All of lore.kernel.org
 help / color / mirror / Atom feed
From: Kees Cook <keescook@chromium.org>
To: linux-kernel@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
	Sargun Dhillon <sargun@sargun.me>,
	Christian Brauner <christian@brauner.io>,
	"David S. Miller" <davem@davemloft.net>,
	Christoph Hellwig <hch@lst.de>, Tycho Andersen <tycho@tycho.ws>,
	Jakub Kicinski <kuba@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Aleksa Sarai <cyphar@cyphar.com>,
	Matt Denton <mpdenton@google.com>, Jann Horn <jannh@google.com>,
	Chris Palmer <palmer@google.com>,
	Robert Sesek <rsesek@google.com>,
	Giuseppe Scrivano <gscrivan@redhat.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andy Lutomirski <luto@amacapital.net>,
	Will Drewry <wad@chromium.org>, Shuah Khan <shuah@kernel.org>,
	netdev@vger.kernel.org, containers@lists.linux-foundation.org,
	linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kselftest@vger.kernel.org
Subject: [PATCH v4 01/11] net/scm: Regularize compat handling of scm_detach_fds()
Date: Mon, 15 Jun 2020 20:25:14 -0700	[thread overview]
Message-ID: <20200616032524.460144-2-keescook@chromium.org> (raw)
In-Reply-To: <20200616032524.460144-1-keescook@chromium.org>

Duplicate the cleanups from commit 2618d530dd8b ("net/scm: cleanup
scm_detach_fds") into the compat code.

Move the check added in commit 1f466e1f15cf ("net: cleanly handle kernel
vs user buffers for ->msg_control") to before the compat call, even
though it should be impossible for an in-kernel call to also be compat.

Correct the int "flags" argument to unsigned int to match fd_install()
and similar APIs.

Regularize any remaining differences, including a whitespace issue,
a checkpatch warning, and add the check from commit 6900317f5eff ("net,
scm: fix PaX detected msg_controllen overflow in scm_detach_fds") which
fixed an overflow unique to 64-bit. To avoid confusion when comparing
the compat handler to the native handler, just include the same check
in the compat handler.

Fixes: 48a87cc26c13 ("net: netprio: fd passed in SCM_RIGHTS datagram not set correctly")
Fixes: d84295067fc7 ("net: net_cls: fd passed in SCM_RIGHTS datagram not set correctly")
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 include/net/scm.h |  1 +
 net/compat.c      | 55 +++++++++++++++++++++--------------------------
 net/core/scm.c    | 18 ++++++++--------
 3 files changed, 35 insertions(+), 39 deletions(-)

diff --git a/include/net/scm.h b/include/net/scm.h
index 1ce365f4c256..581a94d6c613 100644
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -37,6 +37,7 @@ struct scm_cookie {
 #endif
 };
 
+int __scm_install_fd(struct file *file, int __user *ufd, unsigned int o_flags);
 void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm);
 void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm);
 int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm);
diff --git a/net/compat.c b/net/compat.c
index 5e3041a2c37d..27d477fdcaa0 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -281,39 +281,31 @@ int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *dat
 	return 0;
 }
 
-void scm_detach_fds_compat(struct msghdr *kmsg, struct scm_cookie *scm)
+static int scm_max_fds_compat(struct msghdr *msg)
 {
-	struct compat_cmsghdr __user *cm = (struct compat_cmsghdr __user *) kmsg->msg_control;
-	int fdmax = (kmsg->msg_controllen - sizeof(struct compat_cmsghdr)) / sizeof(int);
-	int fdnum = scm->fp->count;
-	struct file **fp = scm->fp->fp;
-	int __user *cmfptr;
-	int err = 0, i;
+	if (msg->msg_controllen <= sizeof(struct compat_cmsghdr))
+		return 0;
+	return (msg->msg_controllen - sizeof(struct compat_cmsghdr)) / sizeof(int);
+}
 
-	if (fdnum < fdmax)
-		fdmax = fdnum;
+void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm)
+{
+	struct compat_cmsghdr __user *cm =
+		(struct compat_cmsghdr __user *)msg->msg_control;
+	unsigned int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0;
+	int fdmax = min_t(int, scm_max_fds_compat(msg), scm->fp->count);
+	int __user *cmsg_data = CMSG_USER_DATA(cm);
+	int err = 0, i;
 
-	for (i = 0, cmfptr = (int __user *) CMSG_COMPAT_DATA(cm); i < fdmax; i++, cmfptr++) {
-		int new_fd;
-		err = security_file_receive(fp[i]);
+	for (i = 0; i < fdmax; i++) {
+		err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
 		if (err)
 			break;
-		err = get_unused_fd_flags(MSG_CMSG_CLOEXEC & kmsg->msg_flags
-					  ? O_CLOEXEC : 0);
-		if (err < 0)
-			break;
-		new_fd = err;
-		err = put_user(new_fd, cmfptr);
-		if (err) {
-			put_unused_fd(new_fd);
-			break;
-		}
-		/* Bump the usage count and install the file. */
-		fd_install(new_fd, get_file(fp[i]));
 	}
 
 	if (i > 0) {
 		int cmlen = CMSG_COMPAT_LEN(i * sizeof(int));
+
 		err = put_user(SOL_SOCKET, &cm->cmsg_level);
 		if (!err)
 			err = put_user(SCM_RIGHTS, &cm->cmsg_type);
@@ -321,16 +313,19 @@ void scm_detach_fds_compat(struct msghdr *kmsg, struct scm_cookie *scm)
 			err = put_user(cmlen, &cm->cmsg_len);
 		if (!err) {
 			cmlen = CMSG_COMPAT_SPACE(i * sizeof(int));
-			kmsg->msg_control += cmlen;
-			kmsg->msg_controllen -= cmlen;
+			if (msg->msg_controllen < cmlen)
+				cmlen = msg->msg_controllen;
+			msg->msg_control += cmlen;
+			msg->msg_controllen -= cmlen;
 		}
 	}
-	if (i < fdnum)
-		kmsg->msg_flags |= MSG_CTRUNC;
+
+	if (i < scm->fp->count || (scm->fp->count && fdmax <= 0))
+		msg->msg_flags |= MSG_CTRUNC;
 
 	/*
-	 * All of the files that fit in the message have had their
-	 * usage counts incremented, so we just free the list.
+	 * All of the files that fit in the message have had their usage counts
+	 * incremented, so we just free the list.
 	 */
 	__scm_destroy(scm);
 }
diff --git a/net/core/scm.c b/net/core/scm.c
index 875df1c2989d..6151678c73ed 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -280,7 +280,7 @@ void put_cmsg_scm_timestamping(struct msghdr *msg, struct scm_timestamping_inter
 }
 EXPORT_SYMBOL(put_cmsg_scm_timestamping);
 
-static int __scm_install_fd(struct file *file, int __user *ufd, int o_flags)
+int __scm_install_fd(struct file *file, int __user *ufd, unsigned int o_flags)
 {
 	struct socket *sock;
 	int new_fd;
@@ -319,29 +319,29 @@ static int scm_max_fds(struct msghdr *msg)
 
 void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
 {
-	struct cmsghdr __user *cm
-		= (__force struct cmsghdr __user*)msg->msg_control;
-	int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0;
+	struct cmsghdr __user *cm =
+		(__force struct cmsghdr __user *)msg->msg_control;
+	unsigned int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0;
 	int fdmax = min_t(int, scm_max_fds(msg), scm->fp->count);
 	int __user *cmsg_data = CMSG_USER_DATA(cm);
 	int err = 0, i;
 
+	/* no use for FD passing from kernel space callers */
+	if (WARN_ON_ONCE(!msg->msg_control_is_user))
+		return;
+
 	if (msg->msg_flags & MSG_CMSG_COMPAT) {
 		scm_detach_fds_compat(msg, scm);
 		return;
 	}
 
-	/* no use for FD passing from kernel space callers */
-	if (WARN_ON_ONCE(!msg->msg_control_is_user))
-		return;
-
 	for (i = 0; i < fdmax; i++) {
 		err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
 		if (err)
 			break;
 	}
 
-	if (i > 0)  {
+	if (i > 0) {
 		int cmlen = CMSG_LEN(i * sizeof(int));
 
 		err = put_user(SOL_SOCKET, &cm->cmsg_level);
-- 
2.25.1


  reply	other threads:[~2020-06-16  3:25 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-16  3:25 [PATCH v4 00/11] Add seccomp notifier ioctl that enables adding fds Kees Cook
2020-06-16  3:25 ` Kees Cook [this message]
2020-06-16  3:25 ` [PATCH v4 02/11] fs: Move __scm_install_fd() to __fd_install_received() Kees Cook
2020-06-16  5:29   ` Sargun Dhillon
2020-06-16  5:48     ` Kees Cook
2020-06-17 15:25   ` David Laight
2020-06-17 18:40     ` Kees Cook
2020-06-18  8:56   ` Christian Brauner
2020-06-18 20:05     ` Kees Cook
2020-06-16  3:25 ` [PATCH v4 03/11] fs: Add fd_install_received() wrapper for __fd_install_received() Kees Cook
2020-06-17 15:35   ` David Laight
2020-06-17 19:58     ` Kees Cook
2020-06-18  8:19       ` David Laight
2020-06-16  3:25 ` [PATCH v4 04/11] pidfd: Replace open-coded partial fd_install_received() Kees Cook
2020-06-16  3:25 ` [PATCH v4 05/11] fs: Expand __fd_install_received() to accept fd Kees Cook
2020-06-16  3:25 ` [PATCH v4 06/11] seccomp: Introduce addfd ioctl to seccomp user notifier Kees Cook
2020-06-16  3:25 ` [PATCH v4 07/11] selftests/seccomp: Test SECCOMP_IOCTL_NOTIF_ADDFD Kees Cook
2020-06-16  3:25 ` [PATCH v4 08/11] selftests/seccomp: Make kcmp() less required Kees Cook
2020-06-16 14:57   ` Tycho Andersen
2020-06-16 16:03     ` Kees Cook
2020-06-16  3:25 ` [PATCH v4 09/11] selftests/seccomp: Rename user_trap_syscall() to user_notif_syscall() Kees Cook
2020-06-16 14:56   ` Tycho Andersen
2020-06-16  3:25 ` [PATCH v4 10/11] seccomp: Switch addfd to Extensible Argument ioctl Kees Cook
2020-06-16 14:55   ` Tycho Andersen
2020-06-16 16:05     ` Kees Cook
2020-06-16 16:18       ` Tycho Andersen
2020-06-16  3:25 ` [PATCH v4 11/11] seccomp: Fix ioctl number for SECCOMP_IOCTL_NOTIF_ID_VALID Kees Cook
2020-06-18 22:16 ` [PATCH v4 00/11] Add seccomp notifier ioctl that enables adding fds Sargun Dhillon

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200616032524.460144-2-keescook@chromium.org \
    --to=keescook@chromium.org \
    --cc=christian@brauner.io \
    --cc=containers@lists.linux-foundation.org \
    --cc=cyphar@cyphar.com \
    --cc=davem@davemloft.net \
    --cc=gregkh@linuxfoundation.org \
    --cc=gscrivan@redhat.com \
    --cc=hch@lst.de \
    --cc=jannh@google.com \
    --cc=kuba@kernel.org \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=mpdenton@google.com \
    --cc=netdev@vger.kernel.org \
    --cc=palmer@google.com \
    --cc=rsesek@google.com \
    --cc=sargun@sargun.me \
    --cc=shuah@kernel.org \
    --cc=tycho@tycho.ws \
    --cc=viro@zeniv.linux.org.uk \
    --cc=wad@chromium.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.