bpf: af_unix: Implement BPF iterator for UNIX domain socket.

This patch implements the BPF iterator for the UNIX domain socket.

Currently, the batch optimisation introduced for the TCP iterator in the
commit 04c7820b776f ("bpf: tcp: Bpf iter batching and lock_sock") is not
used for the UNIX domain socket.  It will require replacing the big lock
for the hash table with small locks for each hash list not to block other
processes.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210814015718.42704-2-kuniyu@amazon.co.jp

diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h
index 57890b357f85175ac3a93be5a369c77b339aef3c..bed4b99645812ae2a99516124f3827a9f3e88b2f 100644 (file)
--- a/include/linux/btf_ids.h
+++ b/include/linux/btf_ids.h
@@ -172,7 +172,8 @@ extern struct btf_id_set name;
        BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP_TW, tcp_timewait_sock)          \
        BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP6, tcp6_sock)                    \
        BTF_SOCK_TYPE(BTF_SOCK_TYPE_UDP, udp_sock)                      \
-       BTF_SOCK_TYPE(BTF_SOCK_TYPE_UDP6, udp6_sock)
+       BTF_SOCK_TYPE(BTF_SOCK_TYPE_UDP6, udp6_sock)                    \
+       BTF_SOCK_TYPE(BTF_SOCK_TYPE_UNIX, unix_sock)
 
 enum {
 #define BTF_SOCK_TYPE(name, str) name,

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 1c2224f05b513bda98a9a9f40d5b00b158aea44f..bad8f19174e3a1ba59ca459ab8ab80ad39436508 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -113,6 +113,7 @@
 #include <linux/security.h>
 #include <linux/freezer.h>
 #include <linux/file.h>
+#include <linux/btf_ids.h>
 
 #include "scm.h"
 
@@ -3143,6 +3144,64 @@ static const struct seq_operations unix_seq_ops = {
        .stop   = unix_seq_stop,
        .show   = unix_seq_show,
 };
+
+#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL)
+struct bpf_iter__unix {
+       __bpf_md_ptr(struct bpf_iter_meta *, meta);
+       __bpf_md_ptr(struct unix_sock *, unix_sk);
+       uid_t uid __aligned(8);
+};
+
+static int unix_prog_seq_show(struct bpf_prog *prog, struct bpf_iter_meta *meta,
+                             struct unix_sock *unix_sk, uid_t uid)
+{
+       struct bpf_iter__unix ctx;
+
+       meta->seq_num--;  /* skip SEQ_START_TOKEN */
+       ctx.meta = meta;
+       ctx.unix_sk = unix_sk;
+       ctx.uid = uid;
+       return bpf_iter_run_prog(prog, &ctx);
+}
+
+static int bpf_iter_unix_seq_show(struct seq_file *seq, void *v)
+{
+       struct bpf_iter_meta meta;
+       struct bpf_prog *prog;
+       struct sock *sk = v;
+       uid_t uid;
+
+       if (v == SEQ_START_TOKEN)
+               return 0;
+
+       uid = from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk));
+       meta.seq = seq;
+       prog = bpf_iter_get_info(&meta, false);
+       return unix_prog_seq_show(prog, &meta, v, uid);
+}
+
+static void bpf_iter_unix_seq_stop(struct seq_file *seq, void *v)
+{
+       struct bpf_iter_meta meta;
+       struct bpf_prog *prog;
+
+       if (!v) {
+               meta.seq = seq;
+               prog = bpf_iter_get_info(&meta, true);
+               if (prog)
+                       (void)unix_prog_seq_show(prog, &meta, v, 0);
+       }
+
+       unix_seq_stop(seq, v);
+}
+
+static const struct seq_operations bpf_iter_unix_seq_ops = {
+       .start  = unix_seq_start,
+       .next   = unix_seq_next,
+       .stop   = bpf_iter_unix_seq_stop,
+       .show   = bpf_iter_unix_seq_show,
+};
+#endif
 #endif
 
 static const struct net_proto_family unix_family_ops = {
@@ -3183,6 +3242,35 @@ static struct pernet_operations unix_net_ops = {
        .exit = unix_net_exit,
 };
 
+#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+DEFINE_BPF_ITER_FUNC(unix, struct bpf_iter_meta *meta,
+                    struct unix_sock *unix_sk, uid_t uid)
+
+static const struct bpf_iter_seq_info unix_seq_info = {
+       .seq_ops                = &bpf_iter_unix_seq_ops,
+       .init_seq_private       = bpf_iter_init_seq_net,
+       .fini_seq_private       = bpf_iter_fini_seq_net,
+       .seq_priv_size          = sizeof(struct seq_net_private),
+};
+
+static struct bpf_iter_reg unix_reg_info = {
+       .target                 = "unix",
+       .ctx_arg_info_size      = 1,
+       .ctx_arg_info           = {
+               { offsetof(struct bpf_iter__unix, unix_sk),
+                 PTR_TO_BTF_ID_OR_NULL },
+       },
+       .seq_info               = &unix_seq_info,
+};
+
+static void __init bpf_iter_register(void)
+{
+       unix_reg_info.ctx_arg_info[0].btf_id = btf_sock_ids[BTF_SOCK_TYPE_UNIX];
+       if (bpf_iter_reg_target(&unix_reg_info))
+               pr_warn("Warning: could not register bpf iterator unix\n");
+}
+#endif
+
 static int __init af_unix_init(void)
 {
        int rc = -1;
@@ -3198,6 +3286,11 @@ static int __init af_unix_init(void)
        sock_register(&unix_family_ops);
        register_pernet_subsys(&unix_net_ops);
        unix_bpf_build_proto();
+
+#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+       bpf_iter_register();
+#endif
+
 out:
        return rc;
 }