6.12-stable review patch. If anyone has any objections, please let me know.
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From: Eduard Zingerman eddyz87@gmail.com
commit 81f6d0530ba031b5f038a091619bf2ff29568852 upstream.
When processing calls to global sub-programs, verifier decides whether to invalidate all packet pointers in current state depending on the changes_pkt_data property of the global sub-program.
Because of this, an extension program replacing a global sub-program must be compatible with changes_pkt_data property of the sub-program being replaced.
This commit: - adds changes_pkt_data flag to struct bpf_prog_aux: - this flag is set in check_cfg() for main sub-program; - in jit_subprogs() for other sub-programs; - modifies bpf_check_attach_btf_id() to check changes_pkt_data flag; - moves call to check_attach_btf_id() after the call to check_cfg(), because it needs changes_pkt_data flag to be set:
bpf_check: ... ... - check_attach_btf_id resolve_pseudo_ldimm64 resolve_pseudo_ldimm64 --> bpf_prog_is_offloaded bpf_prog_is_offloaded check_cfg check_cfg + check_attach_btf_id ... ...
The following fields are set by check_attach_btf_id(): - env->ops - prog->aux->attach_btf_trace - prog->aux->attach_func_name - prog->aux->attach_func_proto - prog->aux->dst_trampoline - prog->aux->mod - prog->aux->saved_dst_attach_type - prog->aux->saved_dst_prog_type - prog->expected_attach_type
Neither of these fields are used by resolve_pseudo_ldimm64() or bpf_prog_offload_verifier_prep() (for netronome and netdevsim drivers), so the reordering is safe.
Suggested-by: Alexei Starovoitov alexei.starovoitov@gmail.com Signed-off-by: Eduard Zingerman eddyz87@gmail.com Link: https://lore.kernel.org/r/20241210041100.1898468-6-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov ast@kernel.org [ shung-hsi.yu: both jits_use_priv_stack and priv_stack_requested fields are missing from context because "bpf: Support private stack for bpf progs" series is not present.] Signed-off-by: Shung-Hsi Yu shung-hsi.yu@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/bpf.h | 1 + kernel/bpf/verifier.c | 16 ++++++++++++---- 2 files changed, 13 insertions(+), 4 deletions(-)
--- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1499,6 +1499,7 @@ struct bpf_prog_aux { bool exception_cb; bool exception_boundary; bool is_extended; /* true if extended by freplace program */ + 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; --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -16650,6 +16650,7 @@ 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); @@ -20152,6 +20153,7 @@ static int jit_subprogs(struct bpf_verif 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]); @@ -22022,6 +22024,12 @@ int bpf_check_attach_target(struct bpf_v "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"); @@ -22487,10 +22495,6 @@ int bpf_check(struct bpf_prog **prog, un 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; @@ -22505,6 +22509,10 @@ int bpf_check(struct bpf_prog **prog, un 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;