From 9ffccb76062ab882e45bbfb9d370e366c27fa04b Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Tue, 29 Oct 2019 15:30:27 +0100 Subject: [PATCH] selftests/bpf: Test narrow load from bpf_sysctl.write There are tests for full and narrows loads from bpf_sysctl.file_pos, but for bpf_sysctl.write only full load is tested. Add the missing test. Suggested-by: Andrey Ignatov Signed-off-by: Ilya Leoshkevich Signed-off-by: Daniel Borkmann Acked-by: Andrey Ignatov Link: https://lore.kernel.org/bpf/20191029143027.28681-1-iii@linux.ibm.com --- tools/testing/selftests/bpf/test_sysctl.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/tools/testing/selftests/bpf/test_sysctl.c b/tools/testing/selftests/bpf/test_sysctl.c index a320e3844b17..7aff907003d3 100644 --- a/tools/testing/selftests/bpf/test_sysctl.c +++ b/tools/testing/selftests/bpf/test_sysctl.c @@ -120,6 +120,29 @@ static struct sysctl_test tests[] = { .newval = "(none)", /* same as default, should fail anyway */ .result = OP_EPERM, }, + { + .descr = "ctx:write sysctl:write read ok narrow", + .insns = { + /* u64 w = (u16)write & 1; */ +#if __BYTE_ORDER == __LITTLE_ENDIAN + BPF_LDX_MEM(BPF_H, BPF_REG_7, BPF_REG_1, + offsetof(struct bpf_sysctl, write)), +#else + BPF_LDX_MEM(BPF_H, BPF_REG_7, BPF_REG_1, + offsetof(struct bpf_sysctl, write) + 2), +#endif + BPF_ALU64_IMM(BPF_AND, BPF_REG_7, 1), + /* return 1 - w; */ + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_ALU64_REG(BPF_SUB, BPF_REG_0, BPF_REG_7), + BPF_EXIT_INSN(), + }, + .attach_type = BPF_CGROUP_SYSCTL, + .sysctl = "kernel/domainname", + .open_flags = O_WRONLY, + .newval = "(none)", /* same as default, should fail anyway */ + .result = OP_EPERM, + }, { .descr = "ctx:write sysctl:read write reject", .insns = {