fentry and fexit programs are similar to kprobe and kretprobe, but they
are newer and they have practically zero overhead to call before or
after kernel function. Also, fexit programs are focused on access to
arguments rather than the return value.
Those kind of programs were introduced in the following patchset:
https://lwn.net/Articles/804112/
Signed-off-by: Michal Rostecki <mrostecki@opensuse.org>
Map iteration can yield stale keys and values by virtue of sharing a
data structure with BPF programs which can modify it. However, all
accesses remain perfectly safe and will not cause memory corruption or
data races.
Map and ProgramData objects had unnecessarily cloned strings for their
names, despite them being just as easily available to external users via
bpf.maps() and bpf.programs().
This commit improves section detection.
Previously, a section named "xdp_metadata" would be interpretted as a
program section, which is incorrect. This commit first attempts to
identify a BPF section by name, then by section.kind() ==
SectionKind::Text (executable code). The computed section kind is
stored in the Section so variants can be easily matched on later.
Signed-off-by: Dave Tucker <dave@dtucker.co.uk>
When a BPF program doesn't specify the target kernel version, the
most compatible option is to set the program kernel version to match
the currently running kernel.
In kernel 4.15 and additional parameter was added to allow maps to have
names but using this breaks on older kernels.
This change makes it so the name is only added on kernels 4.15 and
newer.
This commit fixes name parsing of sk_skb sections such that both named
and unnamed variants will work correctly.
Signed-off-by: Dave Tucker <dave@dtucker.co.uk>
This change adds support for the following program types:
* raw tracepoint
* LSM
Supporting LSM programs involved a necessity of supporting more
load_attrs for the BPF_PROG_LOAD operation, concretely:
* expected_attach_type - for LSM programs, it has always to be set to
BPF_LSM_MAC
* attach_btf_obj_fd - it's often used to reference the file descriptor of
program's BTF info, altough in case of LSM programs, it only has to
contain the value 0, which means the vmlinux object file (usually
/sys/kernel/btf/vmlinux)
* attach_btf_id - ID of the BTF object, which in case of LSM programs is
the ID of the function (the LSM hook)
The example of LSM program using that functionality can be found here:
https://github.com/vadorovsky/aya-example-lsmFixes: #9
Signed-off-by: William Findlay <william@williamfindlay.com>
Signed-off-by: Michal Rostecki <mrostecki@opensuse.org>
I found a corner case in my own development workflow that caused the existing macro to not
work properly. The following changes appear to fix things. Ideally, we could add some test
cases to CI to prevent regressions. This would require creating a dedicated directory to
hold test cases so that we can "include" them at compile time.
This is a helper macro that can be used to include bytes at compile-time that can then be
used in Bpf::load(). Unlike std's include_bytes!(), this macro also ensures that the
resulting byte array is correctly aligned so that it can be parsed as an ELF binary.
Signed-off-by: William Findlay <william@williamfindlay.com>