kernel/tools/testing/selftests/bpf/bpf_kfuncs.h, branch linux-rolling-stable

bpf: widen dynptr size/offset to 64 bit

2025-10-27T16:56:26Z

Dynptr currently caps size and offset at 24 bits, which isn’t sufficient for file-backed use cases; even 32 bits can be limiting. Refactor dynptr helpers/kfuncs to use 64-bit size and offset, ensuring consistency across the APIs. This change does not affect internals of xdp, skb or other dynptrs, which continue to behave as before. Also it does not break binary compatibility. The widening enables large-file access support via dynptr, implemented in the next patches. Signed-off-by: Mykyta Yatsenko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20251026203853.135105-3-mykyta.yatsenko5@gmail.com Signed-off-by: Alexei Starovoitov

selftests/bpf: Cover read access to skb metadata via dynptr

2025-08-18T17:29:42Z

Exercise reading from SKB metadata area in two new ways: 1. indirectly, with bpf_dynptr_read(), and 2. directly, with bpf_dynptr_slice(). Signed-off-by: Jakub Sitnicki Signed-off-by: Martin KaFai Lau Reviewed-by: Jesse Brandeburg Acked-by: Eduard Zingerman Link: https://patch.msgid.link/20250814-skb-metadata-thru-dynptr-v7-6-8a39e636e0fb@cloudflare.com

bpf: Fix key serial argument of bpf_lookup_user_key()

2025-06-18T01:15:27Z

The underlying lookup_user_key() function uses a signed 32 bit integer for key serial numbers because legitimate serial numbers are positive (and > 3) and keyrings are negative. Using a u32 for the keyring in the bpf function doesn't currently cause any conversion problems but will start to trip the signed to unsigned conversion warnings when the kernel enables them, so convert the argument to signed (and update the tests accordingly) before it acquires more users. Signed-off-by: James Bottomley Reviewed-by: Roberto Sassu Link: https://lore.kernel.org/r/84cdb0775254d297d75e21f577089f64abdfbd28.camel@HansenPartnership.com Signed-off-by: Alexei Starovoitov

selftests/bpf: Test kfuncs that set and remove xattr from BPF programs

2025-02-14T03:35:32Z

Two sets of tests are added to exercise the not _locked and _locked version of the kfuncs. For both tests, user space accesses xattr security.bpf.foo on a testfile. The BPF program is triggered by user space access (on LSM hook inode_[set|get]_xattr) and sets or removes xattr security.bpf.bar. Then user space then validates that xattr security.bpf.bar is set or removed as expected. Note that, in both tests, the BPF programs use the not _locked kfuncs. The verifier picks the proper kfuncs based on the calling context. Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20250130213549.3353349-6-song@kernel.org Signed-off-by: Alexei Starovoitov

selftests/bpf: Add tests for bpf_get_dentry_xattr

2024-08-07T18:28:04Z

Add test for bpf_get_dentry_xattr on hook security_inode_getxattr. Verify that the kfunc can read the xattr. Also test failing getxattr from user space by returning non-zero from the LSM bpf program. Acked-by: Christian Brauner Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20240806230904.71194-4-song@kernel.org Signed-off-by: Alexei Starovoitov

bpf: Change bpf_session_cookie return value to __u64 *

2024-06-21T17:32:36Z

This reverts [1] and changes return value for bpf_session_cookie in bpf selftests. Having long * might lead to problems on 32-bit architectures. Fixes: 2b8dd87332cd ("bpf: Make bpf_session_cookie() kfunc return long *") Suggested-by: Andrii Nakryiko Signed-off-by: Jiri Olsa Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240619081624.1620152-1-jolsa@kernel.org

selftests/bpf: Add kprobe session cookie test

2024-04-30T17:23:25Z

Adding kprobe session test that verifies the cookie value get properly propagated from entry to return program. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240430112830.1184228-8-jolsa@kernel.org

selftests/bpf: Add kprobe session test

2024-04-30T17:23:01Z

Adding kprobe session test and testing that the entry program return value controls execution of the return probe program. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240430112830.1184228-7-jolsa@kernel.org

selftests/bpf: mark dynptr kfuncs __weak to make them optional on old kernels

2024-02-06T04:02:38Z

Mark dynptr kfuncs as __weak to allow verifier_global_subprogs/arg_ctx_{perf,kprobe,raw_tp} subtests to be loadable on old kernels. Because bpf_dynptr_from_xdp() kfunc is used from arg_tag_dynptr BPF program in progs/verifier_global_subprogs.c *and* is not marked as __weak, loading any subtest from verifier_global_subprogs fails on old kernels that don't have bpf_dynptr_from_xdp() kfunc defined. Even if arg_tag_dynptr program itself is not loaded, libbpf bails out on non-weak reference to bpf_dynptr_from_xdp (that can't be resolved), which shared across all programs in progs/verifier_global_subprogs.c. So mark all dynptr-related kfuncs as __weak to unblock libbpf CI ([0]). In the upcoming "kfunc in vmlinux.h" work we should make sure that kfuncs are always declared __weak as well. [0] https://github.com/libbpf/libbpf/actions/runs/7792673215/job/21251250831?pr=776#step:4:7961 Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240206004008.1541513-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov

libbpf: add bpf_core_cast() macro

2024-01-30T23:55:50Z

Add bpf_core_cast() macro that wraps bpf_rdonly_cast() kfunc. It's more ergonomic than kfunc, as it automatically extracts btf_id with bpf_core_type_id_kernel(), and works with type names. It also casts result to (T *) pointer. See the definition of the macro, it's self-explanatory. libbpf declares bpf_rdonly_cast() extern as __weak __ksym and should be safe to not conflict with other possible declarations in user code. But we do have a conflict with current BPF selftests that declare their externs with first argument as `void *obj`, while libbpf opts into more permissive `const void *obj`. This causes conflict, so we fix up BPF selftests uses in the same patch. Acked-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240130212023.183765-2-andrii@kernel.org Signed-off-by: Martin KaFai Lau