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Message-ID: <20250508013021.79654-4-kuniyu@amazon.com>
Date: Wed, 7 May 2025 18:29:15 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
<pabeni@...hat.com>, Willem de Bruijn <willemb@...gle.com>
CC: Simon Horman <horms@...nel.org>, Christian Brauner <brauner@...nel.org>,
Kuniyuki Iwashima <kuniyu@...zon.com>, Kuniyuki Iwashima
<kuni1840@...il.com>, <netdev@...r.kernel.org>
Subject: [PATCH v1 net-next 3/7] scm: Move scm_recv() from scm.h to scm.c.
scm_recv() has been placed in scm.h since the pre-git era for no
particular reason (I think), which makes the file really fragile.
For example, when you move SOCK_PASSCRED from include/linux/net.h to
enum sock_flags in include/net/sock.h, you will see weird build failure
due to terrible dependency.
The next patch moves SOCK_PASSXXX to sk->sk_flags to better handle the
new flag for SO_PASSRIGHTS.
To avoid the build failure, let's move scm_recv(_unix())? and its
callees to scm.c.
Note that only scm_recv() needs to be exported for Bluetooth.
scm_send() should be moved to scm.c too, but I'll revisit later.
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
include/net/scm.h | 121 ++-------------------------------------------
net/core/scm.c | 122 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 126 insertions(+), 117 deletions(-)
diff --git a/include/net/scm.h b/include/net/scm.h
index 22bb49589fde..84c4707e78a5 100644
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -102,123 +102,10 @@ static __inline__ int scm_send(struct socket *sock, struct msghdr *msg,
return __scm_send(sock, msg, scm);
}
-#ifdef CONFIG_SECURITY_NETWORK
-static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
-{
- struct lsm_context ctx;
- int err;
-
- if (test_bit(SOCK_PASSSEC, &sock->flags)) {
- err = security_secid_to_secctx(scm->secid, &ctx);
-
- if (err >= 0) {
- put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, ctx.len,
- ctx.context);
- security_release_secctx(&ctx);
- }
- }
-}
-
-static inline bool scm_has_secdata(struct socket *sock)
-{
- return test_bit(SOCK_PASSSEC, &sock->flags);
-}
-#else
-static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
-{ }
-
-static inline bool scm_has_secdata(struct socket *sock)
-{
- return false;
-}
-#endif /* CONFIG_SECURITY_NETWORK */
-
-static __inline__ void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm)
-{
- struct file *pidfd_file = NULL;
- int len, pidfd;
-
- /* put_cmsg() doesn't return an error if CMSG is truncated,
- * that's why we need to opencode these checks here.
- */
- if (msg->msg_flags & MSG_CMSG_COMPAT)
- len = sizeof(struct compat_cmsghdr) + sizeof(int);
- else
- len = sizeof(struct cmsghdr) + sizeof(int);
-
- if (msg->msg_controllen < len) {
- msg->msg_flags |= MSG_CTRUNC;
- return;
- }
-
- if (!scm->pid)
- return;
-
- pidfd = pidfd_prepare(scm->pid, 0, &pidfd_file);
-
- if (put_cmsg(msg, SOL_SOCKET, SCM_PIDFD, sizeof(int), &pidfd)) {
- if (pidfd_file) {
- put_unused_fd(pidfd);
- fput(pidfd_file);
- }
-
- return;
- }
-
- if (pidfd_file)
- fd_install(pidfd, pidfd_file);
-}
-
-static inline bool __scm_recv_common(struct socket *sock, struct msghdr *msg,
- struct scm_cookie *scm, int flags)
-{
- if (!msg->msg_control) {
- if (test_bit(SOCK_PASSCRED, &sock->flags) ||
- test_bit(SOCK_PASSPIDFD, &sock->flags) ||
- scm->fp || scm_has_secdata(sock))
- msg->msg_flags |= MSG_CTRUNC;
- scm_destroy(scm);
- return false;
- }
-
- if (test_bit(SOCK_PASSCRED, &sock->flags)) {
- struct user_namespace *current_ns = current_user_ns();
- struct ucred ucreds = {
- .pid = scm->creds.pid,
- .uid = from_kuid_munged(current_ns, scm->creds.uid),
- .gid = from_kgid_munged(current_ns, scm->creds.gid),
- };
- put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds);
- }
-
- scm_passec(sock, msg, scm);
-
- if (scm->fp)
- scm_detach_fds(msg, scm);
-
- return true;
-}
-
-static inline void scm_recv(struct socket *sock, struct msghdr *msg,
- struct scm_cookie *scm, int flags)
-{
- if (!__scm_recv_common(sock, msg, scm, flags))
- return;
-
- scm_destroy_cred(scm);
-}
-
-static inline void scm_recv_unix(struct socket *sock, struct msghdr *msg,
- struct scm_cookie *scm, int flags)
-{
- if (!__scm_recv_common(sock, msg, scm, flags))
- return;
-
- if (test_bit(SOCK_PASSPIDFD, &sock->flags))
- scm_pidfd_recv(msg, scm);
-
- scm_destroy_cred(scm);
-}
+void scm_recv(struct socket *sock, struct msghdr *msg,
+ struct scm_cookie *scm, int flags);
+void scm_recv_unix(struct socket *sock, struct msghdr *msg,
+ struct scm_cookie *scm, int flags);
static inline int scm_recv_one_fd(struct file *f, int __user *ufd,
unsigned int flags)
diff --git a/net/core/scm.c b/net/core/scm.c
index 733c0cbd393d..3f756f00e41e 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -404,3 +404,125 @@ struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
return new_fpl;
}
EXPORT_SYMBOL(scm_fp_dup);
+
+#ifdef CONFIG_SECURITY_NETWORK
+static void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
+{
+ struct lsm_context ctx;
+ int err;
+
+ if (test_bit(SOCK_PASSSEC, &sock->flags)) {
+ err = security_secid_to_secctx(scm->secid, &ctx);
+
+ if (err >= 0) {
+ put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, ctx.len,
+ ctx.context);
+
+ security_release_secctx(&ctx);
+ }
+ }
+}
+
+static bool scm_has_secdata(struct socket *sock)
+{
+ return test_bit(SOCK_PASSSEC, &sock->flags);
+}
+#else
+static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
+{ }
+
+static inline bool scm_has_secdata(struct socket *sock)
+{
+ return false;
+}
+#endif
+
+static void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm)
+{
+ struct file *pidfd_file = NULL;
+ int len, pidfd;
+
+ /* put_cmsg() doesn't return an error if CMSG is truncated,
+ * that's why we need to opencode these checks here.
+ */
+ if (msg->msg_flags & MSG_CMSG_COMPAT)
+ len = sizeof(struct compat_cmsghdr) + sizeof(int);
+ else
+ len = sizeof(struct cmsghdr) + sizeof(int);
+
+ if (msg->msg_controllen < len) {
+ msg->msg_flags |= MSG_CTRUNC;
+ return;
+ }
+
+ if (!scm->pid)
+ return;
+
+ pidfd = pidfd_prepare(scm->pid, 0, &pidfd_file);
+
+ if (put_cmsg(msg, SOL_SOCKET, SCM_PIDFD, sizeof(int), &pidfd)) {
+ if (pidfd_file) {
+ put_unused_fd(pidfd);
+ fput(pidfd_file);
+ }
+
+ return;
+ }
+
+ if (pidfd_file)
+ fd_install(pidfd, pidfd_file);
+}
+
+static bool __scm_recv_common(struct socket *sock, struct msghdr *msg,
+ struct scm_cookie *scm, int flags)
+{
+ if (!msg->msg_control) {
+ if (test_bit(SOCK_PASSCRED, &sock->flags) ||
+ test_bit(SOCK_PASSPIDFD, &sock->flags) ||
+ scm->fp || scm_has_secdata(sock))
+ msg->msg_flags |= MSG_CTRUNC;
+
+ scm_destroy(scm);
+ return false;
+ }
+
+ if (test_bit(SOCK_PASSCRED, &sock->flags)) {
+ struct user_namespace *current_ns = current_user_ns();
+ struct ucred ucreds = {
+ .pid = scm->creds.pid,
+ .uid = from_kuid_munged(current_ns, scm->creds.uid),
+ .gid = from_kgid_munged(current_ns, scm->creds.gid),
+ };
+
+ put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds);
+ }
+
+ scm_passec(sock, msg, scm);
+
+ if (scm->fp)
+ scm_detach_fds(msg, scm);
+
+ return true;
+}
+
+void scm_recv(struct socket *sock, struct msghdr *msg,
+ struct scm_cookie *scm, int flags)
+{
+ if (!__scm_recv_common(sock, msg, scm, flags))
+ return;
+
+ scm_destroy_cred(scm);
+}
+EXPORT_SYMBOL(scm_recv);
+
+void scm_recv_unix(struct socket *sock, struct msghdr *msg,
+ struct scm_cookie *scm, int flags)
+{
+ if (!__scm_recv_common(sock, msg, scm, flags))
+ return;
+
+ if (test_bit(SOCK_PASSPIDFD, &sock->flags))
+ scm_pidfd_recv(msg, scm);
+
+ scm_destroy_cred(scm);
+}
--
2.49.0
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