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selftests/bpf: fix -Wstrict-aliasing in test_sockopt_sk.c
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Let's use union with u8[4] and u32 members for sockopt buffer,
that should fix any possible aliasing issues.

test_sockopt_sk.c: In function ‘getsetsockopt’:
test_sockopt_sk.c:115:2: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
  if (*(__u32 *)buf != 0x55AA*2) {
  ^~
test_sockopt_sk.c:116:3: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
   log_err("Unexpected getsockopt(SO_SNDBUF) 0x%x != 0x55AA*2",
   ^~~~~~~

Fixes: 8a027dc ("selftests/bpf: add sockopt test that exercises sk helpers")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Stanislav Fomichev authored and Daniel Borkmann committed Jun 28, 2019
1 parent 2ec1899 commit 2d6dbb9
Showing 1 changed file with 24 additions and 27 deletions.
51 changes: 24 additions & 27 deletions tools/testing/selftests/bpf/test_sockopt_sk.c
Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,10 @@
static int getsetsockopt(void)
{
int fd, err;
char buf[4] = {};
union {
char u8[4];
__u32 u32;
} buf = {};
socklen_t optlen;

fd = socket(AF_INET, SOCK_STREAM, 0);
Expand All @@ -33,48 +36,48 @@ static int getsetsockopt(void)

/* IP_TOS - BPF bypass */

buf[0] = 0x08;
err = setsockopt(fd, SOL_IP, IP_TOS, buf, 1);
buf.u8[0] = 0x08;
err = setsockopt(fd, SOL_IP, IP_TOS, &buf, 1);
if (err) {
log_err("Failed to call setsockopt(IP_TOS)");
goto err;
}

buf[0] = 0x00;
buf.u8[0] = 0x00;
optlen = 1;
err = getsockopt(fd, SOL_IP, IP_TOS, buf, &optlen);
err = getsockopt(fd, SOL_IP, IP_TOS, &buf, &optlen);
if (err) {
log_err("Failed to call getsockopt(IP_TOS)");
goto err;
}

if (buf[0] != 0x08) {
if (buf.u8[0] != 0x08) {
log_err("Unexpected getsockopt(IP_TOS) buf[0] 0x%02x != 0x08",
buf[0]);
buf.u8[0]);
goto err;
}

/* IP_TTL - EPERM */

buf[0] = 1;
err = setsockopt(fd, SOL_IP, IP_TTL, buf, 1);
buf.u8[0] = 1;
err = setsockopt(fd, SOL_IP, IP_TTL, &buf, 1);
if (!err || errno != EPERM) {
log_err("Unexpected success from setsockopt(IP_TTL)");
goto err;
}

/* SOL_CUSTOM - handled by BPF */

buf[0] = 0x01;
err = setsockopt(fd, SOL_CUSTOM, 0, buf, 1);
buf.u8[0] = 0x01;
err = setsockopt(fd, SOL_CUSTOM, 0, &buf, 1);
if (err) {
log_err("Failed to call setsockopt");
goto err;
}

buf[0] = 0x00;
buf.u32 = 0x00;
optlen = 4;
err = getsockopt(fd, SOL_CUSTOM, 0, buf, &optlen);
err = getsockopt(fd, SOL_CUSTOM, 0, &buf, &optlen);
if (err) {
log_err("Failed to call getsockopt");
goto err;
Expand All @@ -84,37 +87,31 @@ static int getsetsockopt(void)
log_err("Unexpected optlen %d != 1", optlen);
goto err;
}
if (buf[0] != 0x01) {
log_err("Unexpected buf[0] 0x%02x != 0x01", buf[0]);
if (buf.u8[0] != 0x01) {
log_err("Unexpected buf[0] 0x%02x != 0x01", buf.u8[0]);
goto err;
}

/* SO_SNDBUF is overwritten */

buf[0] = 0x01;
buf[1] = 0x01;
buf[2] = 0x01;
buf[3] = 0x01;
err = setsockopt(fd, SOL_SOCKET, SO_SNDBUF, buf, 4);
buf.u32 = 0x01010101;
err = setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &buf, 4);
if (err) {
log_err("Failed to call setsockopt(SO_SNDBUF)");
goto err;
}

buf[0] = 0x00;
buf[1] = 0x00;
buf[2] = 0x00;
buf[3] = 0x00;
buf.u32 = 0x00;
optlen = 4;
err = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, buf, &optlen);
err = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &buf, &optlen);
if (err) {
log_err("Failed to call getsockopt(SO_SNDBUF)");
goto err;
}

if (*(__u32 *)buf != 0x55AA*2) {
if (buf.u32 != 0x55AA*2) {
log_err("Unexpected getsockopt(SO_SNDBUF) 0x%x != 0x55AA*2",
*(__u32 *)buf);
buf.u32);
goto err;
}

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