[ Upstream commit 9c3de619e1 ]
When receiving netlink messages, libbpf was using a statically allocated
stack buffer of 4k bytes. This happened to work fine on systems with a 4k
page size, but on systems with larger page sizes it can lead to truncated
messages. The user-visible impact of this was that libbpf would insist no
XDP program was attached to some interfaces because that bit of the netlink
message got chopped off.
Fix this by switching to a dynamically allocated buffer; we borrow the
approach from iproute2 of using recvmsg() with MSG_PEEK|MSG_TRUNC to get
the actual size of the pending message before receiving it, adjusting the
buffer as necessary. While we're at it, also add retries on interrupted
system calls around the recvmsg() call.
v2:
- Move peek logic to libbpf_netlink_recv(), don't double free on ENOMEM.
Fixes: 8bbb77b7c7 ("libbpf: Add various netlink helpers")
Reported-by: Zhiqian Guan <zhguan@redhat.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20220211234819.612288-1-toke@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Netlink helpers I added in 8bbb77b7c7 ("libbpf: Add various netlink
helpers") used char * casts everywhere, and there were a few more that
existed from before.
Convert all of them to void * cast, as it is treated equivalently by
clang/gcc for the purposes of pointer arithmetic and to follow the
convention elsewhere in the kernel/libbpf.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210619041454.417577-2-memxor@gmail.com
Coverity complains about OOB writes to nlmsghdr. There is no OOB as we
write to the trailing buffer, but static analyzers and compilers may
rightfully be confused as the nlmsghdr pointer has subobject provenance
(and hence subobject bounds).
Fix this by using an explicit request structure containing the nlmsghdr,
struct tcmsg/ifinfomsg, and attribute buffer.
Also switch nh_tail (renamed to req_tail) to cast req * to char * so
that it can be understood as arithmetic on pointer to the representation
array (hence having same bound as request structure), which should
further appease analyzers.
As a bonus, callers don't have to pass sizeof(req) all the time now, as
size is implicitly obtained using the pointer. While at it, also reduce
the size of attribute buffer to 128 bytes (132 for ifinfomsg using
functions due to the padding).
Summary of problem:
Even though C standard allows interconvertibility of pointer to first
member and pointer to struct, for the purposes of alias analysis it
would still consider the first as having pointer value "pointer to T"
where T is type of first member hence having subobject bounds,
allowing analyzers within reason to complain when object is accessed
beyond the size of pointed to object.
The only exception to this rule may be when a char * is formed to a
member subobject. It is not possible for the compiler to be able to
tell the intent of the programmer that it is a pointer to member
object or the underlying representation array of the containing
object, so such diagnosis is suppressed.
Fixes: 715c5ce454 ("libbpf: Add low level TC-BPF management API")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210619041454.417577-1-memxor@gmail.com
This got lost during the refactoring across versions. We always use
NLM_F_EXCL when creating some TC object, so reflect what the function
says and set the flag.
Fixes: 715c5ce454 ("libbpf: Add low level TC-BPF management API")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210612023502.1283837-3-memxor@gmail.com
Coverity complained about this being unreachable code. It is right
because we already enforce flags to be unset, so a check validating
the flag value is redundant.
Fixes: 715c5ce454 ("libbpf: Add low level TC-BPF management API")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210612023502.1283837-2-memxor@gmail.com
Implement changes to error reporting for high-level libbpf APIs to make them
less surprising and less error-prone to users:
- in all the cases when error happens, errno is set to an appropriate error
value;
- in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and
error code is communicated through errno; this applies both to APIs that
already returned NULL before (so now they communicate more detailed error
codes), as well as for many APIs that used ERR_PTR() macro and encoded
error numbers as fake pointers.
- in legacy (default) mode, those APIs that were returning ERR_PTR(err),
continue doing so, but still set errno.
With these changes, errno can be always used to extract actual error,
regardless of legacy or libbpf 1.0 modes. This is utilized internally in
libbpf in places where libbpf uses it's own high-level APIs.
libbpf_get_error() is adapted to handle both cases completely transparently to
end-users (and is used by libbpf consistently as well).
More context, justification, and discussion can be found in "Libbpf: the road
to v1.0" document ([0]).
[0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210525035935.1461796-5-andrii@kernel.org
This adds functions that wrap the netlink API used for adding, manipulating,
and removing traffic control filters.
The API summary:
A bpf_tc_hook represents a location where a TC-BPF filter can be attached.
This means that creating a hook leads to creation of the backing qdisc,
while destruction either removes all filters attached to a hook, or destroys
qdisc if requested explicitly (as discussed below).
The TC-BPF API functions operate on this bpf_tc_hook to attach, replace,
query, and detach tc filters. All functions return 0 on success, and a
negative error code on failure.
bpf_tc_hook_create - Create a hook
Parameters:
@hook - Cannot be NULL, ifindex > 0, attach_point must be set to
proper enum constant. Note that parent must be unset when
attach_point is one of BPF_TC_INGRESS or BPF_TC_EGRESS. Note
that as an exception BPF_TC_INGRESS|BPF_TC_EGRESS is also a
valid value for attach_point.
Returns -EOPNOTSUPP when hook has attach_point as BPF_TC_CUSTOM.
bpf_tc_hook_destroy - Destroy a hook
Parameters:
@hook - Cannot be NULL. The behaviour depends on value of
attach_point. If BPF_TC_INGRESS, all filters attached to
the ingress hook will be detached. If BPF_TC_EGRESS, all
filters attached to the egress hook will be detached. If
BPF_TC_INGRESS|BPF_TC_EGRESS, the clsact qdisc will be
deleted, also detaching all filters. As before, parent must
be unset for these attach_points, and set for BPF_TC_CUSTOM.
It is advised that if the qdisc is operated on by many programs,
then the program at least check that there are no other existing
filters before deleting the clsact qdisc. An example is shown
below:
DECLARE_LIBBPF_OPTS(bpf_tc_hook, .ifindex = if_nametoindex("lo"),
.attach_point = BPF_TC_INGRESS);
/* set opts as NULL, as we're not really interested in
* getting any info for a particular filter, but just
* detecting its presence.
*/
r = bpf_tc_query(&hook, NULL);
if (r == -ENOENT) {
/* no filters */
hook.attach_point = BPF_TC_INGRESS|BPF_TC_EGREESS;
return bpf_tc_hook_destroy(&hook);
} else {
/* failed or r == 0, the latter means filters do exist */
return r;
}
Note that there is a small race between checking for no
filters and deleting the qdisc. This is currently unavoidable.
Returns -EOPNOTSUPP when hook has attach_point as BPF_TC_CUSTOM.
bpf_tc_attach - Attach a filter to a hook
Parameters:
@hook - Cannot be NULL. Represents the hook the filter will be
attached to. Requirements for ifindex and attach_point are
same as described in bpf_tc_hook_create, but BPF_TC_CUSTOM
is also supported. In that case, parent must be set to the
handle where the filter will be attached (using BPF_TC_PARENT).
E.g. to set parent to 1:16 like in tc command line, the
equivalent would be BPF_TC_PARENT(1, 16).
@opts - Cannot be NULL. The following opts are optional:
* handle - The handle of the filter
* priority - The priority of the filter
Must be >= 0 and <= UINT16_MAX
Note that when left unset, they will be auto-allocated by
the kernel. The following opts must be set:
* prog_fd - The fd of the loaded SCHED_CLS prog
The following opts must be unset:
* prog_id - The ID of the BPF prog
The following opts are optional:
* flags - Currently only BPF_TC_F_REPLACE is allowed. It
allows replacing an existing filter instead of
failing with -EEXIST.
The following opts will be filled by bpf_tc_attach on a
successful attach operation if they are unset:
* handle - The handle of the attached filter
* priority - The priority of the attached filter
* prog_id - The ID of the attached SCHED_CLS prog
This way, the user can know what the auto allocated values
for optional opts like handle and priority are for the newly
attached filter, if they were unset.
Note that some other attributes are set to fixed default
values listed below (this holds for all bpf_tc_* APIs):
protocol as ETH_P_ALL, direct action mode, chain index of 0,
and class ID of 0 (this can be set by writing to the
skb->tc_classid field from the BPF program).
bpf_tc_detach
Parameters:
@hook - Cannot be NULL. Represents the hook the filter will be
detached from. Requirements are same as described above
in bpf_tc_attach.
@opts - Cannot be NULL. The following opts must be set:
* handle, priority
The following opts must be unset:
* prog_fd, prog_id, flags
bpf_tc_query
Parameters:
@hook - Cannot be NULL. Represents the hook where the filter lookup will
be performed. Requirements are same as described above in
bpf_tc_attach().
@opts - Cannot be NULL. The following opts must be set:
* handle, priority
The following opts must be unset:
* prog_fd, prog_id, flags
The following fields will be filled by bpf_tc_query upon a
successful lookup:
* prog_id
Some usage examples (using BPF skeleton infrastructure):
BPF program (test_tc_bpf.c):
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
SEC("classifier")
int cls(struct __sk_buff *skb)
{
return 0;
}
Userspace loader:
struct test_tc_bpf *skel = NULL;
int fd, r;
skel = test_tc_bpf__open_and_load();
if (!skel)
return -ENOMEM;
fd = bpf_program__fd(skel->progs.cls);
DECLARE_LIBBPF_OPTS(bpf_tc_hook, hook, .ifindex =
if_nametoindex("lo"), .attach_point =
BPF_TC_INGRESS);
/* Create clsact qdisc */
r = bpf_tc_hook_create(&hook);
if (r < 0)
goto end;
DECLARE_LIBBPF_OPTS(bpf_tc_opts, opts, .prog_fd = fd);
r = bpf_tc_attach(&hook, &opts);
if (r < 0)
goto end;
/* Print the auto allocated handle and priority */
printf("Handle=%u", opts.handle);
printf("Priority=%u", opts.priority);
opts.prog_fd = opts.prog_id = 0;
bpf_tc_detach(&hook, &opts);
end:
test_tc_bpf__destroy(skel);
This is equivalent to doing the following using tc command line:
# tc qdisc add dev lo clsact
# tc filter add dev lo ingress bpf obj foo.o sec classifier da
# tc filter del dev lo ingress handle <h> prio <p> bpf
... where the handle and priority can be found using:
# tc filter show dev lo ingress
Another example replacing a filter (extending prior example):
/* We can also choose both (or one), let's try replacing an
* existing filter.
*/
DECLARE_LIBBPF_OPTS(bpf_tc_opts, replace_opts, .handle =
opts.handle, .priority = opts.priority,
.prog_fd = fd);
r = bpf_tc_attach(&hook, &replace_opts);
if (r == -EEXIST) {
/* Expected, now use BPF_TC_F_REPLACE to replace it */
replace_opts.flags = BPF_TC_F_REPLACE;
return bpf_tc_attach(&hook, &replace_opts);
} else if (r < 0) {
return r;
}
/* There must be no existing filter with these
* attributes, so cleanup and return an error.
*/
replace_opts.prog_fd = replace_opts.prog_id = 0;
bpf_tc_detach(&hook, &replace_opts);
return -1;
To obtain info of a particular filter:
/* Find info for filter with handle 1 and priority 50 */
DECLARE_LIBBPF_OPTS(bpf_tc_opts, info_opts, .handle = 1,
.priority = 50);
r = bpf_tc_query(&hook, &info_opts);
if (r == -ENOENT)
printf("Filter not found");
else if (r < 0)
return r;
printf("Prog ID: %u", info_opts.prog_id);
return 0;
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net> # libbpf API design
[ Daniel: also did major patch cleanup ]
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210512103451.989420-3-memxor@gmail.com
This change introduces a few helpers to wrap open coded attribute
preparation in netlink.c. It also adds a libbpf_netlink_send_recv() that
is useful to wrap send + recv handling in a generic way. Subsequent patch
will also use this function for sending and receiving a netlink response.
The libbpf_nl_get_link() helper has been removed instead, moving socket
creation into the newly named libbpf_netlink_send_recv().
Every nested attribute's closure must happen using the helper
nlattr_end_nested(), which sets its length properly. NLA_F_NESTED is
enforced using nlattr_begin_nested() helper. Other simple attributes
can be added directly.
The maxsz parameter corresponds to the size of the request structure
which is being filled in, so for instance with req being:
struct {
struct nlmsghdr nh;
struct tcmsg t;
char buf[4096];
} req;
Then, maxsz should be sizeof(req).
This change also converts the open coded attribute preparation with these
helpers. Note that the only failure the internal call to nlattr_add()
could result in the nested helper would be -EMSGSIZE, hence that is what
we return to our caller.
The libbpf_netlink_send_recv() call takes care of opening the socket,
sending the netlink message, receiving the response, potentially invoking
callbacks, and return errors if any, and then finally close the socket.
This allows users to avoid identical socket setup code in different places.
The only user of libbpf_nl_get_link() has been converted to make use of it.
__bpf_set_link_xdp_fd_replace() has also been refactored to use it.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
[ Daniel: major patch cleanup ]
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210512103451.989420-2-memxor@gmail.com
Otherwise, there exists a small window between the opening and closing
of the socket fd where it may leak into processes launched by some other
thread.
Fixes: 949abbe884 ("libbpf: add function to setup XDP")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210317115857.6536-1-memxor@gmail.com
Most of libbpf source files already include libbpf_internal.h, so it's a good
place to centralize identifier poisoning. So move kernel integer type
poisoning there. And also add reallocarray to a poison list to prevent
accidental use of it. libbpf_reallocarray() should be used universally
instead.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200819013607.3607269-4-andriin@fb.com
Most netlink-related functions were unique to bpftool usage, so I moved them
into net.c. Few functions are still used by both bpftool and libbpf itself
internally, so I've copy-pasted them (libbpf_nl_get_link,
libbpf_netlink_open). It's a bit of duplication of code, but better separation
of libbpf as a library with public API and bpftool, relying on unexposed
functions in libbpf.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200819013607.3607269-3-andriin@fb.com
The commit in the Fixes tag changed get_xdp_id to only return prog_id
if flags is 0, but there are other XDP flags than the modes - e.g.,
XDP_FLAGS_UPDATE_IF_NOEXIST. Since the intention was only to look at
MODE flags, clear other ones before checking if flags is 0.
Fixes: f07cbad297 ("libbpf: Fix bpf_get_link_xdp_id flags handling")
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrey Ignatov <rdna@fb.com>
Currently if one of XDP_FLAGS_{DRV,HW,SKB}_MODE flags is passed to
bpf_get_link_xdp_id() and there is a single XDP program attached to
ifindex, that program's id will be returned by bpf_get_link_xdp_id() in
prog_id argument no matter what mode the program is attached in, i.e.
flags argument is not taken into account.
For example, if there is a single program attached with
XDP_FLAGS_SKB_MODE but user calls bpf_get_link_xdp_id() with flags =
XDP_FLAGS_DRV_MODE, that skb program will be returned.
Fix it by returning info->prog_id only if user didn't specify flags. If
flags is specified then return corresponding mode-specific-field from
struct xdp_link_info.
The initial error was introduced in commit 50db9f0731 ("libbpf: Add a
support for getting xdp prog id on ifindex") and then refactored in
473f4e133a so 473f4e133a is used in the Fixes tag.
Fixes: 473f4e133a ("libbpf: Add bpf_get_link_xdp_info() function to get more XDP information")
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/0e9e30490b44b447bb2bebc69c7135e7fe7e4e40.1586236080.git.rdna@fb.com
Builds of Fedora's kernel-tools package started to fail with "may be
used uninitialized" warnings for nl_pid in bpf_set_link_xdp_fd() and
bpf_get_link_xdp_info() on the s390 architecture.
Although libbpf_netlink_open() always returns a negative number when it
does not set *nl_pid, the compiler does not determine this and thus
believes the variable might be used uninitialized. Assuage gcc's fears
by explicitly initializing nl_pid.
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1807781
Signed-off-by: Jeremy Cline <jcline@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200404051430.698058-1-jcline@redhat.com
This adds a new function to set the XDP fd while specifying the FD of the
program to replace, using the newly added IFLA_XDP_EXPECTED_FD netlink
parameter. The new function uses the opts struct mechanism to be extendable
in the future.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158515700857.92963.7052131201257841700.stgit@toke.dk
It's been a recurring issue with types like u32 slipping into libbpf source
code accidentally. This is not detected during builds inside kernel source
tree, but becomes a compilation error in libbpf's Github repo. Libbpf is
supposed to use only __{s,u}{8,16,32,64} typedefs, so poison {s,u}{8,16,32,64}
explicitly in every .c file. Doing that in a bit more centralized way, e.g.,
inside libbpf_internal.h breaks selftests, which are both using kernel u32 and
libbpf_internal.h.
This patch also fixes a new u32 occurence in libbpf.c, added recently.
Fixes: 590a008882 ("bpf: libbpf: Add STRUCT_OPS support")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200110181916.271446-1-andriin@fb.com
Currently, libbpf only provides a function to get a single ID for the XDP
program attached to the interface. However, it can be useful to get the
full set of program IDs attached, along with the attachment mode, in one
go. Add a new getter function to support this, using an extendible
structure to carry the information. Express the old bpf_get_link_id()
function in terms of the new function.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/157333185164.88376.7520653040667637246.stgit@toke.dk
The netlink functions were using fprintf(stderr, ) directly to print out
error messages, instead of going through the usual logging macros. This
makes it impossible for the calling application to silence or redirect
those error messages. Fix this by switching to pr_warn() in nlattr.c and
netlink.c.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/157333185055.88376.15999360127117901443.stgit@toke.dk
Since we have a dedicated netlink attributes for xdp setup on a
particular interface, it is now possible to retrieve the program id that
is currently attached to the interface. The use case is targeted for
sample xdp programs, which will store the program id just after loading
bpf program onto iface. On shutdown, the sample will make sure that it
can unload the program by querying again the iface and verifying that
both program id's matches.
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
libbpf is maturing as a library and gaining features that no other bpf libraries support
(BPF Type Format, bpf to bpf calls, etc)
Many Apache2 licensed projects (like bcc, bpftrace, gobpf, cilium, etc)
would like to use libbpf, but cannot do this yet, since Apache Foundation explicitly
states that LGPL is incompatible with Apache2.
Hence let's relicense libbpf as dual license LGPL-2.1 or BSD-2-Clause,
since BSD-2 is compatible with Apache2.
Dual LGPL or Apache2 is invalid combination.
Fix license mistake in Makefile as well.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: David Beckett <david.beckett@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Joe Stringer <joe@ovn.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
libbpf is used more and more outside kernel tree. That means the library
should follow good practices in library design and implementation to
play well with third party code that uses it.
One of such practices is to have a common prefix (or a few) for every
interface, function or data structure, library provides. I helps to
avoid name conflicts with other libraries and keeps API consistent.
Inconsistent names in libbpf already cause problems in real life. E.g.
an application can't use both libbpf and libnl due to conflicting
symbols.
Having common prefix will help to fix current and avoid future problems.
libbpf already uses the following prefixes for its interfaces:
* bpf_ for bpf system call wrappers, program/map/elf-object
abstractions and a few other things;
* btf_ for BTF related API;
* libbpf_ for everything else.
The patch adds libbpf_ prefix to interfaces in nlattr.h that use none of
mentioned above prefixes and doesn't fit well into the first two
categories.
Since affected part of API is used in bpftool, the patch applies
corresponding change to bpftool as well. Having it in a separate patch
will cause a state of tree where bpftool is broken what may not be a
good idea.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
libbpf is used more and more outside kernel tree. That means the library
should follow good practices in library design and implementation to
play well with third party code that uses it.
One of such practices is to have a common prefix (or a few) for every
interface, function or data structure, library provides. I helps to
avoid name conflicts with other libraries and keeps API consistent.
Inconsistent names in libbpf already cause problems in real life. E.g.
an application can't use both libbpf and libnl due to conflicting
symbols.
Having common prefix will help to fix current and avoid future problems.
libbpf already uses the following prefixes for its interfaces:
* bpf_ for bpf system call wrappers, program/map/elf-object
abstractions and a few other things;
* btf_ for BTF related API;
* libbpf_ for everything else.
The patch adds libbpf_ prefix to functions and typedef in libbpf.h that
use none of mentioned above prefixes and doesn't fit well into the first
two categories.
Since affected part of API is used in bpftool, the patch applies
corresponding change to bpftool as well. Having it in a separate patch
will cause a state of tree where bpftool is broken what may not be a
good idea.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This typedef is used only by implementation in netlink.c. Nothing uses
it in public API. Move it to netlink.c.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Commit f7010770fb ("tools/bpf: move bpf/lib netlink related
functions into a new file") introduced a while loop for the
netlink recv path. This while loop is needed since the
buffer in recv syscall may not be enough to hold all the
information and in such cases multiple recv calls are needed.
There is a bug introduced by the above commit as
the while loop may block on recv syscall if there is no
more messages are expected. The netlink message header
flag NLM_F_MULTI is used to indicate that more messages
are expected and this patch fixed the bug by doing
further recv syscall only if multipart message is expected.
The patch added another fix regarding to message length of 0.
When netlink recv returns message length of 0, there will be
no more messages for returning data so the while loop
can end.
Fixes: f7010770fb ("tools/bpf: move bpf/lib netlink related functions into a new file")
Reported-by: Björn Töpel <bjorn.topel@intel.com>
Tested-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch added a few netlink attribute parsing functions
and the netlink API functions to query networking links, tc classes,
tc qdiscs and tc filters. For example, the following API is
to get networking links:
int nl_get_link(int sock, unsigned int nl_pid,
dump_nlmsg_t dump_link_nlmsg,
void *cookie);
Note that when the API is called, the user also provided a
callback function with the following signature:
int (*dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);
The "cookie" is the parameter the user passed to the API and will
be available for the callback function.
The "msg" is the information about the result, e.g., ifinfomsg or
tcmsg. The "tb" is the parsed netlink attributes.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
There are no functionality change for this patch.
In the subsequent patches, more netlink related library functions
will be added and a separate file is better than cluttering bpf.c.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Andrii Nakryiko
Toke Høiland-Jørgensen
Kumar Kartikeya Dwivedi
Andrii Nakryiko
David Ahern
Andrey Ignatov
Jeremy Cline
Maciej Fijalkowski
Alexei Starovoitov
Yonghong Song