELD32:
+ return common + nla_attr_size(sizeof(u32));
+ case NLA_STRING:
+ case NLA_NUL_STRING:
+ case NLA_BINARY:
+ /* maximum is common, u32 min-length/max-length */
+ return common + 2 * nla_attr_size(sizeof(u32));
+ case NLA_FLAG:
+ return common;
+ }
+
+ /* this should then cause a warning later */
+ return 0;
+}
+
+static int
+__netlink_policy_dump_write_attr(struct netlink_policy_dump_state *state,
+ struct sk_buff *skb,
+ const struct nla_policy *pt,
+ int nestattr)
+{
+ int estimate = netlink_policy_dump_attr_size_estimate(pt);
+ enum netlink_attribute_type type;
+ struct nlattr *attr;
+
+ attr = nla_nest_start(skb, nestattr);
+ if (!attr)
+ return -ENOBUFS;
+
+ switch (pt->type) {
+ default:
+ case NLA_UNSPEC:
+ case NLA_REJECT:
+ /* skip - use NLA_MIN_LEN to advertise such */
+ nla_nest_cancel(skb, attr);
+ return -ENODATA;
+ case NLA_NESTED:
+ type = NL_ATTR_TYPE_NESTED;
+ fallthrough;
+ case NLA_NESTED_ARRAY:
+ if (pt->type == NLA_NESTED_ARRAY)
+ type = NL_ATTR_TYPE_NESTED_ARRAY;
+ if (state && pt->nested_policy && pt->len &&
+ (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_IDX,
+ netlink_policy_dump_get_policy_idx(state,
+ pt->nested_policy,
+ pt->len)) ||
+ 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;
+
+ if (pt->validation_type == NLA_VALIDATE_MASK) {
+ if (nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MASK,
+ pt->mask,
+ NL_POLICY_TYPE_ATTR_PAD))
+ goto nla_put_failure;
+ break;
+ }
+
+ 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_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->validation_type == NLA_VALIDATE_RANGE ||
+ pt->validation_type == NLA_VALIDATE_RANGE_WARN_TOO_LONG) {
+ struct netlink_range_validation range;
+
+ nla_get_range_unsigned(pt, &range);
+
+ if (range.min &&
+ nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MIN_LENGTH,
+ range.min))
+ goto nla_put_failure;
+
+ if (range.max < U16_MAX &&
+ nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MAX_LENGTH,
+ range.max))
+ goto nla_put_failure;
+ } else if (pt->len &&
+ nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MAX_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;
+
+ nla_nest_end(skb, attr);
+ WARN_ON(attr->nla_len > estimate);
+
+ return 0;
+nla_put_failure:
+ nla_nest_cancel(skb, attr);
+ return -ENOBUFS;
+}
+
+/**
+ * netlink_policy_dump_write_attr - write a given attribute policy
+ * @skb: the message skb to write to
+ * @pt: the attribute's policy
+ * @nestattr: the nested attribute ID to use
+ *
+ * Returns: 0 on success, an error code otherwise; -%ENODATA is
+ * special, indicating that there's no policy data and
+ * the attribute is generally rejected.
+ */
+int netlink_policy_dump_write_attr(struct sk_buff *skb,
+ const struct nla_policy *pt,
+ int nestattr)
+{
+ return __netlink_policy_dump_write_attr(NULL, skb, pt, nestattr);
+}
+
+/**
+ * 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)
+{
+ const struct nla_policy *pt;
+ struct nlattr *policy;
+ bool again;
+ int err;
+
+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;
+
+ err = __netlink_policy_dump_write_attr(state, skb, pt, state->attr_idx);
+ if (err == -ENODATA) {
+ nla_nest_cancel(skb, policy);
+ again = true;
+ goto next;
+ } else if (err) {
+ goto nla_put_failure;
+ }
+
+ /* finish and move state to next attribute */
+ 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;
+}
+
+/**
+ * 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)
+{
+ kfree(state);
+}
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