bpf: Switch BPF probe insns to bpf_probe_read_kernel

Commit 2a02759ef5f8 ("bpf: Add support for BTF pointers to interpreter")
explicitly states that the pointer to BTF object is a pointer to a kernel
object or NULL. Therefore we should also switch to using the strict kernel
probe helper which is restricted to kernel addresses only when architectures
have non-overlapping address spaces.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/d2b90827837685424a4b8008dfe0460558abfada.1572649915.git.daniel@iogearbox.net

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 8d3fbc86ca5e2e0e691588d639323455aa03b402..df82d5a42b237d7377a07cb9d790ad223c39a588 100644 (file)
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1306,11 +1306,12 @@ bool bpf_opcode_in_insntable(u8 code)
 }
 
 #ifndef CONFIG_BPF_JIT_ALWAYS_ON
-u64 __weak bpf_probe_read(void * dst, u32 size, const void * unsafe_ptr)
+u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr)
 {
        memset(dst, 0, size);
        return -EFAULT;
 }
+
 /**
  *     __bpf_prog_run - run eBPF program on a given context
  *     @regs: is the array of MAX_BPF_EXT_REG eBPF pseudo-registers
@@ -1566,9 +1567,9 @@ out:
        LDST(W,  u32)
        LDST(DW, u64)
 #undef LDST
-#define LDX_PROBE(SIZEOP, SIZE)                                                \
-       LDX_PROBE_MEM_##SIZEOP:                                         \
-               bpf_probe_read(&DST, SIZE, (const void *)(long) SRC);   \
+#define LDX_PROBE(SIZEOP, SIZE)                                                        \
+       LDX_PROBE_MEM_##SIZEOP:                                                 \
+               bpf_probe_read_kernel(&DST, SIZE, (const void *)(long) SRC);    \
                CONT;
        LDX_PROBE(B,  1)
        LDX_PROBE(H,  2)