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[bpf-next,v5,07/13] xsk: Validate xsk_tx_metadata flags

Message ID 20231102225837.1141915-8-sdf@google.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series xsk: TX metadata | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR fail PR summary
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1354 this patch: 1354
netdev/cc_maintainers warning 4 maintainers not CCed: edumazet@google.com pabeni@redhat.com jonathan.lemon@gmail.com davem@davemloft.net
netdev/build_clang success Errors and warnings before: 1379 this patch: 1379
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1382 this patch: 1382
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 50 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
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Commit Message

Stanislav Fomichev Nov. 2, 2023, 10:58 p.m. UTC 
Accept only the flags that the kernel knows about to make
sure we can extend this field in the future. Note that only
in XDP_COPY mode we propagate the error signal back to the user
(via sendmsg). For zerocopy mode we silently skip the metadata
for the descriptors that have wrong flags (since we process
the descriptors deep in the driver).

Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 include/net/xdp_sock_drv.h | 23 ++++++++++++++++++++++-
 net/xdp/xsk.c              |  4 ++++
 2 files changed, 26 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/include/net/xdp_sock_drv.h b/include/net/xdp_sock_drv.h
index e2558ac3e195..5885176ea01e 100644
--- a/include/net/xdp_sock_drv.h
+++ b/include/net/xdp_sock_drv.h
@@ -165,12 +165,28 @@  static inline void *xsk_buff_raw_get_data(struct xsk_buff_pool *pool, u64 addr)
 	return xp_raw_get_data(pool, addr);
 }
 
+#define XDP_TXMD_FLAGS_VALID ( \
+		XDP_TXMD_FLAGS_TIMESTAMP | \
+		XDP_TXMD_FLAGS_CHECKSUM | \
+	0)
+
+static inline bool xsk_buff_valid_tx_metadata(struct xsk_tx_metadata *meta)
+{
+	return !(meta->request.flags & ~XDP_TXMD_FLAGS_VALID);
+}
+
 static inline struct xsk_tx_metadata *xsk_buff_get_metadata(struct xsk_buff_pool *pool, u64 addr)
 {
+	struct xsk_tx_metadata *meta;
+
 	if (!pool->tx_metadata_len)
 		return NULL;
 
-	return xp_raw_get_data(pool, addr) - pool->tx_metadata_len;
+	meta = xp_raw_get_data(pool, addr) - pool->tx_metadata_len;
+	if (unlikely(!xsk_buff_valid_tx_metadata(meta)))
+		return NULL; /* no way to signal the error to the user */
+
+	return meta;
 }
 
 static inline void xsk_buff_dma_sync_for_cpu(struct xdp_buff *xdp, struct xsk_buff_pool *pool)
@@ -332,6 +348,11 @@  static inline void *xsk_buff_raw_get_data(struct xsk_buff_pool *pool, u64 addr)
 	return NULL;
 }
 
+static inline bool xsk_buff_valid_tx_metadata(struct xsk_tx_metadata *meta)
+{
+	return false;
+}
+
 static inline struct xsk_tx_metadata *xsk_buff_get_metadata(struct xsk_buff_pool *pool, u64 addr)
 {
 	return NULL;
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 84fd10201f2a..0e81ae6bfff4 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -728,6 +728,10 @@  static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
 			}
 
 			meta = buffer - xs->pool->tx_metadata_len;
+			if (unlikely(!xsk_buff_valid_tx_metadata(meta))) {
+				err = -EINVAL;
+				goto free_err;
+			}
 
 			if (meta->request.flags & XDP_TXMD_FLAGS_CHECKSUM) {
 				if (unlikely(meta->request.csum_start +