Reverse parsing lets YNL convert bad and missing attr pointers
from extack into a string like "missing attribute nest1.nest2.attr_name".
It's a feature that's unique to YNL C AFAIU (even the Python YNL
can't do nested reverse parsing). Add support for reverse-parsing
of sub-messages.
To simplify the logic and the code annotate the type policies
with extra metadata. Mark the selectors and the messages with
the information we need. We assume that key / selector always
precedes the sub-message while parsing (and also if there are
multiple sub-messages like in rt-link they are interleaved
selector 1 ... submsg 1 ... selector 2 .. submsg 2, not
selector 1 ... selector 2 ... submsg 1 ... submsg 2).
The rt-link sample in a subsequent changes shows reverse parsing
of sub-messages in action.
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250515231650.1325372-8-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Adjust parsing and rendering appropriately to make sub-messages work.
Rendering is pretty trivial, as the submsg -> netlink conversion looks
like rendering a nest in which only one attr was set. Only trick
is that we use the enum value of the sub-message rather than the nest
as the type, and effectively skip one layer of nesting. A real double
nested struct would look like this:
[SELECTOR]
[SUBMSG]
[NEST]
[MSG1-ATTR]
A submsg "is" the nest so by skipping I mean:
[SELECTOR]
[SUBMSG]
[MSG1-ATTR]
There is no extra validation in YNL if caller has set the selector
matching the submsg type (e.g. link type = "macvlan" but the nest
attrs are set to carry "veth"). Let the kernel handle that.
Parsing side is a little more specialized as we need to render and
insert a new kind of function which switches between what to parse
based on the selector. But code isn't too complicated.
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250515231650.1325372-7-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Strings from the kernel are guaranteed to be null terminated and
ynl_attr_validate() checks for this. But it doesn't check if the string
has a len of 0, which would cause problems when trying to access
data[len - 1]. Fix this by checking that len is positive.
Signed-off-by: David Wei <dw@davidwei.uk>
Link: https://patch.msgid.link/20250503043050.861238-1-dw@davidwei.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Classic netlink makes extensive use of flags. Support specifying
them the same way as attributes are specified (using a helper),
for example:
rt_link_newlink_req_set_nlflags(req, NLM_F_CREATE | NLM_F_ECHO);
Wrap the code up in a RenderInfo predicate. I think that some
genetlink families may want this, too. It should be easy to
add a spec property later.
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20250429154704.2613851-5-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Classic netlink has static family IDs specified in YAML,
there is no family name -> ID lookup. Support providing
the ID info to the library via the generated struct and
make library use it. Since NETLINK_ROUTE is ID 0 we need
an extra boolean to indicate classic_id is to be used.
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250410014658.782120-8-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
netlink reports which attribute was incorrect by sending back
an attribute offset. Offset points to the address of struct nlattr,
but to interpret the type we also need the nesting path.
Attribute IDs have different meaning in different nests
of the same message.
Correct the condition for "is the offset within current attribute".
ynl_attr_data_len() does not include the attribute header,
so the end offset was off by 4 bytes.
This means that we'd always skip over flags and empty nests.
The devmem tests, for example, issues an invalid request with
empty queue nests, resulting in the following error:
YNL failed: Kernel error: missing attribute: .queues.ifindex
The message is incorrect, "queues" nest does not have an "ifindex"
attribute defined. With this fix we decend correctly into the nest:
YNL failed: Kernel error: missing attribute: .queues.id
Fixes: 86878f14d7 ("tools: ynl: user space helpers")
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250124012130.1121227-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Donald points out that we don't check for overflows.
Stash the length of the message on nlmsg_pid (nlmsg_seq would
do as well). This allows the attribute helpers to remain
self-contained (no extra arguments). Also let the put
helpers continue to return nothing. The error is checked
only in (newly introduced) ynl_msg_end().
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://lore.kernel.org/r/20240305185000.964773-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
All callers to mnl_cb_run2() call mnl_socket_recvfrom() right before.
Wrap the two in a helper, take typed arguments (struct ynl_parse_arg),
instead of hoping that all callers remember that parser error handling
requires yarg.
In case of ynl_sock_read_family() we will no longer check for kernel
returning no data, but that would be a kernel bug, not worth complicating
the code to catch this. Calling mnl_cb_run2() on an empty buffer
is legal and results in STOP (1).
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Link: https://lore.kernel.org/r/20240227223032.1835527-9-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
All YNL parsing code expects a pointer to struct ynl_parse_arg AKA yarg.
For dump was pass in struct ynl_dump_state, which works fine, because
struct ynl_dump_state and struct ynl_parse_arg have identical layout
for the members that matter.. but it's a bit hacky.
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Link: https://lore.kernel.org/r/20240227223032.1835527-7-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Don't use mnl attr helpers, we're trying to remove the libmnl
dependency. Create both signed and unsigned helpers, libmnl
had unsigned helpers, so code generator no longer needs
the mnl_type() hack.
The new helpers are written from first principles, but are
hopefully not too buggy.
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Link: https://lore.kernel.org/r/20240227223032.1835527-3-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We never increment the group number iterator, so all groups
get recorded into index 0 of the mcast_groups[] array.
As a result YNL can only handle using the last group.
For example using the "netdev" sample on kernel with
page pool commands results in:
$ ./samples/netdev
YNL: Multicast group 'mgmt' not found
Most families have only one multicast group, so this hasn't
been noticed. Plus perhaps developers usually test the last
group which would have worked.
Fixes: 86878f14d7 ("tools: ynl: user space helpers")
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Link: https://lore.kernel.org/r/20240226214019.1255242-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
There is one common error handler in ynl - ynl_cb_error().
It expects priv to be a pointer to struct ynl_parse_arg AKA yarg.
To avoid potential crashes if we encounter a stray NLMSG_ERROR
always pass yarg as priv (or a struct which has it as the first
member).
ynl_cb_null() has a similar problem directly - it expects yarg
but priv passed by the caller is ys.
Found by code inspection.
Fixes: 86878f14d7 ("tools: ynl: user space helpers")
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Link: https://lore.kernel.org/r/20240220161112.2735195-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Support genetlink families using simple fixed headers.
Assume fixed header is identical for all ops of the family for now.
Fixed headers are added to the request and reply structs as a _hdr
member, and copied to/from netlink messages appropriately.
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://lore.kernel.org/r/20231213231432.2944749-4-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Introduce support for attribute type bitfield32.
Note that since the generated code works with struct nla_bitfield32,
the generator adds netlink.h to the list of includes for userspace
headers in case any bitfield32 is present.
Note that this is added only to genetlink-legacy scheme as requested
by Jakub Kicinski.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20231021112711.660606-3-jiri@resnulli.us
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Add "fixed" part of the user space Netlink Spec-based library.
This will get linked with the protocol implementations to form
a full API.
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
