diff --git a/include/net/netlink.h b/include/net/netlink.h index 557b67f1db99..c0411f14fb53 100644 --- a/include/net/netlink.h +++ b/include/net/netlink.h @@ -1933,4 +1933,10 @@ void nla_get_range_unsigned(const struct nla_policy *pt, void nla_get_range_signed(const struct nla_policy *pt, struct netlink_range_validation_signed *range); +int netlink_policy_dump_start(const struct nla_policy *policy, + unsigned int maxtype, + unsigned long *state); +bool netlink_policy_dump_loop(unsigned long *state); +int netlink_policy_dump_write(struct sk_buff *skb, unsigned long state); + #endif diff --git a/include/uapi/linux/genetlink.h b/include/uapi/linux/genetlink.h index 877f7fa95466..9c0636ec2286 100644 --- a/include/uapi/linux/genetlink.h +++ b/include/uapi/linux/genetlink.h @@ -48,6 +48,7 @@ enum { CTRL_CMD_NEWMCAST_GRP, CTRL_CMD_DELMCAST_GRP, CTRL_CMD_GETMCAST_GRP, /* unused */ + CTRL_CMD_GETPOLICY, __CTRL_CMD_MAX, }; @@ -62,6 +63,7 @@ enum { CTRL_ATTR_MAXATTR, CTRL_ATTR_OPS, CTRL_ATTR_MCAST_GROUPS, + CTRL_ATTR_POLICY, __CTRL_ATTR_MAX, }; diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h index 0a4d73317759..eac8a6a648ea 100644 --- a/include/uapi/linux/netlink.h +++ b/include/uapi/linux/netlink.h @@ -249,4 +249,107 @@ struct nla_bitfield32 { __u32 selector; }; +/* + * policy descriptions - it's specific to each family how this is used + * Normally, it should be retrieved via a dump inside another attribute + * specifying where it applies. + */ + +/** + * enum netlink_attribute_type - type of an attribute + * @NL_ATTR_TYPE_INVALID: unused + * @NL_ATTR_TYPE_FLAG: flag attribute (present/not present) + * @NL_ATTR_TYPE_U8: 8-bit unsigned attribute + * @NL_ATTR_TYPE_U16: 16-bit unsigned attribute + * @NL_ATTR_TYPE_U32: 32-bit unsigned attribute + * @NL_ATTR_TYPE_U64: 64-bit unsigned attribute + * @NL_ATTR_TYPE_S8: 8-bit signed attribute + * @NL_ATTR_TYPE_S16: 16-bit signed attribute + * @NL_ATTR_TYPE_S32: 32-bit signed attribute + * @NL_ATTR_TYPE_S64: 64-bit signed attribute + * @NL_ATTR_TYPE_BINARY: binary data, min/max length may be specified + * @NL_ATTR_TYPE_STRING: string, min/max length may be specified + * @NL_ATTR_TYPE_NUL_STRING: NUL-terminated string, + * min/max length may be specified + * @NL_ATTR_TYPE_NESTED: nested, i.e. the content of this attribute + * consists of sub-attributes. The nested policy and maxtype + * inside may be specified. + * @NL_ATTR_TYPE_NESTED_ARRAY: nested array, i.e. the content of this + * attribute contains sub-attributes whose type is irrelevant + * (just used to separate the array entries) and each such array + * entry has attributes again, the policy for those inner ones + * and the corresponding maxtype may be specified. + * @NL_ATTR_TYPE_BITFIELD32: &struct nla_bitfield32 attribute + */ +enum netlink_attribute_type { + NL_ATTR_TYPE_INVALID, + + NL_ATTR_TYPE_FLAG, + + NL_ATTR_TYPE_U8, + NL_ATTR_TYPE_U16, + NL_ATTR_TYPE_U32, + NL_ATTR_TYPE_U64, + + NL_ATTR_TYPE_S8, + NL_ATTR_TYPE_S16, + NL_ATTR_TYPE_S32, + NL_ATTR_TYPE_S64, + + NL_ATTR_TYPE_BINARY, + NL_ATTR_TYPE_STRING, + NL_ATTR_TYPE_NUL_STRING, + + NL_ATTR_TYPE_NESTED, + NL_ATTR_TYPE_NESTED_ARRAY, + + NL_ATTR_TYPE_BITFIELD32, +}; + +/** + * enum netlink_policy_type_attr - policy type attributes + * @NL_POLICY_TYPE_ATTR_UNSPEC: unused + * @NL_POLICY_TYPE_ATTR_TYPE: type of the attribute, + * &enum netlink_attribute_type (U32) + * @NL_POLICY_TYPE_ATTR_MIN_VALUE_S: minimum value for signed + * integers (S64) + * @NL_POLICY_TYPE_ATTR_MAX_VALUE_S: maximum value for signed + * integers (S64) + * @NL_POLICY_TYPE_ATTR_MIN_VALUE_U: minimum value for unsigned + * integers (U64) + * @NL_POLICY_TYPE_ATTR_MAX_VALUE_U: maximum value for unsigned + * integers (U64) + * @NL_POLICY_TYPE_ATTR_MIN_LENGTH: minimum length for binary + * attributes, no minimum if not given (U32) + * @NL_POLICY_TYPE_ATTR_MAX_LENGTH: maximum length for binary + * attributes, no maximum if not given (U32) + * @NL_POLICY_TYPE_ATTR_POLICY_IDX: sub policy for nested and + * nested array types (U32) + * @NL_POLICY_TYPE_ATTR_POLICY_MAXTYPE: maximum sub policy + * attribute for nested and nested array types, this can + * in theory be < the size of the policy pointed to by + * the index, if limited inside the nesting (U32) + * @NL_POLICY_TYPE_ATTR_BITFIELD32_MASK: valid mask for the + * bitfield32 type (U32) + * @NL_POLICY_TYPE_ATTR_PAD: pad attribute for 64-bit alignment + */ +enum netlink_policy_type_attr { + NL_POLICY_TYPE_ATTR_UNSPEC, + NL_POLICY_TYPE_ATTR_TYPE, + NL_POLICY_TYPE_ATTR_MIN_VALUE_S, + NL_POLICY_TYPE_ATTR_MAX_VALUE_S, + NL_POLICY_TYPE_ATTR_MIN_VALUE_U, + NL_POLICY_TYPE_ATTR_MAX_VALUE_U, + NL_POLICY_TYPE_ATTR_MIN_LENGTH, + NL_POLICY_TYPE_ATTR_MAX_LENGTH, + NL_POLICY_TYPE_ATTR_POLICY_IDX, + NL_POLICY_TYPE_ATTR_POLICY_MAXTYPE, + NL_POLICY_TYPE_ATTR_BITFIELD32_MASK, + NL_POLICY_TYPE_ATTR_PAD, + + /* keep last */ + __NL_POLICY_TYPE_ATTR_MAX, + NL_POLICY_TYPE_ATTR_MAX = __NL_POLICY_TYPE_ATTR_MAX - 1 +}; + #endif /* _UAPI__LINUX_NETLINK_H */ diff --git a/net/netlink/Makefile b/net/netlink/Makefile index de42df7f0068..e05202708c90 100644 --- a/net/netlink/Makefile +++ b/net/netlink/Makefile @@ -3,7 +3,7 @@ # Makefile for the netlink driver. # -obj-y := af_netlink.o genetlink.o +obj-y := af_netlink.o genetlink.o policy.o obj-$(CONFIG_NETLINK_DIAG) += netlink_diag.o netlink_diag-y := diag.o diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c index 9f357aa22b94..2f049692e012 100644 --- a/net/netlink/genetlink.c +++ b/net/netlink/genetlink.c @@ -1043,6 +1043,80 @@ static int genl_ctrl_event(int event, const struct genl_family *family, return 0; } +static int ctrl_dumppolicy(struct sk_buff *skb, struct netlink_callback *cb) +{ + const struct genl_family *rt; + unsigned int fam_id = cb->args[0]; + int err; + + if (!fam_id) { + struct nlattr *tb[CTRL_ATTR_MAX + 1]; + + err = genlmsg_parse(cb->nlh, &genl_ctrl, tb, + genl_ctrl.maxattr, + genl_ctrl.policy, cb->extack); + if (err) + return err; + + if (!tb[CTRL_ATTR_FAMILY_ID] && !tb[CTRL_ATTR_FAMILY_NAME]) + return -EINVAL; + + if (tb[CTRL_ATTR_FAMILY_ID]) { + fam_id = nla_get_u16(tb[CTRL_ATTR_FAMILY_ID]); + } else { + rt = genl_family_find_byname( + nla_data(tb[CTRL_ATTR_FAMILY_NAME])); + if (!rt) + return -ENOENT; + fam_id = rt->id; + } + } + + rt = genl_family_find_byid(fam_id); + if (!rt) + return -ENOENT; + + if (!rt->policy) + return -ENODATA; + + err = netlink_policy_dump_start(rt->policy, rt->maxattr, &cb->args[1]); + if (err) + return err; + + while (netlink_policy_dump_loop(&cb->args[1])) { + void *hdr; + struct nlattr *nest; + + hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, + cb->nlh->nlmsg_seq, &genl_ctrl, + NLM_F_MULTI, CTRL_CMD_GETPOLICY); + if (!hdr) + goto nla_put_failure; + + if (nla_put_u16(skb, CTRL_ATTR_FAMILY_ID, rt->id)) + goto nla_put_failure; + + nest = nla_nest_start(skb, CTRL_ATTR_POLICY); + if (!nest) + goto nla_put_failure; + + if (netlink_policy_dump_write(skb, cb->args[1])) + goto nla_put_failure; + + nla_nest_end(skb, nest); + + genlmsg_end(skb, hdr); + continue; + +nla_put_failure: + genlmsg_cancel(skb, hdr); + break; + } + + cb->args[0] = fam_id; + return skb->len; +} + static const struct genl_ops genl_ctrl_ops[] = { { .cmd = CTRL_CMD_GETFAMILY, @@ -1050,6 +1124,10 @@ static const struct genl_ops genl_ctrl_ops[] = { .doit = ctrl_getfamily, .dumpit = ctrl_dumpfamily, }, + { + .cmd = CTRL_CMD_GETPOLICY, + .dumpit = ctrl_dumppolicy, + }, }; static const struct genl_multicast_group genl_ctrl_groups[] = { 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 + * + * Copyright 2019 Intel Corporation + */ + +#include +#include +#include +#include + +#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; +}