This is also what iproute2 does ([1]) when creating a default broadcast address
with `ip addr add 192.168.1.5/24 brd + dev eth0`.
Also, kernel does in fib_add_ifaddr() ([2]):
```
__be32 addr = ifa->ifa_local;
__be32 prefix = ifa->ifa_address & mask;
...
/* Add broadcast address, if it is explicitly assigned. */
if (ifa->ifa_broadcast && ifa->ifa_broadcast != htonl(0xFFFFFFFF))
fib_magic(RTM_NEWROUTE, RTN_BROADCAST, ifa->ifa_broadcast, 32,
prim, 0);
if (!ipv4_is_zeronet(prefix) && !(ifa->ifa_flags & IFA_F_SECONDARY) &&
(prefix != addr || ifa->ifa_prefixlen < 32)) {
if (!(ifa->ifa_flags & IFA_F_NOPREFIXROUTE))
fib_magic(RTM_NEWROUTE,
dev->flags & IFF_LOOPBACK ? RTN_LOCAL : RTN_UNICAST,
prefix, ifa->ifa_prefixlen, prim,
ifa->ifa_rt_priority);
/* Add network specific broadcasts, when it takes a sense */
if (ifa->ifa_prefixlen < 31) {
fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix, 32,
prim, 0);
fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix | ~mask,
32, prim, 0);
}
}
```
Which means by default kernel already adds those special broadcast routes which
are identical to what we configure with IFA_BROADCAST. However, kernel too bases
them on the peer (IFA_ADDRESS).
[1] https://git.kernel.org/pub/scm/network/iproute2/iproute2.git/tree/ip/ipaddress.c?id=d5391e186f04214315a5a80797c78e50ad9f5271#n2380
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/ipv4/fib_frontend.c?id=bef1d88263ff769f15aa0e1515cdcede84e61d15#n1109
- track the broadcast address in NMPlatformIP4Address. For addresses
that we receive from kernel and that we cache in NMPlatform, this
allows us to show the additional information. For example, we
can see it in debug logging.
- when setting the address, we still mostly generate our default
broadcast address. This is done in the only relevant caller
nm_platform_ip4_address_sync(). Basically, we merely moved setting
the broadcast address to the caller.
That is, because no callers explicitly set the "use_ip4_broadcast_address"
flag (yet). However, in the future some caller might want to set an explicit
broadcast address.
In practice, we currently don't support configuring special broadcast
addresses in NetworkManager. Instead, we always add the default one with
"address|~netmask" (for plen < 31).
Note that a main point of IFA_BROADCAST is to add a broadcast route to
the local table. Also note that kernel anyway will add such a
"address|~netmask" route, that is regardless whether IFA_BROADCAST is
set or not. Hence, setting it or not makes very little difference for
normal broadcast addresses -- because kernel tends to add this route either
way. It would make a difference if NetworkManager configured an unusual
IFA_BROADCAST address or an address for prefixes >= 31 (in which cases
kernel wouldn't add them automatically). But we don't do that at the
moment.
So, while what NM does has little effect in practice, it still seems
more correct to add the broadcast address, only so that you see it in
`ip addr show`.
In several cases, the layer 2 and layer 3 type are very similar, also from
kernel's point of view. For example, "gre"/"gretap" and "ip6tnl"/"ip6gre"/"ip6gretap"
and "macvlan"/"macvtap".
While it makes sense that these have different NMLinkType types
(NM_LINK_TYPE_MACV{LAN,TAP}) and different NMPObject types
(NMPObjectLnkMacv{lan,tap}), it makes less sense that they have
different NMPlatformLnk* structs.
Remove the NMPlatformLnkMacvtap typedef. A typedef does not make things simpler,
but is rather confusing. Because several API that we would usually have, does
not exist for the typedef (e.g. there is no nm_platform_lnk_macvtap_to_string()).
Note that we also don't have such a typedef for NMPlatformLnkIp6Tnl
and NMPlatformLnkGre, which has the same ambiguity between the link type
and the struct with the data.
The abbreviations "ns" and "ms" seem not very clear to me. Spell them
out to nsec/msec. Also, in parts we already used the longer abbreviations,
so it wasn't consistent.
- systemd-networkd and initscripts both support it.
- it seems suggested to configure routes with scope "link" on AWS.
- the scope is only supported for IPv4 routes. Kernel ignores the
attribute for IPv6 routes.
- we don't support the aliases like "link" or "global". Instead
only the numeric value is supported. This is different from
systemd-networkd, which accepts names like "global" and "link",
but no numerical values. I think restricting ourself only to
the aliases unnecessarily limits what is possible on netlink.
The alternative would be to allow aliases and numbers both,
but that causes multiple ways to define something and has
thus downsides. So, only numeric values.
- when setting rtm_scope to RT_SCOPE_NOWHERE (0, the default), kernel
will coerce that to RT_SCOPE_LINK. This ambiguity of nowhere vs. link
is a problem, but we don't do anything about it.
- The other problem is, that when deleting a route with scope RT_SCOPE_NOWHERE,
this acts as a wild care and removes the first route that matches (given the
other route attributes). That means, NetworkManager has no meaningful
way to delete a route with scope zero, there is always the danger that
we might delete the wrong route. But this is nothing new to this
patch. The problem existed already previously, except that
NetworkManager could only add routes with scope nowhere (i.e. link).
Track whether IP addresses were added by NM or externally. In this way
it becomes possible in a later commit to add prefix route only for
addresses added by NM.
IPv6 router advertisement messages contain the following parameters
(RFC 4861):
- Reachable time: 32-bit unsigned integer. The time, in
milliseconds, that a node assumes a neighbor is reachable after
having received a reachability confirmation. Used by the Neighbor
Unreachability Detection algorithm. A value of zero means
unspecified (by this router).
- Retrans Timer: 32-bit unsigned integer. The time, in milliseconds,
between retransmitted Neighbor Solicitation messages. Used by
address resolution and the Neighbor Unreachability Detection
algorithm. A value of zero means unspecified (by this router).
Currently NM ignores them; however, since it leaves accept_ra=1, the
kernel parses RAs and applies those parameters for us [1].
In the next commit kernel handling of RAs will be disabled, so let NM
set those neighbor-related parameters.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/ipv6/ndisc.c?h=v5.2#n1353
Drop nm_platform_link_get_address_as_bytes() and introduce
nmp_link_address_get_as_bytes() so that it becomes possible to obtain
also the broadcast address without an additional lookup of the link.
We no longer add these. If you use Emacs, configure it yourself.
Also, due to our "smart-tab" usage the editor anyway does a subpar
job handling our tabs. However, on the upside every user can choose
whatever tab-width he/she prefers. If "smart-tabs" are used properly
(like we do), every tab-width will work.
No manual changes, just ran commands:
F=($(git grep -l -e '-\*-'))
sed '1 { /\/\* *-\*- *[mM]ode.*\*\/$/d }' -i "${F[@]}"
sed '1,4 { /^\(#\|--\|dnl\) *-\*- [mM]ode/d }' -i "${F[@]}"
Check remaining lines with:
git grep -e '-\*-'
The ultimate purpose of this is to cleanup our files and eventually use
SPDX license identifiers. For that, first get rid of the boilerplate lines.
While at it, rename the "addr" field to "l_address". The term "addr" is
used over and over. Instead we should use distinct names that make it
easier to navigate the code.
clang (3.4.2-9.el7) on CentOS 7.6 fails related to nm_hash_update_vals().
I am not even quoting the error message, it's totally non-understandable.
nm_hash_update_vals() uses typeof(), and in some obscure cases, clang dislikes
when the argument itself is some complex macro. I didn't fully understand why,
but this works around it.
I would prefer to fix nm_hash_update_vals() to not have this limitation.
But I don't know how.
There is probably no downside to have this an inline function instead of
a macro.
When changing the number of VFs the kernel can block for very long
time in the write() to sysfs, especially if autoprobe-drivers is
enabled. Turn the nm_platform_link_set_sriov_params() into an
asynchronous function.
In general, all fields of public NMPlatform* structs must be
plain/simple. Meaning: copying the struct must be possible without
caring about cloning/duplicating memory.
In other words, if there are fields which lifetime is limited,
then these fields cannot be inside the public part NMPlatform*.
That is why
- "NMPlatformLink.kind", "NMPlatformQdisc.kind", "NMPlatformTfilter.kind"
are set by platform code to an interned string (g_intern_string())
that has a static lifetime.
- the "ingress_qos_map" field is inside the ref-counted struct NMPObjectLnkVlan
and not NMPlatformLnkVlan. This field requires managing the lifetime
of the array and NMPlatformLnkVlan cannot provide that.
See also for example NMPClass.cmd_obj_copy() which can deep-copy an object.
But this is only suitable for fields in NMPObject*. The purpose of this
rule is that you always can safely copy a NMPlatform* struct without
worrying about the ownership and lifetime of the fields (the field's
lifetime is unlimited).
This rule and managing of resource lifetime is the main reason for the
NMPlatform*/NMPObject* split. NMPlatform* structs simply have no mechanism
for copying/releasing fields, that is why the NMPObject* counterpart exists
(which is ref-counted and has a copy and destructor function).
This is violated in tc_commit() for the "kind" strings. The lifetime
of these strings is tied to the setting instance.
We cannot intern the strings (because these are arbitrary strings
and interned strings are leaked indefinitely). We also cannot g_strdup()
the strings, because NMPlatform* is not supposed to own strings.
So, just add comments that warn about this ugliness.
The more correct solution would be to move the "kind" fields inside
NMPObjectQdisc and NMPObjectTfilter, but that is a lot of extra effort.
Arguably, the structure is used inside a union with another (larger)
struct, hence no memory is saved.
In fact, it may well be slower performance wise to access a boolean bitfield
than a gboolean (int).
Still, boolean fields in structures should be bool:1 bitfields for
consistency.
Kernel calls the netlink attribute TCA_FQ_CODEL_MEMORY_LIMIT. Likewise,
iproute2 calls this "memory_limit".
Rename because TC parameters are inherrently tied to the kernel
implementation and we should use the familiar name.
iproute2 uses the special value ~0u to indicate not to set
TCA_FQ_CODEL_CE_THRESHOLD in RTM_NEWQDISC. When not explicitly
setting the value, kernel treats the threshold as disabled.
However note that 0xFFFFFFFFu is not an invalid threshold (as far as
kernel is concerned). Thus, we should not use that as value to indicate
that the value is unset. Note that iproute2 uses the special value ~0u
only internally thereby making it impossible to set the threshold to
0xFFFFFFFFu). But kernel does not have this limitation.
Maybe the cleanest way would be to add another field to NMPlatformQDisc:
guint32 ce_threshold;
bool ce_threshold_set:1;
that indicates whether the threshold is enable or not.
But note that kernel does:
static void codel_params_init(struct codel_params *params)
{
...
params->ce_threshold = CODEL_DISABLED_THRESHOLD;
static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
{
...
if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
}
static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
{
...
if (q->cparams.ce_threshold != CODEL_DISABLED_THRESHOLD &&
nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,
codel_time_to_us(q->cparams.ce_threshold)))
goto nla_put_failure;
This means, kernel internally uses the special value 0x83126E97u to indicate
that the threshold is disabled (WTF). That is because
(((guint64) 0x83126E97u) * NSEC_PER_USEC) >> CODEL_SHIFT == CODEL_DISABLED_THRESHOLD
So in kernel API this value is reserved (and has a special meaning
to indicate that the threshold is disabled). So, instead of adding a
ce_threshold_set flag, use the same value that kernel anyway uses.
The memory-limit is an unsigned integer. It is ugly (if not wrong) to compare unsigned
values with "-1". When comparing with the default value we must also use an u32 type.
Instead add a define NM_PLATFORM_FQ_CODEL_MEMORY_LIMIT_UNSET.
Note that like iproute2 we treat NM_PLATFORM_FQ_CODEL_MEMORY_LIMIT_UNSET
to indicate to not set TCA_FQ_CODEL_MEMORY_LIMIT in RTM_NEWQDISC. This
special value is entirely internal to NetworkManager (or iproute2) and
kernel will then choose a default memory limit (of 32MB). So setting
NM_PLATFORM_FQ_CODEL_MEMORY_LIMIT_UNSET means to leave it to kernel to
choose a value (which then chooses 32MB).
See kernel's net/sched/sch_fq_codel.c:
static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
{
...
q->memory_limit = 32 << 20; /* 32 MBytes */
static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
...
if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]));
Note that not having zero as default value is problematic. In fields like
"NMPlatformIP4Route.table_coerced" and "NMPlatformRoutingRule.suppress_prefixlen_inverse"
we avoid this problem by storing a coerced value in the structure so that zero is still
the default. We don't do that here for memory-limit, so the caller must always explicitly
set the value.
Next we will need to detect more kernel features. First refactor the
handling of these to require less code changes and be more efficient.
A plain nm_platform_kernel_support_get() only reqiures to access an
array in the common case.
The other important change is that the function no longer requires a
NMPlatform instance. This allows us to check kernel support from
anywhere. The only thing is that we require kernel support to be
initialized before calling this function. That means, an NMPlatform
instance must have detected support before.
(cherry picked from commit ee269b318e)
In some cases it is convenient to specify ranges of bridge vlans, as
already supported by iproute2 and natively by kernel. With this commit
it becomes possible to add a range in this way:
nmcli connection modify eth0-slave +bridge-port.vlans "100-200 untagged"
vlan ranges can't be PVIDs because only one PVID vlan can exist.
https://bugzilla.redhat.com/show_bug.cgi?id=1652910
(cherry picked from commit 7093515777)
