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authorbrakmo <brakmo@fb.com>2019-05-29 02:59:36 +0300
committerAlexei Starovoitov <ast@kernel.org>2019-06-01 02:41:29 +0300
commit5cf1e91456301f8c4f6bbc63ff76cff12f92f31b (patch)
treebb669628f303c2d9e20a218c8dbed541d40504ea /kernel
parent1f52f6c0b0e846908e9c1082dab1b3f7088b82ac (diff)
downloadlinux-5cf1e91456301f8c4f6bbc63ff76cff12f92f31b.tar.xz
bpf: cgroup inet skb programs can return 0 to 3
Allows cgroup inet skb programs to return values in the range [0, 3]. The second bit is used to deterine if congestion occurred and higher level protocol should decrease rate. E.g. TCP would call tcp_enter_cwr() The bpf_prog must set expected_attach_type to BPF_CGROUP_INET_EGRESS at load time if it uses the new return values (i.e. 2 or 3). The expected_attach_type is currently not enforced for BPF_PROG_TYPE_CGROUP_SKB. e.g Meaning the current bpf_prog with expected_attach_type setting to BPF_CGROUP_INET_EGRESS can attach to BPF_CGROUP_INET_INGRESS. Blindly enforcing expected_attach_type will break backward compatibility. This patch adds a enforce_expected_attach_type bit to only enforce the expected_attach_type when it uses the new return value. Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/syscall.c12
-rw-r--r--kernel/bpf/verifier.c16
2 files changed, 25 insertions, 3 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 3d546b6f4646..1539774d78c7 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1585,6 +1585,14 @@ bpf_prog_load_check_attach_type(enum bpf_prog_type prog_type,
default:
return -EINVAL;
}
+ case BPF_PROG_TYPE_CGROUP_SKB:
+ switch (expected_attach_type) {
+ case BPF_CGROUP_INET_INGRESS:
+ case BPF_CGROUP_INET_EGRESS:
+ return 0;
+ default:
+ return -EINVAL;
+ }
default:
return 0;
}
@@ -1836,6 +1844,10 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,
case BPF_PROG_TYPE_CGROUP_SOCK:
case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
return attach_type == prog->expected_attach_type ? 0 : -EINVAL;
+ case BPF_PROG_TYPE_CGROUP_SKB:
+ return prog->enforce_expected_attach_type &&
+ prog->expected_attach_type != attach_type ?
+ -EINVAL : 0;
default:
return 0;
}
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2778417e6e0c..5c2cb5bd84ce 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5508,11 +5508,16 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
static int check_return_code(struct bpf_verifier_env *env)
{
+ struct tnum enforce_attach_type_range = tnum_unknown;
struct bpf_reg_state *reg;
struct tnum range = tnum_range(0, 1);
switch (env->prog->type) {
case BPF_PROG_TYPE_CGROUP_SKB:
+ if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) {
+ range = tnum_range(0, 3);
+ enforce_attach_type_range = tnum_range(2, 3);
+ }
case BPF_PROG_TYPE_CGROUP_SOCK:
case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
case BPF_PROG_TYPE_SOCK_OPS:
@@ -5531,18 +5536,23 @@ static int check_return_code(struct bpf_verifier_env *env)
}
if (!tnum_in(range, reg->var_off)) {
+ char tn_buf[48];
+
verbose(env, "At program exit the register R0 ");
if (!tnum_is_unknown(reg->var_off)) {
- char tn_buf[48];
-
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
verbose(env, "has value %s", tn_buf);
} else {
verbose(env, "has unknown scalar value");
}
- verbose(env, " should have been 0 or 1\n");
+ tnum_strn(tn_buf, sizeof(tn_buf), range);
+ verbose(env, " should have been %s\n", tn_buf);
return -EINVAL;
}
+
+ if (!tnum_is_unknown(enforce_attach_type_range) &&
+ tnum_in(enforce_attach_type_range, reg->var_off))
+ env->prog->enforce_expected_attach_type = 1;
return 0;
}