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linux-stable-mirror/include/linux/genl_magic_func.h
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Christoph Böhmwalder a9c4b1d376 drbd: remove DRBD_GENLA_F_MANDATORY flag handling 
DRBD used a custom mechanism to mark netlink attributes as "mandatory":
bit 14 of nla_type was repurposed as DRBD_GENLA_F_MANDATORY. Attributes
sent from userspace that had this bit present and that were unknown
to the kernel would lead to an error.

Since commit ef6243acb4 ("genetlink: optionally validate strictly/dumps"),
the generic netlink layer rejects unknown top-level attributes when
strict validation is enabled. DRBD never opted out of strict
validation, so unknown top-level attributes are already rejected by
the netlink core.

The mandatory flag mechanism was required for nested attributes, because
these are parsed liberally, silently dropping attributes unknown to the
kernel.

This prepares for the move to a new YNL-based family, which will use the
now-default strict parsing.
The current family is not expected to gain any new attributes, which
makes this change safe.

Old userspace that still sets bit 14 is unaffected: nla_type()
strips it before __nla_validate_parse() performs attribute validation,
so the bit never reaches DRBD.

Remove all references to the mandatory flag in DRBD.

Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Link: https://patch.msgid.link/20260403132953.2248751-1-christoph.boehmwalder@linbit.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2026-04-06 20:21:37 -06:00

414 lines
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef GENL_MAGIC_FUNC_H
#define GENL_MAGIC_FUNC_H
#include <linux/args.h>
#include <linux/build_bug.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 CONCATENATE(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];
#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 = nla_parse_nested_deprecated(ntb, maxtype, tla, \
s_name ## _nl_policy, NULL); \
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
*/
static const char *CONCATENATE(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, \
},
#define ZZZ_genl_ops CONCATENATE(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 CONCATENATE(GENL_MAGIC_FAMILY, _genl_family)
static struct genl_family ZZZ_genl_family;
/*
* Magic: define multicast groups
* Magic: define multicast group registration helper
*/
#define ZZZ_genl_mcgrps CONCATENATE(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 CONCATENATE(GENL_MAGIC_FAMILY, group_ids) {
#undef GENL_mc_group
#define GENL_mc_group(group) CONCATENATE(GENL_MAGIC_FAMILY, _group_ ## group),
#include GENL_MAGIC_INCLUDE_FILE
};
#undef GENL_mc_group
#define GENL_mc_group(group) \
static int CONCATENATE(GENL_MAGIC_FAMILY, _genl_multicast_ ## group)( \
struct sk_buff *skb, gfp_t flags) \
{ \
unsigned int group_id = \
CONCATENATE(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)
static struct genl_family ZZZ_genl_family __ro_after_init = {
.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(CONCATENATE(GENL_MAGIC_FAMILY, _tla_nl_policy))-1,
.policy = CONCATENATE(GENL_MAGIC_FAMILY, _tla_nl_policy),
#ifdef GENL_MAGIC_FAMILY_PRE_DOIT
.pre_doit = GENL_MAGIC_FAMILY_PRE_DOIT,
.post_doit = GENL_MAGIC_FAMILY_POST_DOIT,
#endif
.ops = ZZZ_genl_ops,
.n_ops = ARRAY_SIZE(ZZZ_genl_ops),
.mcgrps = ZZZ_genl_mcgrps,
.resv_start_op = 42, /* drbd is currently the only user */
.n_mcgrps = ARRAY_SIZE(ZZZ_genl_mcgrps),
.module = THIS_MODULE,
};
int CONCATENATE(GENL_MAGIC_FAMILY, _genl_register)(void)
{
return genl_register_family(&ZZZ_genl_family);
}
void CONCATENATE(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 */
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