Commit 35346ab6 authored by Hou Tao's avatar Hou Tao Committed by Alexei Starovoitov
Browse files

bpf: Factor out helpers for ctx access checking 



Factor out two helpers to check the read access of ctx for raw tp
and BTF function. bpf_tracing_ctx_access() is used to check
the read access to argument is valid, and bpf_tracing_btf_ctx_access()
checks whether the btf type of argument is valid besides the checking
of argument read. bpf_tracing_btf_ctx_access() will be used by the
following patch.

Signed-off-by: default avatarHou Tao <houtao1@huawei.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20211025064025.2567443-3-houtao1@huawei.com
parent 31a645ae

include/linux/bpf.h

+23 −0
Original line number Diff line number Diff line
@@ -1650,6 +1650,29 @@ bool bpf_prog_test_check_kfunc_call(u32 kfunc_id, struct module *owner); 
bool btf_ctx_access(int off, int size, enum bpf_access_type type,

		    const struct bpf_prog *prog,

		    struct bpf_insn_access_aux *info);



static inline bool bpf_tracing_ctx_access(int off, int size,

					  enum bpf_access_type type)

{

	if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)

		return false;

	if (type != BPF_READ)

		return false;

	if (off % size != 0)

		return false;

	return true;

}



static inline bool bpf_tracing_btf_ctx_access(int off, int size,

					      enum bpf_access_type type,

					      const struct bpf_prog *prog,

					      struct bpf_insn_access_aux *info)

{

	if (!bpf_tracing_ctx_access(off, size, type))

		return false;

	return btf_ctx_access(off, size, type, prog, info);

}



int btf_struct_access(struct bpf_verifier_log *log, const struct btf *btf,

		      const struct btf_type *t, int off, int size,

		      enum bpf_access_type atype,

kernel/trace/bpf_trace.c

+2 −14
Original line number Diff line number Diff line
@@ -1646,13 +1646,7 @@ static bool raw_tp_prog_is_valid_access(int off, int size, 
					const struct bpf_prog *prog,

					struct bpf_insn_access_aux *info)

{

	if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)

		return false;

	if (type != BPF_READ)

		return false;

	if (off % size != 0)

		return false;

	return true;

	return bpf_tracing_ctx_access(off, size, type);

}



static bool tracing_prog_is_valid_access(int off, int size,
@@ -1660,13 +1654,7 @@ static bool tracing_prog_is_valid_access(int off, int size, 
					 const struct bpf_prog *prog,

					 struct bpf_insn_access_aux *info)

{

	if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)

		return false;

	if (type != BPF_READ)

		return false;

	if (off % size != 0)

		return false;

	return btf_ctx_access(off, size, type, prog, info);

	return bpf_tracing_btf_ctx_access(off, size, type, prog, info);

}



int __weak bpf_prog_test_run_tracing(struct bpf_prog *prog,

net/ipv4/bpf_tcp_ca.c

+1 −8
Original line number Diff line number Diff line
@@ -81,14 +81,7 @@ static bool bpf_tcp_ca_is_valid_access(int off, int size, 
				       const struct bpf_prog *prog,

				       struct bpf_insn_access_aux *info)

{

	if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)

		return false;

	if (type != BPF_READ)

		return false;

	if (off % size != 0)

		return false;



	if (!btf_ctx_access(off, size, type, prog, info))

	if (!bpf_tracing_btf_ctx_access(off, size, type, prog, info))

		return false;



	if (info->reg_type == PTR_TO_BTF_ID && info->btf_id == sock_id)