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-rw-r--r--kernel/bpf/verifier.c437
1 files changed, 288 insertions, 149 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index d906775e12c1..5f26f7ad124f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -276,43 +276,132 @@ static void print_verifier_state(struct bpf_verifier_env *env,
 			verbose(env, ")");
 		}
 	}
-	for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
-		if (state->stack_slot_type[i] == STACK_SPILL)
-			verbose(env, " fp%d=%s", -MAX_BPF_STACK + i,
-				reg_type_str[state->spilled_regs[i / BPF_REG_SIZE].type]);
+	for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
+		if (state->stack[i].slot_type[0] == STACK_SPILL)
+			verbose(env, " fp%d=%s",
+				-MAX_BPF_STACK + i * BPF_REG_SIZE,
+				reg_type_str[state->stack[i].spilled_ptr.type]);
 	}
 	verbose(env, "\n");
 }
 
-static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx)
+static int copy_stack_state(struct bpf_verifier_state *dst,
+			    const struct bpf_verifier_state *src)
 {
-	struct bpf_verifier_stack_elem *elem;
-	int insn_idx;
+	if (!src->stack)
+		return 0;
+	if (WARN_ON_ONCE(dst->allocated_stack < src->allocated_stack)) {
+		/* internal bug, make state invalid to reject the program */
+		memset(dst, 0, sizeof(*dst));
+		return -EFAULT;
+	}
+	memcpy(dst->stack, src->stack,
+	       sizeof(*src->stack) * (src->allocated_stack / BPF_REG_SIZE));
+	return 0;
+}
+
+/* do_check() starts with zero-sized stack in struct bpf_verifier_state to
+ * make it consume minimal amount of memory. check_stack_write() access from
+ * the program calls into realloc_verifier_state() to grow the stack size.
+ * Note there is a non-zero 'parent' pointer inside bpf_verifier_state
+ * which this function copies over. It points to previous bpf_verifier_state
+ * which is never reallocated
+ */
+static int realloc_verifier_state(struct bpf_verifier_state *state, int size,
+				  bool copy_old)
+{
+	u32 old_size = state->allocated_stack;
+	struct bpf_stack_state *new_stack;
+	int slot = size / BPF_REG_SIZE;
+
+	if (size <= old_size || !size) {
+		if (copy_old)
+			return 0;
+		state->allocated_stack = slot * BPF_REG_SIZE;
+		if (!size && old_size) {
+			kfree(state->stack);
+			state->stack = NULL;
+		}
+		return 0;
+	}
+	new_stack = kmalloc_array(slot, sizeof(struct bpf_stack_state),
+				  GFP_KERNEL);
+	if (!new_stack)
+		return -ENOMEM;
+	if (copy_old) {
+		if (state->stack)
+			memcpy(new_stack, state->stack,
+			       sizeof(*new_stack) * (old_size / BPF_REG_SIZE));
+		memset(new_stack + old_size / BPF_REG_SIZE, 0,
+		       sizeof(*new_stack) * (size - old_size) / BPF_REG_SIZE);
+	}
+	state->allocated_stack = slot * BPF_REG_SIZE;
+	kfree(state->stack);
+	state->stack = new_stack;
+	return 0;
+}
+
+static void free_verifier_state(struct bpf_verifier_state *state)
+{
+	kfree(state->stack);
+	kfree(state);
+}
+
+/* copy verifier state from src to dst growing dst stack space
+ * when necessary to accommodate larger src stack
+ */
+static int copy_verifier_state(struct bpf_verifier_state *dst,
+			       const struct bpf_verifier_state *src)
+{
+	int err;
+
+	err = realloc_verifier_state(dst, src->allocated_stack, false);
+	if (err)
+		return err;
+	memcpy(dst, src, offsetof(struct bpf_verifier_state, allocated_stack));
+	return copy_stack_state(dst, src);
+}
+
+static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
+		     int *insn_idx)
+{
+	struct bpf_verifier_state *cur = env->cur_state;
+	struct bpf_verifier_stack_elem *elem, *head = env->head;
+	int err;
 
 	if (env->head == NULL)
-		return -1;
+		return -ENOENT;
 
-	memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state));
-	insn_idx = env->head->insn_idx;
+	if (cur) {
+		err = copy_verifier_state(cur, &head->st);
+		if (err)
+			return err;
+	}
+	if (insn_idx)
+		*insn_idx = head->insn_idx;
 	if (prev_insn_idx)
-		*prev_insn_idx = env->head->prev_insn_idx;
-	elem = env->head->next;
-	kfree(env->head);
+		*prev_insn_idx = head->prev_insn_idx;
+	elem = head->next;
+	kfree(head);
 	env->head = elem;
 	env->stack_size--;
-	return insn_idx;
+	return 0;
 }
 
 static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
 					     int insn_idx, int prev_insn_idx)
 {
+	struct bpf_verifier_state *cur = env->cur_state;
 	struct bpf_verifier_stack_elem *elem;
+	int err;
 
-	elem = kmalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
+	elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
 	if (!elem)
 		goto err;
 
-	memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state));
+	err = copy_verifier_state(&elem->st, cur);
+	if (err)
+		return NULL;
 	elem->insn_idx = insn_idx;
 	elem->prev_insn_idx = prev_insn_idx;
 	elem->next = env->head;
@@ -325,7 +414,7 @@ static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
 	return &elem->st;
 err:
 	/* pop all elements and return */
-	while (pop_stack(env, NULL) >= 0);
+	while (!pop_stack(env, NULL, NULL));
 	return NULL;
 }
 
@@ -550,7 +639,7 @@ static void mark_reg_read(const struct bpf_verifier_state *state, u32 regno)
 static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
 			 enum reg_arg_type t)
 {
-	struct bpf_reg_state *regs = env->cur_state.regs;
+	struct bpf_reg_state *regs = env->cur_state->regs;
 
 	if (regno >= MAX_BPF_REG) {
 		verbose(env, "R%d is invalid\n", regno);
@@ -563,7 +652,7 @@ static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
 			verbose(env, "R%d !read_ok\n", regno);
 			return -EACCES;
 		}
-		mark_reg_read(&env->cur_state, regno);
+		mark_reg_read(env->cur_state, regno);
 	} else {
 		/* check whether register used as dest operand can be written to */
 		if (regno == BPF_REG_FP) {
@@ -601,10 +690,21 @@ static int check_stack_write(struct bpf_verifier_env *env,
 			     struct bpf_verifier_state *state, int off,
 			     int size, int value_regno)
 {
-	int i, spi = (MAX_BPF_STACK + off) / BPF_REG_SIZE;
+	int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
+
+	err = realloc_verifier_state(state, round_up(slot + 1, BPF_REG_SIZE),
+				     true);
+	if (err)
+		return err;
 	/* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
 	 * so it's aligned access and [off, off + size) are within stack limits
 	 */
+	if (!env->allow_ptr_leaks &&
+	    state->stack[spi].slot_type[0] == STACK_SPILL &&
+	    size != BPF_REG_SIZE) {
+		verbose(env, "attempt to corrupt spilled pointer on stack\n");
+		return -EACCES;
+	}
 
 	if (value_regno >= 0 &&
 	    is_spillable_regtype(state->regs[value_regno].type)) {
@@ -616,17 +716,18 @@ static int check_stack_write(struct bpf_verifier_env *env,
 		}
 
 		/* save register state */
-		state->spilled_regs[spi] = state->regs[value_regno];
-		state->spilled_regs[spi].live |= REG_LIVE_WRITTEN;
+		state->stack[spi].spilled_ptr = state->regs[value_regno];
+		state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
 
 		for (i = 0; i < BPF_REG_SIZE; i++)
-			state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL;
+			state->stack[spi].slot_type[i] = STACK_SPILL;
 	} else {
 		/* regular write of data into stack */
-		state->spilled_regs[spi] = (struct bpf_reg_state) {};
+		state->stack[spi].spilled_ptr = (struct bpf_reg_state) {};
 
 		for (i = 0; i < size; i++)
-			state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC;
+			state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] =
+				STACK_MISC;
 	}
 	return 0;
 }
@@ -637,10 +738,10 @@ static void mark_stack_slot_read(const struct bpf_verifier_state *state, int slo
 
 	while (parent) {
 		/* if read wasn't screened by an earlier write ... */
-		if (state->spilled_regs[slot].live & REG_LIVE_WRITTEN)
+		if (state->stack[slot].spilled_ptr.live & REG_LIVE_WRITTEN)
 			break;
 		/* ... then we depend on parent's value */
-		parent->spilled_regs[slot].live |= REG_LIVE_READ;
+		parent->stack[slot].spilled_ptr.live |= REG_LIVE_READ;
 		state = parent;
 		parent = state->parent;
 	}
@@ -650,34 +751,37 @@ static int check_stack_read(struct bpf_verifier_env *env,
 			    struct bpf_verifier_state *state, int off, int size,
 			    int value_regno)
 {
-	u8 *slot_type;
-	int i, spi;
+	int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
+	u8 *stype;
 
-	slot_type = &state->stack_slot_type[MAX_BPF_STACK + off];
+	if (state->allocated_stack <= slot) {
+		verbose(env, "invalid read from stack off %d+0 size %d\n",
+			off, size);
+		return -EACCES;
+	}
+	stype = state->stack[spi].slot_type;
 
-	if (slot_type[0] == STACK_SPILL) {
+	if (stype[0] == STACK_SPILL) {
 		if (size != BPF_REG_SIZE) {
 			verbose(env, "invalid size of register spill\n");
 			return -EACCES;
 		}
 		for (i = 1; i < BPF_REG_SIZE; i++) {
-			if (slot_type[i] != STACK_SPILL) {
+			if (stype[(slot - i) % BPF_REG_SIZE] != STACK_SPILL) {
 				verbose(env, "corrupted spill memory\n");
 				return -EACCES;
 			}
 		}
 
-		spi = (MAX_BPF_STACK + off) / BPF_REG_SIZE;
-
 		if (value_regno >= 0) {
 			/* restore register state from stack */
-			state->regs[value_regno] = state->spilled_regs[spi];
+			state->regs[value_regno] = state->stack[spi].spilled_ptr;
 			mark_stack_slot_read(state, spi);
 		}
 		return 0;
 	} else {
 		for (i = 0; i < size; i++) {
-			if (slot_type[i] != STACK_MISC) {
+			if (stype[(slot - i) % BPF_REG_SIZE] != STACK_MISC) {
 				verbose(env, "invalid read from stack off %d+%d size %d\n",
 					off, i, size);
 				return -EACCES;
@@ -694,7 +798,8 @@ static int check_stack_read(struct bpf_verifier_env *env,
 static int __check_map_access(struct bpf_verifier_env *env, u32 regno, int off,
 			    int size)
 {
-	struct bpf_map *map = env->cur_state.regs[regno].map_ptr;
+	struct bpf_reg_state *regs = cur_regs(env);
+	struct bpf_map *map = regs[regno].map_ptr;
 
 	if (off < 0 || size <= 0 || off + size > map->value_size) {
 		verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n",
@@ -706,9 +811,9 @@ static int __check_map_access(struct bpf_verifier_env *env, u32 regno, int off,
 
 /* check read/write into a map element with possible variable offset */
 static int check_map_access(struct bpf_verifier_env *env, u32 regno,
-				int off, int size)
+			    int off, int size)
 {
-	struct bpf_verifier_state *state = &env->cur_state;
+	struct bpf_verifier_state *state = env->cur_state;
 	struct bpf_reg_state *reg = &state->regs[regno];
 	int err;
 
@@ -783,7 +888,7 @@ static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
 static int __check_packet_access(struct bpf_verifier_env *env, u32 regno,
 				 int off, int size)
 {
-	struct bpf_reg_state *regs = env->cur_state.regs;
+	struct bpf_reg_state *regs = cur_regs(env);
 	struct bpf_reg_state *reg = &regs[regno];
 
 	if (off < 0 || size <= 0 || (u64)off + size > reg->range) {
@@ -797,7 +902,7 @@ static int __check_packet_access(struct bpf_verifier_env *env, u32 regno,
 static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
 			       int size)
 {
-	struct bpf_reg_state *regs = env->cur_state.regs;
+	struct bpf_reg_state *regs = cur_regs(env);
 	struct bpf_reg_state *reg = &regs[regno];
 	int err;
 
@@ -866,7 +971,7 @@ static bool __is_pointer_value(bool allow_ptr_leaks,
 
 static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
 {
-	return __is_pointer_value(env->allow_ptr_leaks, &env->cur_state.regs[regno]);
+	return __is_pointer_value(env->allow_ptr_leaks, cur_regs(env) + regno);
 }
 
 static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
@@ -968,8 +1073,9 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 			    int bpf_size, enum bpf_access_type t,
 			    int value_regno)
 {
-	struct bpf_verifier_state *state = &env->cur_state;
-	struct bpf_reg_state *reg = &state->regs[regno];
+	struct bpf_verifier_state *state = env->cur_state;
+	struct bpf_reg_state *regs = cur_regs(env);
+	struct bpf_reg_state *reg = regs + regno;
 	int size, err = 0;
 
 	size = bpf_size_to_bytes(bpf_size);
@@ -993,7 +1099,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 
 		err = check_map_access(env, regno, off, size);
 		if (!err && t == BPF_READ && value_regno >= 0)
-			mark_reg_unknown(env, state->regs, value_regno);
+			mark_reg_unknown(env, regs, value_regno);
 
 	} else if (reg->type == PTR_TO_CTX) {
 		enum bpf_reg_type reg_type = SCALAR_VALUE;
@@ -1028,14 +1134,14 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 			 * case, we know the offset is zero.
 			 */
 			if (reg_type == SCALAR_VALUE)
-				mark_reg_unknown(env, state->regs, value_regno);
+				mark_reg_unknown(env, regs, value_regno);
 			else
-				mark_reg_known_zero(env, state->regs,
+				mark_reg_known_zero(env, regs,
 						    value_regno);
-			state->regs[value_regno].id = 0;
-			state->regs[value_regno].off = 0;
-			state->regs[value_regno].range = 0;
-			state->regs[value_regno].type = reg_type;
+			regs[value_regno].id = 0;
+			regs[value_regno].off = 0;
+			regs[value_regno].range = 0;
+			regs[value_regno].type = reg_type;
 		}
 
 	} else if (reg->type == PTR_TO_STACK) {
@@ -1061,19 +1167,12 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 		if (env->prog->aux->stack_depth < -off)
 			env->prog->aux->stack_depth = -off;
 
-		if (t == BPF_WRITE) {
-			if (!env->allow_ptr_leaks &&
-			    state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL &&
-			    size != BPF_REG_SIZE) {
-				verbose(env, "attempt to corrupt spilled pointer on stack\n");
-				return -EACCES;
-			}
+		if (t == BPF_WRITE)
 			err = check_stack_write(env, state, off, size,
 						value_regno);
-		} else {
+		else
 			err = check_stack_read(env, state, off, size,
 					       value_regno);
-		}
 	} else if (reg_is_pkt_pointer(reg)) {
 		if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
 			verbose(env, "cannot write into packet\n");
@@ -1087,7 +1186,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 		}
 		err = check_packet_access(env, regno, off, size);
 		if (!err && t == BPF_READ && value_regno >= 0)
-			mark_reg_unknown(env, state->regs, value_regno);
+			mark_reg_unknown(env, regs, value_regno);
 	} else {
 		verbose(env, "R%d invalid mem access '%s'\n", regno,
 			reg_type_str[reg->type]);
@@ -1095,11 +1194,11 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
 	}
 
 	if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ &&
-	    state->regs[value_regno].type == SCALAR_VALUE) {
+	    regs[value_regno].type == SCALAR_VALUE) {
 		/* b/h/w load zero-extends, mark upper bits as known 0 */
-		state->regs[value_regno].var_off = tnum_cast(
-					state->regs[value_regno].var_off, size);
-		__update_reg_bounds(&state->regs[value_regno]);
+		regs[value_regno].var_off =
+			tnum_cast(regs[value_regno].var_off, size);
+		__update_reg_bounds(&regs[value_regno]);
 	}
 	return err;
 }
@@ -1156,9 +1255,9 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
 				int access_size, bool zero_size_allowed,
 				struct bpf_call_arg_meta *meta)
 {
-	struct bpf_verifier_state *state = &env->cur_state;
+	struct bpf_verifier_state *state = env->cur_state;
 	struct bpf_reg_state *regs = state->regs;
-	int off, i;
+	int off, i, slot, spi;
 
 	if (regs[regno].type != PTR_TO_STACK) {
 		/* Allow zero-byte read from NULL, regardless of pointer type */
@@ -1198,7 +1297,11 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
 	}
 
 	for (i = 0; i < access_size; i++) {
-		if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) {
+		slot = -(off + i) - 1;
+		spi = slot / BPF_REG_SIZE;
+		if (state->allocated_stack <= slot ||
+		    state->stack[spi].slot_type[slot % BPF_REG_SIZE] !=
+			STACK_MISC) {
 			verbose(env, "invalid indirect read from stack off %d+%d size %d\n",
 				off, i, access_size);
 			return -EACCES;
@@ -1211,7 +1314,7 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
 				   int access_size, bool zero_size_allowed,
 				   struct bpf_call_arg_meta *meta)
 {
-	struct bpf_reg_state *regs = env->cur_state.regs, *reg = &regs[regno];
+	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
 
 	switch (reg->type) {
 	case PTR_TO_PACKET:
@@ -1229,7 +1332,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
 			  enum bpf_arg_type arg_type,
 			  struct bpf_call_arg_meta *meta)
 {
-	struct bpf_reg_state *regs = env->cur_state.regs, *reg = &regs[regno];
+	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
 	enum bpf_reg_type expected_type, type = reg->type;
 	int err = 0;
 
@@ -1514,7 +1617,7 @@ static int check_raw_mode(const struct bpf_func_proto *fn)
  */
 static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
 {
-	struct bpf_verifier_state *state = &env->cur_state;
+	struct bpf_verifier_state *state = env->cur_state;
 	struct bpf_reg_state *regs = state->regs, *reg;
 	int i;
 
@@ -1522,10 +1625,10 @@ static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
 		if (reg_is_pkt_pointer_any(&regs[i]))
 			mark_reg_unknown(env, regs, i);
 
-	for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
-		if (state->stack_slot_type[i] != STACK_SPILL)
+	for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
+		if (state->stack[i].slot_type[0] != STACK_SPILL)
 			continue;
-		reg = &state->spilled_regs[i / BPF_REG_SIZE];
+		reg = &state->stack[i].spilled_ptr;
 		if (reg_is_pkt_pointer_any(reg))
 			__mark_reg_unknown(reg);
 	}
@@ -1533,9 +1636,8 @@ static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
 
 static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
 {
-	struct bpf_verifier_state *state = &env->cur_state;
 	const struct bpf_func_proto *fn = NULL;
-	struct bpf_reg_state *regs = state->regs;
+	struct bpf_reg_state *regs;
 	struct bpf_call_arg_meta meta;
 	bool changes_data;
 	int i, err;
@@ -1603,6 +1705,7 @@ static int check_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
 			return err;
 	}
 
+	regs = cur_regs(env);
 	/* reset caller saved regs */
 	for (i = 0; i < CALLER_SAVED_REGS; i++) {
 		mark_reg_not_init(env, regs, caller_saved[i]);
@@ -1691,7 +1794,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
 				   const struct bpf_reg_state *ptr_reg,
 				   const struct bpf_reg_state *off_reg)
 {
-	struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg;
+	struct bpf_reg_state *regs = cur_regs(env), *dst_reg;
 	bool known = tnum_is_const(off_reg->var_off);
 	s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value,
 	    smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value;
@@ -1703,13 +1806,13 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
 	dst_reg = &regs[dst];
 
 	if (WARN_ON_ONCE(known && (smin_val != smax_val))) {
-		print_verifier_state(env, &env->cur_state);
+		print_verifier_state(env, env->cur_state);
 		verbose(env,
 			"verifier internal error: known but bad sbounds\n");
 		return -EINVAL;
 	}
 	if (WARN_ON_ONCE(known && (umin_val != umax_val))) {
-		print_verifier_state(env, &env->cur_state);
+		print_verifier_state(env, env->cur_state);
 		verbose(env,
 			"verifier internal error: known but bad ubounds\n");
 		return -EINVAL;
@@ -1890,7 +1993,7 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
 				      struct bpf_reg_state *dst_reg,
 				      struct bpf_reg_state src_reg)
 {
-	struct bpf_reg_state *regs = env->cur_state.regs;
+	struct bpf_reg_state *regs = cur_regs(env);
 	u8 opcode = BPF_OP(insn->code);
 	bool src_known, dst_known;
 	s64 smin_val, smax_val;
@@ -2111,7 +2214,7 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
 static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
 				   struct bpf_insn *insn)
 {
-	struct bpf_reg_state *regs = env->cur_state.regs, *dst_reg, *src_reg;
+	struct bpf_reg_state *regs = cur_regs(env), *dst_reg, *src_reg;
 	struct bpf_reg_state *ptr_reg = NULL, off_reg = {0};
 	u8 opcode = BPF_OP(insn->code);
 	int rc;
@@ -2185,12 +2288,12 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
 
 	/* Got here implies adding two SCALAR_VALUEs */
 	if (WARN_ON_ONCE(ptr_reg)) {
-		print_verifier_state(env, &env->cur_state);
+		print_verifier_state(env, env->cur_state);
 		verbose(env, "verifier internal error: unexpected ptr_reg\n");
 		return -EINVAL;
 	}
 	if (WARN_ON(!src_reg)) {
-		print_verifier_state(env, &env->cur_state);
+		print_verifier_state(env, env->cur_state);
 		verbose(env, "verifier internal error: no src_reg\n");
 		return -EINVAL;
 	}
@@ -2200,7 +2303,7 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
 /* check validity of 32-bit and 64-bit arithmetic operations */
 static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
 {
-	struct bpf_reg_state *regs = env->cur_state.regs;
+	struct bpf_reg_state *regs = cur_regs(env);
 	u8 opcode = BPF_OP(insn->code);
 	int err;
 
@@ -2421,10 +2524,10 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *state,
 			/* keep the maximum range already checked */
 			regs[i].range = max(regs[i].range, new_range);
 
-	for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
-		if (state->stack_slot_type[i] != STACK_SPILL)
+	for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
+		if (state->stack[i].slot_type[0] != STACK_SPILL)
 			continue;
-		reg = &state->spilled_regs[i / BPF_REG_SIZE];
+		reg = &state->stack[i].spilled_ptr;
 		if (reg->type == type && reg->id == dst_reg->id)
 			reg->range = max_t(u16, reg->range, new_range);
 	}
@@ -2674,17 +2777,17 @@ static void mark_map_regs(struct bpf_verifier_state *state, u32 regno,
 	for (i = 0; i < MAX_BPF_REG; i++)
 		mark_map_reg(regs, i, id, is_null);
 
-	for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
-		if (state->stack_slot_type[i] != STACK_SPILL)
+	for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
+		if (state->stack[i].slot_type[0] != STACK_SPILL)
 			continue;
-		mark_map_reg(state->spilled_regs, i / BPF_REG_SIZE, id, is_null);
+		mark_map_reg(&state->stack[i].spilled_ptr, 0, id, is_null);
 	}
 }
 
 static int check_cond_jmp_op(struct bpf_verifier_env *env,
 			     struct bpf_insn *insn, int *insn_idx)
 {
-	struct bpf_verifier_state *other_branch, *this_branch = &env->cur_state;
+	struct bpf_verifier_state *other_branch, *this_branch = env->cur_state;
 	struct bpf_reg_state *regs = this_branch->regs, *dst_reg;
 	u8 opcode = BPF_OP(insn->code);
 	int err;
@@ -2876,7 +2979,7 @@ static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
 /* verify BPF_LD_IMM64 instruction */
 static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
 {
-	struct bpf_reg_state *regs = env->cur_state.regs;
+	struct bpf_reg_state *regs = cur_regs(env);
 	int err;
 
 	if (BPF_SIZE(insn->code) != BPF_DW) {
@@ -2937,7 +3040,7 @@ static bool may_access_skb(enum bpf_prog_type type)
  */
 static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
 {
-	struct bpf_reg_state *regs = env->cur_state.regs;
+	struct bpf_reg_state *regs = cur_regs(env);
 	u8 mode = BPF_MODE(insn->code);
 	int i, err;
 
@@ -2999,7 +3102,7 @@ static int check_return_code(struct bpf_verifier_env *env)
 		return 0;
 	}
 
-	reg = &env->cur_state.regs[BPF_REG_0];
+	reg = cur_regs(env) + BPF_REG_0;
 	if (reg->type != SCALAR_VALUE) {
 		verbose(env, "At program exit the register R0 is not a known value (%s)\n",
 			reg_type_str[reg->type]);
@@ -3363,6 +3466,57 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
 	return false;
 }
 
+static bool stacksafe(struct bpf_verifier_state *old,
+		      struct bpf_verifier_state *cur,
+		      struct idpair *idmap)
+{
+	int i, spi;
+
+	/* if explored stack has more populated slots than current stack
+	 * such stacks are not equivalent
+	 */
+	if (old->allocated_stack > cur->allocated_stack)
+		return false;
+
+	/* walk slots of the explored stack and ignore any additional
+	 * slots in the current stack, since explored(safe) state
+	 * didn't use them
+	 */
+	for (i = 0; i < old->allocated_stack; i++) {
+		spi = i / BPF_REG_SIZE;
+
+		if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID)
+			continue;
+		if (old->stack[spi].slot_type[i % BPF_REG_SIZE] !=
+		    cur->stack[spi].slot_type[i % BPF_REG_SIZE])
+			/* Ex: old explored (safe) state has STACK_SPILL in
+			 * this stack slot, but current has has STACK_MISC ->
+			 * this verifier states are not equivalent,
+			 * return false to continue verification of this path
+			 */
+			return false;
+		if (i % BPF_REG_SIZE)
+			continue;
+		if (old->stack[spi].slot_type[0] != STACK_SPILL)
+			continue;
+		if (!regsafe(&old->stack[spi].spilled_ptr,
+			     &cur->stack[spi].spilled_ptr,
+			     idmap))
+			/* when explored and current stack slot are both storing
+			 * spilled registers, check that stored pointers types
+			 * are the same as well.
+			 * Ex: explored safe path could have stored
+			 * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8}
+			 * but current path has stored:
+			 * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16}
+			 * such verifier states are not equivalent.
+			 * return false to continue verification of this path
+			 */
+			return false;
+	}
+	return true;
+}
+
 /* compare two verifier states
  *
  * all states stored in state_list are known to be valid, since
@@ -3407,37 +3561,8 @@ static bool states_equal(struct bpf_verifier_env *env,
 			goto out_free;
 	}
 
-	for (i = 0; i < MAX_BPF_STACK; i++) {
-		if (old->stack_slot_type[i] == STACK_INVALID)
-			continue;
-		if (old->stack_slot_type[i] != cur->stack_slot_type[i])
-			/* Ex: old explored (safe) state has STACK_SPILL in
-			 * this stack slot, but current has has STACK_MISC ->
-			 * this verifier states are not equivalent,
-			 * return false to continue verification of this path
-			 */
-			goto out_free;
-		if (i % BPF_REG_SIZE)
-			continue;
-		if (old->stack_slot_type[i] != STACK_SPILL)
-			continue;
-		if (!regsafe(&old->spilled_regs[i / BPF_REG_SIZE],
-			     &cur->spilled_regs[i / BPF_REG_SIZE],
-			     idmap))
-			/* when explored and current stack slot are both storing
-			 * spilled registers, check that stored pointers types
-			 * are the same as well.
-			 * Ex: explored safe path could have stored
-			 * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8}
-			 * but current path has stored:
-			 * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16}
-			 * such verifier states are not equivalent.
-			 * return false to continue verification of this path
-			 */
-			goto out_free;
-		else
-			continue;
-	}
+	if (!stacksafe(old, cur, idmap))
+		goto out_free;
 	ret = true;
 out_free:
 	kfree(idmap);
@@ -3473,17 +3598,19 @@ static bool do_propagate_liveness(const struct bpf_verifier_state *state,
 		}
 	}
 	/* ... and stack slots */
-	for (i = 0; i < MAX_BPF_STACK / BPF_REG_SIZE; i++) {
-		if (parent->stack_slot_type[i * BPF_REG_SIZE] != STACK_SPILL)
+	for (i = 0; i < state->allocated_stack / BPF_REG_SIZE &&
+		    i < parent->allocated_stack / BPF_REG_SIZE; i++) {
+		if (parent->stack[i].slot_type[0] != STACK_SPILL)
 			continue;
-		if (state->stack_slot_type[i * BPF_REG_SIZE] != STACK_SPILL)
+		if (state->stack[i].slot_type[0] != STACK_SPILL)
 			continue;
-		if (parent->spilled_regs[i].live & REG_LIVE_READ)
+		if (parent->stack[i].spilled_ptr.live & REG_LIVE_READ)
 			continue;
-		if (writes && (state->spilled_regs[i].live & REG_LIVE_WRITTEN))
+		if (writes &&
+		    (state->stack[i].spilled_ptr.live & REG_LIVE_WRITTEN))
 			continue;
-		if (state->spilled_regs[i].live & REG_LIVE_READ) {
-			parent->spilled_regs[i].live |= REG_LIVE_READ;
+		if (state->stack[i].spilled_ptr.live & REG_LIVE_READ) {
+			parent->stack[i].spilled_ptr.live |= REG_LIVE_READ;
 			touched = true;
 		}
 	}
@@ -3513,6 +3640,7 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 {
 	struct bpf_verifier_state_list *new_sl;
 	struct bpf_verifier_state_list *sl;
+	struct bpf_verifier_state *cur = env->cur_state;
 	int i;
 
 	sl = env->explored_states[insn_idx];
@@ -3523,7 +3651,7 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 		return 0;
 
 	while (sl != STATE_LIST_MARK) {
-		if (states_equal(env, &sl->state, &env->cur_state)) {
+		if (states_equal(env, &sl->state, cur)) {
 			/* reached equivalent register/stack state,
 			 * prune the search.
 			 * Registers read by the continuation are read by us.
@@ -3534,7 +3662,7 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 			 * they'll be immediately forgotten as we're pruning
 			 * this state and will pop a new one.
 			 */
-			propagate_liveness(&sl->state, &env->cur_state);
+			propagate_liveness(&sl->state, cur);
 			return 1;
 		}
 		sl = sl->next;
@@ -3546,16 +3674,16 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 	 * it will be rejected. Since there are no loops, we won't be
 	 * seeing this 'insn_idx' instruction again on the way to bpf_exit
 	 */
-	new_sl = kmalloc(sizeof(struct bpf_verifier_state_list), GFP_USER);
+	new_sl = kzalloc(sizeof(struct bpf_verifier_state_list), GFP_KERNEL);
 	if (!new_sl)
 		return -ENOMEM;
 
 	/* add new state to the head of linked list */
-	memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state));
+	copy_verifier_state(&new_sl->state, cur);
 	new_sl->next = env->explored_states[insn_idx];
 	env->explored_states[insn_idx] = new_sl;
 	/* connect new state to parentage chain */
-	env->cur_state.parent = &new_sl->state;
+	cur->parent = &new_sl->state;
 	/* clear write marks in current state: the writes we did are not writes
 	 * our child did, so they don't screen off its reads from us.
 	 * (There are no read marks in current state, because reads always mark
@@ -3563,10 +3691,10 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 	 * explored_states can get read marks.)
 	 */
 	for (i = 0; i < BPF_REG_FP; i++)
-		env->cur_state.regs[i].live = REG_LIVE_NONE;
-	for (i = 0; i < MAX_BPF_STACK / BPF_REG_SIZE; i++)
-		if (env->cur_state.stack_slot_type[i * BPF_REG_SIZE] == STACK_SPILL)
-			env->cur_state.spilled_regs[i].live = REG_LIVE_NONE;
+		cur->regs[i].live = REG_LIVE_NONE;
+	for (i = 0; i < cur->allocated_stack / BPF_REG_SIZE; i++)
+		if (cur->stack[i].slot_type[0] == STACK_SPILL)
+			cur->stack[i].spilled_ptr.live = REG_LIVE_NONE;
 	return 0;
 }
 
@@ -3581,15 +3709,19 @@ static int ext_analyzer_insn_hook(struct bpf_verifier_env *env,
 
 static int do_check(struct bpf_verifier_env *env)
 {
-	struct bpf_verifier_state *state = &env->cur_state;
+	struct bpf_verifier_state *state;
 	struct bpf_insn *insns = env->prog->insnsi;
-	struct bpf_reg_state *regs = state->regs;
+	struct bpf_reg_state *regs;
 	int insn_cnt = env->prog->len;
 	int insn_idx, prev_insn_idx = 0;
 	int insn_processed = 0;
 	bool do_print_state = false;
 
-	init_reg_state(env, regs);
+	state = kzalloc(sizeof(struct bpf_verifier_state), GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+	env->cur_state = state;
+	init_reg_state(env, state->regs);
 	state->parent = NULL;
 	insn_idx = 0;
 	for (;;) {
@@ -3637,7 +3769,7 @@ static int do_check(struct bpf_verifier_env *env)
 			else
 				verbose(env, "\nfrom %d to %d:",
 					prev_insn_idx, insn_idx);
-			print_verifier_state(env, &env->cur_state);
+			print_verifier_state(env, state);
 			do_print_state = false;
 		}
 
@@ -3651,6 +3783,7 @@ static int do_check(struct bpf_verifier_env *env)
 		if (err)
 			return err;
 
+		regs = cur_regs(env);
 		if (class == BPF_ALU || class == BPF_ALU64) {
 			err = check_alu_op(env, insn);
 			if (err)
@@ -3818,8 +3951,10 @@ static int do_check(struct bpf_verifier_env *env)
 				if (err)
 					return err;
 process_bpf_exit:
-				insn_idx = pop_stack(env, &prev_insn_idx);
-				if (insn_idx < 0) {
+				err = pop_stack(env, &prev_insn_idx, &insn_idx);
+				if (err < 0) {
+					if (err != -ENOENT)
+						return err;
 					break;
 				} else {
 					do_print_state = true;
@@ -4359,9 +4494,11 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
 	env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
 
 	ret = do_check(env);
+	free_verifier_state(env->cur_state);
+	env->cur_state = NULL;
 
 skip_full_check:
-	while (pop_stack(env, NULL) >= 0);
+	while (!pop_stack(env, NULL, NULL));
 	free_states(env);
 
 	if (ret == 0)
@@ -4464,9 +4601,11 @@ int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,
 	env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
 
 	ret = do_check(env);
+	free_verifier_state(env->cur_state);
+	env->cur_state = NULL;
 
 skip_full_check:
-	while (pop_stack(env, NULL) >= 0);
+	while (!pop_stack(env, NULL, NULL));
 	free_states(env);
 
 	mutex_unlock(&bpf_verifier_lock);
generated by cgit-pink 1.4.1 (git 2.36.1) at 2024-09-24 08:39:52 +0000