On 7/29/21 4:36 PM, Kuniyuki Iwashima wrote:
If there are no abstract sockets, this prog can output the same result
compared to /proc/net/unix.
# cat /sys/fs/bpf/unix | head -n 2
Num RefCount Protocol Flags Type St Inode Path
ffff9ab7122db000: 00000002 00000000 00010000 0001 01 10623 private/defer
# cat /proc/net/unix | head -n 2
Num RefCount Protocol Flags Type St Inode Path
ffff9ab7122db000: 00000002 00000000 00010000 0001 01 10623 private/defer
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxxxx>
---
.../selftests/bpf/prog_tests/bpf_iter.c | 17 +++++
.../selftests/bpf/progs/bpf_iter_unix.c | 75 +++++++++++++++++++
2 files changed, 92 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_unix.c
diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
index 1f1aade56504..4746bac68d36 100644
--- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
@@ -13,6 +13,7 @@
#include "bpf_iter_tcp6.skel.h"
#include "bpf_iter_udp4.skel.h"
#include "bpf_iter_udp6.skel.h"
+#include "bpf_iter_unix.skel.h"
#include "bpf_iter_test_kern1.skel.h"
#include "bpf_iter_test_kern2.skel.h"
#include "bpf_iter_test_kern3.skel.h"
@@ -313,6 +314,20 @@ static void test_udp6(void)
bpf_iter_udp6__destroy(skel);
}
+static void test_unix(void)
+{
+ struct bpf_iter_unix *skel;
+
+ skel = bpf_iter_unix__open_and_load();
+ if (CHECK(!skel, "bpf_iter_unix__open_and_load",
+ "skeleton open_and_load failed\n"))
+ return;
+
+ do_dummy_read(skel->progs.dump_unix);
+
+ bpf_iter_unix__destroy(skel);
+}
+
/* The expected string is less than 16 bytes */
static int do_read_with_fd(int iter_fd, const char *expected,
bool read_one_char)
@@ -1255,6 +1270,8 @@ void test_bpf_iter(void)
test_udp4();
if (test__start_subtest("udp6"))
test_udp6();
+ if (test__start_subtest("unix"))
+ test_unix();
if (test__start_subtest("anon"))
test_anon_iter(false);
if (test__start_subtest("anon-read-one-char"))
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_unix.c b/tools/testing/selftests/bpf/progs/bpf_iter_unix.c
new file mode 100644
index 000000000000..285ec2f7944d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_unix.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright Amazon.com Inc. or its affiliates. */
+#include "bpf_iter.h"
Could you add bpf_iter__unix to bpf_iter.h similar to bpf_iter__sockmap?
The main purpose is to make test tolerating with old vmlinux.h.
+#include "bpf_tracing_net.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+
+char _license[] SEC("license") = "GPL";
+
+#define __SO_ACCEPTCON (1 << 16)
+#define UNIX_HASH_SIZE 256
+#define UNIX_ABSTRACT(unix_sk) (unix_sk->addr->hash < UNIX_HASH_SIZE)
Could you add the above three define's in bpf_tracing_net.h?
We try to keep all these common defines in a common header for
potential reusability.
+
+static long sock_i_ino(const struct sock *sk)
+{
+ const struct socket *sk_socket = sk->sk_socket;
+ const struct inode *inode;
+ unsigned long ino;
+
+ if (!sk_socket)
+ return 0;
+
+ inode = &container_of(sk_socket, struct socket_alloc, socket)->vfs_inode;
+ bpf_probe_read_kernel(&ino, sizeof(ino), &inode->i_ino);
+ return ino;
+}
+
+SEC("iter/unix")
+int dump_unix(struct bpf_iter__unix *ctx)
+{
+ struct unix_sock *unix_sk = ctx->unix_sk;
+ struct sock *sk = (struct sock *)unix_sk;
+ struct seq_file *seq;
+ __u32 seq_num;
+
+ if (!unix_sk)
+ return 0;
+
+ seq = ctx->meta->seq;
+ seq_num = ctx->meta->seq_num;
+ if (seq_num == 0)
+ BPF_SEQ_PRINTF(seq, "Num RefCount Protocol Flags "
+ "Type St Inode Path\n");
+
+ BPF_SEQ_PRINTF(seq, "%pK: %08X %08X %08X %04X %02X %5lu",
+ unix_sk,
+ sk->sk_refcnt.refs.counter,
+ 0,
+ sk->sk_state == TCP_LISTEN ? __SO_ACCEPTCON : 0,
+ sk->sk_type,
+ sk->sk_socket ?
+ (sk->sk_state == TCP_ESTABLISHED ?
+ SS_CONNECTED : SS_UNCONNECTED) :
+ (sk->sk_state == TCP_ESTABLISHED ?
+ SS_CONNECTING : SS_DISCONNECTING),
+ sock_i_ino(sk));
+
+ if (unix_sk->addr) {
+ if (UNIX_ABSTRACT(unix_sk))
+ /* Abstract UNIX domain socket can contain '\0' in
+ * the path, and it should be escaped. However, it
+ * requires loops and the BPF verifier rejects it.
+ * So here, print only the escaped first byte to
+ * indicate it is an abstract UNIX domain socket.
+ * (See: unix_seq_show() and commit e7947ea770d0d)
+ */
+ BPF_SEQ_PRINTF(seq, " @");
+ else
+ BPF_SEQ_PRINTF(seq, " %s", unix_sk->addr->name->sun_path);
+ }
I looked at af_unix.c, for the above "if (unix_sk->addr) { ... }" code,
the following is the kernel source code,
if (u->addr) { // under unix_table_lock here
int i, len;
seq_putc(seq, ' ');
i = 0;
len = u->addr->len - sizeof(short);
if (!UNIX_ABSTRACT(s))
len--;
else {
seq_putc(seq, '@');
i++;
}
for ( ; i < len; i++)
seq_putc(seq, u->addr->name->sun_path[i] ?:
'@');
}
It does not seem to match bpf program non UNIX_ABSTRACT case.
I am not familiar with unix socket so it would be good if you can
explain a little more.
For verifier issue with loops, do we have a maximum upper bound for
u->addr->len? If yes, does bounded loop work?
+
+ BPF_SEQ_PRINTF(seq, "\n");
+
+ return 0;
+}
