@@ -2437,6 +2437,12 @@ union bpf_attr {
* Read a userspace pointer safely.
* Return
* 0 on success or negative error
+ *
+ * int bpf_probe_read_kernel(void *dst, int size, void *src)
+ * Description
+ * Read a kernel pointer safely.
+ * Return
+ * 0 on success or negative error
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -2538,7 +2544,8 @@ union bpf_attr {
FN(tcp_sock), \
FN(skb_ecn_set_ce), \
FN(get_listener_sock), \
- FN(probe_read_user),
+ FN(probe_read_user), \
+ FN(probe_read_kernel),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
@@ -153,6 +153,26 @@ static const struct bpf_func_proto bpf_probe_read_proto = {
.arg3_type = ARG_ANYTHING,
};
+BPF_CALL_3(bpf_probe_read_kernel, void *, dst, u32, size, const void *, unsafe_ptr)
+{
+ int ret;
+
+ ret = probe_kernel_read(dst, unsafe_ptr, size);
+ if (unlikely(ret < 0))
+ memset(dst, 0, size);
+
+ return ret;
+}
+
+static const struct bpf_func_proto bpf_probe_read_kernel_proto = {
+ .func = bpf_probe_read_kernel,
+ .gpl_only = true,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_UNINIT_MEM,
+ .arg2_type = ARG_CONST_SIZE_OR_ZERO,
+ .arg3_type = ARG_ANYTHING,
+};
+
BPF_CALL_3(bpf_probe_read_user, void *, dst, u32, size, const void *, unsafe_ptr)
{
int ret;
@@ -593,6 +613,8 @@ tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_probe_read_proto;
case BPF_FUNC_probe_read_user:
return &bpf_probe_read_user_proto;
+ case BPF_FUNC_probe_read_kernel:
+ return &bpf_probe_read_kernel_proto;
case BPF_FUNC_ktime_get_ns:
return &bpf_ktime_get_ns_proto;
case BPF_FUNC_tail_call:
The bpf_probe_read function is ambiguous in whether the pointer being read is a kernel or user one. Add a specific function for kernel pointer in this patch. Previous patches add it for userspace pointers. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> --- include/uapi/linux/bpf.h | 9 ++++++++- kernel/trace/bpf_trace.c | 22 ++++++++++++++++++++++ 2 files changed, 30 insertions(+), 1 deletion(-)