From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx> Date: Thu, 16 Mar 2023 14:15:24 +0100 > Implement SCM_PIDFD, a new type of CMSG type analogical to SCM_CREDENTIALS, > but it contains pidfd instead of plain pid, which allows programmers not > to care about PID reuse problem. > > Cc: "David S. Miller" <davem@xxxxxxxxxxxxx> > Cc: Eric Dumazet <edumazet@xxxxxxxxxx> > Cc: Jakub Kicinski <kuba@xxxxxxxxxx> > Cc: Paolo Abeni <pabeni@xxxxxxxxxx> > Cc: Leon Romanovsky <leon@xxxxxxxxxx> > Cc: David Ahern <dsahern@xxxxxxxxxx> > Cc: Arnd Bergmann <arnd@xxxxxxxx> > Cc: Kees Cook <keescook@xxxxxxxxxxxx> > Cc: Christian Brauner <brauner@xxxxxxxxxx> > Cc: linux-kernel@xxxxxxxxxxxxxxx > Cc: netdev@xxxxxxxxxxxxxxx > Cc: linux-arch@xxxxxxxxxxxxxxx > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx> > --- > arch/alpha/include/uapi/asm/socket.h | 2 ++ > arch/mips/include/uapi/asm/socket.h | 2 ++ > arch/parisc/include/uapi/asm/socket.h | 2 ++ > arch/sparc/include/uapi/asm/socket.h | 2 ++ > include/linux/net.h | 1 + > include/linux/socket.h | 1 + > include/net/scm.h | 16 +++++++++++++++- > include/uapi/asm-generic/socket.h | 2 ++ > net/core/sock.c | 11 +++++++++++ > net/mptcp/sockopt.c | 1 + > net/unix/af_unix.c | 18 +++++++++++++----- > tools/include/uapi/asm-generic/socket.h | 2 ++ > 12 files changed, 54 insertions(+), 6 deletions(-) > > diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h > index 739891b94136..ff310613ae64 100644 > --- a/arch/alpha/include/uapi/asm/socket.h > +++ b/arch/alpha/include/uapi/asm/socket.h > @@ -137,6 +137,8 @@ > > #define SO_RCVMARK 75 > > +#define SO_PASSPIDFD 76 > + > #if !defined(__KERNEL__) > > #if __BITS_PER_LONG == 64 > diff --git a/arch/mips/include/uapi/asm/socket.h b/arch/mips/include/uapi/asm/socket.h > index 18f3d95ecfec..762dcb80e4ec 100644 > --- a/arch/mips/include/uapi/asm/socket.h > +++ b/arch/mips/include/uapi/asm/socket.h > @@ -148,6 +148,8 @@ > > #define SO_RCVMARK 75 > > +#define SO_PASSPIDFD 76 > + > #if !defined(__KERNEL__) > > #if __BITS_PER_LONG == 64 > diff --git a/arch/parisc/include/uapi/asm/socket.h b/arch/parisc/include/uapi/asm/socket.h > index f486d3dfb6bb..df16a3e16d64 100644 > --- a/arch/parisc/include/uapi/asm/socket.h > +++ b/arch/parisc/include/uapi/asm/socket.h > @@ -129,6 +129,8 @@ > > #define SO_RCVMARK 0x4049 > > +#define SO_PASSPIDFD 0x404A > + > #if !defined(__KERNEL__) > > #if __BITS_PER_LONG == 64 > diff --git a/arch/sparc/include/uapi/asm/socket.h b/arch/sparc/include/uapi/asm/socket.h > index 2fda57a3ea86..6e2847804fea 100644 > --- a/arch/sparc/include/uapi/asm/socket.h > +++ b/arch/sparc/include/uapi/asm/socket.h > @@ -130,6 +130,8 @@ > > #define SO_RCVMARK 0x0054 > > +#define SO_PASSPIDFD 0x0055 > + > #if !defined(__KERNEL__) > > > diff --git a/include/linux/net.h b/include/linux/net.h > index b73ad8e3c212..c234dfbe7a30 100644 > --- a/include/linux/net.h > +++ b/include/linux/net.h > @@ -43,6 +43,7 @@ struct net; > #define SOCK_PASSSEC 4 > #define SOCK_SUPPORT_ZC 5 > #define SOCK_CUSTOM_SOCKOPT 6 > +#define SOCK_PASSPIDFD 7 > > #ifndef ARCH_HAS_SOCKET_TYPES > /** > diff --git a/include/linux/socket.h b/include/linux/socket.h > index 13c3a237b9c9..6bf90f251910 100644 > --- a/include/linux/socket.h > +++ b/include/linux/socket.h > @@ -177,6 +177,7 @@ static inline size_t msg_data_left(struct msghdr *msg) > #define SCM_RIGHTS 0x01 /* rw: access rights (array of int) */ > #define SCM_CREDENTIALS 0x02 /* rw: struct ucred */ > #define SCM_SECURITY 0x03 /* rw: security label */ > +#define SCM_PIDFD 0x04 /* ro: pidfd (int) */ > > struct ucred { > __u32 pid; > diff --git a/include/net/scm.h b/include/net/scm.h > index 585adc1346bd..4617fbc65294 100644 > --- a/include/net/scm.h > +++ b/include/net/scm.h > @@ -124,7 +124,9 @@ static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg, > struct scm_cookie *scm, int flags) > { > if (!msg->msg_control) { > - if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp || > + if (test_bit(SOCK_PASSCRED, &sock->flags) || > + test_bit(SOCK_PASSPIDFD, &sock->flags) || > + scm->fp || nit: I'd remove newline here. > scm_has_secdata(sock)) > msg->msg_flags |= MSG_CTRUNC; > scm_destroy(scm); > @@ -141,6 +143,18 @@ static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg, > put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds); > } > > + if (test_bit(SOCK_PASSPIDFD, &sock->flags)) { > + int pidfd; > + > + if (WARN_ON_ONCE(!scm->pid) || > + !pid_has_task(scm->pid, PIDTYPE_TGID)) Can we change pidfd_create() to return -ESRCH as it has the same test ? > + pidfd = -ESRCH; > + else > + pidfd = pidfd_create(scm->pid, 0); Then we can change this part like: int pidfd = pidfd_create(scm->pid, 0); WARN_ON_ONCE(!scm->pid); Thanks, Kuniyuki > + > + put_cmsg(msg, SOL_SOCKET, SCM_PIDFD, sizeof(int), &pidfd); > + } > + > scm_destroy_cred(scm); > > scm_passec(sock, msg, scm); > diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h > index 638230899e98..b76169fdb80b 100644 > --- a/include/uapi/asm-generic/socket.h > +++ b/include/uapi/asm-generic/socket.h > @@ -132,6 +132,8 @@ > > #define SO_RCVMARK 75 > > +#define SO_PASSPIDFD 76 > + > #if !defined(__KERNEL__) > > #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__)) > diff --git a/net/core/sock.c b/net/core/sock.c > index c25888795390..3f974246ba3e 100644 > --- a/net/core/sock.c > +++ b/net/core/sock.c > @@ -1246,6 +1246,13 @@ int sk_setsockopt(struct sock *sk, int level, int optname, > clear_bit(SOCK_PASSCRED, &sock->flags); > break; > > + case SO_PASSPIDFD: > + if (valbool) > + set_bit(SOCK_PASSPIDFD, &sock->flags); > + else > + clear_bit(SOCK_PASSPIDFD, &sock->flags); > + break; > + > case SO_TIMESTAMP_OLD: > case SO_TIMESTAMP_NEW: > case SO_TIMESTAMPNS_OLD: > @@ -1737,6 +1744,10 @@ int sk_getsockopt(struct sock *sk, int level, int optname, > v.val = !!test_bit(SOCK_PASSCRED, &sock->flags); > break; > > + case SO_PASSPIDFD: > + v.val = !!test_bit(SOCK_PASSPIDFD, &sock->flags); > + break; > + > case SO_PEERCRED: > { > struct ucred peercred; > diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c > index 8a9656248b0f..bd80e707d0b3 100644 > --- a/net/mptcp/sockopt.c > +++ b/net/mptcp/sockopt.c > @@ -355,6 +355,7 @@ static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname, > case SO_BROADCAST: > case SO_BSDCOMPAT: > case SO_PASSCRED: > + case SO_PASSPIDFD: > case SO_PASSSEC: > case SO_RXQ_OVFL: > case SO_WIFI_STATUS: > diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c > index 0b0f18ecce44..b0ac768752fa 100644 > --- a/net/unix/af_unix.c > +++ b/net/unix/af_unix.c > @@ -1361,7 +1361,8 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr, > if (err) > goto out; > > - if (test_bit(SOCK_PASSCRED, &sock->flags) && > + if ((test_bit(SOCK_PASSCRED, &sock->flags) || > + test_bit(SOCK_PASSPIDFD, &sock->flags)) && > !unix_sk(sk)->addr) { > err = unix_autobind(sk); > if (err) > @@ -1469,7 +1470,8 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr, > if (err) > goto out; > > - if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr) { > + if ((test_bit(SOCK_PASSCRED, &sock->flags) || > + test_bit(SOCK_PASSPIDFD, &sock->flags)) && !u->addr) { > err = unix_autobind(sk); > if (err) > goto out; > @@ -1670,6 +1672,8 @@ static void unix_sock_inherit_flags(const struct socket *old, > { > 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); > } > @@ -1819,8 +1823,10 @@ static bool unix_passcred_enabled(const struct socket *sock, > const struct sock *other) > { > return test_bit(SOCK_PASSCRED, &sock->flags) || > + test_bit(SOCK_PASSPIDFD, &sock->flags) || > !other->sk_socket || > - test_bit(SOCK_PASSCRED, &other->sk_socket->flags); > + test_bit(SOCK_PASSCRED, &other->sk_socket->flags) || > + test_bit(SOCK_PASSPIDFD, &other->sk_socket->flags); > } > > /* > @@ -1922,7 +1928,8 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg, > goto out; > } > > - if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr) { > + if ((test_bit(SOCK_PASSCRED, &sock->flags) || > + test_bit(SOCK_PASSPIDFD, &sock->flags)) && !u->addr) { > err = unix_autobind(sk); > if (err) > goto out; > @@ -2824,7 +2831,8 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state, > /* Never glue messages from different writers */ > if (!unix_skb_scm_eq(skb, &scm)) > break; > - } else if (test_bit(SOCK_PASSCRED, &sock->flags)) { > + } else if (test_bit(SOCK_PASSCRED, &sock->flags) || > + test_bit(SOCK_PASSPIDFD, &sock->flags)) { > /* Copy credentials */ > scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid); > unix_set_secdata(&scm, skb); > diff --git a/tools/include/uapi/asm-generic/socket.h b/tools/include/uapi/asm-generic/socket.h > index 8756df13be50..fbbc4bf53ee3 100644 > --- a/tools/include/uapi/asm-generic/socket.h > +++ b/tools/include/uapi/asm-generic/socket.h > @@ -121,6 +121,8 @@ > > #define SO_RCVMARK 75 > > +#define SO_PASSPIDFD 76 > + > #if !defined(__KERNEL__) > > #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__)) > -- > 2.34.1