[PATCH 5.15 08/71] bpf: Generalize check_ctx_reg for reuse with other types

5.15-stable review patch. If anyone has any objections, please let me know.

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From: Daniel Borkmann daniel@iogearbox.net

commit be80a1d3f9dbe5aee79a325964f7037fe2d92f30 upstream.

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 Signed-off-by: Edward Liaw edliaw@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/bpf_verifier.h | 4 ++-- kernel/bpf/btf.c | 2 +- kernel/bpf/verifier.c | 21 +++++++++++---------- 3 files changed, 14 insertions(+), 13 deletions(-)

--- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -541,8 +541,8 @@ bpf_prog_offload_replace_insn(struct bpf 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);

--- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -5558,7 +5558,7 @@ static int btf_check_func_arg_match(stru 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[base_type(reg->type)] && !type_flag(reg->type)))) { --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3980,16 +3980,16 @@ static int get_callee_stack_depth(struct } #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; }

@@ -3997,7 +3997,8 @@ int check_ctx_reg(struct bpf_verifier_en 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; }

@@ -4447,7 +4448,7 @@ static int check_mem_access(struct bpf_v return -EACCES; }

- err = check_ctx_reg(env, reg, regno); + err = check_ptr_off_reg(env, reg, regno); if (err < 0) return err;

@@ -5327,7 +5328,7 @@ static int check_func_arg(struct bpf_ver 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; } @@ -9561,7 +9562,7 @@ static int check_ld_abs(struct bpf_verif 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;