diff options
| -rw-r--r-- | include/linux/bpf.h | 1 | ||||
| -rw-r--r-- | include/linux/bpf_verifier.h | 1 | ||||
| -rw-r--r-- | include/linux/filter.h | 2 | ||||
| -rw-r--r-- | kernel/bpf/core.c | 2 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 78 | ||||
| -rw-r--r-- | net/core/filter.c | 65 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/changes_pkt_data.c | 76 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/changes_pkt_data.c | 26 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/changes_pkt_data_freplace.c | 18 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/tc_bpf2bpf.c | 2 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/verifier_sock.c | 56 |
11 files changed, 280 insertions, 47 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index eaee2a819f4c..fe392d074973 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1527,6 +1527,7 @@ struct bpf_prog_aux { bool is_extended; /* true if extended by freplace program */ bool jits_use_priv_stack; bool priv_stack_requested; + bool changes_pkt_data; u64 prog_array_member_cnt; /* counts how many times as member of prog_array */ struct mutex ext_mutex; /* mutex for is_extended and prog_array_member_cnt */ struct bpf_arena *arena; diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index f4290c179bee..48b7b2eeb7e2 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -659,6 +659,7 @@ struct bpf_subprog_info { bool args_cached: 1; /* true if bpf_fastcall stack region is used by functions that can't be inlined */ bool keep_fastcall_stack: 1; + bool changes_pkt_data: 1; enum priv_stack_mode priv_stack_mode; u8 arg_cnt; diff --git a/include/linux/filter.h b/include/linux/filter.h index 3a21947f2fd4..0477254bc2d3 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1122,7 +1122,7 @@ bool bpf_jit_supports_insn(struct bpf_insn *insn, bool in_arena); bool bpf_jit_supports_private_stack(void); u64 bpf_arch_uaddress_limit(void); void arch_bpf_stack_walk(bool (*consume_fn)(void *cookie, u64 ip, u64 sp, u64 bp), void *cookie); -bool bpf_helper_changes_pkt_data(void *func); +bool bpf_helper_changes_pkt_data(enum bpf_func_id func_id); static inline bool bpf_dump_raw_ok(const struct cred *cred) { diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index a2327c4fdc8b..6fa8041d4831 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2936,7 +2936,7 @@ void __weak bpf_jit_compile(struct bpf_prog *prog) { } -bool __weak bpf_helper_changes_pkt_data(void *func) +bool __weak bpf_helper_changes_pkt_data(enum bpf_func_id func_id) { return false; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 01fbef9576e0..c2e5d0e6e3d0 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2597,16 +2597,36 @@ static int cmp_subprogs(const void *a, const void *b) ((struct bpf_subprog_info *)b)->start; } +/* Find subprogram that contains instruction at 'off' */ +static struct bpf_subprog_info *find_containing_subprog(struct bpf_verifier_env *env, int off) +{ + struct bpf_subprog_info *vals = env->subprog_info; + int l, r, m; + + if (off >= env->prog->len || off < 0 || env->subprog_cnt == 0) + return NULL; + + l = 0; + r = env->subprog_cnt - 1; + while (l < r) { + m = l + (r - l + 1) / 2; + if (vals[m].start <= off) + l = m; + else + r = m - 1; + } + return &vals[l]; +} + +/* Find subprogram that starts exactly at 'off' */ static int find_subprog(struct bpf_verifier_env *env, int off) { struct bpf_subprog_info *p; - p = bsearch(&off, env->subprog_info, env->subprog_cnt, - sizeof(env->subprog_info[0]), cmp_subprogs); - if (!p) + p = find_containing_subprog(env, off); + if (!p || p->start != off) return -ENOENT; return p - env->subprog_info; - } static int add_subprog(struct bpf_verifier_env *env, int off) @@ -10022,6 +10042,8 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, verbose(env, "Func#%d ('%s') is global and assumed valid.\n", subprog, sub_name); + if (env->subprog_info[subprog].changes_pkt_data) + clear_all_pkt_pointers(env); /* mark global subprog for verifying after main prog */ subprog_aux(env, subprog)->called = true; clear_caller_saved_regs(env, caller->regs); @@ -10708,7 +10730,7 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn } /* With LD_ABS/IND some JITs save/restore skb from r1. */ - changes_data = bpf_helper_changes_pkt_data(fn->func); + changes_data = bpf_helper_changes_pkt_data(func_id); if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) { verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n", func_id_name(func_id), func_id); @@ -16226,6 +16248,29 @@ enforce_retval: return 0; } +static void mark_subprog_changes_pkt_data(struct bpf_verifier_env *env, int off) +{ + struct bpf_subprog_info *subprog; + + subprog = find_containing_subprog(env, off); + subprog->changes_pkt_data = true; +} + +/* 't' is an index of a call-site. + * 'w' is a callee entry point. + * Eventually this function would be called when env->cfg.insn_state[w] == EXPLORED. + * Rely on DFS traversal order and absence of recursive calls to guarantee that + * callee's change_pkt_data marks would be correct at that moment. + */ +static void merge_callee_effects(struct bpf_verifier_env *env, int t, int w) +{ + struct bpf_subprog_info *caller, *callee; + + caller = find_containing_subprog(env, t); + callee = find_containing_subprog(env, w); + caller->changes_pkt_data |= callee->changes_pkt_data; +} + /* non-recursive DFS pseudo code * 1 procedure DFS-iterative(G,v): * 2 label v as discovered @@ -16359,6 +16404,7 @@ static int visit_func_call_insn(int t, struct bpf_insn *insns, bool visit_callee) { int ret, insn_sz; + int w; insn_sz = bpf_is_ldimm64(&insns[t]) ? 2 : 1; ret = push_insn(t, t + insn_sz, FALLTHROUGH, env); @@ -16370,8 +16416,10 @@ static int visit_func_call_insn(int t, struct bpf_insn *insns, mark_jmp_point(env, t + insn_sz); if (visit_callee) { + w = t + insns[t].imm + 1; mark_prune_point(env, t); - ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env); + merge_callee_effects(env, t, w); + ret = push_insn(t, w, BRANCH, env); } return ret; } @@ -16688,6 +16736,8 @@ static int visit_insn(int t, struct bpf_verifier_env *env) mark_prune_point(env, t); mark_jmp_point(env, t); } + if (bpf_helper_call(insn) && bpf_helper_changes_pkt_data(insn->imm)) + mark_subprog_changes_pkt_data(env, t); if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL) { struct bpf_kfunc_call_arg_meta meta; @@ -16822,6 +16872,7 @@ walk_cfg: } } ret = 0; /* cfg looks good */ + env->prog->aux->changes_pkt_data = env->subprog_info[0].changes_pkt_data; err_free: kvfree(insn_state); @@ -20311,6 +20362,7 @@ static int jit_subprogs(struct bpf_verifier_env *env) func[i]->aux->num_exentries = num_exentries; func[i]->aux->tail_call_reachable = env->subprog_info[i].tail_call_reachable; func[i]->aux->exception_cb = env->subprog_info[i].is_exception_cb; + func[i]->aux->changes_pkt_data = env->subprog_info[i].changes_pkt_data; if (!i) func[i]->aux->exception_boundary = env->seen_exception; func[i] = bpf_int_jit_compile(func[i]); @@ -22175,6 +22227,12 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, "Extension programs should be JITed\n"); return -EINVAL; } + if (prog->aux->changes_pkt_data && + !aux->func[subprog]->aux->changes_pkt_data) { + bpf_log(log, + "Extension program changes packet data, while original does not\n"); + return -EINVAL; + } } if (!tgt_prog->jited) { bpf_log(log, "Can attach to only JITed progs\n"); @@ -22640,10 +22698,6 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 if (ret < 0) goto skip_full_check; - ret = check_attach_btf_id(env); - if (ret) - goto skip_full_check; - ret = resolve_pseudo_ldimm64(env); if (ret < 0) goto skip_full_check; @@ -22658,6 +22712,10 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3 if (ret < 0) goto skip_full_check; + ret = check_attach_btf_id(env); + if (ret) + goto skip_full_check; + ret = mark_fastcall_patterns(env); if (ret < 0) goto skip_full_check; diff --git a/net/core/filter.c b/net/core/filter.c index 6625b3f563a4..21131ec25f24 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7899,42 +7899,37 @@ static const struct bpf_func_proto bpf_tcp_raw_check_syncookie_ipv6_proto = { #endif /* CONFIG_INET */ -bool bpf_helper_changes_pkt_data(void *func) -{ - if (func == bpf_skb_vlan_push || - func == bpf_skb_vlan_pop || - func == bpf_skb_store_bytes || - func == bpf_skb_change_proto || - func == bpf_skb_change_head || - func == sk_skb_change_head || - func == bpf_skb_change_tail || - func == sk_skb_change_tail || - func == bpf_skb_adjust_room || - func == sk_skb_adjust_room || - func == bpf_skb_pull_data || - func == sk_skb_pull_data || - func == bpf_clone_redirect || - func == bpf_l3_csum_replace || - func == bpf_l4_csum_replace || - func == bpf_xdp_adjust_head || - func == bpf_xdp_adjust_meta || - func == bpf_msg_pull_data || - func == bpf_msg_push_data || - func == bpf_msg_pop_data || - func == bpf_xdp_adjust_tail || -#if IS_ENABLED(CONFIG_IPV6_SEG6_BPF) - func == bpf_lwt_seg6_store_bytes || - func == bpf_lwt_seg6_adjust_srh || - func == bpf_lwt_seg6_action || -#endif -#ifdef CONFIG_INET - func == bpf_sock_ops_store_hdr_opt || -#endif - func == bpf_lwt_in_push_encap || - func == bpf_lwt_xmit_push_encap) +bool bpf_helper_changes_pkt_data(enum bpf_func_id func_id) +{ + switch (func_id) { + case BPF_FUNC_clone_redirect: + case BPF_FUNC_l3_csum_replace: + case BPF_FUNC_l4_csum_replace: + case BPF_FUNC_lwt_push_encap: + case BPF_FUNC_lwt_seg6_action: + case BPF_FUNC_lwt_seg6_adjust_srh: + case BPF_FUNC_lwt_seg6_store_bytes: + case BPF_FUNC_msg_pop_data: + case BPF_FUNC_msg_pull_data: + case BPF_FUNC_msg_push_data: + case BPF_FUNC_skb_adjust_room: + case BPF_FUNC_skb_change_head: + case BPF_FUNC_skb_change_proto: + case BPF_FUNC_skb_change_tail: + case BPF_FUNC_skb_pull_data: + case BPF_FUNC_skb_store_bytes: + case BPF_FUNC_skb_vlan_pop: + case BPF_FUNC_skb_vlan_push: + case BPF_FUNC_store_hdr_opt: + case BPF_FUNC_xdp_adjust_head: + case BPF_FUNC_xdp_adjust_meta: + case BPF_FUNC_xdp_adjust_tail: + /* tail-called program could call any of the above */ + case BPF_FUNC_tail_call: return true; - - return false; + default: + return false; + } } const struct bpf_func_proto bpf_event_output_data_proto __weak; diff --git a/tools/testing/selftests/bpf/prog_tests/changes_pkt_data.c b/tools/testing/selftests/bpf/prog_tests/changes_pkt_data.c new file mode 100644 index 000000000000..c0c7202f6c5c --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/changes_pkt_data.c @@ -0,0 +1,76 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "bpf/libbpf.h" +#include "changes_pkt_data_freplace.skel.h" +#include "changes_pkt_data.skel.h" +#include <test_progs.h> + +static void print_verifier_log(const char *log) +{ + if (env.verbosity >= VERBOSE_VERY) + fprintf(stdout, "VERIFIER LOG:\n=============\n%s=============\n", log); +} + +static void test_aux(const char *main_prog_name, const char *freplace_prog_name, bool expect_load) +{ + struct changes_pkt_data_freplace *freplace = NULL; + struct bpf_program *freplace_prog = NULL; + LIBBPF_OPTS(bpf_object_open_opts, opts); + struct changes_pkt_data *main = NULL; + char log[16*1024]; + int err; + + opts.kernel_log_buf = log; + opts.kernel_log_size = sizeof(log); + if (env.verbosity >= VERBOSE_SUPER) + opts.kernel_log_level = 1 | 2 | 4; + main = changes_pkt_data__open_opts(&opts); + if (!ASSERT_OK_PTR(main, "changes_pkt_data__open")) + goto out; + err = changes_pkt_data__load(main); + print_verifier_log(log); + if (!ASSERT_OK(err, "changes_pkt_data__load")) + goto out; + freplace = changes_pkt_data_freplace__open_opts(&opts); + if (!ASSERT_OK_PTR(freplace, "changes_pkt_data_freplace__open")) + goto out; + freplace_prog = bpf_object__find_program_by_name(freplace->obj, freplace_prog_name); + if (!ASSERT_OK_PTR(freplace_prog, "freplace_prog")) + goto out; + bpf_program__set_autoload(freplace_prog, true); + bpf_program__set_autoattach(freplace_prog, true); + bpf_program__set_attach_target(freplace_prog, + bpf_program__fd(main->progs.dummy), + main_prog_name); + err = changes_pkt_data_freplace__load(freplace); + print_verifier_log(log); + if (expect_load) { + ASSERT_OK(err, "changes_pkt_data_freplace__load"); + } else { + ASSERT_ERR(err, "changes_pkt_data_freplace__load"); + ASSERT_HAS_SUBSTR(log, "Extension program changes packet data", "error log"); + } + +out: + changes_pkt_data_freplace__destroy(freplace); + changes_pkt_data__destroy(main); +} + +/* There are two global subprograms in both changes_pkt_data.skel.h: + * - one changes packet data; + * - another does not. + * It is ok to freplace subprograms that change packet data with those + * that either do or do not. It is only ok to freplace subprograms + * that do not change packet data with those that do not as well. + * The below tests check outcomes for each combination of such freplace. + */ +void test_changes_pkt_data_freplace(void) +{ + if (test__start_subtest("changes_with_changes")) + test_aux("changes_pkt_data", "changes_pkt_data", true); + if (test__start_subtest("changes_with_doesnt_change")) + test_aux("changes_pkt_data", "does_not_change_pkt_data", true); + if (test__start_subtest("doesnt_change_with_changes")) + test_aux("does_not_change_pkt_data", "changes_pkt_data", false); + if (test__start_subtest("doesnt_change_with_doesnt_change")) + test_aux("does_not_change_pkt_data", "does_not_change_pkt_data", true); +} diff --git a/tools/testing/selftests/bpf/progs/changes_pkt_data.c b/tools/testing/selftests/bpf/progs/changes_pkt_data.c new file mode 100644 index 000000000000..f87da8e9d6b3 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/changes_pkt_data.c @@ -0,0 +1,26 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/bpf.h> +#include <bpf/bpf_helpers.h> + +__noinline +long changes_pkt_data(struct __sk_buff *sk, __u32 len) +{ + return bpf_skb_pull_data(sk, len); +} + +__noinline __weak +long does_not_change_pkt_data(struct __sk_buff *sk, __u32 len) +{ + return 0; +} + +SEC("tc") +int dummy(struct __sk_buff *sk) +{ + changes_pkt_data(sk, 0); + does_not_change_pkt_data(sk, 0); + return 0; +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/changes_pkt_data_freplace.c b/tools/testing/selftests/bpf/progs/changes_pkt_data_freplace.c new file mode 100644 index 000000000000..0e525beb8603 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/changes_pkt_data_freplace.c @@ -0,0 +1,18 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/bpf.h> +#include <bpf/bpf_helpers.h> + +SEC("?freplace") +long changes_pkt_data(struct __sk_buff *sk, __u32 len) +{ + return bpf_skb_pull_data(sk, len); +} + +SEC("?freplace") +long does_not_change_pkt_data(struct __sk_buff *sk, __u32 len) +{ + return 0; +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c b/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c index d1a57f7d09bd..fe6249d99b31 100644 --- a/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c +++ b/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c @@ -11,6 +11,8 @@ int subprog_tc(struct __sk_buff *skb) __sink(skb); __sink(ret); + /* let verifier know that 'subprog_tc' can change pointers to skb->data */ + bpf_skb_change_proto(skb, 0, 0); return ret; } diff --git a/tools/testing/selftests/bpf/progs/verifier_sock.c b/tools/testing/selftests/bpf/progs/verifier_sock.c index d3e70e38e442..0d5e56dffabb 100644 --- a/tools/testing/selftests/bpf/progs/verifier_sock.c +++ b/tools/testing/selftests/bpf/progs/verifier_sock.c @@ -50,6 +50,13 @@ struct { __uint(map_flags, BPF_F_NO_PREALLOC); } sk_storage_map SEC(".maps"); +struct { + __uint(type, BPF_MAP_TYPE_PROG_ARRAY); + __uint(max_entries, 1); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(__u32)); +} jmp_table SEC(".maps"); + SEC("cgroup/skb") __description("skb->sk: no NULL check") __failure __msg("invalid mem access 'sock_common_or_null'") @@ -1037,4 +1044,53 @@ __naked void sock_create_read_src_port(void) : __clobber_all); } +__noinline +long skb_pull_data2(struct __sk_buff *sk, __u32 len) +{ + return bpf_skb_pull_data(sk, len); +} + +__noinline +long skb_pull_data1(struct __sk_buff *sk, __u32 len) +{ + return skb_pull_data2(sk, len); +} + +/* global function calls bpf_skb_pull_data(), which invalidates packet + * pointers established before global function call. + */ +SEC("tc") +__failure __msg("invalid mem access") +int invalidate_pkt_pointers_from_global_func(struct __sk_buff *sk) +{ + int *p = (void *)(long)sk->data; + + if ((void *)(p + 1) > (void *)(long)sk->data_end) + return TCX_DROP; + skb_pull_data1(sk, 0); + *p = 42; /* this is unsafe */ + return TCX_PASS; +} + +__noinline +int tail_call(struct __sk_buff *sk) +{ + bpf_tail_call_static(sk, &jmp_table, 0); + return 0; +} + +/* Tail calls invalidate packet pointers. */ +SEC("tc") +__failure __msg("invalid mem access") +int invalidate_pkt_pointers_by_tail_call(struct __sk_buff *sk) +{ + int *p = (void *)(long)sk->data; + + if ((void *)(p + 1) > (void *)(long)sk->data_end) + return TCX_DROP; + tail_call(sk); + *p = 42; /* this is unsafe */ + return TCX_PASS; +} + char _license[] SEC("license") = "GPL"; |