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genetlink: add small version of ops

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We want to add maxattr and policy back to genl_ops, to enable
dumping per command policy to user space. This, however, would
cause bloat for all the families with global policies. Introduce
smaller version of ops (half the size of genl_ops). Translate
these smaller ops into a full blown struct before use in the
core.

v1:
 - use struct assignment
 - put a full copy of the op in struct genl_dumpit_info
 - s/light/small/

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jakub Kicinski 2020-10-02 14:49:53 -07:00 committed by David S. Miller
parent e508673696
commit 0b588afdd1
3 changed files with 135 additions and 47 deletions
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2
drivers/thermal/thermal_netlink.c
View File

@ -545,7 +545,7 @@ static int thermal_genl_cmd_dumpit(struct sk_buff *skb,
{
struct param p = { .msg = skb };
const struct genl_dumpit_info *info = genl_dumpit_info(cb);
int cmd = info->ops->cmd;
int cmd = info->op.cmd;
int ret;
void *hdr;

53
include/net/genetlink.h
View File

@ -41,6 +41,8 @@ struct genl_info;
* (private)
* @ops: the operations supported by this family
* @n_ops: number of operations supported by this family
* @small_ops: the small-struct operations supported by this family
* @n_small_ops: number of small-struct operations supported by this family
*/
struct genl_family {
int id; /* private */
@ -52,6 +54,7 @@ struct genl_family {
u8 netnsok:1;
u8 parallel_ops:1;
u8 n_ops;
u8 n_small_ops;
u8 n_mcgrps;
const struct nla_policy *policy;
int (*pre_doit)(const struct genl_ops *ops,
@ -61,6 +64,7 @@ struct genl_family {
struct sk_buff *skb,
struct genl_info *info);
const struct genl_ops * ops;
const struct genl_small_ops *small_ops;
const struct genl_multicast_group *mcgrps;
struct module *module;
};
@ -108,23 +112,26 @@ enum genl_validate_flags {
};
/**
* struct genl_info - info that is available during dumpit op call
* @family: generic netlink family - for internal genl code usage
* @ops: generic netlink ops - for internal genl code usage
* @attrs: netlink attributes
* struct genl_small_ops - generic netlink operations (small version)
* @cmd: command identifier
* @internal_flags: flags used by the family
* @flags: flags
* @validate: validation flags from enum genl_validate_flags
* @doit: standard command callback
* @dumpit: callback for dumpers
*
* This is a cut-down version of struct genl_ops for users who don't need
* most of the ancillary infra and want to save space.
*/
struct genl_dumpit_info {
const struct genl_family *family;
const struct genl_ops *ops;
struct nlattr **attrs;
struct genl_small_ops {
int (*doit)(struct sk_buff *skb, struct genl_info *info);
int (*dumpit)(struct sk_buff *skb, struct netlink_callback *cb);
u8 cmd;
u8 internal_flags;
u8 flags;
u8 validate;
};
static inline const struct genl_dumpit_info *
genl_dumpit_info(struct netlink_callback *cb)
{
return cb->data;
}
/**
* struct genl_ops - generic netlink operations
* @cmd: command identifier
@ -148,6 +155,24 @@ struct genl_ops {
u8 validate;
};
/**
* struct genl_info - info that is available during dumpit op call
* @family: generic netlink family - for internal genl code usage
* @ops: generic netlink ops - for internal genl code usage
* @attrs: netlink attributes
*/
struct genl_dumpit_info {
const struct genl_family *family;
struct genl_ops op;
struct nlattr **attrs;
};
static inline const struct genl_dumpit_info *
genl_dumpit_info(struct netlink_callback *cb)
{
return cb->data;
}
int genl_register_family(struct genl_family *family);
int genl_unregister_family(const struct genl_family *family);
void genl_notify(const struct genl_family *family, struct sk_buff *skb,

127
net/netlink/genetlink.c
View File

@ -107,16 +107,75 @@ static const struct genl_family *genl_family_find_byname(char *name)
return NULL;
}
static const struct genl_ops *genl_get_cmd(u8 cmd,
const struct genl_family *family)
static int genl_get_cmd_cnt(const struct genl_family *family)
{
return family->n_ops + family->n_small_ops;
}
static void genl_op_from_full(const struct genl_family *family,
unsigned int i, struct genl_ops *op)
{
*op = family->ops[i];
}
static int genl_get_cmd_full(u8 cmd, const struct genl_family *family,
struct genl_ops *op)
{
int i;
for (i = 0; i < family->n_ops; i++)
if (family->ops[i].cmd == cmd)
return &family->ops[i];
if (family->ops[i].cmd == cmd) {
genl_op_from_full(family, i, op);
return 0;
}
return NULL;
return -ENOENT;
}
static void genl_op_from_small(const struct genl_family *family,
unsigned int i, struct genl_ops *op)
{
memset(op, 0, sizeof(*op));
op->doit = family->small_ops[i].doit;
op->dumpit = family->small_ops[i].dumpit;
op->cmd = family->small_ops[i].cmd;
op->internal_flags = family->small_ops[i].internal_flags;
op->flags = family->small_ops[i].flags;
op->validate = family->small_ops[i].validate;
}
static int genl_get_cmd_small(u8 cmd, const struct genl_family *family,
struct genl_ops *op)
{
int i;
for (i = 0; i < family->n_small_ops; i++)
if (family->small_ops[i].cmd == cmd) {
genl_op_from_small(family, i, op);
return 0;
}
return -ENOENT;
}
static int genl_get_cmd(u8 cmd, const struct genl_family *family,
struct genl_ops *op)
{
if (!genl_get_cmd_full(cmd, family, op))
return 0;
return genl_get_cmd_small(cmd, family, op);
}
static void genl_get_cmd_by_index(unsigned int i,
const struct genl_family *family,
struct genl_ops *op)
{
if (i < family->n_ops)
genl_op_from_full(family, i, op);
else if (i < family->n_ops + family->n_small_ops)
genl_op_from_small(family, i - family->n_ops, op);
else
WARN_ON_ONCE(1);
}
static int genl_allocate_reserve_groups(int n_groups, int *first_id)
@ -286,22 +345,25 @@ static void genl_unregister_mc_groups(const struct genl_family *family)
static int genl_validate_ops(const struct genl_family *family)
{
const struct genl_ops *ops = family->ops;
unsigned int n_ops = family->n_ops;
int i, j;
if (WARN_ON(n_ops && !ops))
if (WARN_ON(family->n_ops && !family->ops) ||
WARN_ON(family->n_small_ops && !family->small_ops))
return -EINVAL;
if (!n_ops)
return 0;
for (i = 0; i < genl_get_cmd_cnt(family); i++) {
struct genl_ops op;
for (i = 0; i < n_ops; i++) {
if (ops[i].dumpit == NULL && ops[i].doit == NULL)
genl_get_cmd_by_index(i, family, &op);
if (op.dumpit == NULL && op.doit == NULL)
return -EINVAL;
for (j = i + 1; j < n_ops; j++)
if (ops[i].cmd == ops[j].cmd)
for (j = i + 1; j < genl_get_cmd_cnt(family); j++) {
struct genl_ops op2;
genl_get_cmd_by_index(j, family, &op2);
if (op.cmd == op2.cmd)
return -EINVAL;
}
}
return 0;
@ -524,7 +586,7 @@ no_attrs:
return -ENOMEM;
}
info->family = ctx->family;
info->ops = ops;
info->op = *ops;
info->attrs = attrs;
cb->data = info;
@ -546,7 +608,7 @@ no_attrs:
static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
{
const struct genl_ops *ops = genl_dumpit_info(cb)->ops;
const struct genl_ops *ops = &genl_dumpit_info(cb)->op;
int rc;
genl_lock();
@ -558,7 +620,7 @@ static int genl_lock_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
static int genl_lock_done(struct netlink_callback *cb)
{
const struct genl_dumpit_info *info = genl_dumpit_info(cb);
const struct genl_ops *ops = info->ops;
const struct genl_ops *ops = &info->op;
int rc = 0;
if (ops->done) {
@ -574,7 +636,7 @@ static int genl_lock_done(struct netlink_callback *cb)
static int genl_parallel_done(struct netlink_callback *cb)
{
const struct genl_dumpit_info *info = genl_dumpit_info(cb);
const struct genl_ops *ops = info->ops;
const struct genl_ops *ops = &info->op;
int rc = 0;
if (ops->done)
@ -682,9 +744,9 @@ static int genl_family_rcv_msg(const struct genl_family *family,
struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
const struct genl_ops *ops;
struct net *net = sock_net(skb->sk);
struct genlmsghdr *hdr = nlmsg_data(nlh);
struct genl_ops op;
int hdrlen;
/* this family doesn't exist in this netns */
@ -695,24 +757,23 @@ static int genl_family_rcv_msg(const struct genl_family *family,
if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
return -EINVAL;
ops = genl_get_cmd(hdr->cmd, family);
if (ops == NULL)
if (genl_get_cmd(hdr->cmd, family, &op))
return -EOPNOTSUPP;
if ((ops->flags & GENL_ADMIN_PERM) &&
if ((op.flags & GENL_ADMIN_PERM) &&
!netlink_capable(skb, CAP_NET_ADMIN))
return -EPERM;
if ((ops->flags & GENL_UNS_ADMIN_PERM) &&
if ((op.flags & GENL_UNS_ADMIN_PERM) &&
!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
return -EPERM;
if ((nlh->nlmsg_flags & NLM_F_DUMP) == NLM_F_DUMP)
return genl_family_rcv_msg_dumpit(family, skb, nlh, extack,
ops, hdrlen, net);
&op, hdrlen, net);
else
return genl_family_rcv_msg_doit(family, skb, nlh, extack,
ops, hdrlen, net);
&op, hdrlen, net);
}
static int genl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
@ -765,7 +826,7 @@ static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
nla_put_u32(skb, CTRL_ATTR_MAXATTR, family->maxattr))
goto nla_put_failure;
if (family->n_ops) {
if (genl_get_cmd_cnt(family)) {
struct nlattr *nla_ops;
int i;
@ -773,14 +834,16 @@ static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
if (nla_ops == NULL)
goto nla_put_failure;
for (i = 0; i < family->n_ops; i++) {
for (i = 0; i < genl_get_cmd_cnt(family); i++) {
struct nlattr *nest;
const struct genl_ops *ops = &family->ops[i];
u32 op_flags = ops->flags;
struct genl_ops op;
u32 op_flags;
if (ops->dumpit)
genl_get_cmd_by_index(i, family, &op);
op_flags = op.flags;
if (op.dumpit)
op_flags |= GENL_CMD_CAP_DUMP;
if (ops->doit)
if (op.doit)
op_flags |= GENL_CMD_CAP_DO;
if (family->policy)
op_flags |= GENL_CMD_CAP_HASPOL;
@ -789,7 +852,7 @@ static int ctrl_fill_info(const struct genl_family *family, u32 portid, u32 seq,
if (nest == NULL)
goto nla_put_failure;
if (nla_put_u32(skb, CTRL_ATTR_OP_ID, ops->cmd) ||
if (nla_put_u32(skb, CTRL_ATTR_OP_ID, op.cmd) ||
nla_put_u32(skb, CTRL_ATTR_OP_FLAGS, op_flags))
goto nla_put_failure;