diff options
author | Alexei Starovoitov <ast@kernel.org> | 2020-08-26 12:47:57 -0700 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2020-08-26 12:50:36 -0700 |
commit | 1fc0e18b6e06cbc174a814d8fe69d37212287d1f (patch) | |
tree | 9c85e9701630619b177f54108794bed961bd1b93 | |
parent | 7100ff7c62682c2332300ffde8706578e1098e13 (diff) | |
parent | 1410620cf20e7e23cce17983e9a81af659b28583 (diff) |
Merge branch 'resolve_prog_type'
Udip Pant says:
====================
This patch series adds changes in verifier to make decisions such as granting
of read / write access or enforcement of return code status based on
the program type of the target program while using dynamic program
extension (of type BPF_PROG_TYPE_EXT).
The BPF_PROG_TYPE_EXT type can be used to extend types such as XDP, SKB
and others. Since the BPF_PROG_TYPE_EXT program type on itself is just a
placeholder for those, we need this extended check for those extended
programs to actually work with proper access, while using this option.
Patch #1 includes changes in the verifier.
Patch #2 adds selftests to verify write access on a packet for a valid
extension program type
Patch #3 adds selftests to verify proper check for the return code
Patch #4 adds selftests to ensure access permissions and restrictions
for some map types such sockmap.
Changelogs:
v2 -> v3:
* more comprehensive resolution of the program type in the verifier
based on the target program (and not just for the packet access)
* selftests for checking return code and map access
* Also moved this patch to 'bpf-next' from 'bpf' tree
v1 -> v2:
* extraction of the logic to resolve prog type into a separate method
* selftests to check for packet access for a valid freplace prog
====================
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
-rw-r--r-- | kernel/bpf/verifier.c | 32 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c | 68 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c | 27 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/freplace_attach_probe.c | 40 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/freplace_cls_redirect.c | 34 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/freplace_connect_v4_prog.c | 19 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/test_pkt_access.c | 20 |
7 files changed, 229 insertions, 11 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7e5908b83ec7..8a097a85d01b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2625,11 +2625,19 @@ static int check_map_access(struct bpf_verifier_env *env, u32 regno, #define MAX_PACKET_OFF 0xffff +static enum bpf_prog_type resolve_prog_type(struct bpf_prog *prog) +{ + return prog->aux->linked_prog ? prog->aux->linked_prog->type + : prog->type; +} + static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, const struct bpf_call_arg_meta *meta, enum bpf_access_type t) { - switch (env->prog->type) { + enum bpf_prog_type prog_type = resolve_prog_type(env->prog); + + switch (prog_type) { /* Program types only with direct read access go here! */ case BPF_PROG_TYPE_LWT_IN: case BPF_PROG_TYPE_LWT_OUT: @@ -4186,7 +4194,7 @@ err_type: static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id) { enum bpf_attach_type eatype = env->prog->expected_attach_type; - enum bpf_prog_type type = env->prog->type; + enum bpf_prog_type type = resolve_prog_type(env->prog); if (func_id != BPF_FUNC_map_update_elem) return false; @@ -7376,7 +7384,7 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) u8 mode = BPF_MODE(insn->code); int i, err; - if (!may_access_skb(env->prog->type)) { + if (!may_access_skb(resolve_prog_type(env->prog))) { verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n"); return -EINVAL; } @@ -7464,11 +7472,12 @@ static int check_return_code(struct bpf_verifier_env *env) const struct bpf_prog *prog = env->prog; struct bpf_reg_state *reg; struct tnum range = tnum_range(0, 1); + enum bpf_prog_type prog_type = resolve_prog_type(env->prog); int err; /* LSM and struct_ops func-ptr's return type could be "void" */ - if ((env->prog->type == BPF_PROG_TYPE_STRUCT_OPS || - env->prog->type == BPF_PROG_TYPE_LSM) && + if ((prog_type == BPF_PROG_TYPE_STRUCT_OPS || + prog_type == BPF_PROG_TYPE_LSM) && !prog->aux->attach_func_proto->type) return 0; @@ -7487,7 +7496,7 @@ static int check_return_code(struct bpf_verifier_env *env) return -EACCES; } - switch (env->prog->type) { + switch (prog_type) { case BPF_PROG_TYPE_CGROUP_SOCK_ADDR: if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG || env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG || @@ -9243,6 +9252,7 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env, struct bpf_prog *prog) { + enum bpf_prog_type prog_type = resolve_prog_type(prog); /* * Validate that trace type programs use preallocated hash maps. * @@ -9260,8 +9270,8 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env, * now, but warnings are emitted so developers are made aware of * the unsafety and can fix their programs before this is enforced. */ - if (is_tracing_prog_type(prog->type) && !is_preallocated_map(map)) { - if (prog->type == BPF_PROG_TYPE_PERF_EVENT) { + if (is_tracing_prog_type(prog_type) && !is_preallocated_map(map)) { + if (prog_type == BPF_PROG_TYPE_PERF_EVENT) { verbose(env, "perf_event programs can only use preallocated hash map\n"); return -EINVAL; } @@ -9273,8 +9283,8 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env, verbose(env, "trace type programs with run-time allocated hash maps are unsafe. Switch to preallocated hash maps.\n"); } - if ((is_tracing_prog_type(prog->type) || - prog->type == BPF_PROG_TYPE_SOCKET_FILTER) && + if ((is_tracing_prog_type(prog_type) || + prog_type == BPF_PROG_TYPE_SOCKET_FILTER) && map_value_has_spin_lock(map)) { verbose(env, "tracing progs cannot use bpf_spin_lock yet\n"); return -EINVAL; @@ -9986,7 +9996,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) insn->code = BPF_LDX | BPF_PROBE_MEM | BPF_SIZE((insn)->code); env->prog->aux->num_exentries++; - } else if (env->prog->type != BPF_PROG_TYPE_STRUCT_OPS) { + } else if (resolve_prog_type(env->prog) != BPF_PROG_TYPE_STRUCT_OPS) { verbose(env, "Writes through BTF pointers are not allowed\n"); return -EINVAL; } diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c index 197d0d217b56..a550dab9ba7a 100644 --- a/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c +++ b/tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c @@ -123,6 +123,7 @@ static void test_func_replace(void) "freplace/get_skb_len", "freplace/get_skb_ifindex", "freplace/get_constant", + "freplace/test_pkt_write_access_subprog", }; test_fexit_bpf2bpf_common("./fexit_bpf2bpf.o", "./test_pkt_access.o", @@ -141,10 +142,77 @@ static void test_func_replace_verify(void) prog_name, false); } +static void test_func_sockmap_update(void) +{ + const char *prog_name[] = { + "freplace/cls_redirect", + }; + test_fexit_bpf2bpf_common("./freplace_cls_redirect.o", + "./test_cls_redirect.o", + ARRAY_SIZE(prog_name), + prog_name, false); +} + +static void test_obj_load_failure_common(const char *obj_file, + const char *target_obj_file) + +{ + /* + * standalone test that asserts failure to load freplace prog + * because of invalid return code. + */ + struct bpf_object *obj = NULL, *pkt_obj; + int err, pkt_fd; + __u32 duration = 0; + + err = bpf_prog_load(target_obj_file, BPF_PROG_TYPE_UNSPEC, + &pkt_obj, &pkt_fd); + /* the target prog should load fine */ + if (CHECK(err, "tgt_prog_load", "file %s err %d errno %d\n", + target_obj_file, err, errno)) + return; + DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts, + .attach_prog_fd = pkt_fd, + ); + + obj = bpf_object__open_file(obj_file, &opts); + if (CHECK(IS_ERR_OR_NULL(obj), "obj_open", + "failed to open %s: %ld\n", obj_file, + PTR_ERR(obj))) + goto close_prog; + + /* It should fail to load the program */ + err = bpf_object__load(obj); + if (CHECK(!err, "bpf_obj_load should fail", "err %d\n", err)) + goto close_prog; + +close_prog: + if (!IS_ERR_OR_NULL(obj)) + bpf_object__close(obj); + bpf_object__close(pkt_obj); +} + +static void test_func_replace_return_code(void) +{ + /* test invalid return code in the replaced program */ + test_obj_load_failure_common("./freplace_connect_v4_prog.o", + "./connect4_prog.o"); +} + +static void test_func_map_prog_compatibility(void) +{ + /* test with spin lock map value in the replaced program */ + test_obj_load_failure_common("./freplace_attach_probe.o", + "./test_attach_probe.o"); +} + void test_fexit_bpf2bpf(void) { test_target_no_callees(); test_target_yes_callees(); test_func_replace(); test_func_replace_verify(); + test_func_sockmap_update(); + test_func_replace_return_code(); + test_func_map_prog_compatibility(); } diff --git a/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c b/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c index 98e1efe14549..49a84a3a2306 100644 --- a/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c +++ b/tools/testing/selftests/bpf/progs/fexit_bpf2bpf.c @@ -1,8 +1,10 @@ // SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2019 Facebook */ #include <linux/stddef.h> +#include <linux/if_ether.h> #include <linux/ipv6.h> #include <linux/bpf.h> +#include <linux/tcp.h> #include <bpf/bpf_helpers.h> #include <bpf/bpf_endian.h> #include <bpf/bpf_tracing.h> @@ -151,4 +153,29 @@ int new_get_constant(long val) test_get_constant = 1; return test_get_constant; /* original get_constant() returns val - 122 */ } + +__u64 test_pkt_write_access_subprog = 0; +SEC("freplace/test_pkt_write_access_subprog") +int new_test_pkt_write_access_subprog(struct __sk_buff *skb, __u32 off) +{ + + void *data = (void *)(long)skb->data; + void *data_end = (void *)(long)skb->data_end; + struct tcphdr *tcp; + + if (off > sizeof(struct ethhdr) + sizeof(struct ipv6hdr)) + return -1; + + tcp = data + off; + if (tcp + 1 > data_end) + return -1; + + /* make modifications to the packet data */ + tcp->check++; + tcp->syn = 0; + + test_pkt_write_access_subprog = 1; + return 0; +} + char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/freplace_attach_probe.c b/tools/testing/selftests/bpf/progs/freplace_attach_probe.c new file mode 100644 index 000000000000..bb2a77c5b62b --- /dev/null +++ b/tools/testing/selftests/bpf/progs/freplace_attach_probe.c @@ -0,0 +1,40 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2020 Facebook + +#include <linux/ptrace.h> +#include <linux/bpf.h> +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +#define VAR_NUM 2 + +struct hmap_elem { + struct bpf_spin_lock lock; + int var[VAR_NUM]; +}; + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(max_entries, 1); + __type(key, __u32); + __type(value, struct hmap_elem); +} hash_map SEC(".maps"); + +SEC("freplace/handle_kprobe") +int new_handle_kprobe(struct pt_regs *ctx) +{ + struct hmap_elem zero = {}, *val; + int key = 0; + + val = bpf_map_lookup_elem(&hash_map, &key); + if (!val) + return 1; + /* spin_lock in hash map */ + bpf_spin_lock(&val->lock); + val->var[0] = 99; + bpf_spin_unlock(&val->lock); + + return 0; +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/freplace_cls_redirect.c b/tools/testing/selftests/bpf/progs/freplace_cls_redirect.c new file mode 100644 index 000000000000..68a5a9db928a --- /dev/null +++ b/tools/testing/selftests/bpf/progs/freplace_cls_redirect.c @@ -0,0 +1,34 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2020 Facebook + +#include <linux/stddef.h> +#include <linux/bpf.h> +#include <linux/pkt_cls.h> +#include <bpf/bpf_endian.h> +#include <bpf/bpf_helpers.h> + +struct bpf_map_def SEC("maps") sock_map = { + .type = BPF_MAP_TYPE_SOCKMAP, + .key_size = sizeof(int), + .value_size = sizeof(int), + .max_entries = 2, +}; + +SEC("freplace/cls_redirect") +int freplace_cls_redirect_test(struct __sk_buff *skb) +{ + int ret = 0; + const int zero = 0; + struct bpf_sock *sk; + + sk = bpf_map_lookup_elem(&sock_map, &zero); + if (!sk) + return TC_ACT_SHOT; + + ret = bpf_map_update_elem(&sock_map, &zero, sk, 0); + bpf_sk_release(sk); + + return ret == 0 ? TC_ACT_OK : TC_ACT_SHOT; +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/freplace_connect_v4_prog.c b/tools/testing/selftests/bpf/progs/freplace_connect_v4_prog.c new file mode 100644 index 000000000000..544e5ac90461 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/freplace_connect_v4_prog.c @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2020 Facebook + +#include <linux/stddef.h> +#include <linux/ipv6.h> +#include <linux/bpf.h> +#include <linux/in.h> +#include <sys/socket.h> +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_endian.h> + +SEC("freplace/connect_v4_prog") +int new_connect_v4_prog(struct bpf_sock_addr *ctx) +{ + // return value thats in invalid range + return 255; +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/test_pkt_access.c b/tools/testing/selftests/bpf/progs/test_pkt_access.c index e72eba4a93d2..852051064507 100644 --- a/tools/testing/selftests/bpf/progs/test_pkt_access.c +++ b/tools/testing/selftests/bpf/progs/test_pkt_access.c @@ -79,6 +79,24 @@ int get_skb_ifindex(int val, struct __sk_buff *skb, int var) return skb->ifindex * val * var; } +__attribute__ ((noinline)) +int test_pkt_write_access_subprog(struct __sk_buff *skb, __u32 off) +{ + void *data = (void *)(long)skb->data; + void *data_end = (void *)(long)skb->data_end; + struct tcphdr *tcp = NULL; + + if (off > sizeof(struct ethhdr) + sizeof(struct ipv6hdr)) + return -1; + + tcp = data + off; + if (tcp + 1 > data_end) + return -1; + /* make modification to the packet data */ + tcp->check++; + return 0; +} + SEC("classifier/test_pkt_access") int test_pkt_access(struct __sk_buff *skb) { @@ -117,6 +135,8 @@ int test_pkt_access(struct __sk_buff *skb) if (test_pkt_access_subprog3(3, skb) != skb->len * 3 * skb->ifindex) return TC_ACT_SHOT; if (tcp) { + if (test_pkt_write_access_subprog(skb, (void *)tcp - data)) + return TC_ACT_SHOT; if (((void *)(tcp) + 20) > data_end || proto != 6) return TC_ACT_SHOT; barrier(); /* to force ordering of checks */ |