selftests/bpf: Test narrow load from bpf_sysctl.write (9ffccb76) · Commits · 戴 / test

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 <rdna@fb.com> Signed-off-by:

Ilya Leoshkevich <iii@linux.ibm.com> Signed-off-by:

Daniel Borkmann <daniel@iogearbox.net> Acked-by:

Andrey Ignatov <rdna@fb.com> Link: https://lore.kernel.org/bpf/20191029143027.28681-1-iii@linux.ibm.com

tools/testing/selftests/bpf/test_sysctl.c

+23 −0

Original line number	Diff line number	Diff line
		@@ -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 = {

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