From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 6253D3DDDBB; Mon, 31 Aug 2026 11:21:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788175295; cv=none; b=aymOXKAfHDhE+4W1zuDwc1ta2Pu7wuFhFldCvwrpM3+1e4WDMmJCf7AhtT/ot4S9AVTx2+/YzP+ARX7vC2qXAEANUlLu9D5ITdWEMIqREMVPkM4Ar9lv1lq+Zo24eyj5YFcOtwFQAJHOVZj6A+YNqskgoL6lygUwz2pprlIhetE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788175295; c=relaxed/simple; bh=8y7i7XdLNk6YD1ieQIQKQPtW6EPU/d87CtG5vVgfh1w=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=B09Gt1u2RCLBrsDCA23037hUQNXddjbM1Txx/OgSaQ7fed7Wkz27kGUJ1b8u8TLUnYSi93SD1RvRlty+UxW9N5NGoN9a+SvGq479TZXmZOWyzWnfV24HRpLXSDM+9Q7keTws2rJ2bzKh8I3KkppZTlIRwrWlStWpkeCeDXJXdcw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FcYLf6t+; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FcYLf6t+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B8ADA1F000E9; Mon, 31 Aug 2026 11:21:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788175294; bh=f7vAua/SuxVzCWdPf5sdxe/QtAK3nj/ceXJVxPpgBGA=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=FcYLf6t+LlM1BO9qm87ob0a3d8IwchOV8AYH8r1W4Zs9l9g/A4bDil//1y8tkQsXi gxPa0CsVXBy539tFp8UVMy095LDLpvrvXq+RidnHvadiVKRYDjOjb8Jpn4RfJltqSK /FNdhJ3zN/03Zzvqiu2YX1/4vaW4mAaTafk10QVm36wmJFyUwVQQQrqHX2ZOYtp/pi Z1Zeg5vnjM78BDbgx7S79JESiisWj62b0vFH7U4SLmnQH9o7UjTrM7BuABG2QrkX1g UGEjnGNrZexDKSQoKSrseDXYSJdvCo0RyiFqaTz8RQKcpajriLs2j2zLmjmRfIBzBp yQ+SWqWTG5yGw== From: Christian Brauner Date: Mon, 31 Aug 2026 13:21:14 +0200 Subject: [PATCH 02/10] af_unix: record the pid of the sending thread Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260831-work-unix-passpidfd-v1-2-70cbfda0c7ba@kernel.org> References: <20260831-work-unix-passpidfd-v1-0-70cbfda0c7ba@kernel.org> In-Reply-To: <20260831-work-unix-passpidfd-v1-0-70cbfda0c7ba@kernel.org> To: Jakub Kicinski , Kuniyuki Iwashima , Oleg Nesterov Cc: "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Willem de Bruijn , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Alexander Viro , Jan Kara , linux-fsdevel@vger.kernel.org, Alexander Mikhalitsyn , "Christian Brauner (Amutable)" X-Mailer: b4 0.17-dev-db0b7 X-Developer-Signature: v=1; a=openpgp-sha256; l=6397; i=brauner@kernel.org; h=from:subject:message-id; bh=8y7i7XdLNk6YD1ieQIQKQPtW6EPU/d87CtG5vVgfh1w=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWRNTd6Y4/vmr6vwwQ0JtxdsMGh3PmKQdXJGaT6HhmgUz 70naTvSO0pZGMS4GGTFFFkc2k3C5ZbzVGw2ytSAmcPKBDKEgYtTACby+gEjw/Ttf/nmsCy1rXZa tMmxyEVy84cdld+Kp5Z0Be+VddabGM7I8Mft7QKdvTemCU4IXZ/uYcnz9lGo/tF79b+znB74GdU 7MwEA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Currently only the struct pid of the thread-group leader is recorded. The identity of the actual thread that sent the message or is connected to a given socket cannot be retrieved. Add the plumbing to make it possible to retrieve a pidfd for the sender. Nothing uses the thread-specific struct pid yet. No functional changes. Signed-off-by: Christian Brauner (Amutable) --- include/net/scm.h | 7 +++---- net/core/scm.c | 21 +++++++++++++++++---- net/unix/af_unix.c | 23 +++++++++++++---------- net/unix/af_unix.h | 3 ++- 4 files changed, 35 insertions(+), 19 deletions(-) diff --git a/include/net/scm.h b/include/net/scm.h index 86ae6bc109ec..aa7d15c5fc27 100644 --- a/include/net/scm.h +++ b/include/net/scm.h @@ -42,7 +42,7 @@ struct scm_fp_list { }; struct scm_cookie { - struct pid *pid; /* Skb credentials */ + DECLARE_PIDS(pid, PIDTYPE_TGID); /* Skb credentials by pid type */ struct scm_fp_list *fp; /* Passed files */ struct scm_creds creds; /* Skb credentials */ #ifdef CONFIG_SECURITY_NETWORK @@ -69,7 +69,7 @@ static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_co static __inline__ void scm_set_cred(struct scm_cookie *scm, struct pid *pid, kuid_t uid, kgid_t gid) { - scm->pid = get_pid(pid); + scm->pid[PIDTYPE_TGID] = get_pid(pid); scm->creds.pid = pid_vnr(pid); scm->creds.uid = uid; scm->creds.gid = gid; @@ -77,8 +77,7 @@ static __inline__ void scm_set_cred(struct scm_cookie *scm, static __inline__ void scm_destroy_cred(struct scm_cookie *scm) { - put_pid(scm->pid); - scm->pid = NULL; + put_pids(scm->pid); } static __inline__ void scm_destroy(struct scm_cookie *scm) diff --git a/net/core/scm.c b/net/core/scm.c index f0d44ecdb11f..9b9e119c353a 100644 --- a/net/core/scm.c +++ b/net/core/scm.c @@ -149,6 +149,7 @@ EXPORT_SYMBOL(__scm_destroy); static inline int scm_replace_pid(struct scm_cookie *scm, struct pid *pid) { + struct pid *thread_pid; int err; /* drop all previous references */ @@ -158,7 +159,18 @@ static inline int scm_replace_pid(struct scm_cookie *scm, struct pid *pid) if (unlikely(err)) return err; - scm->pid = pid; + /* A sender naming its own thread-group sends from the current thread. */ + if (pid == task_tgid(current)) + thread_pid = task_pid(current); + else + thread_pid = pid; + + err = pidfs_register_pid(thread_pid); + if (unlikely(err)) + return err; + + scm->pid[PIDTYPE_TGID] = pid; + scm->pid[PIDTYPE_PID] = get_pid(thread_pid); scm->creds.pid = pid_vnr(pid); return 0; } @@ -207,7 +219,8 @@ int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p) if (err) goto error; - if (!p->pid || pid_vnr(p->pid) != creds.pid) { + if (!p->pid[PIDTYPE_TGID] || + pid_vnr(p->pid[PIDTYPE_TGID]) != creds.pid) { struct pid *pid; err = -ESRCH; pid = find_get_pid(creds.pid); @@ -504,10 +517,10 @@ static void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm) return; } - if (!scm->pid) + if (!scm->pid[PIDTYPE_TGID]) return; - pidfd = pidfd_prepare(scm->pid, PIDFD_STALE, &pidfd_file); + pidfd = pidfd_prepare(scm->pid[PIDTYPE_TGID], PIDFD_STALE, &pidfd_file); if (put_cmsg(msg, SOL_SOCKET, SCM_PIDFD, sizeof(int), &pidfd)) { if (pidfd_file) { diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 13f9926bf205..011af84e3626 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1973,7 +1973,7 @@ static void unix_destruct_scm(struct sk_buff *skb) { struct scm_cookie scm = {}; - swap(scm.pid, UNIXCB(skb).pid); + swap_pids(scm.pid, UNIXCB(skb).pid); if (UNIXCB(skb).fp) unix_detach_fds(&scm, skb); @@ -1991,7 +1991,7 @@ static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool sen { int err = 0; - UNIXCB(skb).pid = get_pid(scm->pid); + get_pids(UNIXCB(skb).pid, scm->pid); UNIXCB(skb).uid = scm->creds.uid; UNIXCB(skb).gid = scm->creds.gid; UNIXCB(skb).fp = NULL; @@ -2005,7 +2005,10 @@ static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool sen static void unix_skb_to_scm(struct sk_buff *skb, struct scm_cookie *scm) { - scm_set_cred(scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid); + get_pids(scm->pid, UNIXCB(skb).pid); + scm->creds.pid = pid_vnr(scm->pid[PIDTYPE_TGID]); + scm->creds.uid = UNIXCB(skb).uid; + scm->creds.gid = UNIXCB(skb).gid; unix_set_secdata(scm, skb); } @@ -2025,20 +2028,20 @@ static void unix_skb_to_scm(struct sk_buff *skb, struct scm_cookie *scm) static int unix_maybe_add_creds(struct sk_buff *skb, const struct sock *sk, const struct sock *other) { - if (UNIXCB(skb).pid) + if (UNIXCB(skb).pid[PIDTYPE_TGID]) return 0; if (unix_may_passcred(sk) || unix_may_passcred(other) || !other->sk_socket) { - struct pid *pid; int err; - pid = task_tgid(current); - err = pidfs_register_pid(pid); - if (unlikely(err)) + get_task_pids(UNIXCB(skb).pid, current); + err = pidfs_register_pids(UNIXCB(skb).pid); + if (unlikely(err)) { + put_pids(UNIXCB(skb).pid); return err; + } - UNIXCB(skb).pid = get_pid(pid); current_uid_gid(&UNIXCB(skb).uid, &UNIXCB(skb).gid); } @@ -2048,7 +2051,7 @@ static int unix_maybe_add_creds(struct sk_buff *skb, const struct sock *sk, static bool unix_skb_scm_eq(struct sk_buff *skb, struct scm_cookie *scm) { - return UNIXCB(skb).pid == scm->pid && + return UNIXCB(skb).pid[PIDTYPE_TGID] == scm->pid[PIDTYPE_TGID] && uid_eq(UNIXCB(skb).uid, scm->creds.uid) && gid_eq(UNIXCB(skb).gid, scm->creds.gid) && unix_secdata_eq(scm, skb); diff --git a/net/unix/af_unix.h b/net/unix/af_unix.h index 8119dbeef3a3..402742895acc 100644 --- a/net/unix/af_unix.h +++ b/net/unix/af_unix.h @@ -2,6 +2,7 @@ #ifndef __AF_UNIX_H #define __AF_UNIX_H +#include #include #define UNIX_HASH_MOD (256 - 1) @@ -11,7 +12,7 @@ struct sock *unix_peer_get(struct sock *sk); struct unix_skb_parms { - struct pid *pid; /* skb credentials */ + DECLARE_PIDS(pid, PIDTYPE_TGID); /* skb credentials by pid type */ kuid_t uid; kgid_t gid; struct scm_fp_list *fp; /* Passed files */ -- 2.53.0