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>,
Tycho Andersen <tycho@tycho.ws>,
David Laight <David.Laight@ACULAB.COM>,
Christoph Hellwig <hch@lst.de>,
"David S. Miller" <davem@davemloft.net>,
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 v6 1/7] net/scm: Regularize compat handling of scm_detach_fds()
Date: Mon, 6 Jul 2020 13:17:14 -0700 [thread overview]
Message-ID: <20200706201720.3482959-2-keescook@chromium.org> (raw)
In-Reply-To: <20200706201720.3482959-1-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
next prev parent reply other threads:[~2020-07-06 20:18 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-06 20:17 [PATCH v6 0/7] Add seccomp notifier ioctl that enables adding fds Kees Cook
2020-07-06 20:17 ` Kees Cook [this message]
2020-07-07 11:41 ` [PATCH v6 1/7] net/scm: Regularize compat handling of scm_detach_fds() Christian Brauner
2020-07-08 23:46 ` Kees Cook
2020-07-06 20:17 ` [PATCH v6 2/7] fs: Move __scm_install_fd() to __receive_fd() Kees Cook
2020-07-07 6:49 ` Christoph Hellwig
2020-07-07 11:45 ` Christian Brauner
2020-07-06 20:17 ` [PATCH v6 3/7] fs: Add receive_fd() wrapper for __receive_fd() Kees Cook
2020-07-07 6:49 ` Christoph Hellwig
2020-07-07 11:49 ` Christian Brauner
2020-07-08 23:48 ` Kees Cook
2020-07-06 20:17 ` [PATCH v6 4/7] pidfd: Replace open-coded partial receive_fd() Kees Cook
2020-07-07 12:22 ` Christian Brauner
2020-07-08 23:49 ` Kees Cook
2020-07-09 6:35 ` Kees Cook
2020-07-09 12:54 ` Christian Brauner
2020-07-06 20:17 ` [PATCH v6 5/7] fs: Expand __receive_fd() to accept existing fd Kees Cook
2020-07-07 12:38 ` Christian Brauner
2020-07-08 23:52 ` Kees Cook
2020-07-06 20:17 ` [PATCH v6 6/7] seccomp: Introduce addfd ioctl to seccomp user notifier Kees Cook
2020-07-07 13:30 ` Christian Brauner
2020-07-09 6:12 ` Kees Cook
2020-07-09 13:08 ` Christian Brauner
2020-07-09 6:17 ` [PATCH v6.1 " Kees Cook
2020-07-09 6:22 ` Kees Cook
2020-07-06 20:17 ` [PATCH v6 7/7] selftests/seccomp: Test SECCOMP_IOCTL_NOTIF_ADDFD Kees Cook
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