mirrors/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2025-11-04 10:40:15 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

net/scm: Regularize compat handling of scm_detach_fds()

Browse source 
Duplicate the cleanups from commit 2618d530dd ("net/scm: cleanup
scm_detach_fds") into the compat code.

Replace open-coded __receive_sock() with a call to the helper.

Move the check added in commit 1f466e1f15 ("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 6900317f5e ("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.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Sargun Dhillon <sargun@sargun.me>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2020-06-09 16:11:29 -07:00
parent 4969f8a073
commit c0029de509
3 changed files with 37 additions and 47 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
include/net/scm.h
View file

@ -37,6 +37,7 @@ struct scm_cookie {
#endif #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(struct msghdr *msg, struct scm_cookie *scm);
void scm_detach_fds_compat(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); int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm);

56
net/compat.c
View file

@ -281,40 +281,31 @@ int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *dat
return 0; 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; if (msg->msg_controllen <= sizeof(struct compat_cmsghdr))
int fdmax = (kmsg->msg_controllen - sizeof(struct compat_cmsghdr)) / sizeof(int); return 0;
int fdnum = scm->fp->count; return (msg->msg_controllen - sizeof(struct compat_cmsghdr)) / sizeof(int);
struct file **fp = scm->fp->fp; }
int __user *cmfptr;
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; int err = 0, i;
if (fdnum < fdmax) for (i = 0; i < fdmax; i++) {
fdmax = fdnum; err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
for (i = 0, cmfptr = (int __user *) CMSG_COMPAT_DATA(cm); i < fdmax; i++, cmfptr++) {
int new_fd;
err = security_file_receive(fp[i]);
if (err) if (err)
break; 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. */
__receive_sock(fp[i]);
fd_install(new_fd, get_file(fp[i]));
} }
if (i > 0) { if (i > 0) {
int cmlen = CMSG_COMPAT_LEN(i * sizeof(int)); int cmlen = CMSG_COMPAT_LEN(i * sizeof(int));
err = put_user(SOL_SOCKET, &cm->cmsg_level); err = put_user(SOL_SOCKET, &cm->cmsg_level);
if (!err) if (!err)
err = put_user(SCM_RIGHTS, &cm->cmsg_type); err = put_user(SCM_RIGHTS, &cm->cmsg_type);
@ -322,16 +313,19 @@ void scm_detach_fds_compat(struct msghdr *kmsg, struct scm_cookie *scm)
err = put_user(cmlen, &cm->cmsg_len); err = put_user(cmlen, &cm->cmsg_len);
if (!err) { if (!err) {
cmlen = CMSG_COMPAT_SPACE(i * sizeof(int)); cmlen = CMSG_COMPAT_SPACE(i * sizeof(int));
kmsg->msg_control += cmlen; if (msg->msg_controllen < cmlen)
kmsg->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 * All of the files that fit in the message have had their usage counts
* usage counts incremented, so we just free the list. * incremented, so we just free the list.
*/ */
__scm_destroy(scm); __scm_destroy(scm);
} }

27
net/core/scm.c
View file

@ -280,9 +280,8 @@ void put_cmsg_scm_timestamping(struct msghdr *msg, struct scm_timestamping_inter
} }
EXPORT_SYMBOL(put_cmsg_scm_timestamping); 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; int new_fd;
int error; int error;
@ -300,12 +299,8 @@ static int __scm_install_fd(struct file *file, int __user *ufd, int o_flags)
return error; return error;
} }
/* Bump the usage count and install the file. */ /* Bump the sock usage counts, if any. */
sock = sock_from_file(file, &error); __receive_sock(file);
if (sock) {
sock_update_netprioidx(&sock->sk->sk_cgrp_data);
sock_update_classid(&sock->sk->sk_cgrp_data);
}
fd_install(new_fd, get_file(file)); fd_install(new_fd, get_file(file));
return 0; return 0;
} }
@ -319,29 +314,29 @@ static int scm_max_fds(struct msghdr *msg)
void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm) void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
{ {
struct cmsghdr __user *cm struct cmsghdr __user *cm =
= (__force struct cmsghdr __user*)msg->msg_control; (__force struct cmsghdr __user *)msg->msg_control;
int o_flags = (msg->msg_flags & MSG_CMSG_CLOEXEC) ? O_CLOEXEC : 0; 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 fdmax = min_t(int, scm_max_fds(msg), scm->fp->count);
int __user *cmsg_data = CMSG_USER_DATA(cm); int __user *cmsg_data = CMSG_USER_DATA(cm);
int err = 0, i; 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) { if (msg->msg_flags & MSG_CMSG_COMPAT) {
scm_detach_fds_compat(msg, scm); scm_detach_fds_compat(msg, scm);
return; 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++) { for (i = 0; i < fdmax; i++) {
err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags); err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
if (err) if (err)
break; break;
} }
if (i > 0) { if (i > 0) {
int cmlen = CMSG_LEN(i * sizeof(int)); int cmlen = CMSG_LEN(i * sizeof(int));
err = put_user(SOL_SOCKET, &cm->cmsg_level); err = put_user(SOL_SOCKET, &cm->cmsg_level);