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genetlink: introduce per-sock family private storage 

Introduce an xarray for Generic netlink family to store per-socket
private. Initialize this xarray only if family uses per-socket privs.

Introduce genl_sk_priv_get() to get the socket priv pointer for a family
and initialize it in case it does not exist.
Introduce __genl_sk_priv_get() to obtain socket priv pointer for a
family under RCU read lock.

Allow family to specify the priv size, init() and destroy() callbacks.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Jiri Pirko 2023-12-16 13:29:57 +01:00 committed by Paolo Abeni
parent 5648de0b1f
commit a731132424
2 changed files with 154 additions and 1 deletions
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11
include/net/genetlink.h
View File

@ -51,6 +51,9 @@ struct genl_info;
* @split_ops: the split do/dump form of operation definition
* @n_split_ops: number of entries in @split_ops, not that with split do/dump
* ops the number of entries is not the same as number of commands
* @sock_priv_size: the size of per-socket private memory
* @sock_priv_init: the per-socket private memory initializer
* @sock_priv_destroy: the per-socket private memory destructor
*
* Attribute policies (the combination of @policy and @maxattr fields)
* can be attached at the family level or at the operation level.
@ -84,11 +87,17 @@ struct genl_family {
const struct genl_multicast_group *mcgrps;
struct module *module;
size_t sock_priv_size;
void (*sock_priv_init)(void *priv);
void (*sock_priv_destroy)(void *priv);
/* private: internal use only */
/* protocol family identifier */
int id;
/* starting number of multicast group IDs in this family */
unsigned int mcgrp_offset;
/* list of per-socket privs */
struct xarray *sock_privs;
};
/**
@ -298,6 +307,8 @@ static inline bool genl_info_is_ntf(const struct genl_info *info)
return !info->nlhdr;
}
void *__genl_sk_priv_get(struct genl_family *family, struct sock *sk);
void *genl_sk_priv_get(struct genl_family *family, struct sock *sk);
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,

144
net/netlink/genetlink.c
View File

@ -631,6 +631,138 @@ static int genl_validate_ops(const struct genl_family *family)
return 0;
}
static void *genl_sk_priv_alloc(struct genl_family *family)
{
void *priv;
priv = kzalloc(family->sock_priv_size, GFP_KERNEL);
if (!priv)
return ERR_PTR(-ENOMEM);
if (family->sock_priv_init)
family->sock_priv_init(priv);
return priv;
}
static void genl_sk_priv_free(const struct genl_family *family, void *priv)
{
if (family->sock_priv_destroy)
family->sock_priv_destroy(priv);
kfree(priv);
}
static int genl_sk_privs_alloc(struct genl_family *family)
{
if (!family->sock_priv_size)
return 0;
family->sock_privs = kzalloc(sizeof(*family->sock_privs), GFP_KERNEL);
if (!family->sock_privs)
return -ENOMEM;
xa_init(family->sock_privs);
return 0;
}
static void genl_sk_privs_free(const struct genl_family *family)
{
unsigned long id;
void *priv;
if (!family->sock_priv_size)
return;
xa_for_each(family->sock_privs, id, priv)
genl_sk_priv_free(family, priv);
xa_destroy(family->sock_privs);
kfree(family->sock_privs);
}
static void genl_sk_priv_free_by_sock(struct genl_family *family,
struct sock *sk)
{
void *priv;
if (!family->sock_priv_size)
return;
priv = xa_erase(family->sock_privs, (unsigned long) sk);
if (!priv)
return;
genl_sk_priv_free(family, priv);
}
static void genl_release(struct sock *sk, unsigned long *groups)
{
struct genl_family *family;
unsigned int id;
down_read(&cb_lock);
idr_for_each_entry(&genl_fam_idr, family, id)
genl_sk_priv_free_by_sock(family, sk);
up_read(&cb_lock);
}
/**
* __genl_sk_priv_get - Get family private pointer for socket, if exists
*
* @family: family
* @sk: socket
*
* Lookup a private memory for a Generic netlink family and specified socket.
*
* Caller should make sure this is called in RCU read locked section.
*
* Return: valid pointer on success, otherwise negative error value
* encoded by ERR_PTR(), NULL in case priv does not exist.
*/
void *__genl_sk_priv_get(struct genl_family *family, struct sock *sk)
{
if (WARN_ON_ONCE(!family->sock_privs))
return ERR_PTR(-EINVAL);
return xa_load(family->sock_privs, (unsigned long) sk);
}
/**
* genl_sk_priv_get - Get family private pointer for socket
*
* @family: family
* @sk: socket
*
* Lookup a private memory for a Generic netlink family and specified socket.
* Allocate the private memory in case it was not already done.
*
* Return: valid pointer on success, otherwise negative error value
* encoded by ERR_PTR().
*/
void *genl_sk_priv_get(struct genl_family *family, struct sock *sk)
{
void *priv, *old_priv;
priv = __genl_sk_priv_get(family, sk);
if (priv)
return priv;
/* priv for the family does not exist so far, create it. */
priv = genl_sk_priv_alloc(family);
if (IS_ERR(priv))
return ERR_CAST(priv);
old_priv = xa_cmpxchg(family->sock_privs, (unsigned long) sk, NULL,
priv, GFP_KERNEL);
if (old_priv) {
genl_sk_priv_free(family, priv);
if (xa_is_err(old_priv))
return ERR_PTR(xa_err(old_priv));
/* Race happened, priv for the socket was already inserted. */
return old_priv;
}
return priv;
}
/**
* genl_register_family - register a generic netlink family
* @family: generic netlink family
@ -659,6 +791,10 @@ int genl_register_family(struct genl_family *family)
goto errout_locked;
}
err = genl_sk_privs_alloc(family);
if (err)
goto errout_locked;
/*
* Sadly, a few cases need to be special-cased
* due to them having previously abused the API
@ -679,7 +815,7 @@ int genl_register_family(struct genl_family *family)
start, end + 1, GFP_KERNEL);
if (family->id < 0) {
err = family->id;
goto errout_locked;
goto errout_sk_privs_free;
}
err = genl_validate_assign_mc_groups(family);
@ -698,6 +834,8 @@ int genl_register_family(struct genl_family *family)
errout_remove:
idr_remove(&genl_fam_idr, family->id);
errout_sk_privs_free:
genl_sk_privs_free(family);
errout_locked:
genl_unlock_all();
return err;
@ -728,6 +866,9 @@ int genl_unregister_family(const struct genl_family *family)
up_write(&cb_lock);
wait_event(genl_sk_destructing_waitq,
atomic_read(&genl_sk_destructing_cnt) == 0);
genl_sk_privs_free(family);
genl_unlock();
genl_ctrl_event(CTRL_CMD_DELFAMILY, family, NULL, 0);
@ -1708,6 +1849,7 @@ static int __net_init genl_pernet_init(struct net *net)
.input = genl_rcv,
.flags = NL_CFG_F_NONROOT_RECV,
.bind = genl_bind,
.release = genl_release,
};
/* we'll bump the group number right afterwards */