Merge branch 'add-the-missing-bpf_link_type-invocation-for-sockmap'

Hou Tao says: ==================== Add the missing BPF_LINK_TYPE invocation for sockmap From: Hou Tao <[email protected]> Hi, The tiny patch set fixes the out-of-bound read problem when reading the fdinfo of sock map link fd. And in order to spot such omission early for the newly-added link type in the future, it also checks the validity of the link->type and adds a WARN_ONCE() for missed invocation. Please see individual patches for more details. And comments are always welcome. v3: * patch Rust-for-Linux#2: check and warn the validity of link->type instead of adding a static assertion for bpf_link_type_strs array. v2: http://lore.kernel.org/bpf/[email protected] ==================== Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Andrii Nakryiko <[email protected]>
Darksonn · Oct 24, 2024 · d5fb316 · d5fb316
2 parents 9806f28 + 8421d4c
commit d5fb316
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Showing 4 changed files with 16 additions and 5 deletions.
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
@@ -146,6 +146,7 @@ BPF_LINK_TYPE(BPF_LINK_TYPE_XDP, xdp)
 BPF_LINK_TYPE(BPF_LINK_TYPE_NETFILTER, netfilter)
 BPF_LINK_TYPE(BPF_LINK_TYPE_TCX, tcx)
 BPF_LINK_TYPE(BPF_LINK_TYPE_NETKIT, netkit)
+BPF_LINK_TYPE(BPF_LINK_TYPE_SOCKMAP, sockmap)
 #endif
 #ifdef CONFIG_PERF_EVENTS
 BPF_LINK_TYPE(BPF_LINK_TYPE_PERF_EVENT, perf)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
@@ -1121,6 +1121,9 @@ enum bpf_attach_type {
 
 #define MAX_BPF_ATTACH_TYPE __MAX_BPF_ATTACH_TYPE
 
+/* Add BPF_LINK_TYPE(type, name) in bpf_types.h to keep bpf_link_type_strs[]
+ * in sync with the definitions below.
+ */
 enum bpf_link_type {
 	BPF_LINK_TYPE_UNSPEC = 0,
 	BPF_LINK_TYPE_RAW_TRACEPOINT = 1,

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
@@ -3069,13 +3069,17 @@ static void bpf_link_show_fdinfo(struct seq_file *m, struct file *filp)
 {
 	const struct bpf_link *link = filp->private_data;
 	const struct bpf_prog *prog = link->prog;
+	enum bpf_link_type type = link->type;
 	char prog_tag[sizeof(prog->tag) * 2 + 1] = { };
 
-	seq_printf(m,
-		   "link_type:\t%s\n"
-		   "link_id:\t%u\n",
-		   bpf_link_type_strs[link->type],
-		   link->id);
+	if (type < ARRAY_SIZE(bpf_link_type_strs) && bpf_link_type_strs[type]) {
+		seq_printf(m, "link_type:\t%s\n", bpf_link_type_strs[type]);
+	} else {
+		WARN_ONCE(1, "missing BPF_LINK_TYPE(...) for link type %u\n", type);
+		seq_printf(m, "link_type:\t<%u>\n", type);
+	}
+	seq_printf(m, "link_id:\t%u\n", link->id);
+
 	if (prog) {
 		bin2hex(prog_tag, prog->tag, sizeof(prog->tag));
 		seq_printf(m,

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
@@ -1121,6 +1121,9 @@ enum bpf_attach_type {
 
 #define MAX_BPF_ATTACH_TYPE __MAX_BPF_ATTACH_TYPE
 
+/* Add BPF_LINK_TYPE(type, name) in bpf_types.h to keep bpf_link_type_strs[]
+ * in sync with the definitions below.
+ */
 enum bpf_link_type {
 	BPF_LINK_TYPE_UNSPEC = 0,
 	BPF_LINK_TYPE_RAW_TRACEPOINT = 1,