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genetlink: introduce and use genl_family_attrbuf()
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This helper function allows family implementations to access
their family's attrbuf. This gets rid of the attrbuf usage
in families, and also adds locking validation, since it's not
valid to use the attrbuf with parallel_ops or outside of the
dumpit callback.

Signed-off-by: Johannes Berg <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@jmberg-intel @davem330
jmberg-intel authored and davem330 committed Oct 27, 2016
1 parent 4fe77d8 commit c90c39d
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Showing 6 changed files with 55 additions and 35 deletions.
2 changes: 2 additions & 0 deletions include/net/genetlink.h
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Original file line number Diff line number Diff line change
Expand Up @@ -73,6 +73,8 @@ struct genl_family {
struct module *module;
};

struct nlattr **genl_family_attrbuf(struct genl_family *family);

/**
* struct genl_info - receiving information
* @snd_seq: sending sequence number
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7 changes: 4 additions & 3 deletions net/ieee802154/nl802154.c
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Original file line number Diff line number Diff line change
Expand Up @@ -263,13 +263,14 @@ nl802154_prepare_wpan_dev_dump(struct sk_buff *skb,

if (!cb->args[0]) {
err = nlmsg_parse(cb->nlh, GENL_HDRLEN + nl802154_fam.hdrsize,
nl802154_fam.attrbuf, nl802154_fam.maxattr,
genl_family_attrbuf(&nl802154_fam),
nl802154_fam.maxattr,
nl802154_policy);
if (err)
goto out_unlock;

*wpan_dev = __cfg802154_wpan_dev_from_attrs(sock_net(skb->sk),
nl802154_fam.attrbuf);
genl_family_attrbuf(&nl802154_fam));
if (IS_ERR(*wpan_dev)) {
err = PTR_ERR(*wpan_dev);
goto out_unlock;
Expand Down Expand Up @@ -575,7 +576,7 @@ static int nl802154_dump_wpan_phy_parse(struct sk_buff *skb,
struct netlink_callback *cb,
struct nl802154_dump_wpan_phy_state *state)
{
struct nlattr **tb = nl802154_fam.attrbuf;
struct nlattr **tb = genl_family_attrbuf(&nl802154_fam);
int ret = nlmsg_parse(cb->nlh, GENL_HDRLEN + nl802154_fam.hdrsize,
tb, nl802154_fam.maxattr, nl802154_policy);

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19 changes: 19 additions & 0 deletions net/netlink/genetlink.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1096,6 +1096,25 @@ static int __init genl_init(void)

subsys_initcall(genl_init);

/**
* genl_family_attrbuf - return family's attrbuf
* @family: the family
*
* Return the family's attrbuf, while validating that it's
* actually valid to access it.
*
* You cannot use this function with a family that has parallel_ops
* and you can only use it within (pre/post) doit/dumpit callbacks.
*/
struct nlattr **genl_family_attrbuf(struct genl_family *family)
{
if (!WARN_ON(family->parallel_ops))
lockdep_assert_held(&genl_mutex);

return family->attrbuf;
}
EXPORT_SYMBOL(genl_family_attrbuf);

static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
gfp_t flags)
{
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9 changes: 4 additions & 5 deletions net/nfc/netlink.c
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Original file line number Diff line number Diff line change
Expand Up @@ -120,21 +120,20 @@ static int nfc_genl_send_target(struct sk_buff *msg, struct nfc_target *target,

static struct nfc_dev *__get_device_from_cb(struct netlink_callback *cb)
{
struct nlattr **attrbuf = genl_family_attrbuf(&nfc_genl_family);
struct nfc_dev *dev;
int rc;
u32 idx;

rc = nlmsg_parse(cb->nlh, GENL_HDRLEN + nfc_genl_family.hdrsize,
nfc_genl_family.attrbuf,
nfc_genl_family.maxattr,
nfc_genl_policy);
attrbuf, nfc_genl_family.maxattr, nfc_genl_policy);
if (rc < 0)
return ERR_PTR(rc);

if (!nfc_genl_family.attrbuf[NFC_ATTR_DEVICE_INDEX])
if (!attrbuf[NFC_ATTR_DEVICE_INDEX])
return ERR_PTR(-EINVAL);

idx = nla_get_u32(nfc_genl_family.attrbuf[NFC_ATTR_DEVICE_INDEX]);
idx = nla_get_u32(attrbuf[NFC_ATTR_DEVICE_INDEX]);

dev = nfc_get_device(idx);
if (!dev)
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2 changes: 1 addition & 1 deletion net/tipc/netlink.c
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Original file line number Diff line number Diff line change
Expand Up @@ -262,7 +262,7 @@ int tipc_nlmsg_parse(const struct nlmsghdr *nlh, struct nlattr ***attr)
{
u32 maxattr = tipc_genl_family.maxattr;

*attr = tipc_genl_family.attrbuf;
*attr = genl_family_attrbuf(&tipc_genl_family);
if (!*attr)
return -EOPNOTSUPP;

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51 changes: 25 additions & 26 deletions net/wireless/nl80211.c
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Original file line number Diff line number Diff line change
Expand Up @@ -551,13 +551,14 @@ static int nl80211_prepare_wdev_dump(struct sk_buff *skb,

if (!cb->args[0]) {
err = nlmsg_parse(cb->nlh, GENL_HDRLEN + nl80211_fam.hdrsize,
nl80211_fam.attrbuf, nl80211_fam.maxattr,
nl80211_policy);
genl_family_attrbuf(&nl80211_fam),
nl80211_fam.maxattr, nl80211_policy);
if (err)
goto out_unlock;

*wdev = __cfg80211_wdev_from_attrs(sock_net(skb->sk),
nl80211_fam.attrbuf);
*wdev = __cfg80211_wdev_from_attrs(
sock_net(skb->sk),
genl_family_attrbuf(&nl80211_fam));
if (IS_ERR(*wdev)) {
err = PTR_ERR(*wdev);
goto out_unlock;
Expand Down Expand Up @@ -1881,7 +1882,7 @@ static int nl80211_dump_wiphy_parse(struct sk_buff *skb,
struct netlink_callback *cb,
struct nl80211_dump_wiphy_state *state)
{
struct nlattr **tb = nl80211_fam.attrbuf;
struct nlattr **tb = genl_family_attrbuf(&nl80211_fam);
int ret = nlmsg_parse(cb->nlh, GENL_HDRLEN + nl80211_fam.hdrsize,
tb, nl80211_fam.maxattr, nl80211_policy);
/* ignore parse errors for backward compatibility */
Expand Down Expand Up @@ -7643,6 +7644,7 @@ static int nl80211_send_survey(struct sk_buff *msg, u32 portid, u32 seq,

static int nl80211_dump_survey(struct sk_buff *skb, struct netlink_callback *cb)
{
struct nlattr **attrbuf = genl_family_attrbuf(&nl80211_fam);
struct survey_info survey;
struct cfg80211_registered_device *rdev;
struct wireless_dev *wdev;
Expand All @@ -7655,7 +7657,7 @@ static int nl80211_dump_survey(struct sk_buff *skb, struct netlink_callback *cb)
return res;

/* prepare_wdev_dump parsed the attributes */
radio_stats = nl80211_fam.attrbuf[NL80211_ATTR_SURVEY_RADIO_STATS];
radio_stats = attrbuf[NL80211_ATTR_SURVEY_RADIO_STATS];

if (!wdev->netdev) {
res = -EINVAL;
Expand Down Expand Up @@ -8478,24 +8480,23 @@ static int nl80211_testmode_dump(struct sk_buff *skb,
*/
phy_idx = cb->args[0] - 1;
} else {
struct nlattr **attrbuf = genl_family_attrbuf(&nl80211_fam);

err = nlmsg_parse(cb->nlh, GENL_HDRLEN + nl80211_fam.hdrsize,
nl80211_fam.attrbuf, nl80211_fam.maxattr,
nl80211_policy);
attrbuf, nl80211_fam.maxattr, nl80211_policy);
if (err)
goto out_err;

rdev = __cfg80211_rdev_from_attrs(sock_net(skb->sk),
nl80211_fam.attrbuf);
rdev = __cfg80211_rdev_from_attrs(sock_net(skb->sk), attrbuf);
if (IS_ERR(rdev)) {
err = PTR_ERR(rdev);
goto out_err;
}
phy_idx = rdev->wiphy_idx;
rdev = NULL;

if (nl80211_fam.attrbuf[NL80211_ATTR_TESTDATA])
cb->args[1] =
(long)nl80211_fam.attrbuf[NL80211_ATTR_TESTDATA];
if (attrbuf[NL80211_ATTR_TESTDATA])
cb->args[1] = (long)attrbuf[NL80211_ATTR_TESTDATA];
}

if (cb->args[1]) {
Expand Down Expand Up @@ -11277,6 +11278,7 @@ static int nl80211_prepare_vendor_dump(struct sk_buff *skb,
struct cfg80211_registered_device **rdev,
struct wireless_dev **wdev)
{
struct nlattr **attrbuf = genl_family_attrbuf(&nl80211_fam);
u32 vid, subcmd;
unsigned int i;
int vcmd_idx = -1;
Expand Down Expand Up @@ -11312,31 +11314,28 @@ static int nl80211_prepare_vendor_dump(struct sk_buff *skb,
}

err = nlmsg_parse(cb->nlh, GENL_HDRLEN + nl80211_fam.hdrsize,
nl80211_fam.attrbuf, nl80211_fam.maxattr,
nl80211_policy);
attrbuf, nl80211_fam.maxattr, nl80211_policy);
if (err)
goto out_unlock;

if (!nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_ID] ||
!nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_SUBCMD]) {
if (!attrbuf[NL80211_ATTR_VENDOR_ID] ||
!attrbuf[NL80211_ATTR_VENDOR_SUBCMD]) {
err = -EINVAL;
goto out_unlock;
}

*wdev = __cfg80211_wdev_from_attrs(sock_net(skb->sk),
nl80211_fam.attrbuf);
*wdev = __cfg80211_wdev_from_attrs(sock_net(skb->sk), attrbuf);
if (IS_ERR(*wdev))
*wdev = NULL;

*rdev = __cfg80211_rdev_from_attrs(sock_net(skb->sk),
nl80211_fam.attrbuf);
*rdev = __cfg80211_rdev_from_attrs(sock_net(skb->sk), attrbuf);
if (IS_ERR(*rdev)) {
err = PTR_ERR(*rdev);
goto out_unlock;
}

vid = nla_get_u32(nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_ID]);
subcmd = nla_get_u32(nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_SUBCMD]);
vid = nla_get_u32(attrbuf[NL80211_ATTR_VENDOR_ID]);
subcmd = nla_get_u32(attrbuf[NL80211_ATTR_VENDOR_SUBCMD]);

for (i = 0; i < (*rdev)->wiphy.n_vendor_commands; i++) {
const struct wiphy_vendor_command *vcmd;
Expand All @@ -11360,9 +11359,9 @@ static int nl80211_prepare_vendor_dump(struct sk_buff *skb,
goto out_unlock;
}

if (nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_DATA]) {
data = nla_data(nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_DATA]);
data_len = nla_len(nl80211_fam.attrbuf[NL80211_ATTR_VENDOR_DATA]);
if (attrbuf[NL80211_ATTR_VENDOR_DATA]) {
data = nla_data(attrbuf[NL80211_ATTR_VENDOR_DATA]);
data_len = nla_len(attrbuf[NL80211_ATTR_VENDOR_DATA]);
}

/* 0 is the first index - add 1 to parse only once */
Expand Down

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