Validate that reading a PTR_TO_BTF_ID field produces a value of type
PTR_TO_MEM|MEM_RDONLY|PTR_UNTRUSTED, if field is a pointer to a
primitive type.
Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
---
.../bpf/progs/mem_rdonly_untrusted.c | 31 +++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/tools/testing/selftests/bpf/progs/mem_rdonly_untrusted.c b/tools/testing/selftests/bpf/progs/mem_rdonly_untrusted.c
index 8185130ede95..4f94c971ae86 100644
--- a/tools/testing/selftests/bpf/progs/mem_rdonly_untrusted.c
+++ b/tools/testing/selftests/bpf/progs/mem_rdonly_untrusted.c
@@ -5,6 +5,37 @@
#include "bpf_misc.h"
#include "../test_kmods/bpf_testmod_kfunc.h"
+SEC("tp_btf/sys_enter")
+__success
+__log_level(2)
+__msg("r8 = *(u64 *)(r7 +0) ; R7_w=ptr_nameidata(off={{[0-9]+}}) R8_w=rdonly_untrusted_mem(sz=0)")
+__msg("r9 = *(u8 *)(r8 +0) ; R8_w=rdonly_untrusted_mem(sz=0) R9_w=scalar")
+int btf_id_to_ptr_mem(void *ctx)
+{
+ struct task_struct *task;
+ struct nameidata *idata;
+ u64 ret, off;
+
+ task = bpf_get_current_task_btf();
+ idata = task->nameidata;
+ off = bpf_core_field_offset(struct nameidata, pathname);
+ /*
+ * asm block to have reliable match target for __msg, equivalent of:
+ * ret = task->nameidata->pathname[0];
+ */
+ asm volatile (
+ "r7 = %[idata];"
+ "r7 += %[off];"
+ "r8 = *(u64 *)(r7 + 0);"
+ "r9 = *(u8 *)(r8 + 0);"
+ "%[ret] = r9;"
+ : [ret]"=r"(ret)
+ : [idata]"r"(idata),
+ [off]"r"(off)
+ : "r7", "r8", "r9");
+ return ret;
+}
+
SEC("socket")
__success
__retval(0)
--
2.47.1
