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Diffstat (limited to 'package/libnl-tiny/src/attr.c')
| -rw-r--r-- | package/libnl-tiny/src/attr.c | 668 |
1 files changed, 0 insertions, 668 deletions
diff --git a/package/libnl-tiny/src/attr.c b/package/libnl-tiny/src/attr.c deleted file mode 100644 index e0f50611cf..0000000000 --- a/package/libnl-tiny/src/attr.c +++ /dev/null @@ -1,668 +0,0 @@ -/* - * lib/attr.c Netlink Attributes - * - * This library is free software; you can redistribute it and/or - * modify it under the terms of the GNU Lesser General Public - * License as published by the Free Software Foundation version 2.1 - * of the License. - * - * Copyright (c) 2003-2008 Thomas Graf <tgraf@suug.ch> - */ - -#include <netlink-local.h> -#include <netlink/netlink.h> -#include <netlink/utils.h> -#include <netlink/addr.h> -#include <netlink/attr.h> -#include <netlink/msg.h> -#include <linux/socket.h> - -/** - * @ingroup msg - * @defgroup attr Attributes - * Netlink Attributes Construction/Parsing Interface - * - * \section attr_sec Netlink Attributes - * Netlink attributes allow for data chunks of arbitary length to be - * attached to a netlink message. Each attribute is encoded with a - * type and length field, both 16 bits, stored in the attribute header - * preceding the attribute data. The main advantage of using attributes - * over packing everything into the family header is that the interface - * stays extendable as new attributes can supersede old attributes while - * remaining backwards compatible. Also attributes can be defined optional - * thus avoiding the transmission of unnecessary empty data blocks. - * Special nested attributes allow for more complex data structures to - * be transmitted, e.g. trees, lists, etc. - * - * While not required, netlink attributes typically follow the family - * header of a netlink message and must be properly aligned to NLA_ALIGNTO: - * @code - * +----------------+- - -+---------------+- - -+------------+- - -+ - * | Netlink Header | Pad | Family Header | Pad | Attributes | Pad | - * +----------------+- - -+---------------+- - -+------------+- - -+ - * @endcode - * - * The actual attributes are chained together each separately aligned to - * NLA_ALIGNTO. The position of an attribute is defined based on the - * length field of the preceding attributes: - * @code - * +-------------+- - -+-------------+- - -+------ - * | Attribute 1 | Pad | Attribute 2 | Pad | ... - * +-------------+- - -+-------------+- - -+------ - * nla_next(attr1)------^ - * @endcode - * - * The attribute itself consists of the attribute header followed by - * the actual payload also aligned to NLA_ALIGNTO. The function nla_data() - * returns a pointer to the start of the payload while nla_len() returns - * the length of the payload in bytes. - * - * \b Note: Be aware, NLA_ALIGNTO equals to 4 bytes, therefore it is not - * safe to dereference any 64 bit data types directly. - * - * @code - * <----------- nla_total_size(payload) -----------> - * <-------- nla_attr_size(payload) ---------> - * +------------------+- - -+- - - - - - - - - +- - -+ - * | Attribute Header | Pad | Payload | Pad | - * +------------------+- - -+- - - - - - - - - +- - -+ - * nla_data(nla)-------------^ - * <- nla_len(nla) -> - * @endcode - * - * @subsection attr_datatypes Attribute Data Types - * A number of basic data types are supported to simplify access and - * validation of netlink attributes. This data type information is - * not encoded in the attribute, both the kernel and userspace part - * are required to share this information on their own. - * - * One of the major advantages of these basic types is the automatic - * validation of each attribute based on an attribute policy. The - * validation covers most of the checks required to safely use - * attributes and thus keeps the individual sanity check to a minimum. - * - * Never access attribute payload without ensuring basic validation - * first, attributes may: - * - not be present even though required - * - contain less actual payload than expected - * - fake a attribute length which exceeds the end of the message - * - contain unterminated character strings - * - * Policies are defined as array of the struct nla_policy. The array is - * indexed with the attribute type, therefore the array must be sized - * accordingly. - * @code - * static struct nla_policy my_policy[ATTR_MAX+1] = { - * [ATTR_FOO] = { .type = ..., .minlen = ..., .maxlen = ... }, - * }; - * - * err = nla_validate(attrs, attrlen, ATTR_MAX, &my_policy); - * @endcode - * - * Some basic validations are performed on every attribute, regardless of type. - * - If the attribute type exceeds the maximum attribute type specified or - * the attribute type is lesser-or-equal than zero, the attribute will - * be silently ignored. - * - If the payload length falls below the \a minlen value the attribute - * will be rejected. - * - If \a maxlen is non-zero and the payload length exceeds the \a maxlen - * value the attribute will be rejected. - * - * - * @par Unspecific Attribute (NLA_UNSPEC) - * This is the standard type if no type is specified. It is used for - * binary data of arbitary length. Typically this attribute carries - * a binary structure or a stream of bytes. - * @par - * @code - * // In this example, we will assume a binary structure requires to - * // be transmitted. The definition of the structure will typically - * // go into a header file available to both the kernel and userspace - * // side. - * // - * // Note: Be careful when putting 64 bit data types into a structure. - * // The attribute payload is only aligned to 4 bytes, dereferencing - * // the member may fail. - * struct my_struct { - * int a; - * int b; - * }; - * - * // The validation function will not enforce an exact length match to - * // allow structures to grow as required. Note: While it is allowed - * // to add members to the end of the structure, changing the order or - * // inserting members in the middle of the structure will break your - * // binary interface. - * static struct nla_policy my_policy[ATTR_MAX+1] = { - * [ATTR_MY_STRICT] = { .type = NLA_UNSPEC, - * .minlen = sizeof(struct my_struct) }, - * - * // The binary structure is appened to the message using nla_put() - * struct my_struct foo = { .a = 1, .b = 2 }; - * nla_put(msg, ATTR_MY_STRUCT, sizeof(foo), &foo); - * - * // On the receiving side, a pointer to the structure pointing inside - * // the message payload is returned by nla_get(). - * if (attrs[ATTR_MY_STRUCT]) - * struct my_struct *foo = nla_get(attrs[ATTR_MY_STRUCT]); - * @endcode - * - * @par Integers (NLA_U8, NLA_U16, NLA_U32, NLA_U64) - * Integers come in different sizes from 8 bit to 64 bit. However, since the - * payload length is aligned to 4 bytes, integers smaller than 32 bit are - * only useful to enforce the maximum range of values. - * @par - * \b Note: There is no difference made between signed and unsigned integers. - * The validation only enforces the minimal payload length required to store - * an integer of specified type. - * @par - * @code - * // Even though possible, it does not make sense to specify .minlen or - * // .maxlen for integer types. The data types implies the corresponding - * // minimal payload length. - * static struct nla_policy my_policy[ATTR_MAX+1] = { - * [ATTR_FOO] = { .type = NLA_U32 }, - * - * // Numeric values can be appended directly using the respective - * // nla_put_uxxx() function - * nla_put_u32(msg, ATTR_FOO, 123); - * - * // Same for the receiving side. - * if (attrs[ATTR_FOO]) - * uint32_t foo = nla_get_u32(attrs[ATTR_FOO]); - * @endcode - * - * @par Character string (NLA_STRING) - * This data type represents a NUL terminated character string of variable - * length. For binary data streams the type NLA_UNSPEC is recommended. - * @par - * @code - * // Enforce a NUL terminated character string of at most 4 characters - * // including the NUL termination. - * static struct nla_policy my_policy[ATTR_MAX+1] = { - * [ATTR_BAR] = { .type = NLA_STRING, maxlen = 4 }, - * - * // nla_put_string() creates a string attribute of the necessary length - * // and appends it to the message including the NUL termination. - * nla_put_string(msg, ATTR_BAR, "some text"); - * - * // It is safe to use the returned character string directly if the - * // attribute has been validated as the validation enforces the proper - * // termination of the string. - * if (attrs[ATTR_BAR]) - * char *text = nla_get_string(attrs[ATTR_BAR]); - * @endcode - * - * @par Flag (NLA_FLAG) - * This attribute type may be used to indicate the presence of a flag. The - * attribute is only valid if the payload length is zero. The presence of - * the attribute header indicates the presence of the flag. - * @par - * @code - * // This attribute type is special as .minlen and .maxlen have no effect. - * static struct nla_policy my_policy[ATTR_MAX+1] = { - * [ATTR_FLAG] = { .type = NLA_FLAG }, - * - * // nla_put_flag() appends a zero sized attribute to the message. - * nla_put_flag(msg, ATTR_FLAG); - * - * // There is no need for a receival function, the presence is the value. - * if (attrs[ATTR_FLAG]) - * // flag is present - * @endcode - * - * @par Micro Seconds (NLA_MSECS) - * - * @par Nested Attribute (NLA_NESTED) - * Attributes can be nested and put into a container to create groups, lists - * or to construct trees of attributes. Nested attributes are often used to - * pass attributes to a subsystem where the top layer has no knowledge of the - * configuration possibilities of each subsystem. - * @par - * \b Note: When validating the attributes using nlmsg_validate() or - * nlmsg_parse() it will only affect the top level attributes. Each - * level of nested attributes must be validated seperately using - * nla_parse_nested() or nla_validate(). - * @par - * @code - * // The minimal length policy may be used to enforce the presence of at - * // least one attribute. - * static struct nla_policy my_policy[ATTR_MAX+1] = { - * [ATTR_OPTS] = { .type = NLA_NESTED, minlen = NLA_HDRLEN }, - * - * // Nested attributes are constructed by enclosing the attributes - * // to be nested with calls to nla_nest_start() respetively nla_nest_end(). - * struct nlattr *opts = nla_nest_start(msg, ATTR_OPTS); - * nla_put_u32(msg, ATTR_FOO, 123); - * nla_put_string(msg, ATTR_BAR, "some text"); - * nla_nest_end(msg, opts); - * - * // Various methods exist to parse nested attributes, the easiest being - * // nla_parse_nested() which also allows validation in the same step. - * if (attrs[ATTR_OPTS]) { - * struct nlattr *nested[ATTR_MAX+1]; - * - * nla_parse_nested(nested, ATTR_MAX, attrs[ATTR_OPTS], &policy); - * - * if (nested[ATTR_FOO]) - * uint32_t foo = nla_get_u32(nested[ATTR_FOO]); - * } - * @endcode - * - * @subsection attr_exceptions Exception Based Attribute Construction - * Often a large number of attributes are added to a message in a single - * function. In order to simplify error handling, a second set of - * construction functions exist which jump to a error label when they - * fail instead of returning an error code. This second set consists - * of macros which are named after their error code based counterpart - * except that the name is written all uppercase. - * - * All of the macros jump to the target \c nla_put_failure if they fail. - * @code - * void my_func(struct nl_msg *msg) - * { - * NLA_PUT_U32(msg, ATTR_FOO, 10); - * NLA_PUT_STRING(msg, ATTR_BAR, "bar"); - * - * return 0; - * - * nla_put_failure: - * return -NLE_NOMEM; - * } - * @endcode - * - * @subsection attr_examples Examples - * @par Example 1.1 Constructing a netlink message with attributes. - * @code - * struct nl_msg *build_msg(int ifindex, struct nl_addr *lladdr, int mtu) - * { - * struct nl_msg *msg; - * struct nlattr *info, *vlan; - * struct ifinfomsg ifi = { - * .ifi_family = AF_INET, - * .ifi_index = ifindex, - * }; - * - * // Allocate a new netlink message, type=RTM_SETLINK, flags=NLM_F_ECHO - * if (!(msg = nlmsg_alloc_simple(RTM_SETLINK, NLM_F_ECHO))) - * return NULL; - * - * // Append the family specific header (struct ifinfomsg) - * if (nlmsg_append(msg, &ifi, sizeof(ifi), NLMSG_ALIGNTO) < 0) - * goto nla_put_failure - * - * // Append a 32 bit integer attribute to carry the MTU - * NLA_PUT_U32(msg, IFLA_MTU, mtu); - * - * // Append a unspecific attribute to carry the link layer address - * NLA_PUT_ADDR(msg, IFLA_ADDRESS, lladdr); - * - * // Append a container for nested attributes to carry link information - * if (!(info = nla_nest_start(msg, IFLA_LINKINFO))) - * goto nla_put_failure; - * - * // Put a string attribute into the container - * NLA_PUT_STRING(msg, IFLA_INFO_KIND, "vlan"); - * - * // Append another container inside the open container to carry - * // vlan specific attributes - * if (!(vlan = nla_nest_start(msg, IFLA_INFO_DATA))) - * goto nla_put_failure; - * - * // add vlan specific info attributes here... - * - * // Finish nesting the vlan attributes and close the second container. - * nla_nest_end(msg, vlan); - * - * // Finish nesting the link info attribute and close the first container. - * nla_nest_end(msg, info); - * - * return msg; - * - * // If any of the construction macros fails, we end up here. - * nla_put_failure: - * nlmsg_free(msg); - * return NULL; - * } - * @endcode - * - * @par Example 2.1 Parsing a netlink message with attributes. - * @code - * int parse_message(struct nl_msg *msg) - * { - * // The policy defines two attributes: a 32 bit integer and a container - * // for nested attributes. - * struct nla_policy attr_policy[ATTR_MAX+1] = { - * [ATTR_FOO] = { .type = NLA_U32 }, - * [ATTR_BAR] = { .type = NLA_NESTED }, - * }; - * struct nlattr *attrs[ATTR_MAX+1]; - * int err; - * - * // The nlmsg_parse() function will make sure that the message contains - * // enough payload to hold the header (struct my_hdr), validates any - * // attributes attached to the messages and stores a pointer to each - * // attribute in the attrs[] array accessable by attribute type. - * if ((err = nlmsg_parse(nlmsg_hdr(msg), sizeof(struct my_hdr), attrs, - * ATTR_MAX, attr_policy)) < 0) - * goto errout; - * - * if (attrs[ATTR_FOO]) { - * // It is safe to directly access the attribute payload without - * // any further checks since nlmsg_parse() enforced the policy. - * uint32_t foo = nla_get_u32(attrs[ATTR_FOO]); - * } - * - * if (attrs[ATTR_BAR]) { - * struct nlattr *nested[NESTED_MAX+1]; - * - * // Attributes nested in a container can be parsed the same way - * // as top level attributes. - * if ((err = nla_parse_nested(nested, NESTED_MAX, attrs[ATTR_BAR], - * nested_policy)) < 0) - * goto errout; - * - * // Process nested attributes here. - * } - * - * err = 0; - * errout: - * return err; - * } - * @endcode - * - * @{ - */ - -/** - * @name Attribute Size Calculation - * @{ - */ - -/** @} */ - -/** - * @name Parsing Attributes - * @{ - */ - -/** - * Check if the attribute header and payload can be accessed safely. - * @arg nla Attribute of any kind. - * @arg remaining Number of bytes remaining in attribute stream. - * - * Verifies that the header and payload do not exceed the number of - * bytes left in the attribute stream. This function must be called - * before access the attribute header or payload when iterating over - * the attribute stream using nla_next(). - * - * @return True if the attribute can be accessed safely, false otherwise. - */ -int nla_ok(const struct nlattr *nla, int remaining) -{ - return remaining >= sizeof(*nla) && - nla->nla_len >= sizeof(*nla) && - nla->nla_len <= remaining; -} - -/** - * Return next attribute in a stream of attributes. - * @arg nla Attribute of any kind. - * @arg remaining Variable to count remaining bytes in stream. - * - * Calculates the offset to the next attribute based on the attribute - * given. The attribute provided is assumed to be accessible, the - * caller is responsible to use nla_ok() beforehand. The offset (length - * of specified attribute including padding) is then subtracted from - * the remaining bytes variable and a pointer to the next attribute is - * returned. - * - * nla_next() can be called as long as remainig is >0. - * - * @return Pointer to next attribute. - */ -struct nlattr *nla_next(const struct nlattr *nla, int *remaining) -{ - int totlen = NLA_ALIGN(nla->nla_len); - - *remaining -= totlen; - return (struct nlattr *) ((char *) nla + totlen); -} - -static uint16_t nla_attr_minlen[NLA_TYPE_MAX+1] = { - [NLA_U8] = sizeof(uint8_t), - [NLA_U16] = sizeof(uint16_t), - [NLA_U32] = sizeof(uint32_t), - [NLA_U64] = sizeof(uint64_t), - [NLA_STRING] = 1, -}; - -static int validate_nla(struct nlattr *nla, int maxtype, - struct nla_policy *policy) -{ - struct nla_policy *pt; - int minlen = 0, type = nla_type(nla); - - if (type <= 0 || type > maxtype) - return 0; - - pt = &policy[type]; - - if (pt->type > NLA_TYPE_MAX) - BUG(); - - 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 -NLE_RANGE; - - if (nla_len(nla) < minlen) - return -NLE_RANGE; - - if (pt->maxlen && nla_len(nla) > pt->maxlen) - return -NLE_RANGE; - - if (pt->type == NLA_STRING) { - char *data = nla_data(nla); - if (data[nla_len(nla) - 1] != '\0') - return -NLE_INVAL; - } - - return 0; -} - - -/** - * Create attribute index based on a stream of attributes. - * @arg tb Index array to be filled (maxtype+1 elements). - * @arg maxtype Maximum attribute type expected and accepted. - * @arg head Head of attribute stream. - * @arg len Length of attribute stream. - * @arg policy Attribute validation policy. - * - * Iterates over the stream of attributes and stores a pointer to each - * attribute in the index array using the attribute type as index to - * the array. Attribute with a type greater than the maximum type - * specified will be silently ignored in order to maintain backwards - * compatibility. If \a policy is not NULL, the attribute will be - * validated using the specified policy. - * - * @see nla_validate - * @return 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) { - int type = nla_type(nla); - - if (type == 0) { - fprintf(stderr, "Illegal nla->nla_type == 0\n"); - continue; - } - - if (type <= maxtype) { - if (policy) { - err = validate_nla(nla, maxtype, policy); - if (err < 0) - goto errout; - } - - tb[type] = nla; - } - } - - if (rem > 0) - fprintf(stderr, "netlink: %d bytes leftover after parsing " - "attributes.\n", rem); - - err = 0; -errout: - return err; -} - -/** - * Validate a stream of attributes. - * @arg head Head of attributes stream. - * @arg len Length of attributes stream. - * @arg maxtype Maximum attribute type expected and accepted. - * @arg policy Validation policy. - * - * Iterates over the stream of attributes and validates each attribute - * one by one using the specified policy. Attributes with a type greater - * than the maximum type specified will be silently ignored in order to - * maintain backwards compatibility. - * - * See \ref attr_datatypes for more details on what kind of validation - * checks are performed on each attribute data type. - * - * @return 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; -} - -/** - * Find a single attribute in a stream of attributes. - * @arg head Head of attributes stream. - * @arg len Length of attributes stream. - * @arg attrtype Attribute type to look for. - * - * Iterates over the stream of attributes and compares each type with - * the type specified. Returns the first attribute which matches the - * type. - * - * @return Pointer to attribute found or NULL. - */ -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_type(nla) == attrtype) - return nla; - - return NULL; -} - -/** @} */ - -/** - * @name Unspecific Attribute - * @{ - */ - -/** - * Reserve space for a attribute. - * @arg msg Netlink Message. - * @arg attrtype Attribute Type. - * @arg attrlen Length of payload. - * - * Reserves room for a attribute in the specified netlink message and - * fills in the attribute header (type, length). Returns NULL if there - * is unsuficient space for the attribute. - * - * Any padding between payload and the start of the next attribute is - * zeroed out. - * - * @return Pointer to start of attribute or NULL on failure. - */ -struct nlattr *nla_reserve(struct nl_msg *msg, int attrtype, int attrlen) -{ - struct nlattr *nla; - int tlen; - - tlen = NLMSG_ALIGN(msg->nm_nlh->nlmsg_len) + nla_total_size(attrlen); - - if ((tlen + msg->nm_nlh->nlmsg_len) > msg->nm_size) - return NULL; - - nla = (struct nlattr *) nlmsg_tail(msg->nm_nlh); - nla->nla_type = attrtype; - nla->nla_len = nla_attr_size(attrlen); - - memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen)); - msg->nm_nlh->nlmsg_len = tlen; - - NL_DBG(2, "msg %p: Reserved %d bytes at offset +%td for attr %d " - "nlmsg_len=%d\n", msg, attrlen, - (void *) nla - nlmsg_data(msg->nm_nlh), - attrtype, msg->nm_nlh->nlmsg_len); - - return nla; -} - -/** - * Add a unspecific attribute to netlink message. - * @arg msg Netlink message. - * @arg attrtype Attribute type. - * @arg datalen Length of data to be used as payload. - * @arg data Pointer to data to be used as attribute payload. - * - * Reserves room for a unspecific attribute and copies the provided data - * into the message as payload of the attribute. Returns an error if there - * is insufficient space for the attribute. - * - * @see nla_reserve - * @return 0 on success or a negative error code. - */ -int nla_put(struct nl_msg *msg, int attrtype, int datalen, const void *data) -{ - struct nlattr *nla; - - nla = nla_reserve(msg, attrtype, datalen); - if (!nla) - return -NLE_NOMEM; - - memcpy(nla_data(nla), data, datalen); - NL_DBG(2, "msg %p: Wrote %d bytes at offset +%td for attr %d\n", - msg, datalen, (void *) nla - nlmsg_data(msg->nm_nlh), attrtype); - - return 0; -} - - - -/** @} */ |