From patchwork Wed Nov 13 21:02:05 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: stsp X-Patchwork-Id: 13874288 X-Patchwork-Delegate: kuba@kernel.org Received: from forward201d.mail.yandex.net (forward201d.mail.yandex.net [178.154.239.220]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4DB17206067; Wed, 13 Nov 2024 21:09:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.154.239.220 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731532146; cv=none; b=SWE225AsXDLcF41YHpxqNKVxGd+uOAJibsmT86qedzBnTp3lLq5H69op2Dj4BobufrG1zHf3yOoG+9WE9DZvxijFN0Mo+fUlhG4fJ0U6RElcAdJeRFoOL+i4OX6esjEN5t9xHZloKxEoX01yk38+1jU4Kz1hIM5Es9w/AnPDDqI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731532146; c=relaxed/simple; bh=DLr2vnINqZVj5aaMJifgR8ShHCLwIiZPOPT0DwCv5S8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=He/GtPXLd6nFerRxoa1+0kUqST1NJA8eEkE4XA+T8W5Vqg2n1V6Em//yrinaeGjbp5Ykl1cUxbXo5bZoBXaPprZSxJIevLFo4eA1dv0+uf/NzE/XF+Mvex/ORhZGgI13PBL1+9nHQLcuAlnu+/Fukv6MDpwFbryQkBDW0hok64I= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=yandex.ru; spf=pass smtp.mailfrom=yandex.ru; dkim=pass (1024-bit key) header.d=yandex.ru header.i=@yandex.ru header.b=NjWQB3AD; arc=none smtp.client-ip=178.154.239.220 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=yandex.ru Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=yandex.ru Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=yandex.ru header.i=@yandex.ru header.b="NjWQB3AD" Received: from forward103d.mail.yandex.net (forward103d.mail.yandex.net [IPv6:2a02:6b8:c41:1300:1:45:d181:d103]) by forward201d.mail.yandex.net (Yandex) with ESMTPS id 2F6F667CD7; Thu, 14 Nov 2024 00:02:51 +0300 (MSK) Received: from mail-nwsmtp-smtp-production-main-81.klg.yp-c.yandex.net (mail-nwsmtp-smtp-production-main-81.klg.yp-c.yandex.net [IPv6:2a02:6b8:c42:864f:0:640:bfcf:0]) by forward103d.mail.yandex.net (Yandex) with ESMTPS id 89DFC609E9; Thu, 14 Nov 2024 00:02:43 +0300 (MSK) Received: by mail-nwsmtp-smtp-production-main-81.klg.yp-c.yandex.net (smtp/Yandex) with ESMTPSA id d2Tv0AUOqSw0-Q4dHx0kH; Thu, 14 Nov 2024 00:02:41 +0300 X-Yandex-Fwd: 1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex.ru; s=mail; t=1731531761; bh=EQpp/xKTJGsUtdCCDtGntRJK9oexOt07DdCvE8bCIi0=; h=Message-ID:Date:Cc:Subject:To:From; b=NjWQB3ADl1exQnTPcEm0ZPnpTSG7MsV71G34FtwSt3I7XjewpREyALeJrcvub3ju9 3Y4j75ptGfDk2qbQCKmturZOenOl+eA5mTABEMH0EfX+v8li0F67TZXN4oufvV/nPl +oWbrabBPjk9dFay0gzcNiPgEfykrBzwj7cHvx5U= Authentication-Results: mail-nwsmtp-smtp-production-main-81.klg.yp-c.yandex.net; dkim=pass header.i=@yandex.ru From: Stas Sergeev To: linux-kernel@vger.kernel.org Cc: Stas Sergeev , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Shuah Khan , Christian Brauner , Jens Axboe , Willem de Bruijn , Pavel Begunkov , Gabriel Krisman Bertazi , Mina Almasry , Oleg Nesterov , Tycho Andersen , Al Viro , Kuniyuki Iwashima , Gou Hao , Abhishek Chauhan , Michal Luczaj , Kees Cook , netdev@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH] net/unix: pass pidfd flags via SCM_PIDFD cmsg Date: Thu, 14 Nov 2024 00:02:05 +0300 Message-ID: <20241113210206.3440784-1-stsp2@yandex.ru> X-Mailer: git-send-email 2.47.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org Currently SCM_PIDFD cmsg cannot be sent via unix socket (returns -EINVAL) and SO_PASSPIDFD doesn't support flags. The created pidfd always has flags set to 0. This patch implements SCM_PIDFD cmsg in AF_UNIX socket, which can be used to send flags to SO_PASSPIDFD-enabled recipient. Self-test is added for the propagation of PIDFD_NONBLOCK flag. This is mainly needed for the future extensions, like eg this one: https://lore.kernel.org/lkml/8288a08e-448b-43c2-82dc-59f87d0d9072@yandex.ru/T/#me1237e46deba8574b77834b7704e63559ffef9cb where it was suggested to try solving the supplementary groups problem with pidfd. Signed-off-by: Stas Sergeev CC: "David S. Miller" CC: Eric Dumazet CC: Jakub Kicinski CC: Paolo Abeni CC: Simon Horman CC: Shuah Khan CC: Christian Brauner CC: Jens Axboe CC: Willem de Bruijn CC: Pavel Begunkov CC: Gabriel Krisman Bertazi CC: Mina Almasry CC: Oleg Nesterov CC: Tycho Andersen CC: Al Viro CC: Kuniyuki Iwashima CC: Gou Hao CC: Abhishek Chauhan CC: Michal Luczaj CC: Kees Cook CC: linux-kernel@vger.kernel.org CC: netdev@vger.kernel.org CC: linux-kselftest@vger.kernel.org --- include/linux/pidfs.h | 9 +++ include/linux/socket.h | 2 +- include/net/af_unix.h | 1 + include/net/scm.h | 10 ++- kernel/pid.c | 6 +- net/core/scm.c | 14 ++++ net/core/sock.c | 1 + net/unix/af_unix.c | 3 + .../testing/selftests/net/af_unix/scm_pidfd.c | 70 +++++++++++++++++-- 9 files changed, 106 insertions(+), 10 deletions(-) diff --git a/include/linux/pidfs.h b/include/linux/pidfs.h index 75bdf9807802..c4c5c1a0c2ad 100644 --- a/include/linux/pidfs.h +++ b/include/linux/pidfs.h @@ -2,7 +2,16 @@ #ifndef _LINUX_PID_FS_H #define _LINUX_PID_FS_H +#include + struct file *pidfs_alloc_file(struct pid *pid, unsigned int flags); void __init pidfs_init(void); +static inline int pidfd_validate_flags(unsigned int flags) +{ + if (flags & ~(PIDFD_NONBLOCK | PIDFD_THREAD)) + return -EINVAL; + return 0; +} + #endif /* _LINUX_PID_FS_H */ diff --git a/include/linux/socket.h b/include/linux/socket.h index d18cc47e89bd..ee27d391e5aa 100644 --- a/include/linux/socket.h +++ b/include/linux/socket.h @@ -178,7 +178,7 @@ 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) */ +#define SCM_PIDFD 0x04 /* r: pidfd, w: pidfd_flags (int) */ struct ucred { __u32 pid; diff --git a/include/net/af_unix.h b/include/net/af_unix.h index 63129c79b8cb..4bc197548c2f 100644 --- a/include/net/af_unix.h +++ b/include/net/af_unix.h @@ -62,6 +62,7 @@ struct unix_skb_parms { #ifdef CONFIG_SECURITY_NETWORK u32 secid; /* Security ID */ #endif + u32 pidfd_flags; u32 consumed; } __randomize_layout; diff --git a/include/net/scm.h b/include/net/scm.h index 0d35c7c77a74..bc64d516b226 100644 --- a/include/net/scm.h +++ b/include/net/scm.h @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -48,6 +49,7 @@ struct scm_cookie { #ifdef CONFIG_SECURITY_NETWORK u32 secid; /* Passed security ID */ #endif + u32 pidfd_flags; }; void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm); @@ -137,6 +139,7 @@ static __inline__ void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm { struct file *pidfd_file = NULL; int len, pidfd; + int err; /* put_cmsg() doesn't return an error if CMSG is truncated, * that's why we need to opencode these checks here. @@ -154,7 +157,12 @@ static __inline__ void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm if (!scm->pid) return; - pidfd = pidfd_prepare(scm->pid, 0, &pidfd_file); + err = pidfd_validate_flags(scm->pidfd_flags); + if (err) { + msg->msg_flags |= MSG_CTRUNC; + return; + } + pidfd = pidfd_prepare(scm->pid, scm->pidfd_flags, &pidfd_file); if (put_cmsg(msg, SOL_SOCKET, SCM_PIDFD, sizeof(int), &pidfd)) { if (pidfd_file) { diff --git a/kernel/pid.c b/kernel/pid.c index 2715afb77eab..b1100ae8ea63 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -629,10 +629,12 @@ static int pidfd_create(struct pid *pid, unsigned int flags) SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags) { int fd; + int err; struct pid *p; - if (flags & ~(PIDFD_NONBLOCK | PIDFD_THREAD)) - return -EINVAL; + err = pidfd_validate_flags(flags); + if (err) + return err; if (pid <= 0) return -EINVAL; diff --git a/net/core/scm.c b/net/core/scm.c index 4f6a14babe5a..3bcdecdacd7e 100644 --- a/net/core/scm.c +++ b/net/core/scm.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include #include @@ -210,6 +211,19 @@ int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p) p->creds.gid = gid; break; } + case SCM_PIDFD: + { + unsigned int flags; + + if (cmsg->cmsg_len != CMSG_LEN(sizeof(flags))) + goto error; + memcpy(&flags, CMSG_DATA(cmsg), sizeof(flags)); + err = pidfd_validate_flags(flags); + if (err) + goto error; + p->pidfd_flags = flags; + break; + } default: goto error; } diff --git a/net/core/sock.c b/net/core/sock.c index 039be95c40cf..d1fce437c035 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2930,6 +2930,7 @@ int __sock_cmsg_send(struct sock *sk, struct cmsghdr *cmsg, /* SCM_RIGHTS and SCM_CREDENTIALS are semantically in SOL_UNIX. */ case SCM_RIGHTS: case SCM_CREDENTIALS: + case SCM_PIDFD: break; default: return -EINVAL; diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 001ccc55ef0f..8b19dfec0221 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1892,6 +1892,7 @@ static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool sen UNIXCB(skb).uid = scm->creds.uid; UNIXCB(skb).gid = scm->creds.gid; UNIXCB(skb).fp = NULL; + UNIXCB(skb).pidfd_flags = scm->pidfd_flags; unix_get_secdata(scm, skb); if (scm->fp && send_fds) err = unix_attach_fds(scm, skb); @@ -2486,6 +2487,7 @@ int __unix_dgram_recvmsg(struct sock *sk, struct msghdr *msg, size_t size, memset(&scm, 0, sizeof(scm)); scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid); + scm.pidfd_flags = UNIXCB(skb).pidfd_flags; unix_set_secdata(&scm, skb); if (!(flags & MSG_PEEK)) { @@ -2873,6 +2875,7 @@ static int unix_stream_read_generic(struct unix_stream_read_state *state, test_bit(SOCK_PASSPIDFD, &sock->flags)) { /* Copy credentials */ scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid); + scm.pidfd_flags = UNIXCB(skb).pidfd_flags; unix_set_secdata(&scm, skb); check_creds = true; } diff --git a/tools/testing/selftests/net/af_unix/scm_pidfd.c b/tools/testing/selftests/net/af_unix/scm_pidfd.c index 7e534594167e..1e70ff253a1d 100644 --- a/tools/testing/selftests/net/af_unix/scm_pidfd.c +++ b/tools/testing/selftests/net/af_unix/scm_pidfd.c @@ -5,6 +5,7 @@ #include #include #include +#include #include #include #include @@ -15,6 +16,11 @@ #include #include +/* There are problems including linux/pidfd.h, so define. */ +#ifndef PIDFD_NONBLOCK +#define PIDFD_NONBLOCK O_NONBLOCK +#endif + #include "../../kselftest_harness.h" #define clean_errno() (errno == 0 ? "None" : strerror(errno)) @@ -126,7 +132,7 @@ static pid_t get_pid_from_fdinfo_file(int pidfd, const char *key, size_t keylen) return result; } -static int cmsg_check(int fd) +static int cmsg_check(int fd, unsigned int pidfd_flags) { struct msghdr msg = { 0 }; struct cmsghdr *cmsg; @@ -136,6 +142,7 @@ static int cmsg_check(int fd) char control[CMSG_SPACE(sizeof(struct ucred)) + CMSG_SPACE(sizeof(int))] = { 0 }; int *pidfd = NULL; + unsigned int flags; pid_t parent_pid; int err; @@ -197,6 +204,13 @@ static int cmsg_check(int fd) return 1; } + flags = fcntl(*pidfd, F_GETFL, 0); + flags &= ~O_ACCMODE; + if (flags != pidfd_flags) { + log_err("SCM_PIDFD flags mismatch: %x != %x", flags, pidfd_flags); + return 1; + } + /* pidfd from SCM_PIDFD should point to the parent process PID */ parent_pid = get_pid_from_fdinfo_file(*pidfd, "Pid:", sizeof("Pid:") - 1); @@ -227,30 +241,49 @@ FIXTURE_VARIANT(scm_pidfd) { int type; bool abstract; + unsigned int flags; }; FIXTURE_VARIANT_ADD(scm_pidfd, stream_pathname) { .type = SOCK_STREAM, .abstract = 0, + .flags = 0, }; FIXTURE_VARIANT_ADD(scm_pidfd, stream_abstract) { .type = SOCK_STREAM, .abstract = 1, + .flags = 0, }; FIXTURE_VARIANT_ADD(scm_pidfd, dgram_pathname) { .type = SOCK_DGRAM, .abstract = 0, + .flags = 0, }; FIXTURE_VARIANT_ADD(scm_pidfd, dgram_abstract) { .type = SOCK_DGRAM, .abstract = 1, + .flags = 0, +}; + +FIXTURE_VARIANT_ADD(scm_pidfd, stream_nonblock) +{ + .type = SOCK_STREAM, + .abstract = 0, + .flags = PIDFD_NONBLOCK, +}; + +FIXTURE_VARIANT_ADD(scm_pidfd, dgram_nonblock) +{ + .type = SOCK_DGRAM, + .abstract = 0, + .flags = PIDFD_NONBLOCK, }; FIXTURE_SETUP(scm_pidfd) @@ -335,7 +368,7 @@ static void client(FIXTURE_DATA(scm_pidfd) *self, close(self->startup_pipe[1]); - if (cmsg_check(cfd)) { + if (cmsg_check(cfd, variant->flags)) { log_err("cmsg_check failed"); child_die(); } @@ -375,6 +408,27 @@ TEST_F(scm_pidfd, test) int err; int pfd; int child_status = 0; + char iobuf; + unsigned int pidfd_flags; + struct msghdr msg = { 0 }; + struct cmsghdr *cmsg; + struct iovec io = { + .iov_base = &iobuf, + .iov_len = sizeof(iobuf) + }; + union { + char buf[CMSG_SPACE(sizeof(pidfd_flags))]; + struct cmsghdr align; + } u; + + msg.msg_iov = &io; + msg.msg_iovlen = 1; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof(u.buf); + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_PIDFD; + cmsg->cmsg_len = CMSG_LEN(sizeof(pidfd_flags)); self->server = socket(AF_UNIX, variant->type, 0); ASSERT_NE(-1, self->server); @@ -414,12 +468,16 @@ TEST_F(scm_pidfd, test) close(self->startup_pipe[0]); if (variant->type == SOCK_DGRAM) { - err = sendto(pfd, "x", sizeof(char), 0, (struct sockaddr *)&self->client_addr->listen_addr, self->client_addr->addrlen); - ASSERT_NE(-1, err); - } else { - err = send(pfd, "x", sizeof(char), 0); + err = connect(pfd, + (struct sockaddr *)&self->client_addr->listen_addr, + self->client_addr->addrlen); ASSERT_NE(-1, err); } + iobuf = 'x'; + pidfd_flags = variant->flags; + memcpy(CMSG_DATA(cmsg), &pidfd_flags, sizeof(pidfd_flags)); + err = sendmsg(pfd, &msg, 0); + ASSERT_NE(-1, err); close(pfd); waitpid(self->client_pid, &child_status, 0);