[PATCH openEuler-5.10 39/48] bpf: Generalize check_ctx_reg for reuse with other types

From: Daniel Borkmann daniel@iogearbox.net

mainline inclusion from mainline-v5.17-rc1 commit be80a1d3f9dbe5aee79a325964f7037fe2d92f30 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I4WT90 CVE: CVE-2021-4204

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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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 Conflicts: include/linux/bpf_verifier.h kernel/bpf/btf.c Signed-off-by: Pu Lehui pulehui@huawei.com Reviewed-by: Kuohai Xu xukuohai@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- include/linux/bpf_verifier.h | 4 ++-- kernel/bpf/btf.c | 2 +- kernel/bpf/verifier.c | 21 +++++++++++---------- 3 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index efc26c4b5f7b..2f6a60c76fbd 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -469,8 +469,8 @@ 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);

/* this lives here instead of in bpf.h because it needs to dereference tgt_prog */ static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog, diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 9d6c55138571..ce69bb25ede8 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -5207,7 +5207,7 @@ int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog, i, btf_kind_str[BTF_INFO_KIND(t->info)]); goto out; } - if (check_ctx_reg(env, &reg[i + 1], i + 1)) + if (check_ptr_off_reg(env, &reg[i + 1], i + 1)) goto out; continue; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index bd2349fb83fc..f6691c77df03 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3359,16 +3359,16 @@ 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; }

@@ -3376,7 +3376,8 @@ 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; }

@@ -3814,7 +3815,7 @@ 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;

@@ -4533,7 +4534,7 @@ 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; } @@ -8301,7 +8302,7 @@ 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;