}
#endif
+static int check_ctx_reg(struct bpf_verifier_env *env,
+ const struct bpf_reg_state *reg, int regno)
+{
+ /* Access to ctx or passing it to a helper is only allowed in
+ * its original, unmodified form.
+ */
+
+ if (reg->off) {
+ verbose(env, "dereference of modified ctx ptr R%d off=%d disallowed\n",
+ regno, reg->off);
+ return -EACCES;
+ }
+
+ if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
+ char tn_buf[48];
+
+ tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
+ verbose(env, "variable ctx access var_off=%s disallowed\n", tn_buf);
+ return -EACCES;
+ }
+
+ return 0;
+}
+
/* truncate register to smaller size (in bytes)
* must be called with size < BPF_REG_SIZE
*/
verbose(env, "R%d leaks addr into ctx\n", value_regno);
return -EACCES;
}
- /* ctx accesses must be at a fixed offset, so that we can
- * determine what type of data were returned.
- */
- if (reg->off) {
- verbose(env,
- "dereference of modified ctx ptr R%d off=%d+%d, ctx+const is allowed, ctx+const+const is not\n",
- regno, reg->off, off - reg->off);
- return -EACCES;
- }
- if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env,
- "variable ctx access var_off=%s off=%d size=%d",
- tn_buf, off, size);
- return -EACCES;
- }
+ err = check_ctx_reg(env, reg, regno);
+ if (err < 0)
+ return err;
+
err = check_ctx_access(env, insn_idx, off, size, t, ®_type);
if (!err && t == BPF_READ && value_regno >= 0) {
/* ctx access returns either a scalar, or a
expected_type = PTR_TO_CTX;
if (type != expected_type)
goto err_type;
+ err = check_ctx_reg(env, reg, regno);
+ if (err < 0)
+ return err;
} else if (arg_type_is_mem_ptr(arg_type)) {
expected_type = PTR_TO_STACK;
/* One exception here. In case function allows for NULL to be
insn->imm = 1;
}
- func = kzalloc(sizeof(prog) * env->subprog_cnt, GFP_KERNEL);
+ func = kcalloc(env->subprog_cnt, sizeof(prog), GFP_KERNEL);
if (!func)
return -ENOMEM;