bpf: Generalize check_ctx_reg for reuse with other types

Generalize the check_ctx_reg() helper function into a more generic named one
so that it can be reused for other register types as well to check whether
their offset is non-zero. No functional change.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 143401d4c9d9ac4048c0d424e3b1776e731df813..e9993172f892e8297487bafc8f54c3002fde4e87 100644 (file)
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -519,8 +519,8 @@ bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off,
 void
 bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt);
 
-int check_ctx_reg(struct bpf_verifier_env *env,
-                 const struct bpf_reg_state *reg, int regno);
+int check_ptr_off_reg(struct bpf_verifier_env *env,
+                     const struct bpf_reg_state *reg, int regno);
 int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                   u32 regno, u32 mem_size);
 

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 33bb8ae4a8047cd6386903432bde96c48bab565c..e16dafeb24504a307c40d1e37c9da6e6ede1a076 100644 (file)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -5686,7 +5686,7 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env,
                                        i, btf_type_str(t));
                                return -EINVAL;
                        }
-                       if (check_ctx_reg(env, reg, regno))
+                       if (check_ptr_off_reg(env, reg, regno))
                                return -EINVAL;
                } else if (is_kfunc && (reg->type == PTR_TO_BTF_ID || reg2btf_ids[reg->type])) {
                        const struct btf_type *reg_ref_t;

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a8587210907d5e80a9c1a82ead1c666cf197cdcc..9b8334068e71be8b2884d0e9dd0e43d81d18db5a 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3969,16 +3969,16 @@ static int get_callee_stack_depth(struct bpf_verifier_env *env,
 }
 #endif
 
-int check_ctx_reg(struct bpf_verifier_env *env,
-                 const struct bpf_reg_state *reg, int regno)
+int check_ptr_off_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.
+       /* Access to this pointer-typed register 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);
+               verbose(env, "dereference of modified %s ptr R%d off=%d disallowed\n",
+                       reg_type_str(env, reg->type), regno, reg->off);
                return -EACCES;
        }
 
@@ -3986,7 +3986,8 @@ int check_ctx_reg(struct bpf_verifier_env *env,
                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);
+               verbose(env, "variable %s access var_off=%s disallowed\n",
+                       reg_type_str(env, reg->type), tn_buf);
                return -EACCES;
        }
 
@@ -4437,7 +4438,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
                        return -EACCES;
                }
 
-               err = check_ctx_reg(env, reg, regno);
+               err = check_ptr_off_reg(env, reg, regno);
                if (err < 0)
                        return err;
 
@@ -5305,7 +5306,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
                return err;
 
        if (type == PTR_TO_CTX) {
-               err = check_ctx_reg(env, reg, regno);
+               err = check_ptr_off_reg(env, reg, regno);
                if (err < 0)
                        return err;
        }
@@ -9651,7 +9652,7 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
                        return err;
        }
 
-       err = check_ctx_reg(env, &regs[ctx_reg], ctx_reg);
+       err = check_ptr_off_reg(env, &regs[ctx_reg], ctx_reg);
        if (err < 0)
                return err;