[PATCH bpf-next v2] bpf: check flags in 'bpf_ringbuf_discard()' and 'bpf_ringbuf_submit()'

[Pedro Tammela]

The current code only checks flags in 'bpf_ringbuf_output()'.

Signed-off-by: Pedro Tammela <pctamm...@mojatatu.com>
---
 include/uapi/linux/bpf.h       |  8 ++++----
 kernel/bpf/ringbuf.c           | 13 +++++++++++--
 tools/include/uapi/linux/bpf.h |  8 ++++----
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 100cb2e4c104..38b0b15f99f0 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -4073,7 +4073,7 @@ union bpf_attr {
  *             Valid pointer with *size* bytes of memory available; NULL,
  *             otherwise.
  *
- * void bpf_ringbuf_submit(void *data, u64 flags)
+ * long bpf_ringbuf_submit(void *data, u64 flags)
  *     Description
  *             Submit reserved ring buffer sample, pointed to by *data*.
  *             If **BPF_RB_NO_WAKEUP** is specified in *flags*, no notification
@@ -4083,9 +4083,9 @@ union bpf_attr {
  *             If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification
  *             of new data availability is sent unconditionally.
  *     Return
- *             Nothing. Always succeeds.
+ *             0 on success, or a negative error in case of failure.
  *
- * void bpf_ringbuf_discard(void *data, u64 flags)
+ * long bpf_ringbuf_discard(void *data, u64 flags)
  *     Description
  *             Discard reserved ring buffer sample, pointed to by *data*.
  *             If **BPF_RB_NO_WAKEUP** is specified in *flags*, no notification
@@ -4095,7 +4095,7 @@ union bpf_attr {
  *             If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification
  *             of new data availability is sent unconditionally.
  *     Return
- *             Nothing. Always succeeds.
+ *             0 on success, or a negative error in case of failure.
  *
  * u64 bpf_ringbuf_query(void *ringbuf, u64 flags)
  *     Description
diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
index f25b719ac786..f76dafe2427e 100644
--- a/kernel/bpf/ringbuf.c
+++ b/kernel/bpf/ringbuf.c
@@ -397,26 +397,35 @@ static void bpf_ringbuf_commit(void *sample, u64 flags, 
bool discard)
 
 BPF_CALL_2(bpf_ringbuf_submit, void *, sample, u64, flags)
 {
+       if (unlikely(flags & ~(BPF_RB_NO_WAKEUP | BPF_RB_FORCE_WAKEUP)))
+               return -EINVAL;
+
        bpf_ringbuf_commit(sample, flags, false /* discard */);
+
        return 0;
 }
 
 const struct bpf_func_proto bpf_ringbuf_submit_proto = {
        .func           = bpf_ringbuf_submit,
-       .ret_type       = RET_VOID,
+       .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_ALLOC_MEM,
        .arg2_type      = ARG_ANYTHING,
 };
 
 BPF_CALL_2(bpf_ringbuf_discard, void *, sample, u64, flags)
 {
+
+       if (unlikely(flags & ~(BPF_RB_NO_WAKEUP | BPF_RB_FORCE_WAKEUP)))
+               return -EINVAL;
+
        bpf_ringbuf_commit(sample, flags, true /* discard */);
+
        return 0;
 }
 
 const struct bpf_func_proto bpf_ringbuf_discard_proto = {
        .func           = bpf_ringbuf_discard,
-       .ret_type       = RET_VOID,
+       .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_ALLOC_MEM,
        .arg2_type      = ARG_ANYTHING,
 };
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 3d6d324184c0..a32eefb786f9 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -4073,7 +4073,7 @@ union bpf_attr {
  *             Valid pointer with *size* bytes of memory available; NULL,
  *             otherwise.
  *
- * void bpf_ringbuf_submit(void *data, u64 flags)
+ * long bpf_ringbuf_submit(void *data, u64 flags)
  *     Description
  *             Submit reserved ring buffer sample, pointed to by *data*.
  *             If **BPF_RB_NO_WAKEUP** is specified in *flags*, no notification
@@ -4083,9 +4083,9 @@ union bpf_attr {
  *             If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification
  *             of new data availability is sent unconditionally.
  *     Return
- *             Nothing. Always succeeds.
+ *             0 on success, or a negative error in case of failure.
  *
- * void bpf_ringbuf_discard(void *data, u64 flags)
+ * long bpf_ringbuf_discard(void *data, u64 flags)
  *     Description
  *             Discard reserved ring buffer sample, pointed to by *data*.
  *             If **BPF_RB_NO_WAKEUP** is specified in *flags*, no notification
@@ -4095,7 +4095,7 @@ union bpf_attr {
  *             If **BPF_RB_FORCE_WAKEUP** is specified in *flags*, notification
  *             of new data availability is sent unconditionally.
  *     Return
- *             Nothing. Always succeeds.
+ *             0 on success, or a negative error in case of failure.
  *
  * u64 bpf_ringbuf_query(void *ringbuf, u64 flags)
  *     Description
-- 
2.25.1