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);