Following discussion in the "bpf: tail calls in sleepable programs" [1], this series extends __bpf_prog_map_compatible() with additional per-program compatibility checks.
The series validates these attributes: * kprobe_write_ctx: for uprobe programs that can update pt_regs. * call_get_func_ip: for tracing programs using bpf_get_func_ip(). * call_session_cookie: for fsession programs using bpf_session_cookie(). * call_session_is_return: for fsession programs using bpf_session_is_return(). For each attribute, prog_array compatibility is one-way: programs without the requirement are rejected when tail-calling into programs that require it. This keeps tail-call runtime assumptions consistent. For example, call_get_func_ip programs rely on func_ip metadata prepared on trampoline stack; tail-calling from a !call_get_func_ip program into such a callee can produce invalid func_ip values. The same class of issue applies to call_session_cookie and call_session_is_return. Links: [1] https://lore.kernel.org/bpf/[email protected]/ Leon Hwang (8): bpf: Add fsession to verbose log in check_get_func_ip() bpf: Disallow !kprobe_write_ctx progs tail-calling kprobe_write_ctx progs bpf: Disallow !call_get_func_ip progs tail-calling call_get_func_ip progs bpf: Disallow !call_session_cookie progs tail-calling call_session_cookie progs bpf: Disallow !call_session_is_return progs tail-calling call_session_is_return progs selftests/bpf: Add a test to verify kprobe_write_ctx compatibility enforcement selftests/bpf: Add a test to verify call_get_func_ip compatibility enforcement selftests/bpf: Add a test to verify session-kfunc compatibility enforcement include/linux/bpf.h | 11 +++-- kernel/bpf/core.c | 15 ++++++ kernel/bpf/verifier.c | 4 +- .../selftests/bpf/prog_tests/attach_probe.c | 44 +++++++++++++++++ .../selftests/bpf/prog_tests/fsession_test.c | 47 +++++++++++++++++++ .../bpf/prog_tests/get_func_ip_test.c | 46 ++++++++++++++++++ .../selftests/bpf/progs/fsession_test.c | 6 +++ .../selftests/bpf/progs/get_func_ip_test.c | 6 +++ .../selftests/bpf/progs/kprobe_write_ctx.c | 6 +++ 9 files changed, 181 insertions(+), 4 deletions(-) -- 2.52.0
