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ipv4: Refactor fib_check_nh
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fib_check_nh is currently huge covering multiple uses cases - device only,
device + gateway, and device + gateway with ONLINK. The next patch adds
validation checks for IPv6 which only further complicates it. So, break
fib_check_nh into 2 helpers - one for gateway validation and one for device
only.

Signed-off-by: David Ahern <dsahern@gmail.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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David Ahern authored and David S. Miller committed Apr 8, 2019
1 parent a4ea5d4 commit 448d724
Showing 1 changed file with 125 additions and 109 deletions.
234 changes: 125 additions & 109 deletions net/ipv4/fib_semantics.c
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Original file line number Diff line number Diff line change
Expand Up @@ -885,134 +885,150 @@ bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
* |
* |-> {local prefix} (terminal node)
*/
static int fib_check_nh(struct fib_config *cfg, struct fib_nh *nh,
struct netlink_ext_ack *extack)
static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
u8 scope, struct netlink_ext_ack *extack)
{
int err = 0;
struct net *net;
struct net_device *dev;
struct fib_result res;
int err;

net = cfg->fc_nlinfo.nl_net;
if (nh->fib_nh_gw4) {
struct fib_result res;

if (nh->fib_nh_flags & RTNH_F_ONLINK) {
unsigned int addr_type;
if (nh->fib_nh_flags & RTNH_F_ONLINK) {
unsigned int addr_type;

if (cfg->fc_scope >= RT_SCOPE_LINK) {
NL_SET_ERR_MSG(extack,
"Nexthop has invalid scope");
return -EINVAL;
}
dev = __dev_get_by_index(net, nh->fib_nh_oif);
if (!dev) {
NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
return -ENODEV;
}
if (!(dev->flags & IFF_UP)) {
NL_SET_ERR_MSG(extack,
"Nexthop device is not up");
return -ENETDOWN;
}
addr_type = inet_addr_type_dev_table(net, dev,
nh->fib_nh_gw4);
if (addr_type != RTN_UNICAST) {
NL_SET_ERR_MSG(extack,
"Nexthop has invalid gateway");
return -EINVAL;
}
if (!netif_carrier_ok(dev))
nh->fib_nh_flags |= RTNH_F_LINKDOWN;
nh->fib_nh_dev = dev;
dev_hold(dev);
nh->fib_nh_scope = RT_SCOPE_LINK;
return 0;
if (scope >= RT_SCOPE_LINK) {
NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
return -EINVAL;
}
rcu_read_lock();
{
struct fib_table *tbl = NULL;
struct flowi4 fl4 = {
.daddr = nh->fib_nh_gw4,
.flowi4_scope = cfg->fc_scope + 1,
.flowi4_oif = nh->fib_nh_oif,
.flowi4_iif = LOOPBACK_IFINDEX,
};

/* It is not necessary, but requires a bit of thinking */
if (fl4.flowi4_scope < RT_SCOPE_LINK)
fl4.flowi4_scope = RT_SCOPE_LINK;

if (cfg->fc_table)
tbl = fib_get_table(net, cfg->fc_table);

if (tbl)
err = fib_table_lookup(tbl, &fl4, &res,
FIB_LOOKUP_IGNORE_LINKSTATE |
FIB_LOOKUP_NOREF);

/* on error or if no table given do full lookup. This
* is needed for example when nexthops are in the local
* table rather than the given table
*/
if (!tbl || err) {
err = fib_lookup(net, &fl4, &res,
FIB_LOOKUP_IGNORE_LINKSTATE);
}

if (err) {
NL_SET_ERR_MSG(extack,
"Nexthop has invalid gateway");
rcu_read_unlock();
return err;
}
dev = __dev_get_by_index(net, nh->fib_nh_oif);
if (!dev) {
NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
return -ENODEV;
}
err = -EINVAL;
if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
goto out;
if (!(dev->flags & IFF_UP)) {
NL_SET_ERR_MSG(extack, "Nexthop device is not up");
return -ENETDOWN;
}
nh->fib_nh_scope = res.scope;
nh->fib_nh_oif = FIB_RES_OIF(res);
nh->fib_nh_dev = dev = FIB_RES_DEV(res);
if (!dev) {
NL_SET_ERR_MSG(extack,
"No egress device for nexthop gateway");
goto out;
addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
if (addr_type != RTN_UNICAST) {
NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
return -EINVAL;
}
dev_hold(dev);
if (!netif_carrier_ok(dev))
nh->fib_nh_flags |= RTNH_F_LINKDOWN;
err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
} else {
struct in_device *in_dev;

if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
NL_SET_ERR_MSG(extack,
"Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
return -EINVAL;
nh->fib_nh_dev = dev;
dev_hold(dev);
nh->fib_nh_scope = RT_SCOPE_LINK;
return 0;
}
rcu_read_lock();
{
struct fib_table *tbl = NULL;
struct flowi4 fl4 = {
.daddr = nh->fib_nh_gw4,
.flowi4_scope = scope + 1,
.flowi4_oif = nh->fib_nh_oif,
.flowi4_iif = LOOPBACK_IFINDEX,
};

/* It is not necessary, but requires a bit of thinking */
if (fl4.flowi4_scope < RT_SCOPE_LINK)
fl4.flowi4_scope = RT_SCOPE_LINK;

if (table)
tbl = fib_get_table(net, table);

if (tbl)
err = fib_table_lookup(tbl, &fl4, &res,
FIB_LOOKUP_IGNORE_LINKSTATE |
FIB_LOOKUP_NOREF);

/* on error or if no table given do full lookup. This
* is needed for example when nexthops are in the local
* table rather than the given table
*/
if (!tbl || err) {
err = fib_lookup(net, &fl4, &res,
FIB_LOOKUP_IGNORE_LINKSTATE);
}
rcu_read_lock();
err = -ENODEV;
in_dev = inetdev_by_index(net, nh->fib_nh_oif);
if (!in_dev)
goto out;
err = -ENETDOWN;
if (!(in_dev->dev->flags & IFF_UP)) {
NL_SET_ERR_MSG(extack, "Device for nexthop is not up");

if (err) {
NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
goto out;
}
nh->fib_nh_dev = in_dev->dev;
dev_hold(nh->fib_nh_dev);
nh->fib_nh_scope = RT_SCOPE_HOST;
if (!netif_carrier_ok(nh->fib_nh_dev))
nh->fib_nh_flags |= RTNH_F_LINKDOWN;
err = 0;
}

err = -EINVAL;
if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
goto out;
}
nh->fib_nh_scope = res.scope;
nh->fib_nh_oif = FIB_RES_OIF(res);
nh->fib_nh_dev = dev = FIB_RES_DEV(res);
if (!dev) {
NL_SET_ERR_MSG(extack,
"No egress device for nexthop gateway");
goto out;
}
dev_hold(dev);
if (!netif_carrier_ok(dev))
nh->fib_nh_flags |= RTNH_F_LINKDOWN;
err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
out:
rcu_read_unlock();
return err;
}

static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
struct netlink_ext_ack *extack)
{
struct in_device *in_dev;
int err;

if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
NL_SET_ERR_MSG(extack,
"Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
return -EINVAL;
}

rcu_read_lock();

err = -ENODEV;
in_dev = inetdev_by_index(net, nh->fib_nh_oif);
if (!in_dev)
goto out;
err = -ENETDOWN;
if (!(in_dev->dev->flags & IFF_UP)) {
NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
goto out;
}

nh->fib_nh_dev = in_dev->dev;
dev_hold(nh->fib_nh_dev);
nh->fib_nh_scope = RT_SCOPE_HOST;
if (!netif_carrier_ok(nh->fib_nh_dev))
nh->fib_nh_flags |= RTNH_F_LINKDOWN;
err = 0;
out:
rcu_read_unlock();
return err;
}

static int fib_check_nh(struct fib_config *cfg, struct fib_nh *nh,
struct netlink_ext_ack *extack)
{
struct net *net = cfg->fc_nlinfo.nl_net;
u32 table = cfg->fc_table;
int err;

if (nh->fib_nh_gw_family == AF_INET)
err = fib_check_nh_v4_gw(net, nh, table, cfg->fc_scope, extack);
else
err = fib_check_nh_nongw(net, nh, extack);

return err;
}

static inline unsigned int fib_laddr_hashfn(__be32 val)
{
unsigned int mask = (fib_info_hash_size - 1);
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