linux.git/tools/include/uapi, branch v6.1.84

bpf: Derive source IP addr via bpf_*_fib_lookup()

2024-03-06T14:45:20+00:00

commit dab4e1f06cabb6834de14264394ccab197007302 upstream.

Extend the bpf_fib_lookup() helper by making it to return the source
IPv4/IPv6 address if the BPF_FIB_LOOKUP_SRC flag is set.

For example, the following snippet can be used to derive the desired
source IP address:

    struct bpf_fib_lookup p = { .ipv4_dst = ip4->daddr };

    ret = bpf_skb_fib_lookup(skb, p, sizeof(p),
            BPF_FIB_LOOKUP_SRC | BPF_FIB_LOOKUP_SKIP_NEIGH);
    if (ret != BPF_FIB_LKUP_RET_SUCCESS)
        return TC_ACT_SHOT;

    /* the p.ipv4_src now contains the source address */

The inability to derive the proper source address may cause malfunctions
in BPF-based dataplanes for hosts containing netdevs with more than one
routable IP address or for multi-homed hosts.

For example, Cilium implements packet masquerading in BPF. If an
egressing netdev to which the Cilium's BPF prog is attached has
multiple IP addresses, then only one [hardcoded] IP address can be used for
masquerading. This breaks connectivity if any other IP address should have
been selected instead, for example, when a public and private addresses
are attached to the same egress interface.

The change was tested with Cilium [1].

Nikolay Aleksandrov helped to figure out the IPv6 addr selection.

[1]: https://github.com/cilium/cilium/pull/28283

Signed-off-by: Martynas Pumputis 
Link: https://lore.kernel.org/r/20231007081415.33502-2-m@lambda.lt
Signed-off-by: Martin KaFai Lau 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Greg Kroah-Hartman

bpf: Add table ID to bpf_fib_lookup BPF helper

2024-03-06T14:45:20+00:00

commit 8ad77e72caae22a1ddcfd0c03f2884929e93b7a4 upstream.

Add ability to specify routing table ID to the `bpf_fib_lookup` BPF
helper.

A new field `tbid` is added to `struct bpf_fib_lookup` used as
parameters to the `bpf_fib_lookup` BPF helper.

When the helper is called with the `BPF_FIB_LOOKUP_DIRECT` and
`BPF_FIB_LOOKUP_TBID` flags the `tbid` field in `struct bpf_fib_lookup`
will be used as the table ID for the fib lookup.

If the `tbid` does not exist the fib lookup will fail with
`BPF_FIB_LKUP_RET_NOT_FWDED`.

The `tbid` field becomes a union over the vlan related output fields
in `struct bpf_fib_lookup` and will be zeroed immediately after usage.

This functionality is useful in containerized environments.

For instance, if a CNI wants to dictate the next-hop for traffic leaving
a container it can create a container-specific routing table and perform
a fib lookup against this table in a "host-net-namespace-side" TC program.

This functionality also allows `ip rule` like functionality at the TC
layer, allowing an eBPF program to pick a routing table based on some
aspect of the sk_buff.

As a concrete use case, this feature will be used in Cilium's SRv6 L3VPN
datapath.

When egress traffic leaves a Pod an eBPF program attached by Cilium will
determine which VRF the egress traffic should target, and then perform a
FIB lookup in a specific table representing this VRF's FIB.

Signed-off-by: Louis DeLosSantos 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20230505-bpf-add-tbid-fib-lookup-v2-1-0a31c22c748c@gmail.com
Signed-off-by: Greg Kroah-Hartman

bpf: Add crosstask check to __bpf_get_stack

2024-01-25T23:27:24+00:00

[ Upstream commit b8e3a87a627b575896e448021e5c2f8a3bc19931 ]

Currently get_perf_callchain only supports user stack walking for
the current task. Passing the correct *crosstask* param will return
0 frames if the task passed to __bpf_get_stack isn't the current
one instead of a single incorrect frame/address. This change
passes the correct *crosstask* param but also does a preemptive
check in __bpf_get_stack if the task is current and returns
-EOPNOTSUPP if it is not.

This issue was found using bpf_get_task_stack inside a BPF
iterator ("iter/task"), which iterates over all tasks.
bpf_get_task_stack works fine for fetching kernel stacks
but because get_perf_callchain relies on the caller to know
if the requested *task* is the current one (via *crosstask*)
it was failing in a confusing way.

It might be possible to get user stacks for all tasks utilizing
something like access_process_vm but that requires the bpf
program calling bpf_get_task_stack to be sleepable and would
therefore be a breaking change.

Fixes: fa28dcb82a38 ("bpf: Introduce helper bpf_get_task_stack()")
Signed-off-by: Jordan Rome 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20231108112334.3433136-1-jordalgo@meta.com
Signed-off-by: Sasha Levin

bpf: Add BPF_FIB_LOOKUP_SKIP_NEIGH for bpf_fib_lookup

2023-10-10T20:00:42+00:00

[ Upstream commit 31de4105f00d64570139bc5494a201b0bd57349f ]

The bpf_fib_lookup() also looks up the neigh table.
This was done before bpf_redirect_neigh() was added.

In the use case that does not manage the neigh table
and requires bpf_fib_lookup() to lookup a fib to
decide if it needs to redirect or not, the bpf prog can
depend only on using bpf_redirect_neigh() to lookup the
neigh. It also keeps the neigh entries fresh and connected.

This patch adds a bpf_fib_lookup flag, SKIP_NEIGH, to avoid
the double neigh lookup when the bpf prog always call
bpf_redirect_neigh() to do the neigh lookup. The params->smac
output is skipped together when SKIP_NEIGH is set because
bpf_redirect_neigh() will figure out the smac also.

Signed-off-by: Martin KaFai Lau 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20230217205515.3583372-1-martin.lau@linux.dev
Stable-dep-of: 5baa0433a15e ("neighbour: fix data-races around n->output")
Signed-off-by: Sasha Levin

bpf: Clarify error expectations from bpf_clone_redirect

2023-10-06T12:56:55+00:00

[ Upstream commit 7cb779a6867fea00b4209bcf6de2f178a743247d ]

Commit 151e887d8ff9 ("veth: Fixing transmit return status for dropped
packets") exposed the fact that bpf_clone_redirect is capable of
returning raw NET_XMIT_XXX return codes.

This is in the conflict with its UAPI doc which says the following:
"0 on success, or a negative error in case of failure."

Update the UAPI to reflect the fact that bpf_clone_redirect can
return positive error numbers, but don't explicitly define
their meaning.

Reported-by: Daniel Borkmann 
Signed-off-by: Stanislav Fomichev 
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20230911194731.286342-1-sdf@google.com
Signed-off-by: Sasha Levin

tools headers UAPI: Sync the linux/in.h with the kernel sources

2023-06-05T07:26:22+00:00

commit 5d1ac59ff7445e51a0e4958fa39ac8aa23691698 upstream.

Picking the changes from:

  91d0b78c5177f3e4 ("inet: Add IP_LOCAL_PORT_RANGE socket option")

Silencing these perf build warnings:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/in.h' differs from latest version at 'include/uapi/linux/in.h'
  diff -u tools/include/uapi/linux/in.h include/uapi/linux/in.h

Signed-off-by: Yanteng Si 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Ian Rogers 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: loongson-kernel@lists.loongnix.cn
Link: https://lore.kernel.org/r/23aabc69956ac94fbf388b05c8be08a64e8c7ccc.1683712945.git.siyanteng@loongson.cn
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Greg Kroah-Hartman

open: return EINVAL for O_DIRECTORY | O_CREAT

2023-05-24T16:32:34+00:00

[ Upstream commit 43b450632676fb60e9faeddff285d9fac94a4f58 ]

After a couple of years and multiple LTS releases we received a report
that the behavior of O_DIRECTORY | O_CREAT changed starting with v5.7.

On kernels prior to v5.7 combinations of O_DIRECTORY, O_CREAT, O_EXCL
had the following semantics:

(1) open("/tmp/d", O_DIRECTORY | O_CREAT)
    * d doesn't exist:                create regular file
    * d exists and is a regular file: ENOTDIR
    * d exists and is a directory:    EISDIR

(2) open("/tmp/d", O_DIRECTORY | O_CREAT | O_EXCL)
    * d doesn't exist:                create regular file
    * d exists and is a regular file: EEXIST
    * d exists and is a directory:    EEXIST

(3) open("/tmp/d", O_DIRECTORY | O_EXCL)
    * d doesn't exist:                ENOENT
    * d exists and is a regular file: ENOTDIR
    * d exists and is a directory:    open directory

On kernels since to v5.7 combinations of O_DIRECTORY, O_CREAT, O_EXCL
have the following semantics:

(1) open("/tmp/d", O_DIRECTORY | O_CREAT)
    * d doesn't exist:                ENOTDIR (create regular file)
    * d exists and is a regular file: ENOTDIR
    * d exists and is a directory:    EISDIR

(2) open("/tmp/d", O_DIRECTORY | O_CREAT | O_EXCL)
    * d doesn't exist:                ENOTDIR (create regular file)
    * d exists and is a regular file: EEXIST
    * d exists and is a directory:    EEXIST

(3) open("/tmp/d", O_DIRECTORY | O_EXCL)
    * d doesn't exist:                ENOENT
    * d exists and is a regular file: ENOTDIR
    * d exists and is a directory:    open directory

This is a fairly substantial semantic change that userspace didn't
notice until Pedro took the time to deliberately figure out corner
cases. Since no one noticed this breakage we can somewhat safely assume
that O_DIRECTORY | O_CREAT combinations are likely unused.

The v5.7 breakage is especially weird because while ENOTDIR is returned
indicating failure a regular file is actually created. This doesn't make
a lot of sense.

Time was spent finding potential users of this combination. Searching on
codesearch.debian.net showed that codebases often express semantical
expectations about O_DIRECTORY | O_CREAT which are completely contrary
to what our code has done and currently does.

The expectation often is that this particular combination would create
and open a directory. This suggests users who tried to use that
combination would stumble upon the counterintuitive behavior no matter
if pre-v5.7 or post v5.7 and quickly realize neither semantics give them
what they want. For some examples see the code examples in [1] to [3]
and the discussion in [4].

There are various ways to address this issue. The lazy/simple option
would be to restore the pre-v5.7 behavior and to just live with that bug
forever. But since there's a real chance that the O_DIRECTORY | O_CREAT
quirk isn't relied upon we should try to get away with murder(ing bad
semantics) first. If we need to Frankenstein pre-v5.7 behavior later so
be it.

So let's simply return EINVAL categorically for O_DIRECTORY | O_CREAT
combinations. In addition to cleaning up the old bug this also opens up
the possiblity to make that flag combination do something more intuitive
in the future.

Starting with this commit the following semantics apply:

(1) open("/tmp/d", O_DIRECTORY | O_CREAT)
    * d doesn't exist:                EINVAL
    * d exists and is a regular file: EINVAL
    * d exists and is a directory:    EINVAL

(2) open("/tmp/d", O_DIRECTORY | O_CREAT | O_EXCL)
    * d doesn't exist:                EINVAL
    * d exists and is a regular file: EINVAL
    * d exists and is a directory:    EINVAL

(3) open("/tmp/d", O_DIRECTORY | O_EXCL)
    * d doesn't exist:                ENOENT
    * d exists and is a regular file: ENOTDIR
    * d exists and is a directory:    open directory

One additional note, O_TMPFILE is implemented as:

    #define __O_TMPFILE    020000000
    #define O_TMPFILE      (__O_TMPFILE | O_DIRECTORY)
    #define O_TMPFILE_MASK (__O_TMPFILE | O_DIRECTORY | O_CREAT)

For older kernels it was important to return an explicit error when
O_TMPFILE wasn't supported. So O_TMPFILE requires that O_DIRECTORY is
raised alongside __O_TMPFILE. It also enforced that O_CREAT wasn't
specified. Since O_DIRECTORY | O_CREAT could be used to create a regular
allowing that combination together with __O_TMPFILE would've meant that
false positives were possible, i.e., that a regular file was created
instead of a O_TMPFILE. This could've been used to trick userspace into
thinking it operated on a O_TMPFILE when it wasn't.

Now that we block O_DIRECTORY | O_CREAT completely the check for O_CREAT
in the __O_TMPFILE branch via if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
can be dropped. Instead we can simply check verify that O_DIRECTORY is
raised via if (!(flags & O_DIRECTORY)) and explain this in two comments.

As Aleksa pointed out O_PATH is unaffected by this change since it
always returned EINVAL if O_CREAT was specified - with or without
O_DIRECTORY.

Link: https://lore.kernel.org/lkml/20230320071442.172228-1-pedro.falcato@gmail.com
Link: https://sources.debian.org/src/flatpak/1.14.4-1/subprojects/libglnx/glnx-dirfd.c/?hl=324#L324 [1]
Link: https://sources.debian.org/src/flatpak-builder/1.2.3-1/subprojects/libglnx/glnx-shutil.c/?hl=251#L251 [2]
Link: https://sources.debian.org/src/ostree/2022.7-2/libglnx/glnx-dirfd.c/?hl=324#L324 [3]
Link: https://www.openwall.com/lists/oss-security/2014/11/26/14 [4]
Reported-by: Pedro Falcato 
Cc: Aleksa Sarai 
Signed-off-by: Linus Torvalds 
Signed-off-by: Christian Brauner 
Signed-off-by: Sasha Levin

tools/headers: Pull in stddef.h to uapi to fix BPF selftests build in CI

2022-11-03T12:45:21+00:00

With recent sync of linux/in.h tools/include headers are now relying on
__DECLARE_FLEX_ARRAY macro, which isn't itself defined inside
tools/include headers anywhere and is instead assumed to be present in
system-wide UAPI header. This breaks isolated environments that don't
have kernel UAPI headers installed system-wide, like BPF CI ([0]).

To fix this, bring in include/uapi/linux/stddef.h into tools/include.
We can't just copy/paste it, though, it has to be processed with
scripts/headers_install.sh, which has a dependency on scripts/unifdef.
So the full command to (re-)generate stddef.h for inclusion into
tools/include directory is:

  $ make scripts_unifdef && \
    cp $KBUILD_OUTPUT/scripts/unifdef scripts/ && \
    scripts/headers_install.sh include/uapi/linux/stddef.h tools/include/uapi/linux/stddef.h

This assumes KBUILD_OUTPUT envvar is set and used for out-of-tree builds.

  [0] https://github.com/kernel-patches/bpf/actions/runs/3379432493/jobs/5610982609

Fixes: 036b8f5b8970 ("tools headers uapi: Update linux/in.h copy")
Signed-off-by: Andrii Nakryiko 
Signed-off-by: Daniel Borkmann 
Cc: Jakub Kicinski 
Cc: Arnaldo Carvalho de Melo 
Link: https://lore.kernel.org/bpf/20221102182517.2675301-2-andrii@kernel.org

tools headers UAPI: Sync linux/perf_event.h with the kernel sources

2022-10-26T13:45:16+00:00

To pick the changes in:

  cfef80bad4cf79cd ("perf/uapi: Define PERF_MEM_SNOOPX_PEER in kernel header file")
  ee3e88dfec23153d ("perf/mem: Introduce PERF_MEM_LVLNUM_{EXTN_MEM|IO}")
  b4e12b2d70fd9ecc ("perf: Kill __PERF_SAMPLE_CALLCHAIN_EARLY")

There is a kernel patch pending that renames PERF_MEM_LVLNUM_EXTN_MEM to
PERF_MEM_LVLNUM_CXL, tooling this time is ahead of the kernel :-)

This thus partially addresses this perf build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/perf_event.h' differs from latest version at 'include/uapi/linux/perf_event.h'
  diff -u tools/include/uapi/linux/perf_event.h include/uapi/linux/perf_event.h

Cc: Adrian Hunter 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Ravi Bangoria 
Link: https://lore.kernel.org/lkml/Y1k53KMdzypmU0WS@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

tools headers uapi: Sync linux/stat.h with the kernel sources

2022-10-25T20:40:48+00:00

To pick the changes from:

  825cf206ed510c4a ("statx: add direct I/O alignment information")

That add a constant that was manually added to tools/perf/trace/beauty/statx.c,
at some point this should move to the shell based automated way.

This silences this perf build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/stat.h' differs from latest version at 'include/uapi/linux/stat.h'
  diff -u tools/include/uapi/linux/stat.h include/uapi/linux/stat.h

Cc: Eric Biggers 
Cc: Adrian Hunter 
Cc: Ian Rogers 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: https://lore.kernel.org/lkml/Y1gGQL5LonnuzeYd@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo