1 files changed, 157 insertions, 20 deletions

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a28e09c7825d..630a7bac1e51 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -755,7 +755,7 @@ static int check_func_arg(struct verifier_env *env, u32 regno,
 	enum bpf_reg_type expected_type;
 	int err = 0;
 
-	if (arg_type == ARG_ANYTHING)
+	if (arg_type == ARG_DONTCARE)
 		return 0;
 
 	if (reg->type == NOT_INIT) {
@@ -763,6 +763,9 @@ static int check_func_arg(struct verifier_env *env, u32 regno,
 		return -EACCES;
 	}
 
+	if (arg_type == ARG_ANYTHING)
+		return 0;
+
 	if (arg_type == ARG_PTR_TO_STACK || arg_type == ARG_PTR_TO_MAP_KEY ||
 	    arg_type == ARG_PTR_TO_MAP_VALUE) {
 		expected_type = PTR_TO_STACK;
@@ -770,6 +773,8 @@ static int check_func_arg(struct verifier_env *env, u32 regno,
 		expected_type = CONST_IMM;
 	} else if (arg_type == ARG_CONST_MAP_PTR) {
 		expected_type = CONST_PTR_TO_MAP;
+	} else if (arg_type == ARG_PTR_TO_CTX) {
+		expected_type = PTR_TO_CTX;
 	} else {
 		verbose("unsupported arg_type %d\n", arg_type);
 		return -EFAULT;
@@ -852,7 +857,7 @@ static int check_call(struct verifier_env *env, int func_id)
 	}
 
 	/* eBPF programs must be GPL compatible to use GPL-ed functions */
-	if (!env->prog->aux->is_gpl_compatible && fn->gpl_only) {
+	if (!env->prog->gpl_compatible && fn->gpl_only) {
 		verbose("cannot call GPL only function from proprietary program\n");
 		return -EINVAL;
 	}
@@ -1172,6 +1177,18 @@ static int check_ld_imm(struct verifier_env *env, struct bpf_insn *insn)
 	return 0;
 }
 
+static bool may_access_skb(enum bpf_prog_type type)
+{
+	switch (type) {
+	case BPF_PROG_TYPE_SOCKET_FILTER:
+	case BPF_PROG_TYPE_SCHED_CLS:
+	case BPF_PROG_TYPE_SCHED_ACT:
+		return true;
+	default:
+		return false;
+	}
+}
+
 /* verify safety of LD_ABS|LD_IND instructions:
  * - they can only appear in the programs where ctx == skb
  * - since they are wrappers of function calls, they scratch R1-R5 registers,
@@ -1194,8 +1211,8 @@ static int check_ld_abs(struct verifier_env *env, struct bpf_insn *insn)
 	struct reg_state *reg;
 	int i, err;
 
-	if (env->prog->aux->prog_type != BPF_PROG_TYPE_SOCKET_FILTER) {
-		verbose("BPF_LD_ABS|IND instructions are only allowed in socket filters\n");
+	if (!may_access_skb(env->prog->type)) {
+		verbose("BPF_LD_ABS|IND instructions not allowed for this program type\n");
 		return -EINVAL;
 	}
 
@@ -1606,11 +1623,10 @@ static int do_check(struct verifier_env *env)
 				return err;
 
 		} else if (class == BPF_LDX) {
-			if (BPF_MODE(insn->code) != BPF_MEM ||
-			    insn->imm != 0) {
-				verbose("BPF_LDX uses reserved fields\n");
-				return -EINVAL;
-			}
+			enum bpf_reg_type src_reg_type;
+
+			/* check for reserved fields is already done */
+
 			/* check src operand */
 			err = check_reg_arg(regs, insn->src_reg, SRC_OP);
 			if (err)
@@ -1629,6 +1645,29 @@ static int do_check(struct verifier_env *env)
 			if (err)
 				return err;
 
+			src_reg_type = regs[insn->src_reg].type;
+
+			if (insn->imm == 0 && BPF_SIZE(insn->code) == BPF_W) {
+				/* saw a valid insn
+				 * dst_reg = *(u32 *)(src_reg + off)
+				 * use reserved 'imm' field to mark this insn
+				 */
+				insn->imm = src_reg_type;
+
+			} else if (src_reg_type != insn->imm &&
+				   (src_reg_type == PTR_TO_CTX ||
+				    insn->imm == PTR_TO_CTX)) {
+				/* ABuser program is trying to use the same insn
+				 * dst_reg = *(u32*) (src_reg + off)
+				 * with different pointer types:
+				 * src_reg == ctx in one branch and
+				 * src_reg == stack|map in some other branch.
+				 * Reject it.
+				 */
+				verbose("same insn cannot be used with different pointers\n");
+				return -EINVAL;
+			}
+
 		} else if (class == BPF_STX) {
 			if (BPF_MODE(insn->code) == BPF_XADD) {
 				err = check_xadd(env, insn);
@@ -1776,6 +1815,13 @@ static int replace_map_fd_with_map_ptr(struct verifier_env *env)
 	int i, j;
 
 	for (i = 0; i < insn_cnt; i++, insn++) {
+		if (BPF_CLASS(insn->code) == BPF_LDX &&
+		    (BPF_MODE(insn->code) != BPF_MEM ||
+		     insn->imm != 0)) {
+			verbose("BPF_LDX uses reserved fields\n");
+			return -EINVAL;
+		}
+
 		if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
 			struct bpf_map *map;
 			struct fd f;
@@ -1867,6 +1913,92 @@ static void convert_pseudo_ld_imm64(struct verifier_env *env)
 			insn->src_reg = 0;
 }
 
+static void adjust_branches(struct bpf_prog *prog, int pos, int delta)
+{
+	struct bpf_insn *insn = prog->insnsi;
+	int insn_cnt = prog->len;
+	int i;
+
+	for (i = 0; i < insn_cnt; i++, insn++) {
+		if (BPF_CLASS(insn->code) != BPF_JMP ||
+		    BPF_OP(insn->code) == BPF_CALL ||
+		    BPF_OP(insn->code) == BPF_EXIT)
+			continue;
+
+		/* adjust offset of jmps if necessary */
+		if (i < pos && i + insn->off + 1 > pos)
+			insn->off += delta;
+		else if (i > pos && i + insn->off + 1 < pos)
+			insn->off -= delta;
+	}
+}
+
+/* convert load instructions that access fields of 'struct __sk_buff'
+ * into sequence of instructions that access fields of 'struct sk_buff'
+ */
+static int convert_ctx_accesses(struct verifier_env *env)
+{
+	struct bpf_insn *insn = env->prog->insnsi;
+	int insn_cnt = env->prog->len;
+	struct bpf_insn insn_buf[16];
+	struct bpf_prog *new_prog;
+	u32 cnt;
+	int i;
+
+	if (!env->prog->aux->ops->convert_ctx_access)
+		return 0;
+
+	for (i = 0; i < insn_cnt; i++, insn++) {
+		if (insn->code != (BPF_LDX | BPF_MEM | BPF_W))
+			continue;
+
+		if (insn->imm != PTR_TO_CTX) {
+			/* clear internal mark */
+			insn->imm = 0;
+			continue;
+		}
+
+		cnt = env->prog->aux->ops->
+			convert_ctx_access(insn->dst_reg, insn->src_reg,
+					   insn->off, insn_buf);
+		if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
+			verbose("bpf verifier is misconfigured\n");
+			return -EINVAL;
+		}
+
+		if (cnt == 1) {
+			memcpy(insn, insn_buf, sizeof(*insn));
+			continue;
+		}
+
+		/* several new insns need to be inserted. Make room for them */
+		insn_cnt += cnt - 1;
+		new_prog = bpf_prog_realloc(env->prog,
+					    bpf_prog_size(insn_cnt),
+					    GFP_USER);
+		if (!new_prog)
+			return -ENOMEM;
+
+		new_prog->len = insn_cnt;
+
+		memmove(new_prog->insnsi + i + cnt, new_prog->insns + i + 1,
+			sizeof(*insn) * (insn_cnt - i - cnt));
+
+		/* copy substitute insns in place of load instruction */
+		memcpy(new_prog->insnsi + i, insn_buf, sizeof(*insn) * cnt);
+
+		/* adjust branches in the whole program */
+		adjust_branches(new_prog, i, cnt - 1);
+
+		/* keep walking new program and skip insns we just inserted */
+		env->prog = new_prog;
+		insn = new_prog->insnsi + i + cnt - 1;
+		i += cnt - 1;
+	}
+
+	return 0;
+}
+
 static void free_states(struct verifier_env *env)
 {
 	struct verifier_state_list *sl, *sln;
@@ -1889,13 +2021,13 @@ static void free_states(struct verifier_env *env)
 	kfree(env->explored_states);
 }
 
-int bpf_check(struct bpf_prog *prog, union bpf_attr *attr)
+int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
 {
 	char __user *log_ubuf = NULL;
 	struct verifier_env *env;
 	int ret = -EINVAL;
 
-	if (prog->len <= 0 || prog->len > BPF_MAXINSNS)
+	if ((*prog)->len <= 0 || (*prog)->len > BPF_MAXINSNS)
 		return -E2BIG;
 
 	/* 'struct verifier_env' can be global, but since it's not small,
@@ -1905,7 +2037,7 @@ int bpf_check(struct bpf_prog *prog, union bpf_attr *attr)
 	if (!env)
 		return -ENOMEM;
 
-	env->prog = prog;
+	env->prog = *prog;
 
 	/* grab the mutex to protect few globals used by verifier */
 	mutex_lock(&bpf_verifier_lock);
@@ -1937,7 +2069,7 @@ int bpf_check(struct bpf_prog *prog, union bpf_attr *attr)
 	if (ret < 0)
 		goto skip_full_check;
 
-	env->explored_states = kcalloc(prog->len,
+	env->explored_states = kcalloc(env->prog->len,
 				       sizeof(struct verifier_state_list *),
 				       GFP_USER);
 	ret = -ENOMEM;
@@ -1954,6 +2086,10 @@ skip_full_check:
 	while (pop_stack(env, NULL) >= 0);
 	free_states(env);
 
+	if (ret == 0)
+		/* program is valid, convert *(u32*)(ctx + off) accesses */
+		ret = convert_ctx_accesses(env);
+
 	if (log_level && log_len >= log_size - 1) {
 		BUG_ON(log_len >= log_size);
 		/* verifier log exceeded user supplied buffer */
@@ -1969,18 +2105,18 @@ skip_full_check:
 
 	if (ret == 0 && env->used_map_cnt) {
 		/* if program passed verifier, update used_maps in bpf_prog_info */
-		prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
-						     sizeof(env->used_maps[0]),
-						     GFP_KERNEL);
+		env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
+							  sizeof(env->used_maps[0]),
+							  GFP_KERNEL);
 
-		if (!prog->aux->used_maps) {
+		if (!env->prog->aux->used_maps) {
 			ret = -ENOMEM;
 			goto free_log_buf;
 		}
 
-		memcpy(prog->aux->used_maps, env->used_maps,
+		memcpy(env->prog->aux->used_maps, env->used_maps,
 		       sizeof(env->used_maps[0]) * env->used_map_cnt);
-		prog->aux->used_map_cnt = env->used_map_cnt;
+		env->prog->aux->used_map_cnt = env->used_map_cnt;
 
 		/* program is valid. Convert pseudo bpf_ld_imm64 into generic
 		 * bpf_ld_imm64 instructions
@@ -1992,11 +2128,12 @@ free_log_buf:
 	if (log_level)
 		vfree(log_buf);
 free_env:
-	if (!prog->aux->used_maps)
+	if (!env->prog->aux->used_maps)
 		/* if we didn't copy map pointers into bpf_prog_info, release
 		 * them now. Otherwise free_bpf_prog_info() will release them.
 		 */
 		release_maps(env);
+	*prog = env->prog;
 	kfree(env);
 	mutex_unlock(&bpf_verifier_lock);
 	return ret;