bpf: selftests: Add bind retry for post_bind{4, 6}

With previous patch, kernel is able to 'put_port' after sys_bind()
fails. Add the test for that case: rebind another port after
sys_bind() fails. If the bind success, it means previous bind
operation is already undoed.

Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220106132022.3470772-4-imagedong@tencent.com

diff --git a/tools/testing/selftests/bpf/test_sock.c b/tools/testing/selftests/bpf/test_sock.c
index 94f9b126f5ed234d9d96a8982c0f04f18ca2a3d8..fe10f81342785df39781dc47450803c79687b6ca 100644 (file)
--- a/tools/testing/selftests/bpf/test_sock.c
+++ b/tools/testing/selftests/bpf/test_sock.c
@@ -35,12 +35,15 @@ struct sock_test {
        /* Endpoint to bind() to */
        const char *ip;
        unsigned short port;
+       unsigned short port_retry;
        /* Expected test result */
        enum {
                LOAD_REJECT,
                ATTACH_REJECT,
                BIND_REJECT,
                SUCCESS,
+               RETRY_SUCCESS,
+               RETRY_REJECT
        } result;
 };
 
@@ -251,6 +254,99 @@ static struct sock_test tests[] = {
                .port = 4098,
                .result = SUCCESS,
        },
+       {
+               .descr = "bind4 deny specific IP & port of TCP, and retry",
+               .insns = {
+                       BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+
+                       /* if (ip == expected && port == expected) */
+                       BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+                                   offsetof(struct bpf_sock, src_ip4)),
+                       BPF_JMP_IMM(BPF_JNE, BPF_REG_7,
+                                   __bpf_constant_ntohl(0x7F000001), 4),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+                                   offsetof(struct bpf_sock, src_port)),
+                       BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 0x1002, 2),
+
+                       /* return DENY; */
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_JMP_A(1),
+
+                       /* else return ALLOW; */
+                       BPF_MOV64_IMM(BPF_REG_0, 1),
+                       BPF_EXIT_INSN(),
+               },
+               .expected_attach_type = BPF_CGROUP_INET4_POST_BIND,
+               .attach_type = BPF_CGROUP_INET4_POST_BIND,
+               .domain = AF_INET,
+               .type = SOCK_STREAM,
+               .ip = "127.0.0.1",
+               .port = 4098,
+               .port_retry = 5000,
+               .result = RETRY_SUCCESS,
+       },
+       {
+               .descr = "bind4 deny specific IP & port of UDP, and retry",
+               .insns = {
+                       BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+
+                       /* if (ip == expected && port == expected) */
+                       BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+                                   offsetof(struct bpf_sock, src_ip4)),
+                       BPF_JMP_IMM(BPF_JNE, BPF_REG_7,
+                                   __bpf_constant_ntohl(0x7F000001), 4),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+                                   offsetof(struct bpf_sock, src_port)),
+                       BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 0x1002, 2),
+
+                       /* return DENY; */
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_JMP_A(1),
+
+                       /* else return ALLOW; */
+                       BPF_MOV64_IMM(BPF_REG_0, 1),
+                       BPF_EXIT_INSN(),
+               },
+               .expected_attach_type = BPF_CGROUP_INET4_POST_BIND,
+               .attach_type = BPF_CGROUP_INET4_POST_BIND,
+               .domain = AF_INET,
+               .type = SOCK_DGRAM,
+               .ip = "127.0.0.1",
+               .port = 4098,
+               .port_retry = 5000,
+               .result = RETRY_SUCCESS,
+       },
+       {
+               .descr = "bind6 deny specific IP & port, and retry",
+               .insns = {
+                       BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
+
+                       /* if (ip == expected && port == expected) */
+                       BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+                                   offsetof(struct bpf_sock, src_ip6[3])),
+                       BPF_JMP_IMM(BPF_JNE, BPF_REG_7,
+                                   __bpf_constant_ntohl(0x00000001), 4),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_6,
+                                   offsetof(struct bpf_sock, src_port)),
+                       BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 0x2001, 2),
+
+                       /* return DENY; */
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_JMP_A(1),
+
+                       /* else return ALLOW; */
+                       BPF_MOV64_IMM(BPF_REG_0, 1),
+                       BPF_EXIT_INSN(),
+               },
+               .expected_attach_type = BPF_CGROUP_INET6_POST_BIND,
+               .attach_type = BPF_CGROUP_INET6_POST_BIND,
+               .domain = AF_INET6,
+               .type = SOCK_STREAM,
+               .ip = "::1",
+               .port = 8193,
+               .port_retry = 9000,
+               .result = RETRY_SUCCESS,
+       },
        {
                .descr = "bind4 allow all",
                .insns = {
@@ -315,14 +411,15 @@ static int attach_sock_prog(int cgfd, int progfd,
        return bpf_prog_attach(progfd, cgfd, attach_type, BPF_F_ALLOW_OVERRIDE);
 }
 
-static int bind_sock(int domain, int type, const char *ip, unsigned short port)
+static int bind_sock(int domain, int type, const char *ip,
+                    unsigned short port, unsigned short port_retry)
 {
        struct sockaddr_storage addr;
        struct sockaddr_in6 *addr6;
        struct sockaddr_in *addr4;
        int sockfd = -1;
        socklen_t len;
-       int err = 0;
+       int res = SUCCESS;
 
        sockfd = socket(domain, type, 0);
        if (sockfd < 0)
@@ -348,21 +445,44 @@ static int bind_sock(int domain, int type, const char *ip, unsigned short port)
                goto err;
        }
 
-       if (bind(sockfd, (const struct sockaddr *)&addr, len) == -1)
-               goto err;
+       if (bind(sockfd, (const struct sockaddr *)&addr, len) == -1) {
+               /* sys_bind() may fail for different reasons, errno has to be
+                * checked to confirm that BPF program rejected it.
+                */
+               if (errno != EPERM)
+                       goto err;
+               if (port_retry)
+                       goto retry;
+               res = BIND_REJECT;
+               goto out;
+       }
 
+       goto out;
+retry:
+       if (domain == AF_INET)
+               addr4->sin_port = htons(port_retry);
+       else
+               addr6->sin6_port = htons(port_retry);
+       if (bind(sockfd, (const struct sockaddr *)&addr, len) == -1) {
+               if (errno != EPERM)
+                       goto err;
+               res = RETRY_REJECT;
+       } else {
+               res = RETRY_SUCCESS;
+       }
        goto out;
 err:
-       err = -1;
+       res = -1;
 out:
        close(sockfd);
-       return err;
+       return res;
 }
 
 static int run_test_case(int cgfd, const struct sock_test *test)
 {
        int progfd = -1;
        int err = 0;
+       int res;
 
        printf("Test case: %s .. ", test->descr);
        progfd = load_sock_prog(test->insns, test->expected_attach_type);
@@ -380,21 +500,11 @@ static int run_test_case(int cgfd, const struct sock_test *test)
                        goto err;
        }
 
-       if (bind_sock(test->domain, test->type, test->ip, test->port) == -1) {
-               /* sys_bind() may fail for different reasons, errno has to be
-                * checked to confirm that BPF program rejected it.
-                */
-               if (test->result == BIND_REJECT && errno == EPERM)
-                       goto out;
-               else
-                       goto err;
-       }
-
+       res = bind_sock(test->domain, test->type, test->ip, test->port,
+                       test->port_retry);
+       if (res > 0 && test->result == res)
+               goto out;
 
-       if (test->result != SUCCESS)
-               goto err;
-
-       goto out;
 err:
        err = -1;
 out: