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: Hou Tao <houtao1@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20211025064025.2567443-3-houtao1@huawei.com

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index aabd354..67f71e7 100644 (file)
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -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,

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index cbcd0d6..7396488 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -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,

diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c
index 57709ac..2cf02b4 100644 (file)
--- a/net/ipv4/bpf_tcp_ca.c
+++ b/net/ipv4/bpf_tcp_ca.c
@@ -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)