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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 <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
This commit is contained in:
Ilya Leoshkevich 2019-10-29 15:30:27 +01:00 committed by Daniel Borkmann
parent 15ab09bdca
commit 9ffccb7606
1 changed files with 23 additions and 0 deletions
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23
tools/testing/selftests/bpf/test_sysctl.c
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@ -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 = {