Merge branch 'bpftool-improvements-kallsymfix'

Daniel Borkmann says:

====================
This work adds correlation of maps and calls into the bpftool
xlated dump in order to help debugging and introspection of
loaded BPF progs. First patch makes kallsyms work on subprogs
with bpf calls, and second implements the actual correlation.
Details and example output can be found in the 2nd patch.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 88 insertions, 5 deletions

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index e2e1c78ce1dc..007802c5ca7d 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -937,10 +937,16 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu)
 static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock)
 {
 	if (atomic_dec_and_test(&prog->aux->refcnt)) {
+		int i;
+
 		trace_bpf_prog_put_rcu(prog);
 		/* bpf_prog_free_id() must be called first */
 		bpf_prog_free_id(prog, do_idr_lock);
+
+		for (i = 0; i < prog->aux->func_cnt; i++)
+			bpf_prog_kallsyms_del(prog->aux->func[i]);
 		bpf_prog_kallsyms_del(prog);
+
 		call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu);
 	}
 }
@@ -1552,6 +1558,67 @@ static int bpf_map_get_fd_by_id(const union bpf_attr *attr)
 	return fd;
 }
 
+static const struct bpf_map *bpf_map_from_imm(const struct bpf_prog *prog,
+					      unsigned long addr)
+{
+	int i;
+
+	for (i = 0; i < prog->aux->used_map_cnt; i++)
+		if (prog->aux->used_maps[i] == (void *)addr)
+			return prog->aux->used_maps[i];
+	return NULL;
+}
+
+static struct bpf_insn *bpf_insn_prepare_dump(const struct bpf_prog *prog)
+{
+	const struct bpf_map *map;
+	struct bpf_insn *insns;
+	u64 imm;
+	int i;
+
+	insns = kmemdup(prog->insnsi, bpf_prog_insn_size(prog),
+			GFP_USER);
+	if (!insns)
+		return insns;
+
+	for (i = 0; i < prog->len; i++) {
+		if (insns[i].code == (BPF_JMP | BPF_TAIL_CALL)) {
+			insns[i].code = BPF_JMP | BPF_CALL;
+			insns[i].imm = BPF_FUNC_tail_call;
+			/* fall-through */
+		}
+		if (insns[i].code == (BPF_JMP | BPF_CALL) ||
+		    insns[i].code == (BPF_JMP | BPF_CALL_ARGS)) {
+			if (insns[i].code == (BPF_JMP | BPF_CALL_ARGS))
+				insns[i].code = BPF_JMP | BPF_CALL;
+			if (!bpf_dump_raw_ok())
+				insns[i].imm = 0;
+			continue;
+		}
+
+		if (insns[i].code != (BPF_LD | BPF_IMM | BPF_DW))
+			continue;
+
+		imm = ((u64)insns[i + 1].imm << 32) | (u32)insns[i].imm;
+		map = bpf_map_from_imm(prog, imm);
+		if (map) {
+			insns[i].src_reg = BPF_PSEUDO_MAP_FD;
+			insns[i].imm = map->id;
+			insns[i + 1].imm = 0;
+			continue;
+		}
+
+		if (!bpf_dump_raw_ok() &&
+		    imm == (unsigned long)prog->aux) {
+			insns[i].imm = 0;
+			insns[i + 1].imm = 0;
+			continue;
+		}
+	}
+
+	return insns;
+}
+
 static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
 				   const union bpf_attr *attr,
 				   union bpf_attr __user *uattr)
@@ -1602,18 +1669,34 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
 	ulen = info.jited_prog_len;
 	info.jited_prog_len = prog->jited_len;
 	if (info.jited_prog_len && ulen) {
-		uinsns = u64_to_user_ptr(info.jited_prog_insns);
-		ulen = min_t(u32, info.jited_prog_len, ulen);
-		if (copy_to_user(uinsns, prog->bpf_func, ulen))
-			return -EFAULT;
+		if (bpf_dump_raw_ok()) {
+			uinsns = u64_to_user_ptr(info.jited_prog_insns);
+			ulen = min_t(u32, info.jited_prog_len, ulen);
+			if (copy_to_user(uinsns, prog->bpf_func, ulen))
+				return -EFAULT;
+		} else {
+			info.jited_prog_insns = 0;
+		}
 	}
 
 	ulen = info.xlated_prog_len;
 	info.xlated_prog_len = bpf_prog_insn_size(prog);
 	if (info.xlated_prog_len && ulen) {
+		struct bpf_insn *insns_sanitized;
+		bool fault;
+
+		if (prog->blinded && !bpf_dump_raw_ok()) {
+			info.xlated_prog_insns = 0;
+			goto done;
+		}
+		insns_sanitized = bpf_insn_prepare_dump(prog);
+		if (!insns_sanitized)
+			return -ENOMEM;
 		uinsns = u64_to_user_ptr(info.xlated_prog_insns);
 		ulen = min_t(u32, info.xlated_prog_len, ulen);
-		if (copy_to_user(uinsns, prog->insnsi, ulen))
+		fault = copy_to_user(uinsns, insns_sanitized, ulen);
+		kfree(insns_sanitized);
+		if (fault)
 			return -EFAULT;
 	}