On Thu, Jun 18, 2020 at 10:56:14AM +0200, Christian Brauner wrote:
On Mon, Jun 15, 2020 at 08:25:15PM -0700, Kees Cook wrote:
In preparation for users of the "install a received file" logic outside of net/ (pidfd and seccomp), relocate and rename __scm_install_fd() from net/core/scm.c to __fd_install_received() in fs/file.c, and provide a wrapper named fd_install_received_user(), as future patches will change the interface to __fd_install_received().
Signed-off-by: Kees Cook keescook@chromium.org
fs/file.c | 47 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/file.h | 8 ++++++++ include/net/scm.h | 1 - net/compat.c | 2 +- net/core/scm.c | 32 +----------------------------- 5 files changed, 57 insertions(+), 33 deletions(-)
diff --git a/fs/file.c b/fs/file.c index abb8b7081d7a..fcfddae0d252 100644 --- a/fs/file.c +++ b/fs/file.c @@ -11,6 +11,7 @@ #include <linux/export.h> #include <linux/fs.h> #include <linux/mm.h> +#include <linux/net.h> #include <linux/sched/signal.h> #include <linux/slab.h> #include <linux/file.h> @@ -18,6 +19,8 @@ #include <linux/bitops.h> #include <linux/spinlock.h> #include <linux/rcupdate.h> +#include <net/cls_cgroup.h> +#include <net/netprio_cgroup.h> unsigned int sysctl_nr_open __read_mostly = 1024*1024; unsigned int sysctl_nr_open_min = BITS_PER_LONG; @@ -931,6 +934,50 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags) return err; } +/**
- __fd_install_received() - Install received file into file descriptor table
- @fd: fd to install into (if negative, a new fd will be allocated)
- @file: struct file that was received from another process
- @ufd_required: true to use @ufd for writing fd number to userspace
- @ufd: __user pointer to write new fd number to
- @o_flags: the O_* flags to apply to the new fd entry
- Installs a received file into the file descriptor table, with appropriate
- checks and count updates. Optionally writes the fd number to userspace.
- Returns -ve on error.
- */
+int __fd_install_received(struct file *file, int __user *ufd, unsigned int o_flags) +{
- struct socket *sock;
- int new_fd;
- int error;
- error = security_file_receive(file);
- if (error)
return error;- new_fd = get_unused_fd_flags(o_flags);
- if (new_fd < 0)
return new_fd;- error = put_user(new_fd, ufd);
- if (error) {
put_unused_fd(new_fd);return error;- }
- /* Bump the usage count and install the file. */
- 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;
+}
static int ksys_dup3(unsigned int oldfd, unsigned int newfd, int flags) { int err = -EBADF; diff --git a/include/linux/file.h b/include/linux/file.h index 122f80084a3e..fe18a1a0d555 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -91,6 +91,14 @@ extern void put_unused_fd(unsigned int fd); extern void fd_install(unsigned int fd, struct file *file); +extern int __fd_install_received(struct file *file, int __user *ufd,
unsigned int o_flags);+static inline int fd_install_received_user(struct file *file, int __user *ufd,
unsigned int o_flags)+{
- return __fd_install_received(file, ufd, o_flags);
+}
Shouldn't this be the other way around such that fd_install_received_user() is the workhorse that has a "ufd" argument and fd_install_received() is the static inline function that doesn't?
extern int fd_install_received_user(struct file *file, int __user *ufd, unsigned int o_flags) static inline int fd_install_received(struct file *file, unsigned int o_flags) { return fd_install_received_user(file, NULL, o_flags); }
So, I think it's all worked out in v5[1], so the helper argument handling is better for the ufd case, as David pointed out earlier. (As in, I think you're reacting to the same general problem here.)
(So I'm on vacation this week some my reviews are selective and spotty but I promise to be back next week. :))
No worries!
-Kees
[1] https://lore.kernel.org/lkml/20200617220327.3731559-1-keescook@chromium.org/