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