| Message ID | 20231207185443.2297160-1-andrii@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | BPF token support in libbpf's BPF object | expand |
On Thu, 2023-12-07 at 10:54 -0800, Andrii Nakryiko wrote: > Add fuller support for BPF token in high-level BPF object APIs. This is the > most frequently used way to work with BPF using libbpf, so supporting BPF > token there is critical. > > Patch #1 is improving kernel-side BPF_TOKEN_CREATE behavior by rejecting to > create "empty" BPF token with no delegation. This seems like saner behavior > which also makes libbpf's caching better overall. If we ever want to create > BPF token with no delegate_xxx options set on BPF FS, we can use a new flag to > enable that. > > Patches #2-#5 refactor libbpf internals, mostly feature detection code, to > prepare it from BPF token FD. > > Patch #6 adds options to pass BPF token into BPF object open options. It also > adds implicit BPF token creation logic to BPF object load step, even without > any explicit involvement of the user. If the environment is setup properly, > BPF token will be created transparently and used implicitly. This allows for > all existing application to gain BPF token support by just linking with > latest version of libbpf library. No source code modifications are required. > All that under assumption that privileged container management agent properly > set up default BPF FS instance at /sys/bpf/fs to allow BPF token creation. > > Patches #7-#8 adds more selftests, validating BPF object APIs work as expected > under unprivileged user namespaced conditions in the presence of BPF token. fwiw, I've read through this patch-set and have not noticed any issues, all seems good to me. Not sure if that worth much as I'm not terribly familiar with code base yet. [...]
On Sun, Dec 10, 2023 at 7:30 AM Eduard Zingerman <eddyz87@gmail.com> wrote: > > On Thu, 2023-12-07 at 10:54 -0800, Andrii Nakryiko wrote: > > Add fuller support for BPF token in high-level BPF object APIs. This is the > > most frequently used way to work with BPF using libbpf, so supporting BPF > > token there is critical. > > > > Patch #1 is improving kernel-side BPF_TOKEN_CREATE behavior by rejecting to > > create "empty" BPF token with no delegation. This seems like saner behavior > > which also makes libbpf's caching better overall. If we ever want to create > > BPF token with no delegate_xxx options set on BPF FS, we can use a new flag to > > enable that. > > > > Patches #2-#5 refactor libbpf internals, mostly feature detection code, to > > prepare it from BPF token FD. > > > > Patch #6 adds options to pass BPF token into BPF object open options. It also > > adds implicit BPF token creation logic to BPF object load step, even without > > any explicit involvement of the user. If the environment is setup properly, > > BPF token will be created transparently and used implicitly. This allows for > > all existing application to gain BPF token support by just linking with > > latest version of libbpf library. No source code modifications are required. > > All that under assumption that privileged container management agent properly > > set up default BPF FS instance at /sys/bpf/fs to allow BPF token creation. > > > > Patches #7-#8 adds more selftests, validating BPF object APIs work as expected > > under unprivileged user namespaced conditions in the presence of BPF token. > > fwiw, I've read through this patch-set and have not noticed any issues, > all seems good to me. Not sure if that worth much as I'm not terribly > familiar with code base yet. Every extra pair of eyes is worth it :) Not finding anything obviously broken is still a good result, thanks! > > [...]
Add fuller support for BPF token in high-level BPF object APIs. This is the most frequently used way to work with BPF using libbpf, so supporting BPF token there is critical. Patch #1 is improving kernel-side BPF_TOKEN_CREATE behavior by rejecting to create "empty" BPF token with no delegation. This seems like saner behavior which also makes libbpf's caching better overall. If we ever want to create BPF token with no delegate_xxx options set on BPF FS, we can use a new flag to enable that. Patches #2-#5 refactor libbpf internals, mostly feature detection code, to prepare it from BPF token FD. Patch #6 adds options to pass BPF token into BPF object open options. It also adds implicit BPF token creation logic to BPF object load step, even without any explicit involvement of the user. If the environment is setup properly, BPF token will be created transparently and used implicitly. This allows for all existing application to gain BPF token support by just linking with latest version of libbpf library. No source code modifications are required. All that under assumption that privileged container management agent properly set up default BPF FS instance at /sys/bpf/fs to allow BPF token creation. Patches #7-#8 adds more selftests, validating BPF object APIs work as expected under unprivileged user namespaced conditions in the presence of BPF token. Andrii Nakryiko (8): bpf: fail BPF_TOKEN_CREATE if no delegation option was set on BPF FS libbpf: split feature detectors definitions from cached results libbpf: further decouple feature checking logic from bpf_object libbpf: move feature detection code into its own file libbpf: wire up token_fd into feature probing logic libbpf: wire up BPF token support at BPF object level selftests/bpf: add BPF object loading tests with explicit token passing selftests/bpf: add tests for BPF object load with implicit token kernel/bpf/token.c | 10 +- tools/lib/bpf/Build | 2 +- tools/lib/bpf/bpf.c | 9 +- tools/lib/bpf/btf.c | 7 +- tools/lib/bpf/elf.c | 2 - tools/lib/bpf/features.c | 478 +++++++++++++++ tools/lib/bpf/libbpf.c | 570 ++++-------------- tools/lib/bpf/libbpf.h | 28 +- tools/lib/bpf/libbpf_internal.h | 36 +- tools/lib/bpf/libbpf_probes.c | 8 +- tools/lib/bpf/str_error.h | 3 + .../testing/selftests/bpf/prog_tests/token.c | 235 ++++++++ tools/testing/selftests/bpf/progs/priv_map.c | 13 + tools/testing/selftests/bpf/progs/priv_prog.c | 13 + 14 files changed, 941 insertions(+), 473 deletions(-) create mode 100644 tools/lib/bpf/features.c create mode 100644 tools/testing/selftests/bpf/progs/priv_map.c create mode 100644 tools/testing/selftests/bpf/progs/priv_prog.c