503 lines
12 KiB
C
503 lines
12 KiB
C
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/*
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* NETLINK Netlink attributes
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*
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* Authors: Thomas Graf <tgraf@suug.ch>
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* Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/jiffies.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <net/netlink.h>
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static u16 nla_attr_minlen[NLA_TYPE_MAX+1] __read_mostly = {
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[NLA_U8] = sizeof(u8),
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[NLA_U16] = sizeof(u16),
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[NLA_U32] = sizeof(u32),
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[NLA_U64] = sizeof(u64),
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[NLA_NESTED] = NLA_HDRLEN,
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};
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static int validate_nla(struct nlattr *nla, int maxtype,
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const struct nla_policy *policy)
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{
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const struct nla_policy *pt;
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int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
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if (type <= 0 || type > maxtype)
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return 0;
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pt = &policy[type];
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BUG_ON(pt->type > NLA_TYPE_MAX);
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switch (pt->type) {
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case NLA_FLAG:
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if (attrlen > 0)
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return -ERANGE;
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break;
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case NLA_NUL_STRING:
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if (pt->len)
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minlen = min_t(int, attrlen, pt->len + 1);
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else
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minlen = attrlen;
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if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL)
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return -EINVAL;
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/* fall through */
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case NLA_STRING:
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if (attrlen < 1)
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return -ERANGE;
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if (pt->len) {
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char *buf = nla_data(nla);
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if (buf[attrlen - 1] == '\0')
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attrlen--;
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if (attrlen > pt->len)
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return -ERANGE;
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}
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break;
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case NLA_BINARY:
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if (pt->len && attrlen > pt->len)
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return -ERANGE;
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break;
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case NLA_NESTED_COMPAT:
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if (attrlen < pt->len)
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return -ERANGE;
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if (attrlen < NLA_ALIGN(pt->len))
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break;
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if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN)
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return -ERANGE;
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nla = nla_data(nla) + NLA_ALIGN(pt->len);
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if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla))
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return -ERANGE;
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break;
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case NLA_NESTED:
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/* a nested attributes is allowed to be empty; if its not,
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* it must have a size of at least NLA_HDRLEN.
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*/
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if (attrlen == 0)
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break;
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default:
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if (pt->len)
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minlen = pt->len;
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else if (pt->type != NLA_UNSPEC)
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minlen = nla_attr_minlen[pt->type];
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if (attrlen < minlen)
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return -ERANGE;
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}
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return 0;
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}
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/**
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* nla_validate - Validate a stream of attributes
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* @head: head of attribute stream
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* @len: length of attribute stream
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* @maxtype: maximum attribute type to be expected
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* @policy: validation policy
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*
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* Validates all attributes in the specified attribute stream against the
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* specified policy. Attributes with a type exceeding maxtype will be
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* ignored. See documenation of struct nla_policy for more details.
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*
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* Returns 0 on success or a negative error code.
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*/
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int nla_validate(struct nlattr *head, int len, int maxtype,
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const struct nla_policy *policy)
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{
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struct nlattr *nla;
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int rem, err;
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nla_for_each_attr(nla, head, len, rem) {
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err = validate_nla(nla, maxtype, policy);
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if (err < 0)
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goto errout;
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}
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err = 0;
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errout:
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return err;
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}
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/**
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* nla_policy_len - Determin the max. length of a policy
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* @policy: policy to use
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* @n: number of policies
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*
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* Determines the max. length of the policy. It is currently used
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* to allocated Netlink buffers roughly the size of the actual
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* message.
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*
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* Returns 0 on success or a negative error code.
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*/
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int
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nla_policy_len(const struct nla_policy *p, int n)
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{
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int i, len = 0;
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for (i = 0; i < n; i++) {
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if (p->len)
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len += nla_total_size(p->len);
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else if (nla_attr_minlen[p->type])
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len += nla_total_size(nla_attr_minlen[p->type]);
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}
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return len;
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}
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/**
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* nla_parse - Parse a stream of attributes into a tb buffer
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* @tb: destination array with maxtype+1 elements
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* @maxtype: maximum attribute type to be expected
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* @head: head of attribute stream
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* @len: length of attribute stream
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* @policy: validation policy
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*
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* Parses a stream of attributes and stores a pointer to each attribute in
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* the tb array accessable via the attribute type. Attributes with a type
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* exceeding maxtype will be silently ignored for backwards compatibility
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* reasons. policy may be set to NULL if no validation is required.
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*
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* Returns 0 on success or a negative error code.
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*/
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int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len,
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const struct nla_policy *policy)
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{
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struct nlattr *nla;
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int rem, err;
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memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
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nla_for_each_attr(nla, head, len, rem) {
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u16 type = nla_type(nla);
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if (type > 0 && type <= maxtype) {
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if (policy) {
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err = validate_nla(nla, maxtype, policy);
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if (err < 0)
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goto errout;
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}
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tb[type] = nla;
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}
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}
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if (unlikely(rem > 0))
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printk(KERN_WARNING "netlink: %d bytes leftover after parsing "
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"attributes.\n", rem);
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err = 0;
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errout:
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return err;
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}
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/**
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* nla_find - Find a specific attribute in a stream of attributes
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* @head: head of attribute stream
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* @len: length of attribute stream
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* @attrtype: type of attribute to look for
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*
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* Returns the first attribute in the stream matching the specified type.
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*/
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struct nlattr *nla_find(struct nlattr *head, int len, int attrtype)
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{
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struct nlattr *nla;
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int rem;
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nla_for_each_attr(nla, head, len, rem)
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if (nla_type(nla) == attrtype)
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return nla;
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return NULL;
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}
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/**
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* nla_strlcpy - Copy string attribute payload into a sized buffer
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* @dst: where to copy the string to
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* @nla: attribute to copy the string from
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* @dstsize: size of destination buffer
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*
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* Copies at most dstsize - 1 bytes into the destination buffer.
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* The result is always a valid NUL-terminated string. Unlike
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* strlcpy the destination buffer is always padded out.
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*
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* Returns the length of the source buffer.
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*/
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size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
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{
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size_t srclen = nla_len(nla);
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char *src = nla_data(nla);
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if (srclen > 0 && src[srclen - 1] == '\0')
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srclen--;
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if (dstsize > 0) {
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size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
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memset(dst, 0, dstsize);
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memcpy(dst, src, len);
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}
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return srclen;
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}
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/**
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* nla_memcpy - Copy a netlink attribute into another memory area
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* @dest: where to copy to memcpy
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* @src: netlink attribute to copy from
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* @count: size of the destination area
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*
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* Note: The number of bytes copied is limited by the length of
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* attribute's payload. memcpy
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*
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* Returns the number of bytes copied.
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*/
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int nla_memcpy(void *dest, const struct nlattr *src, int count)
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{
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int minlen = min_t(int, count, nla_len(src));
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memcpy(dest, nla_data(src), minlen);
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return minlen;
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}
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/**
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* nla_memcmp - Compare an attribute with sized memory area
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* @nla: netlink attribute
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* @data: memory area
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* @size: size of memory area
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*/
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int nla_memcmp(const struct nlattr *nla, const void *data,
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size_t size)
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{
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int d = nla_len(nla) - size;
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if (d == 0)
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d = memcmp(nla_data(nla), data, size);
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return d;
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}
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/**
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* nla_strcmp - Compare a string attribute against a string
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* @nla: netlink string attribute
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* @str: another string
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*/
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int nla_strcmp(const struct nlattr *nla, const char *str)
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{
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int len = strlen(str) + 1;
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int d = nla_len(nla) - len;
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if (d == 0)
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d = memcmp(nla_data(nla), str, len);
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return d;
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}
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#ifdef CONFIG_NET
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/**
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* __nla_reserve - reserve room for attribute on the skb
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* @skb: socket buffer to reserve room on
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* @attrtype: attribute type
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* @attrlen: length of attribute payload
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*
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* Adds a netlink attribute header to a socket buffer and reserves
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* room for the payload but does not copy it.
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*
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* The caller is responsible to ensure that the skb provides enough
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* tailroom for the attribute header and payload.
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*/
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struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
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{
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struct nlattr *nla;
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nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen));
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nla->nla_type = attrtype;
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nla->nla_len = nla_attr_size(attrlen);
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memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));
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return nla;
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}
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EXPORT_SYMBOL(__nla_reserve);
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/**
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* __nla_reserve_nohdr - reserve room for attribute without header
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* @skb: socket buffer to reserve room on
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* @attrlen: length of attribute payload
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*
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* Reserves room for attribute payload without a header.
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*
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* The caller is responsible to ensure that the skb provides enough
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* tailroom for the payload.
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*/
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void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
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{
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void *start;
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start = skb_put(skb, NLA_ALIGN(attrlen));
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memset(start, 0, NLA_ALIGN(attrlen));
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return start;
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}
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EXPORT_SYMBOL(__nla_reserve_nohdr);
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/**
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* nla_reserve - reserve room for attribute on the skb
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* @skb: socket buffer to reserve room on
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* @attrtype: attribute type
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* @attrlen: length of attribute payload
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*
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* Adds a netlink attribute header to a socket buffer and reserves
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* room for the payload but does not copy it.
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*
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* Returns NULL if the tailroom of the skb is insufficient to store
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* the attribute header and payload.
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*/
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struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)
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{
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if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
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return NULL;
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return __nla_reserve(skb, attrtype, attrlen);
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}
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EXPORT_SYMBOL(nla_reserve);
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/**
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* nla_reserve_nohdr - reserve room for attribute without header
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* @skb: socket buffer to reserve room on
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* @attrlen: length of attribute payload
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*
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* Reserves room for attribute payload without a header.
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*
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* Returns NULL if the tailroom of the skb is insufficient to store
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* the attribute payload.
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*/
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|
|
void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)
|
||
|
|
{
|
||
|
|
if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
|
||
|
|
return NULL;
|
||
|
|
|
||
|
|
return __nla_reserve_nohdr(skb, attrlen);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL(nla_reserve_nohdr);
|
||
|
|
|
||
|
|
/**
|
||
|
|
* __nla_put - Add a netlink attribute to a socket buffer
|
||
|
|
* @skb: socket buffer to add attribute to
|
||
|
|
* @attrtype: attribute type
|
||
|
|
* @attrlen: length of attribute payload
|
||
|
|
* @data: head of attribute payload
|
||
|
|
*
|
||
|
|
* The caller is responsible to ensure that the skb provides enough
|
||
|
|
* tailroom for the attribute header and payload.
|
||
|
|
*/
|
||
|
|
void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
|
||
|
|
const void *data)
|
||
|
|
{
|
||
|
|
struct nlattr *nla;
|
||
|
|
|
||
|
|
nla = __nla_reserve(skb, attrtype, attrlen);
|
||
|
|
memcpy(nla_data(nla), data, attrlen);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL(__nla_put);
|
||
|
|
|
||
|
|
/**
|
||
|
|
* __nla_put_nohdr - Add a netlink attribute without header
|
||
|
|
* @skb: socket buffer to add attribute to
|
||
|
|
* @attrlen: length of attribute payload
|
||
|
|
* @data: head of attribute payload
|
||
|
|
*
|
||
|
|
* The caller is responsible to ensure that the skb provides enough
|
||
|
|
* tailroom for the attribute payload.
|
||
|
|
*/
|
||
|
|
void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
|
||
|
|
{
|
||
|
|
void *start;
|
||
|
|
|
||
|
|
start = __nla_reserve_nohdr(skb, attrlen);
|
||
|
|
memcpy(start, data, attrlen);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL(__nla_put_nohdr);
|
||
|
|
|
||
|
|
/**
|
||
|
|
* nla_put - Add a netlink attribute to a socket buffer
|
||
|
|
* @skb: socket buffer to add attribute to
|
||
|
|
* @attrtype: attribute type
|
||
|
|
* @attrlen: length of attribute payload
|
||
|
|
* @data: head of attribute payload
|
||
|
|
*
|
||
|
|
* Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
|
||
|
|
* the attribute header and payload.
|
||
|
|
*/
|
||
|
|
int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
|
||
|
|
{
|
||
|
|
if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
|
||
|
|
return -EMSGSIZE;
|
||
|
|
|
||
|
|
__nla_put(skb, attrtype, attrlen, data);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL(nla_put);
|
||
|
|
|
||
|
|
/**
|
||
|
|
* nla_put_nohdr - Add a netlink attribute without header
|
||
|
|
* @skb: socket buffer to add attribute to
|
||
|
|
* @attrlen: length of attribute payload
|
||
|
|
* @data: head of attribute payload
|
||
|
|
*
|
||
|
|
* Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
|
||
|
|
* the attribute payload.
|
||
|
|
*/
|
||
|
|
int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)
|
||
|
|
{
|
||
|
|
if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
|
||
|
|
return -EMSGSIZE;
|
||
|
|
|
||
|
|
__nla_put_nohdr(skb, attrlen, data);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL(nla_put_nohdr);
|
||
|
|
|
||
|
|
/**
|
||
|
|
* nla_append - Add a netlink attribute without header or padding
|
||
|
|
* @skb: socket buffer to add attribute to
|
||
|
|
* @attrlen: length of attribute payload
|
||
|
|
* @data: head of attribute payload
|
||
|
|
*
|
||
|
|
* Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
|
||
|
|
* the attribute payload.
|
||
|
|
*/
|
||
|
|
int nla_append(struct sk_buff *skb, int attrlen, const void *data)
|
||
|
|
{
|
||
|
|
if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
|
||
|
|
return -EMSGSIZE;
|
||
|
|
|
||
|
|
memcpy(skb_put(skb, attrlen), data, attrlen);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL(nla_append);
|
||
|
|
#endif
|
||
|
|
|
||
|
|
EXPORT_SYMBOL(nla_validate);
|
||
|
|
EXPORT_SYMBOL(nla_policy_len);
|
||
|
|
EXPORT_SYMBOL(nla_parse);
|
||
|
|
EXPORT_SYMBOL(nla_find);
|
||
|
|
EXPORT_SYMBOL(nla_strlcpy);
|
||
|
|
EXPORT_SYMBOL(nla_memcpy);
|
||
|
|
EXPORT_SYMBOL(nla_memcmp);
|
||
|
|
EXPORT_SYMBOL(nla_strcmp);
|