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Date:   Mon, 14 Sep 2020 18:13:23 +0200
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Alexei Starovoitov <ast@...nel.org>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Eelco Chaudron <echaudro@...hat.com>,
        KP Singh <kpsingh@...omium.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: [PATCH bpf-next v4 1/8] bpf: change logging calls from verbose() to
 bpf_log() and use log pointer

From: Toke Høiland-Jørgensen <toke@...hat.com>

In preparation for moving code around, change a bunch of references to
env->log (and the verbose() logging helper) to use bpf_log() and a direct
pointer to struct bpf_verifier_log. While we're touching the function
signature, mark the 'prog' argument to bpf_check_type_match() as const.

Also enhance the bpf_verifier_log_needed() check to handle NULL pointers
for the log struct so we can re-use the code with logging disabled.

Signed-off-by: Toke Høiland-Jørgensen <toke@...hat.com>
---
 include/linux/bpf.h          |    2 +-
 include/linux/bpf_verifier.h |    5 +++-
 kernel/bpf/btf.c             |    6 +++--
 kernel/bpf/verifier.c        |   48 +++++++++++++++++++++---------------------
 4 files changed, 31 insertions(+), 30 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c6d9f2c444f4..5ad4a935a24e 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1394,7 +1394,7 @@ int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
 			     struct bpf_reg_state *regs);
 int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog,
 			  struct bpf_reg_state *reg);
-int btf_check_type_match(struct bpf_verifier_env *env, struct bpf_prog *prog,
+int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog,
 			 struct btf *btf, const struct btf_type *t);
 
 struct bpf_prog *bpf_prog_by_id(u32 id);
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 53c7bd568c5d..20009e766805 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -347,8 +347,9 @@ static inline bool bpf_verifier_log_full(const struct bpf_verifier_log *log)
 
 static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)
 {
-	return (log->level && log->ubuf && !bpf_verifier_log_full(log)) ||
-		log->level == BPF_LOG_KERNEL;
+	return log &&
+		((log->level && log->ubuf && !bpf_verifier_log_full(log)) ||
+		 log->level == BPF_LOG_KERNEL);
 }
 
 #define BPF_MAX_SUBPROGS 256
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index f9ac6935ab3c..2ace56c99c36 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -4401,7 +4401,7 @@ static int btf_check_func_type_match(struct bpf_verifier_log *log,
 }
 
 /* Compare BTFs of given program with BTF of target program */
-int btf_check_type_match(struct bpf_verifier_env *env, struct bpf_prog *prog,
+int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog,
 			 struct btf *btf2, const struct btf_type *t2)
 {
 	struct btf *btf1 = prog->aux->btf;
@@ -4409,7 +4409,7 @@ int btf_check_type_match(struct bpf_verifier_env *env, struct bpf_prog *prog,
 	u32 btf_id = 0;
 
 	if (!prog->aux->func_info) {
-		bpf_log(&env->log, "Program extension requires BTF\n");
+		bpf_log(log, "Program extension requires BTF\n");
 		return -EINVAL;
 	}
 
@@ -4421,7 +4421,7 @@ int btf_check_type_match(struct bpf_verifier_env *env, struct bpf_prog *prog,
 	if (!t1 || !btf_type_is_func(t1))
 		return -EFAULT;
 
-	return btf_check_func_type_match(&env->log, btf1, t1, btf2, t2);
+	return btf_check_func_type_match(log, btf1, t1, btf2, t2);
 }
 
 /* Compare BTF of a function with given bpf_reg_state.
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 814bc6c1ad16..0be7a187fb7f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11043,6 +11043,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 	struct bpf_prog *prog = env->prog;
 	bool prog_extension = prog->type == BPF_PROG_TYPE_EXT;
 	struct bpf_prog *tgt_prog = prog->aux->linked_prog;
+	struct bpf_verifier_log *log = &env->log;
 	u32 btf_id = prog->aux->attach_btf_id;
 	const char prefix[] = "btf_trace_";
 	struct btf_func_model fmodel;
@@ -11070,23 +11071,23 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 		return 0;
 
 	if (!btf_id) {
-		verbose(env, "Tracing programs must provide btf_id\n");
+		bpf_log(log, "Tracing programs must provide btf_id\n");
 		return -EINVAL;
 	}
 	btf = bpf_prog_get_target_btf(prog);
 	if (!btf) {
-		verbose(env,
+		bpf_log(log,
 			"FENTRY/FEXIT program can only be attached to another program annotated with BTF\n");
 		return -EINVAL;
 	}
 	t = btf_type_by_id(btf, btf_id);
 	if (!t) {
-		verbose(env, "attach_btf_id %u is invalid\n", btf_id);
+		bpf_log(log, "attach_btf_id %u is invalid\n", btf_id);
 		return -EINVAL;
 	}
 	tname = btf_name_by_offset(btf, t->name_off);
 	if (!tname) {
-		verbose(env, "attach_btf_id %u doesn't have a name\n", btf_id);
+		bpf_log(log, "attach_btf_id %u doesn't have a name\n", btf_id);
 		return -EINVAL;
 	}
 	if (tgt_prog) {
@@ -11098,18 +11099,18 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 				break;
 			}
 		if (subprog == -1) {
-			verbose(env, "Subprog %s doesn't exist\n", tname);
+			bpf_log(log, "Subprog %s doesn't exist\n", tname);
 			return -EINVAL;
 		}
 		conservative = aux->func_info_aux[subprog].unreliable;
 		if (prog_extension) {
 			if (conservative) {
-				verbose(env,
+				bpf_log(log,
 					"Cannot replace static functions\n");
 				return -EINVAL;
 			}
 			if (!prog->jit_requested) {
-				verbose(env,
+				bpf_log(log,
 					"Extension programs should be JITed\n");
 				return -EINVAL;
 			}
@@ -11117,7 +11118,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 			prog->expected_attach_type = tgt_prog->expected_attach_type;
 		}
 		if (!tgt_prog->jited) {
-			verbose(env, "Can attach to only JITed progs\n");
+			bpf_log(log, "Can attach to only JITed progs\n");
 			return -EINVAL;
 		}
 		if (tgt_prog->type == prog->type) {
@@ -11125,7 +11126,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 			 * Cannot attach program extension to another extension.
 			 * It's ok to attach fentry/fexit to extension program.
 			 */
-			verbose(env, "Cannot recursively attach\n");
+			bpf_log(log, "Cannot recursively attach\n");
 			return -EINVAL;
 		}
 		if (tgt_prog->type == BPF_PROG_TYPE_TRACING &&
@@ -11147,13 +11148,13 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 			 * reasonable stack size. Hence extending fentry is not
 			 * allowed.
 			 */
-			verbose(env, "Cannot extend fentry/fexit\n");
+			bpf_log(log, "Cannot extend fentry/fexit\n");
 			return -EINVAL;
 		}
 		key = ((u64)aux->id) << 32 | btf_id;
 	} else {
 		if (prog_extension) {
-			verbose(env, "Cannot replace kernel functions\n");
+			bpf_log(log, "Cannot replace kernel functions\n");
 			return -EINVAL;
 		}
 		key = btf_id;
@@ -11162,17 +11163,17 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 	switch (prog->expected_attach_type) {
 	case BPF_TRACE_RAW_TP:
 		if (tgt_prog) {
-			verbose(env,
+			bpf_log(log,
 				"Only FENTRY/FEXIT progs are attachable to another BPF prog\n");
 			return -EINVAL;
 		}
 		if (!btf_type_is_typedef(t)) {
-			verbose(env, "attach_btf_id %u is not a typedef\n",
+			bpf_log(log, "attach_btf_id %u is not a typedef\n",
 				btf_id);
 			return -EINVAL;
 		}
 		if (strncmp(prefix, tname, sizeof(prefix) - 1)) {
-			verbose(env, "attach_btf_id %u points to wrong type name %s\n",
+			bpf_log(log, "attach_btf_id %u points to wrong type name %s\n",
 				btf_id, tname);
 			return -EINVAL;
 		}
@@ -11195,7 +11196,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 		return 0;
 	case BPF_TRACE_ITER:
 		if (!btf_type_is_func(t)) {
-			verbose(env, "attach_btf_id %u is not a function\n",
+			bpf_log(log, "attach_btf_id %u is not a function\n",
 				btf_id);
 			return -EINVAL;
 		}
@@ -11206,8 +11207,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 		prog->aux->attach_func_proto = t;
 		if (!bpf_iter_prog_supported(prog))
 			return -EINVAL;
-		ret = btf_distill_func_proto(&env->log, btf, t,
-					     tname, &fmodel);
+		ret = btf_distill_func_proto(log, btf, t, tname, &fmodel);
 		return ret;
 	default:
 		if (!prog_extension)
@@ -11219,18 +11219,18 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 	case BPF_TRACE_FEXIT:
 		prog->aux->attach_func_name = tname;
 		if (prog->type == BPF_PROG_TYPE_LSM) {
-			ret = bpf_lsm_verify_prog(&env->log, prog);
+			ret = bpf_lsm_verify_prog(log, prog);
 			if (ret < 0)
 				return ret;
 		}
 
 		if (!btf_type_is_func(t)) {
-			verbose(env, "attach_btf_id %u is not a function\n",
+			bpf_log(log, "attach_btf_id %u is not a function\n",
 				btf_id);
 			return -EINVAL;
 		}
 		if (prog_extension &&
-		    btf_check_type_match(env, prog, btf, t))
+		    btf_check_type_match(log, prog, btf, t))
 			return -EINVAL;
 		t = btf_type_by_id(btf, t->type);
 		if (!btf_type_is_func_proto(t))
@@ -11249,7 +11249,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 			prog->aux->attach_func_proto = NULL;
 			t = NULL;
 		}
-		ret = btf_distill_func_proto(&env->log, btf, t,
+		ret = btf_distill_func_proto(log, btf, t,
 					     tname, &tr->func.model);
 		if (ret < 0)
 			goto out;
@@ -11261,7 +11261,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 		} else {
 			addr = kallsyms_lookup_name(tname);
 			if (!addr) {
-				verbose(env,
+				bpf_log(log,
 					"The address of function %s cannot be found\n",
 					tname);
 				ret = -ENOENT;
@@ -11291,12 +11291,12 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 				break;
 			}
 			if (ret)
-				verbose(env, "%s is not sleepable\n",
+				bpf_log(log, "%s is not sleepable\n",
 					prog->aux->attach_func_name);
 		} else if (prog->expected_attach_type == BPF_MODIFY_RETURN) {
 			ret = check_attach_modify_return(prog, addr);
 			if (ret)
-				verbose(env, "%s() is not modifiable\n",
+				bpf_log(log, "%s() is not modifiable\n",
 					prog->aux->attach_func_name);
 		}
 		if (ret)

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