bpf: add tests for direct packet access from CGROUP_SKB

Tests are added to make sure CGROUP_SKB cannot access:
  tc_classid, data_meta, flow_keys

and can read and write:
  mark, prority, and cb[0-4]

and can read other fields.

To make selftest with skb->sk work, a dummy sk is added in
bpf_prog_test_run_skb().

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 0c423b8cd75cce9ada273d545216112c829964e0..c89c22c49015ff070f228bece397937d7cdce8b5 100644 (file)
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -10,6 +10,8 @@
 #include <linux/etherdevice.h>
 #include <linux/filter.h>
 #include <linux/sched/signal.h>
+#include <net/sock.h>
+#include <net/tcp.h>
 
 static __always_inline u32 bpf_test_run_one(struct bpf_prog *prog, void *ctx,
                struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE])
@@ -115,6 +117,7 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
        u32 retval, duration;
        int hh_len = ETH_HLEN;
        struct sk_buff *skb;
+       struct sock *sk;
        void *data;
        int ret;
 
@@ -137,11 +140,21 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
                break;
        }
 
+       sk = kzalloc(sizeof(struct sock), GFP_USER);
+       if (!sk) {
+               kfree(data);
+               return -ENOMEM;
+       }
+       sock_net_set(sk, current->nsproxy->net_ns);
+       sock_init_data(NULL, sk);
+
        skb = build_skb(data, 0);
        if (!skb) {
                kfree(data);
+               kfree(sk);
                return -ENOMEM;
        }
+       skb->sk = sk;
 
        skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
        __skb_put(skb, size);
@@ -159,6 +172,7 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
 
                        if (pskb_expand_head(skb, nhead, 0, GFP_USER)) {
                                kfree_skb(skb);
+                               kfree(sk);
                                return -ENOMEM;
                        }
                }
@@ -171,6 +185,7 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
                size = skb_headlen(skb);
        ret = bpf_test_finish(kattr, uattr, skb->data, size, retval, duration);
        kfree_skb(skb);
+       kfree(sk);
        return ret;
 }
 

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index cf4cd32b677255c9fe985d78dd781ac609e352aa..f1ae8d09770fc0b11c3917e6a631443aafd4606e 100644 (file)
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -4862,6 +4862,177 @@ static struct bpf_test tests[] = {
                .result = REJECT,
                .flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS,
        },
+       {
+               "direct packet read test#1 for CGROUP_SKB",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data_end)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1,
+                                   offsetof(struct __sk_buff, len)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+                                   offsetof(struct __sk_buff, pkt_type)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+                                   offsetof(struct __sk_buff, mark)),
+                       BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
+                                   offsetof(struct __sk_buff, mark)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1,
+                                   offsetof(struct __sk_buff, queue_mapping)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_8, BPF_REG_1,
+                                   offsetof(struct __sk_buff, protocol)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_1,
+                                   offsetof(struct __sk_buff, vlan_present)),
+                       BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+                       BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 8),
+                       BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
+                       BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_2, 0),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .result = ACCEPT,
+               .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+       },
+       {
+               "direct packet read test#2 for CGROUP_SKB",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1,
+                                   offsetof(struct __sk_buff, vlan_tci)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+                                   offsetof(struct __sk_buff, vlan_proto)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+                                   offsetof(struct __sk_buff, priority)),
+                       BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
+                                   offsetof(struct __sk_buff, priority)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1,
+                                   offsetof(struct __sk_buff,
+                                            ingress_ifindex)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_8, BPF_REG_1,
+                                   offsetof(struct __sk_buff, tc_index)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_1,
+                                   offsetof(struct __sk_buff, hash)),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .result = ACCEPT,
+               .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+       },
+       {
+               "direct packet read test#3 for CGROUP_SKB",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1,
+                                   offsetof(struct __sk_buff, cb[0])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+                                   offsetof(struct __sk_buff, cb[1])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+                                   offsetof(struct __sk_buff, cb[2])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1,
+                                   offsetof(struct __sk_buff, cb[3])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_8, BPF_REG_1,
+                                   offsetof(struct __sk_buff, cb[4])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_1,
+                                   offsetof(struct __sk_buff, napi_id)),
+                       BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_4,
+                                   offsetof(struct __sk_buff, cb[0])),
+                       BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_5,
+                                   offsetof(struct __sk_buff, cb[1])),
+                       BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
+                                   offsetof(struct __sk_buff, cb[2])),
+                       BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_7,
+                                   offsetof(struct __sk_buff, cb[3])),
+                       BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_8,
+                                   offsetof(struct __sk_buff, cb[4])),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .result = ACCEPT,
+               .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+       },
+       {
+               "direct packet read test#4 for CGROUP_SKB",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+                                   offsetof(struct __sk_buff, family)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+                                   offsetof(struct __sk_buff, remote_ip4)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1,
+                                   offsetof(struct __sk_buff, local_ip4)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+                                   offsetof(struct __sk_buff, remote_ip6[0])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+                                   offsetof(struct __sk_buff, remote_ip6[1])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+                                   offsetof(struct __sk_buff, remote_ip6[2])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+                                   offsetof(struct __sk_buff, remote_ip6[3])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+                                   offsetof(struct __sk_buff, local_ip6[0])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+                                   offsetof(struct __sk_buff, local_ip6[1])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+                                   offsetof(struct __sk_buff, local_ip6[2])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+                                   offsetof(struct __sk_buff, local_ip6[3])),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1,
+                                   offsetof(struct __sk_buff, remote_port)),
+                       BPF_LDX_MEM(BPF_W, BPF_REG_8, BPF_REG_1,
+                                   offsetof(struct __sk_buff, local_port)),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .result = ACCEPT,
+               .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+       },
+       {
+               "invalid access of tc_classid for CGROUP_SKB",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+                                   offsetof(struct __sk_buff, tc_classid)),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .result = REJECT,
+               .errstr = "invalid bpf_context access",
+               .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+       },
+       {
+               "invalid access of data_meta for CGROUP_SKB",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+                                   offsetof(struct __sk_buff, data_meta)),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .result = REJECT,
+               .errstr = "invalid bpf_context access",
+               .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+       },
+       {
+               "invalid access of flow_keys for CGROUP_SKB",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+                                   offsetof(struct __sk_buff, flow_keys)),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .result = REJECT,
+               .errstr = "invalid bpf_context access",
+               .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+       },
+       {
+               "invalid write access to napi_id for CGROUP_SKB",
+               .insns = {
+                       BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_1,
+                                   offsetof(struct __sk_buff, napi_id)),
+                       BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_9,
+                                   offsetof(struct __sk_buff, napi_id)),
+                       BPF_MOV64_IMM(BPF_REG_0, 0),
+                       BPF_EXIT_INSN(),
+               },
+               .result = REJECT,
+               .errstr = "invalid bpf_context access",
+               .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+       },
        {
                "valid cgroup storage access",
                .insns = {