af_unix: Move SOCK_PASS{CRED,PIDFD,SEC} to struct sock.

As explained in the next patch, SO_PASSRIGHTS would have a problem
if we assigned a corresponding bit to socket->flags, so it must be
managed in struct sock.

Mixing socket->flags and sk->sk_flags for similar options will look
confusing, and sk->sk_flags does not have enough space on 32bit system.

Also, as mentioned in commit 16e572626961 ("af_unix: dont send
SCM_CREDENTIALS by default"), SOCK_PASSCRED and SOCK_PASSPID handling
is known to be slow, and managing the flags in struct socket cannot
avoid that for embryo sockets.

Let's move SOCK_PASS{CRED,PIDFD,SEC} to struct sock.

While at it, other SOCK_XXX flags in net.h are grouped as enum.

Note that assign_bit() was atomic, so the writer side is moved down
after lock_sock() in setsockopt(), but the bit is only read once
in sendmsg() and recvmsg(), so lock_sock() is not needed there.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/net.h b/include/linux/net.h
index 0ff950eecc6b9acdbda52918d005e2db4fd85205..f8418d6e33e056c6d9b3998ab296ef29e9927c36 100644 (file)
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -36,14 +36,13 @@ struct net;
  * in sock->flags, but moved into sk->sk_wq->flags to be RCU protected.
  * Eventually all flags will be in sk->sk_wq->flags.
  */
-#define SOCKWQ_ASYNC_NOSPACE   0
-#define SOCKWQ_ASYNC_WAITDATA  1
-#define SOCK_NOSPACE           2
-#define SOCK_PASSCRED          3
-#define SOCK_PASSSEC           4
-#define SOCK_SUPPORT_ZC                5
-#define SOCK_CUSTOM_SOCKOPT    6
-#define SOCK_PASSPIDFD         7
+enum socket_flags {
+       SOCKWQ_ASYNC_NOSPACE,
+       SOCKWQ_ASYNC_WAITDATA,
+       SOCK_NOSPACE,
+       SOCK_SUPPORT_ZC,
+       SOCK_CUSTOM_SOCKOPT,
+};
 
 #ifndef ARCH_HAS_SOCKET_TYPES
 /**

diff --git a/include/net/sock.h b/include/net/sock.h
index 483522377955c130da1ae1ab9751818365b56b01..d90a71f66ab8948400a8cc39869c51d5a86d6007 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -337,6 +337,11 @@ struct sk_filter;
   *    @sk_txtime_deadline_mode: set deadline mode for SO_TXTIME
   *    @sk_txtime_report_errors: set report errors mode for SO_TXTIME
   *    @sk_txtime_unused: unused txtime flags
+  *    @sk_scm_recv_flags: all flags used by scm_recv()
+  *    @sk_scm_credentials: flagged by SO_PASSCRED to recv SCM_CREDENTIALS
+  *    @sk_scm_security: flagged by SO_PASSSEC to recv SCM_SECURITY
+  *    @sk_scm_pidfd: flagged by SO_PASSPIDFD to recv SCM_PIDFD
+  *    @sk_scm_unused: unused flags for scm_recv()
   *    @ns_tracker: tracker for netns reference
   *    @sk_user_frags: xarray of pages the user is holding a reference on.
   *    @sk_owner: reference to the real owner of the socket that calls
@@ -523,7 +528,16 @@ struct sock {
 #endif
        int                     sk_disconnects;
 
-       u8                      sk_txrehash;
+       union {
+               u8              sk_txrehash;
+               u8              sk_scm_recv_flags;
+               struct {
+                       u8      sk_scm_credentials : 1,
+                               sk_scm_security : 1,
+                               sk_scm_pidfd : 1,
+                               sk_scm_unused : 5;
+               };
+       };
        u8                      sk_clockid;
        u8                      sk_txtime_deadline_mode : 1,
                                sk_txtime_report_errors : 1,

diff --git a/net/core/scm.c b/net/core/scm.c
index 66e02b18c3591514f986e339184e5b5490376b65..0225bd94170f79d61b6a05aeb40647965a3f8fd6 100644 (file)
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -406,12 +406,12 @@ struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
 EXPORT_SYMBOL(scm_fp_dup);
 
 #ifdef CONFIG_SECURITY_NETWORK
-static void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
+static void scm_passec(struct sock *sk, struct msghdr *msg, struct scm_cookie *scm)
 {
        struct lsm_context ctx;
        int err;
 
-       if (test_bit(SOCK_PASSSEC, &sock->flags)) {
+       if (sk->sk_scm_security) {
                err = security_secid_to_secctx(scm->secid, &ctx);
 
                if (err >= 0) {
@@ -423,16 +423,16 @@ static void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cooki
        }
 }
 
-static bool scm_has_secdata(struct socket *sock)
+static bool scm_has_secdata(struct sock *sk)
 {
-       return test_bit(SOCK_PASSSEC, &sock->flags);
+       return sk->sk_scm_security;
 }
 #else
-static void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
+static void scm_passec(struct sock *sk, struct msghdr *msg, struct scm_cookie *scm)
 {
 }
 
-static bool scm_has_secdata(struct socket *sock)
+static bool scm_has_secdata(struct sock *sk)
 {
        return false;
 }
@@ -474,20 +474,19 @@ static void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm)
                fd_install(pidfd, pidfd_file);
 }
 
-static bool __scm_recv_common(struct socket *sock, struct msghdr *msg,
+static bool __scm_recv_common(struct sock *sk, 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))
+               if (sk->sk_scm_credentials || sk->sk_scm_pidfd ||
+                   scm->fp || scm_has_secdata(sk))
                        msg->msg_flags |= MSG_CTRUNC;
 
                scm_destroy(scm);
                return false;
        }
 
-       if (test_bit(SOCK_PASSCRED, &sock->flags)) {
+       if (sk->sk_scm_credentials) {
                struct user_namespace *current_ns = current_user_ns();
                struct ucred ucreds = {
                        .pid = scm->creds.pid,
@@ -498,7 +497,7 @@ static bool __scm_recv_common(struct socket *sock, struct msghdr *msg,
                put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds);
        }
 
-       scm_passec(sock, msg, scm);
+       scm_passec(sk, msg, scm);
 
        if (scm->fp)
                scm_detach_fds(msg, scm);
@@ -509,7 +508,7 @@ static bool __scm_recv_common(struct socket *sock, struct msghdr *msg,
 void scm_recv(struct socket *sock, struct msghdr *msg,
              struct scm_cookie *scm, int flags)
 {
-       if (!__scm_recv_common(sock, msg, scm, flags))
+       if (!__scm_recv_common(sock->sk, msg, scm, flags))
                return;
 
        scm_destroy_cred(scm);
@@ -519,10 +518,10 @@ 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))
+       if (!__scm_recv_common(sock->sk, msg, scm, flags))
                return;
 
-       if (test_bit(SOCK_PASSPIDFD, &sock->flags))
+       if (sock->sk->sk_scm_pidfd)
                scm_pidfd_recv(msg, scm);
 
        scm_destroy_cred(scm);

diff --git a/net/core/sock.c b/net/core/sock.c
index fd5f9d3873c14bc76bee86856cce37ef328d41ab..381abf8f25b73573225eda7111c02f370c4a2a22 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1220,24 +1220,6 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
                        return 0;
                }
                return -EPERM;
-       case SO_PASSSEC:
-               if (!IS_ENABLED(CONFIG_SECURITY_NETWORK) || sk_may_scm_recv(sk))
-                       return -EOPNOTSUPP;
-
-               assign_bit(SOCK_PASSSEC, &sock->flags, valbool);
-               return 0;
-       case SO_PASSCRED:
-               if (!sk_may_scm_recv(sk))
-                       return -EOPNOTSUPP;
-
-               assign_bit(SOCK_PASSCRED, &sock->flags, valbool);
-               return 0;
-       case SO_PASSPIDFD:
-               if (!sk_is_unix(sk))
-                       return -EOPNOTSUPP;
-
-               assign_bit(SOCK_PASSPIDFD, &sock->flags, valbool);
-               return 0;
        case SO_TYPE:
        case SO_PROTOCOL:
        case SO_DOMAIN:
@@ -1568,6 +1550,26 @@ set_sndbuf:
                sock_valbool_flag(sk, SOCK_SELECT_ERR_QUEUE, valbool);
                break;
 
+       case SO_PASSCRED:
+               if (sk_may_scm_recv(sk))
+                       sk->sk_scm_credentials = valbool;
+               else
+                       ret = -EOPNOTSUPP;
+               break;
+
+       case SO_PASSSEC:
+               if (IS_ENABLED(CONFIG_SECURITY_NETWORK) && sk_may_scm_recv(sk))
+                       sk->sk_scm_security = valbool;
+               else
+                       ret = -EOPNOTSUPP;
+               break;
+
+       case SO_PASSPIDFD:
+               if (sk_is_unix(sk))
+                       sk->sk_scm_pidfd = valbool;
+               else
+                       ret = -EOPNOTSUPP;
+               break;
 
        case SO_INCOMING_CPU:
                reuseport_update_incoming_cpu(sk, val);
@@ -1867,14 +1869,14 @@ int sk_getsockopt(struct sock *sk, int level, int optname,
                if (!sk_may_scm_recv(sk))
                        return -EOPNOTSUPP;
 
-               v.val = !!test_bit(SOCK_PASSCRED, &sock->flags);
+               v.val = sk->sk_scm_credentials;
                break;
 
        case SO_PASSPIDFD:
                if (!sk_is_unix(sk))
                        return -EOPNOTSUPP;
 
-               v.val = !!test_bit(SOCK_PASSPIDFD, &sock->flags);
+               v.val = sk->sk_scm_pidfd;
                break;
 
        case SO_PEERCRED:
@@ -1974,7 +1976,7 @@ int sk_getsockopt(struct sock *sk, int level, int optname,
                if (!IS_ENABLED(CONFIG_SECURITY_NETWORK) || !sk_may_scm_recv(sk))
                        return -EOPNOTSUPP;
 
-               v.val = !!test_bit(SOCK_PASSSEC, &sock->flags);
+               v.val = sk->sk_scm_security;
                break;
 
        case SO_PEERSEC:

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index a39497fd6e98c4acabbb59dd57f3b8950c6c6efe..27ebda4cd9b93a15d4d4eb42272f418bea57b493 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -767,10 +767,7 @@ static void copy_peercred(struct sock *sk, struct sock *peersk)
 
 static bool unix_may_passcred(const struct sock *sk)
 {
-       struct socket *sock = sk->sk_socket;
-
-       return test_bit(SOCK_PASSCRED, &sock->flags) ||
-               test_bit(SOCK_PASSPIDFD, &sock->flags);
+       return sk->sk_scm_credentials || sk->sk_scm_pidfd;
 }
 
 static int unix_listen(struct socket *sock, int backlog)
@@ -1713,17 +1710,6 @@ static int unix_socketpair(struct socket *socka, struct socket *sockb)
        return 0;
 }
 
-static void unix_sock_inherit_flags(const struct socket *old,
-                                   struct socket *new)
-{
-       if (test_bit(SOCK_PASSCRED, &old->flags))
-               set_bit(SOCK_PASSCRED, &new->flags);
-       if (test_bit(SOCK_PASSPIDFD, &old->flags))
-               set_bit(SOCK_PASSPIDFD, &new->flags);
-       if (test_bit(SOCK_PASSSEC, &old->flags))
-               set_bit(SOCK_PASSSEC, &new->flags);
-}
-
 static int unix_accept(struct socket *sock, struct socket *newsock,
                       struct proto_accept_arg *arg)
 {
@@ -1760,7 +1746,7 @@ static int unix_accept(struct socket *sock, struct socket *newsock,
        unix_state_lock(tsk);
        unix_update_edges(unix_sk(tsk));
        newsock->state = SS_CONNECTED;
-       unix_sock_inherit_flags(sock, newsock);
+       tsk->sk_scm_recv_flags = READ_ONCE(sk->sk_scm_recv_flags);
        sock_graft(tsk, newsock);
        unix_state_unlock(tsk);
        return 0;