From 86f44fcec22ce2979507742bc53db8400e454f46 Mon Sep 17 00:00:00 2001
From: Alexei Starovoitov <ast@kernel.org>
Date: Mon, 8 Aug 2022 20:58:09 -0700
Subject: [PATCH] bpf: Disallow bpf programs call prog_run command.
The verifier cannot perform sufficient validation of bpf_attr->test.ctx_in
pointer, therefore bpf programs should not be allowed to call BPF_PROG_RUN
command from within the program.
To fix this issue split bpf_sys_bpf() bpf helper into normal kern_sys_bpf()
kernel function that can only be used by the kernel light skeleton directly.
Reported-by: YiFei Zhu <zhuyifei@google.com>
Fixes: b1d18a7574d0 ("bpf: Extend sys_bpf commands for bpf_syscall programs.")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
kernel/bpf/syscall.c | 20 ++++++++++++++------
tools/lib/bpf/skel_internal.h | 4 ++--
2 files changed, 16 insertions(+), 8 deletions(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 7dc3f80036310..a1cb0bdc5ad64 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -5071,9 +5071,6 @@ static bool syscall_prog_is_valid_access(int off, int size,
BPF_CALL_3(bpf_sys_bpf, int, cmd, union bpf_attr *, attr, u32, attr_size)
{
- struct bpf_prog * __maybe_unused prog;
- struct bpf_tramp_run_ctx __maybe_unused run_ctx;
-
switch (cmd) {
case BPF_MAP_CREATE:
case BPF_MAP_UPDATE_ELEM:
@@ -5083,6 +5080,18 @@ BPF_CALL_3(bpf_sys_bpf, int, cmd, union bpf_attr *, attr, u32, attr_size)
case BPF_LINK_CREATE:
case BPF_RAW_TRACEPOINT_OPEN:
break;
+ default:
+ return -EINVAL;
+ }
+ return __sys_bpf(cmd, KERNEL_BPFPTR(attr), attr_size);
+}
+
+int kern_sys_bpf(int cmd, union bpf_attr *attr, unsigned int size)
+{
+ struct bpf_prog * __maybe_unused prog;
+ struct bpf_tramp_run_ctx __maybe_unused run_ctx;
+
+ switch (cmd) {
#ifdef CONFIG_BPF_JIT /* __bpf_prog_enter_sleepable used by trampoline and JIT */
case BPF_PROG_TEST_RUN:
if (attr->test.data_in || attr->test.data_out ||
@@ -5113,11 +5122,10 @@ BPF_CALL_3(bpf_sys_bpf, int, cmd, union bpf_attr *, attr, u32, attr_size)
return 0;
#endif
default:
- return -EINVAL;
+ return ____bpf_sys_bpf(cmd, attr, size);
}
- return __sys_bpf(cmd, KERNEL_BPFPTR(attr), attr_size);
}
-EXPORT_SYMBOL(bpf_sys_bpf);
+EXPORT_SYMBOL(kern_sys_bpf);
static const struct bpf_func_proto bpf_sys_bpf_proto = {
.func = bpf_sys_bpf,
diff --git a/tools/lib/bpf/skel_internal.h b/tools/lib/bpf/skel_internal.h
index bd6f4505e7b1e..70adf7b119b99 100644
--- a/tools/lib/bpf/skel_internal.h
+++ b/tools/lib/bpf/skel_internal.h
@@ -66,13 +66,13 @@ struct bpf_load_and_run_opts {
const char *errstr;
};
-long bpf_sys_bpf(__u32 cmd, void *attr, __u32 attr_size);
+long kern_sys_bpf(__u32 cmd, void *attr, __u32 attr_size);
static inline int skel_sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr,
unsigned int size)
{
#ifdef __KERNEL__
- return bpf_sys_bpf(cmd, attr, size);
+ return kern_sys_bpf(cmd, attr, size);
#else
return syscall(__NR_bpf, cmd, attr, size);
#endif
--
2.30.2