diff mbox series

[net] netdev: avoid CFI problems with sock priv helpers

Message ID 20250115161436.648646-1-kuba@kernel.org (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series [net] netdev: avoid CFI problems with sock priv helpers | expand

Checks

Context Check Description
netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for net
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/build_tools success Errors and warnings before: 0 (+0) this patch: 0 (+0)
netdev/cc_maintainers fail 2 blamed authors not CCed: asml.silence@gmail.com willemb@google.com; 4 maintainers not CCed: asml.silence@gmail.com jdamato@fastly.com nicolas.dichtel@6wind.com willemb@google.com
netdev/build_clang success Errors and warnings before: 3 this patch: 3
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 Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 52 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

Commit Message

Jakub Kicinski Jan. 15, 2025, 4:14 p.m. UTC 
Li Li reports that casting away callback type may cause issues
for CFI. Let's generate a small wrapper for each callback,
to make sure compiler sees the anticipated types.

Reported-by: Li Li <dualli@chromium.org>
Link: https://lore.kernel.org/CANBPYPjQVqmzZ4J=rVQX87a9iuwmaetULwbK_5_3YWk2eGzkaA@mail.gmail.com
Fixes: 170aafe35cb9 ("netdev: support binding dma-buf to netdevice")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: donald.hunter@gmail.com
CC: sdf@fomichev.me
CC: almasrymina@google.com
---
 net/core/netdev-genl-gen.c | 14 ++++++++++++--
 tools/net/ynl/ynl-gen-c.py | 16 +++++++++++++---
 2 files changed, 25 insertions(+), 5 deletions(-)

Comments

Mina Almasry Jan. 15, 2025, 5:01 p.m. UTC | #1 
On Wed, Jan 15, 2025 at 8:14 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> Li Li reports that casting away callback type may cause issues
> for CFI. Let's generate a small wrapper for each callback,
> to make sure compiler sees the anticipated types.
>
> Reported-by: Li Li <dualli@chromium.org>
> Link: https://lore.kernel.org/CANBPYPjQVqmzZ4J=rVQX87a9iuwmaetULwbK_5_3YWk2eGzkaA@mail.gmail.com
> Fixes: 170aafe35cb9 ("netdev: support binding dma-buf to netdevice")
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Thanks Jakub,

Reviewed-by: Mina Almasry <almasrymina@google.com>
diff mbox series

Patch

diff --git a/net/core/netdev-genl-gen.c b/net/core/netdev-genl-gen.c
index a89cbd8d87c3..996ac6a449eb 100644
--- a/net/core/netdev-genl-gen.c
+++ b/net/core/netdev-genl-gen.c
@@ -197,6 +197,16 @@  static const struct genl_multicast_group netdev_nl_mcgrps[] = {
 	[NETDEV_NLGRP_PAGE_POOL] = { "page-pool", },
 };
 
+static void __netdev_nl_sock_priv_init(void *priv)
+{
+	netdev_nl_sock_priv_init(priv);
+}
+
+static void __netdev_nl_sock_priv_destroy(void *priv)
+{
+	netdev_nl_sock_priv_destroy(priv);
+}
+
 struct genl_family netdev_nl_family __ro_after_init = {
 	.name		= NETDEV_FAMILY_NAME,
 	.version	= NETDEV_FAMILY_VERSION,
@@ -208,6 +218,6 @@  struct genl_family netdev_nl_family __ro_after_init = {
 	.mcgrps		= netdev_nl_mcgrps,
 	.n_mcgrps	= ARRAY_SIZE(netdev_nl_mcgrps),
 	.sock_priv_size	= sizeof(struct list_head),
-	.sock_priv_init	= (void *)netdev_nl_sock_priv_init,
-	.sock_priv_destroy = (void *)netdev_nl_sock_priv_destroy,
+	.sock_priv_init	= __netdev_nl_sock_priv_init,
+	.sock_priv_destroy = __netdev_nl_sock_priv_destroy,
 };
diff --git a/tools/net/ynl/ynl-gen-c.py b/tools/net/ynl/ynl-gen-c.py
index d8201c4b1520..6750fdb42564 100755
--- a/tools/net/ynl/ynl-gen-c.py
+++ b/tools/net/ynl/ynl-gen-c.py
@@ -2384,6 +2384,17 @@  _C_KW = {
     if not kernel_can_gen_family_struct(family):
         return
 
+    if 'sock-priv' in family.kernel_family:
+        # Generate "trampolines" to make CFI happy
+        cw.write_func("static void", f"__{family.c_name}_nl_sock_priv_init",
+                      [f"{family.c_name}_nl_sock_priv_init(priv);"],
+                      ["void *priv"])
+        cw.nl()
+        cw.write_func("static void", f"__{family.c_name}_nl_sock_priv_destroy",
+                      [f"{family.c_name}_nl_sock_priv_destroy(priv);"],
+                      ["void *priv"])
+        cw.nl()
+
     cw.block_start(f"struct genl_family {family.ident_name}_nl_family __ro_after_init =")
     cw.p('.name\t\t= ' + family.fam_key + ',')
     cw.p('.version\t= ' + family.ver_key + ',')
@@ -2401,9 +2412,8 @@  _C_KW = {
         cw.p(f'.n_mcgrps\t= ARRAY_SIZE({family.c_name}_nl_mcgrps),')
     if 'sock-priv' in family.kernel_family:
         cw.p(f'.sock_priv_size\t= sizeof({family.kernel_family["sock-priv"]}),')
-        # Force cast here, actual helpers take pointer to the real type.
-        cw.p(f'.sock_priv_init\t= (void *){family.c_name}_nl_sock_priv_init,')
-        cw.p(f'.sock_priv_destroy = (void *){family.c_name}_nl_sock_priv_destroy,')
+        cw.p(f'.sock_priv_init\t= __{family.c_name}_nl_sock_priv_init,')
+        cw.p(f'.sock_priv_destroy = __{family.c_name}_nl_sock_priv_destroy,')
     cw.block_end(';')