Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2018-05-24

The following pull-request contains BPF updates for your *net* tree.

The main changes are:

1) Fix a bug in the original fix to prevent out of bounds speculation when
   multiple tail call maps from different branches or calls end up at the
   same tail call helper invocation, from Daniel.

2) Two selftest fixes, one in reuseport_bpf_numa where test is skipped in
   case of missing numa support and another one to update kernel config to
   properly support xdp_meta.sh test, from Anders.

 ...

Would be great if you have a chance to merge net into net-next after that.

The verifier fix would be needed later as a dependency in bpf-next for
upcomig work there. When you do the merge there's a trivial conflict on
BPF side with 849fa50662fb ("bpf/verifier: refine retval R0 state for
bpf_get_stack helper"): Resolution is to keep both functions, the
do_refine_retval_range() and record_func_map().
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 64 insertions, 22 deletions

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 5dd1dcb902bf..dcebf3f7365c 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -156,7 +156,29 @@ struct bpf_verifier_stack_elem {
 #define BPF_COMPLEXITY_LIMIT_INSNS	131072
 #define BPF_COMPLEXITY_LIMIT_STACK	1024
 
-#define BPF_MAP_PTR_POISON ((void *)0xeB9F + POISON_POINTER_DELTA)
+#define BPF_MAP_PTR_UNPRIV	1UL
+#define BPF_MAP_PTR_POISON	((void *)((0xeB9FUL << 1) +	\
+					  POISON_POINTER_DELTA))
+#define BPF_MAP_PTR(X)		((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV))
+
+static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux)
+{
+	return BPF_MAP_PTR(aux->map_state) == BPF_MAP_PTR_POISON;
+}
+
+static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data *aux)
+{
+	return aux->map_state & BPF_MAP_PTR_UNPRIV;
+}
+
+static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux,
+			      const struct bpf_map *map, bool unpriv)
+{
+	BUILD_BUG_ON((unsigned long)BPF_MAP_PTR_POISON & BPF_MAP_PTR_UNPRIV);
+	unpriv |= bpf_map_ptr_unpriv(aux);
+	aux->map_state = (unsigned long)map |
+			 (unpriv ? BPF_MAP_PTR_UNPRIV : 0UL);
+}
 
 struct bpf_call_arg_meta {
 	struct bpf_map *map_ptr;
@@ -2333,6 +2355,29 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
 	return 0;
 }
 
+static int
+record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
+		int func_id, int insn_idx)
+{
+	struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
+
+	if (func_id != BPF_FUNC_tail_call &&
+	    func_id != BPF_FUNC_map_lookup_elem)
+		return 0;
+	if (meta->map_ptr == NULL) {
+		verbose(env, "kernel subsystem misconfigured verifier\n");
+		return -EINVAL;
+	}
+
+	if (!BPF_MAP_PTR(aux->map_state))
+		bpf_map_ptr_store(aux, meta->map_ptr,
+				  meta->map_ptr->unpriv_array);
+	else if (BPF_MAP_PTR(aux->map_state) != meta->map_ptr)
+		bpf_map_ptr_store(aux, BPF_MAP_PTR_POISON,
+				  meta->map_ptr->unpriv_array);
+	return 0;
+}
+
 static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
 {
 	const struct bpf_func_proto *fn = NULL;
@@ -2387,13 +2432,6 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
 	err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta);
 	if (err)
 		return err;
-	if (func_id == BPF_FUNC_tail_call) {
-		if (meta.map_ptr == NULL) {
-			verbose(env, "verifier bug\n");
-			return -EINVAL;
-		}
-		env->insn_aux_data[insn_idx].map_ptr = meta.map_ptr;
-	}
 	err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta);
 	if (err)
 		return err;
@@ -2404,6 +2442,10 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
 	if (err)
 		return err;
 
+	err = record_func_map(env, &meta, func_id, insn_idx);
+	if (err)
+		return err;
+
 	/* Mark slots with STACK_MISC in case of raw mode, stack offset
 	 * is inferred from register state.
 	 */
@@ -2428,8 +2470,6 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
 	} else if (fn->ret_type == RET_VOID) {
 		regs[BPF_REG_0].type = NOT_INIT;
 	} else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) {
-		struct bpf_insn_aux_data *insn_aux;
-
 		regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
 		/* There is no offset yet applied, variable or fixed */
 		mark_reg_known_zero(env, regs, BPF_REG_0);
@@ -2445,11 +2485,6 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
 		}
 		regs[BPF_REG_0].map_ptr = meta.map_ptr;
 		regs[BPF_REG_0].id = ++env->id_gen;
-		insn_aux = &env->insn_aux_data[insn_idx];
-		if (!insn_aux->map_ptr)
-			insn_aux->map_ptr = meta.map_ptr;
-		else if (insn_aux->map_ptr != meta.map_ptr)
-			insn_aux->map_ptr = BPF_MAP_PTR_POISON;
 	} else {
 		verbose(env, "unknown return type %d of func %s#%d\n",
 			fn->ret_type, func_id_name(func_id), func_id);
@@ -5417,6 +5452,7 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
 	struct bpf_insn *insn = prog->insnsi;
 	const struct bpf_func_proto *fn;
 	const int insn_cnt = prog->len;
+	struct bpf_insn_aux_data *aux;
 	struct bpf_insn insn_buf[16];
 	struct bpf_prog *new_prog;
 	struct bpf_map *map_ptr;
@@ -5491,19 +5527,22 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
 			insn->imm = 0;
 			insn->code = BPF_JMP | BPF_TAIL_CALL;
 
+			aux = &env->insn_aux_data[i + delta];
+			if (!bpf_map_ptr_unpriv(aux))
+				continue;
+
 			/* instead of changing every JIT dealing with tail_call
 			 * emit two extra insns:
 			 * if (index >= max_entries) goto out;
 			 * index &= array->index_mask;
 			 * to avoid out-of-bounds cpu speculation
 			 */
-			map_ptr = env->insn_aux_data[i + delta].map_ptr;
-			if (map_ptr == BPF_MAP_PTR_POISON) {
+			if (bpf_map_ptr_poisoned(aux)) {
 				verbose(env, "tail_call abusing map_ptr\n");
 				return -EINVAL;
 			}
-			if (!map_ptr->unpriv_array)
-				continue;
+
+			map_ptr = BPF_MAP_PTR(aux->map_state);
 			insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3,
 						  map_ptr->max_entries, 2);
 			insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3,
@@ -5527,9 +5566,12 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env)
 		 */
 		if (prog->jit_requested && BITS_PER_LONG == 64 &&
 		    insn->imm == BPF_FUNC_map_lookup_elem) {
-			map_ptr = env->insn_aux_data[i + delta].map_ptr;
-			if (map_ptr == BPF_MAP_PTR_POISON ||
-			    !map_ptr->ops->map_gen_lookup)
+			aux = &env->insn_aux_data[i + delta];
+			if (bpf_map_ptr_poisoned(aux))
+				goto patch_call_imm;
+
+			map_ptr = BPF_MAP_PTR(aux->map_state);
+			if (!map_ptr->ops->map_gen_lookup)
 				goto patch_call_imm;
 
 			cnt = map_ptr->ops->map_gen_lookup(map_ptr, insn_buf);