The sock counting (sock_update_netprioidx() and sock_update_classid())
was missing from this implementation of fd installation, compared to
SCM_RIGHTS. Use the new scm helper to get the work done, after adjusting
it to return the installed fd and accept a NULL user pointer.
Fixes: 8649c322f75c ("pid: Implement pidfd_getfd syscall")
Signed-off-by: Kees Cook <keesc...@chromium.org>
---
AFAICT, the following patches are needed for back-porting this to stable:
0462b6bdb644 ("net: add a CMSG_USER_DATA macro")
2618d530dd8b ("net/scm: cleanup scm_detach_fds")
1f466e1f15cf ("net: cleanly handle kernel vs user buffers for ->msg_control")
6e8a4f9dda38 ("net: ignore sock_from_file errors in __scm_install_fd")
---
kernel/pid.c | 12 ++----------
net/compat.c | 2 +-
net/core/scm.c | 27 ++++++++++++++++++++-------
3 files changed, 23 insertions(+), 18 deletions(-)
diff --git a/kernel/pid.c b/kernel/pid.c
index f1496b757162..a7ce4ba898d3 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -42,6 +42,7 @@
#include <linux/sched/signal.h>
#include <linux/sched/task.h>
#include <linux/idr.h>
+#include <net/scm.h>
struct pid init_struct_pid = {
.count = REFCOUNT_INIT(1),
@@ -635,18 +636,9 @@ static int pidfd_getfd(struct pid *pid, int fd)
if (IS_ERR(file))
return PTR_ERR(file);
- ret = security_file_receive(file);
- if (ret) {
- fput(file);
- return ret;
- }
-
- ret = get_unused_fd_flags(O_CLOEXEC);
+ ret = __scm_install_fd(file, NULL, O_CLOEXEC);
if (ret < 0)
fput(file);
- else
- fd_install(ret, file);
-
return ret;
}
diff --git a/net/compat.c b/net/compat.c
index 117f1869bf3b..f8575555b6d7 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -299,7 +299,7 @@ void scm_detach_fds_compat(struct msghdr *msg, struct
scm_cookie *scm)
for (i = 0; i < fdmax; i++) {
err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
- if (err)
+ if (err < 0)
break;
}
diff --git a/net/core/scm.c b/net/core/scm.c
index 86d96152646f..e80648fb4da7 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -280,6 +280,14 @@ void put_cmsg_scm_timestamping(struct msghdr *msg, struct
scm_timestamping_inter
}
EXPORT_SYMBOL(put_cmsg_scm_timestamping);
+/**
+ * __scm_install_fd() - Install received file into file descriptor table
+ *
+ * Installs a received file into the file descriptor table, with appropriate
+ * checks and count updates.
+ *
+ * Returns fd installed or -ve on error.
+ */
int __scm_install_fd(struct file *file, int __user *ufd, int o_flags)
{
struct socket *sock;
@@ -294,20 +302,25 @@ int __scm_install_fd(struct file *file, int __user *ufd,
int o_flags)
if (new_fd < 0)
return new_fd;
- error = put_user(new_fd, ufd);
- if (error) {
- put_unused_fd(new_fd);
- return error;
+ if (ufd) {
+ error = put_user(new_fd, ufd);
+ if (error) {
+ put_unused_fd(new_fd);
+ return error;
+ }
}
- /* Bump the usage count and install the file. */
+ /* Bump the usage count and install the file. The resulting value of
+ * "error" is ignored here since we only need to take action when
+ * the file is a socket and testing "sock" for NULL is sufficient.
+ */
sock = sock_from_file(file, &error);
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));
- return 0;
+ return new_fd;
}
static int scm_max_fds(struct msghdr *msg)
@@ -337,7 +350,7 @@ void scm_detach_fds(struct msghdr *msg, struct scm_cookie
*scm)
for (i = 0; i < fdmax; i++) {
err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags);
- if (err)
+ if (err < 0)
break;
}
--
2.25.1
