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linux-next/include/linux/genl_magic_func.h
Johannes Berg 2a94fe48f3 genetlink: make multicast groups const, prevent abuse 
Register generic netlink multicast groups as an array with
the family and give them contiguous group IDs. Then instead
of passing the global group ID to the various functions that
send messages, pass the ID relative to the family - for most
families that's just 0 because the only have one group.

This avoids the list_head and ID in each group, adding a new
field for the mcast group ID offset to the family.

At the same time, this allows us to prevent abusing groups
again like the quota and dropmon code did, since we can now
check that a family only uses a group it owns.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-11-19 16:39:06 -05:00

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#ifndef GENL_MAGIC_FUNC_H
#define GENL_MAGIC_FUNC_H
#include <linux/genl_magic_struct.h>
/*
* Magic: declare tla policy {{{1
* Magic: declare nested policies
* {{{2
*/
#undef GENL_mc_group
#define GENL_mc_group(group)
#undef GENL_notification
#define GENL_notification(op_name, op_num, mcast_group, tla_list)
#undef GENL_op
#define GENL_op(op_name, op_num, handler, tla_list)
#undef GENL_struct
#define GENL_struct(tag_name, tag_number, s_name, s_fields) \
[tag_name] = { .type = NLA_NESTED },
static struct nla_policy CONCAT_(GENL_MAGIC_FAMILY, _tla_nl_policy)[] = {
#include GENL_MAGIC_INCLUDE_FILE
};
#undef GENL_struct
#define GENL_struct(tag_name, tag_number, s_name, s_fields) \
static struct nla_policy s_name ## _nl_policy[] __read_mostly = \
{ s_fields };
#undef __field
#define __field(attr_nr, attr_flag, name, nla_type, _type, __get, \
__put, __is_signed) \
[attr_nr] = { .type = nla_type },
#undef __array
#define __array(attr_nr, attr_flag, name, nla_type, _type, maxlen, \
__get, __put, __is_signed) \
[attr_nr] = { .type = nla_type, \
.len = maxlen - (nla_type == NLA_NUL_STRING) },
#include GENL_MAGIC_INCLUDE_FILE
#ifndef __KERNEL__
#ifndef pr_info
#define pr_info(args...) fprintf(stderr, args);
#endif
#endif
#ifdef GENL_MAGIC_DEBUG
static void dprint_field(const char *dir, int nla_type,
const char *name, void *valp)
{
__u64 val = valp ? *(__u32 *)valp : 1;
switch (nla_type) {
case NLA_U8: val = (__u8)val;
case NLA_U16: val = (__u16)val;
case NLA_U32: val = (__u32)val;
pr_info("%s attr %s: %d 0x%08x\n", dir,
name, (int)val, (unsigned)val);
break;
case NLA_U64:
val = *(__u64*)valp;
pr_info("%s attr %s: %lld 0x%08llx\n", dir,
name, (long long)val, (unsigned long long)val);
break;
case NLA_FLAG:
if (val)
pr_info("%s attr %s: set\n", dir, name);
break;
}
}
static void dprint_array(const char *dir, int nla_type,
const char *name, const char *val, unsigned len)
{
switch (nla_type) {
case NLA_NUL_STRING:
if (len && val[len-1] == '\0')
len--;
pr_info("%s attr %s: [len:%u] '%s'\n", dir, name, len, val);
break;
default:
/* we can always show 4 byte,
* thats what nlattr are aligned to. */
pr_info("%s attr %s: [len:%u] %02x%02x%02x%02x ...\n",
dir, name, len, val[0], val[1], val[2], val[3]);
}
}
#define DPRINT_TLA(a, op, b) pr_info("%s %s %s\n", a, op, b);
/* Name is a member field name of the struct s.
* If s is NULL (only parsing, no copy requested in *_from_attrs()),
* nla is supposed to point to the attribute containing the information
* corresponding to that struct member. */
#define DPRINT_FIELD(dir, nla_type, name, s, nla) \
do { \
if (s) \
dprint_field(dir, nla_type, #name, &s->name); \
else if (nla) \
dprint_field(dir, nla_type, #name, \
(nla_type == NLA_FLAG) ? NULL \
: nla_data(nla)); \
} while (0)
#define DPRINT_ARRAY(dir, nla_type, name, s, nla) \
do { \
if (s) \
dprint_array(dir, nla_type, #name, \
s->name, s->name ## _len); \
else if (nla) \
dprint_array(dir, nla_type, #name, \
nla_data(nla), nla_len(nla)); \
} while (0)
#else
#define DPRINT_TLA(a, op, b) do {} while (0)
#define DPRINT_FIELD(dir, nla_type, name, s, nla) do {} while (0)
#define DPRINT_ARRAY(dir, nla_type, name, s, nla) do {} while (0)
#endif
/*
* Magic: provide conversion functions {{{1
* populate struct from attribute table:
* {{{2
*/
/* processing of generic netlink messages is serialized.
* use one static buffer for parsing of nested attributes */
static struct nlattr *nested_attr_tb[128];
#ifndef BUILD_BUG_ON
/* Force a compilation error if condition is true */
#define BUILD_BUG_ON(condition) ((void)BUILD_BUG_ON_ZERO(condition))
/* Force a compilation error if condition is true, but also produce a
result (of value 0 and type size_t), so the expression can be used
e.g. in a structure initializer (or where-ever else comma expressions
aren't permitted). */
#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
#endif
#undef GENL_struct
#define GENL_struct(tag_name, tag_number, s_name, s_fields) \
/* *_from_attrs functions are static, but potentially unused */ \
static int __ ## s_name ## _from_attrs(struct s_name *s, \
struct genl_info *info, bool exclude_invariants) \
{ \
const int maxtype = ARRAY_SIZE(s_name ## _nl_policy)-1; \
struct nlattr *tla = info->attrs[tag_number]; \
struct nlattr **ntb = nested_attr_tb; \
struct nlattr *nla; \
int err; \
BUILD_BUG_ON(ARRAY_SIZE(s_name ## _nl_policy) > ARRAY_SIZE(nested_attr_tb)); \
if (!tla) \
return -ENOMSG; \
DPRINT_TLA(#s_name, "<=-", #tag_name); \
err = drbd_nla_parse_nested(ntb, maxtype, tla, s_name ## _nl_policy); \
if (err) \
return err; \
\
s_fields \
return 0; \
} __attribute__((unused)) \
static int s_name ## _from_attrs(struct s_name *s, \
struct genl_info *info) \
{ \
return __ ## s_name ## _from_attrs(s, info, false); \
} __attribute__((unused)) \
static int s_name ## _from_attrs_for_change(struct s_name *s, \
struct genl_info *info) \
{ \
return __ ## s_name ## _from_attrs(s, info, true); \
} __attribute__((unused)) \
#define __assign(attr_nr, attr_flag, name, nla_type, type, assignment...) \
nla = ntb[attr_nr]; \
if (nla) { \
if (exclude_invariants && ((attr_flag) & DRBD_F_INVARIANT)) { \
pr_info("<< must not change invariant attr: %s\n", #name); \
return -EEXIST; \
} \
assignment; \
} else if (exclude_invariants && ((attr_flag) & DRBD_F_INVARIANT)) { \
/* attribute missing from payload, */ \
/* which was expected */ \
} else if ((attr_flag) & DRBD_F_REQUIRED) { \
pr_info("<< missing attr: %s\n", #name); \
return -ENOMSG; \
}
#undef __field
#define __field(attr_nr, attr_flag, name, nla_type, type, __get, __put, \
__is_signed) \
__assign(attr_nr, attr_flag, name, nla_type, type, \
if (s) \
s->name = __get(nla); \
DPRINT_FIELD("<<", nla_type, name, s, nla))
/* validate_nla() already checked nla_len <= maxlen appropriately. */
#undef __array
#define __array(attr_nr, attr_flag, name, nla_type, type, maxlen, \
__get, __put, __is_signed) \
__assign(attr_nr, attr_flag, name, nla_type, type, \
if (s) \
s->name ## _len = \
__get(s->name, nla, maxlen); \
DPRINT_ARRAY("<<", nla_type, name, s, nla))
#include GENL_MAGIC_INCLUDE_FILE
#undef GENL_struct
#define GENL_struct(tag_name, tag_number, s_name, s_fields)
/*
* Magic: define op number to op name mapping {{{1
* {{{2
*/
const char *CONCAT_(GENL_MAGIC_FAMILY, _genl_cmd_to_str)(__u8 cmd)
{
switch (cmd) {
#undef GENL_op
#define GENL_op(op_name, op_num, handler, tla_list) \
case op_num: return #op_name;
#include GENL_MAGIC_INCLUDE_FILE
default:
return "unknown";
}
}
#ifdef __KERNEL__
#include <linux/stringify.h>
/*
* Magic: define genl_ops {{{1
* {{{2
*/
#undef GENL_op
#define GENL_op(op_name, op_num, handler, tla_list) \
{ \
handler \
.cmd = op_name, \
.policy = CONCAT_(GENL_MAGIC_FAMILY, _tla_nl_policy), \
},
#define ZZZ_genl_ops CONCAT_(GENL_MAGIC_FAMILY, _genl_ops)
static struct genl_ops ZZZ_genl_ops[] __read_mostly = {
#include GENL_MAGIC_INCLUDE_FILE
};
#undef GENL_op
#define GENL_op(op_name, op_num, handler, tla_list)
/*
* Define the genl_family, multicast groups, {{{1
* and provide register/unregister functions.
* {{{2
*/
#define ZZZ_genl_family CONCAT_(GENL_MAGIC_FAMILY, _genl_family)
static struct genl_family ZZZ_genl_family __read_mostly = {
.id = GENL_ID_GENERATE,
.name = __stringify(GENL_MAGIC_FAMILY),
.version = GENL_MAGIC_VERSION,
#ifdef GENL_MAGIC_FAMILY_HDRSZ
.hdrsize = NLA_ALIGN(GENL_MAGIC_FAMILY_HDRSZ),
#endif
.maxattr = ARRAY_SIZE(drbd_tla_nl_policy)-1,
};
/*
* Magic: define multicast groups
* Magic: define multicast group registration helper
*/
#define ZZZ_genl_mcgrps CONCAT_(GENL_MAGIC_FAMILY, _genl_mcgrps)
static const struct genl_multicast_group ZZZ_genl_mcgrps[] = {
#undef GENL_mc_group
#define GENL_mc_group(group) { .name = #group, },
#include GENL_MAGIC_INCLUDE_FILE
};
enum CONCAT_(GENL_MAGIC_FAMILY, group_ids) {
#undef GENL_mc_group
#define GENL_mc_group(group) CONCAT_(GENL_MAGIC_FAMILY, _group_ ## group),
#include GENL_MAGIC_INCLUDE_FILE
};
#undef GENL_mc_group
#define GENL_mc_group(group) \
static int CONCAT_(GENL_MAGIC_FAMILY, _genl_multicast_ ## group)( \
struct sk_buff *skb, gfp_t flags) \
{ \
unsigned int group_id = \
CONCAT_(GENL_MAGIC_FAMILY, _group_ ## group); \
return genlmsg_multicast(&ZZZ_genl_family, skb, 0, \
group_id, flags); \
}
#include GENL_MAGIC_INCLUDE_FILE
#undef GENL_mc_group
#define GENL_mc_group(group)
int CONCAT_(GENL_MAGIC_FAMILY, _genl_register)(void)
{
return genl_register_family_with_ops_groups(&ZZZ_genl_family, \
ZZZ_genl_ops, \
ZZZ_genl_mcgrps);
}
void CONCAT_(GENL_MAGIC_FAMILY, _genl_unregister)(void)
{
genl_unregister_family(&ZZZ_genl_family);
}
/*
* Magic: provide conversion functions {{{1
* populate skb from struct.
* {{{2
*/
#undef GENL_op
#define GENL_op(op_name, op_num, handler, tla_list)
#undef GENL_struct
#define GENL_struct(tag_name, tag_number, s_name, s_fields) \
static int s_name ## _to_skb(struct sk_buff *skb, struct s_name *s, \
const bool exclude_sensitive) \
{ \
struct nlattr *tla = nla_nest_start(skb, tag_number); \
if (!tla) \
goto nla_put_failure; \
DPRINT_TLA(#s_name, "-=>", #tag_name); \
s_fields \
nla_nest_end(skb, tla); \
return 0; \
\
nla_put_failure: \
if (tla) \
nla_nest_cancel(skb, tla); \
return -EMSGSIZE; \
} \
static inline int s_name ## _to_priv_skb(struct sk_buff *skb, \
struct s_name *s) \
{ \
return s_name ## _to_skb(skb, s, 0); \
} \
static inline int s_name ## _to_unpriv_skb(struct sk_buff *skb, \
struct s_name *s) \
{ \
return s_name ## _to_skb(skb, s, 1); \
}
#undef __field
#define __field(attr_nr, attr_flag, name, nla_type, type, __get, __put, \
__is_signed) \
if (!exclude_sensitive || !((attr_flag) & DRBD_F_SENSITIVE)) { \
DPRINT_FIELD(">>", nla_type, name, s, NULL); \
if (__put(skb, attr_nr, s->name)) \
goto nla_put_failure; \
}
#undef __array
#define __array(attr_nr, attr_flag, name, nla_type, type, maxlen, \
__get, __put, __is_signed) \
if (!exclude_sensitive || !((attr_flag) & DRBD_F_SENSITIVE)) { \
DPRINT_ARRAY(">>",nla_type, name, s, NULL); \
if (__put(skb, attr_nr, min_t(int, maxlen, \
s->name ## _len + (nla_type == NLA_NUL_STRING)),\
s->name)) \
goto nla_put_failure; \
}
#include GENL_MAGIC_INCLUDE_FILE
/* Functions for initializing structs to default values. */
#undef __field
#define __field(attr_nr, attr_flag, name, nla_type, type, __get, __put, \
__is_signed)
#undef __array
#define __array(attr_nr, attr_flag, name, nla_type, type, maxlen, \
__get, __put, __is_signed)
#undef __u32_field_def
#define __u32_field_def(attr_nr, attr_flag, name, default) \
x->name = default;
#undef __s32_field_def
#define __s32_field_def(attr_nr, attr_flag, name, default) \
x->name = default;
#undef __flg_field_def
#define __flg_field_def(attr_nr, attr_flag, name, default) \
x->name = default;
#undef __str_field_def
#define __str_field_def(attr_nr, attr_flag, name, maxlen) \
memset(x->name, 0, sizeof(x->name)); \
x->name ## _len = 0;
#undef GENL_struct
#define GENL_struct(tag_name, tag_number, s_name, s_fields) \
static void set_ ## s_name ## _defaults(struct s_name *x) __attribute__((unused)); \
static void set_ ## s_name ## _defaults(struct s_name *x) { \
s_fields \
}
#include GENL_MAGIC_INCLUDE_FILE
#endif /* __KERNEL__ */
/* }}}1 */
#endif /* GENL_MAGIC_FUNC_H */
/* vim: set foldmethod=marker foldlevel=1 nofoldenable : */
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