diff options
Diffstat (limited to 'net/netlink')
| -rw-r--r-- | net/netlink/Makefile | 2 | ||||
| -rw-r--r-- | net/netlink/attr.c | 328 |
2 files changed, 329 insertions, 1 deletions
diff --git a/net/netlink/Makefile b/net/netlink/Makefile index 39d9c2d..6817901 100644 --- a/net/netlink/Makefile +++ b/net/netlink/Makefile @@ -2,4 +2,4 @@ # Makefile for the netlink driver. # -obj-y := af_netlink.o +obj-y := af_netlink.o attr.o diff --git a/net/netlink/attr.c b/net/netlink/attr.c new file mode 100644 index 0000000..fffef4a --- /dev/null +++ b/net/netlink/attr.c @@ -0,0 +1,328 @@ +/* + * NETLINK Netlink attributes + * + * Authors: Thomas Graf <tgraf@suug.ch> + * Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> + */ + +#include <linux/config.h> +#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 u16 nla_attr_minlen[NLA_TYPE_MAX+1] __read_mostly = { + [NLA_U8] = sizeof(u8), + [NLA_U16] = sizeof(u16), + [NLA_U32] = sizeof(u32), + [NLA_U64] = sizeof(u64), + [NLA_STRING] = 1, + [NLA_NESTED] = NLA_HDRLEN, +}; + +static int validate_nla(struct nlattr *nla, int maxtype, + struct nla_policy *policy) +{ + struct nla_policy *pt; + int minlen = 0; + + if (nla->nla_type <= 0 || nla->nla_type > maxtype) + return 0; + + pt = &policy[nla->nla_type]; + + BUG_ON(pt->type > NLA_TYPE_MAX); + + if (pt->minlen) + minlen = pt->minlen; + else if (pt->type != NLA_UNSPEC) + minlen = nla_attr_minlen[pt->type]; + + if (pt->type == NLA_FLAG && nla_len(nla) > 0) + return -ERANGE; + + if (nla_len(nla) < 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(struct nlattr *head, int len, int maxtype, + struct nla_policy *policy) +{ + 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_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 + * + * Parses a stream of attributes and stores a pointer to each attribute in + * the tb array accessable 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, struct nlattr *head, int len, + struct nla_policy *policy) +{ + 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->nla_type; + + if (type > 0 && type <= maxtype) { + if (policy) { + err = validate_nla(nla, maxtype, policy); + if (err < 0) + goto errout; + } + + tb[type] = 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(struct nlattr *head, int len, int attrtype) +{ + struct nlattr *nla; + int rem; + + nla_for_each_attr(nla, head, len, rem) + if (nla->nla_type == attrtype) + return nla; + + return NULL; +} + +/** + * nla_strlcpy - Copy string attribute payload into a sized buffer + * @dst: where to copy the string to + * @src: 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, 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; +} + +/** + * __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; +} + +/** + * 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); +} + +/** + * __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); +} + + +/** + * 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 -1 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 -1; + + __nla_put(skb, attrtype, attrlen, data); + return 0; +} + + +EXPORT_SYMBOL(nla_validate); +EXPORT_SYMBOL(nla_parse); +EXPORT_SYMBOL(nla_find); +EXPORT_SYMBOL(nla_strlcpy); +EXPORT_SYMBOL(__nla_reserve); +EXPORT_SYMBOL(nla_reserve); +EXPORT_SYMBOL(__nla_put); +EXPORT_SYMBOL(nla_put); +EXPORT_SYMBOL(nla_memcpy); +EXPORT_SYMBOL(nla_memcmp); +EXPORT_SYMBOL(nla_strcmp); |