From: Tycho Andersen <tycho@tycho.ws>
To: Kees Cook <keescook@chromium.org>
Cc: linux-kernel@vger.kernel.org,
containers@lists.linux-foundation.org, linux-api@vger.kernel.org,
Andy Lutomirski <luto@amacapital.net>,
Oleg Nesterov <oleg@redhat.com>,
"Eric W . Biederman" <ebiederm@xmission.com>,
"Serge E . Hallyn" <serge@hallyn.com>,
Christian Brauner <christian.brauner@ubuntu.com>,
Tyler Hicks <tyhicks@canonical.com>,
Akihiro Suda <suda.akihiro@lab.ntt.co.jp>,
Jann Horn <jannh@google.com>,
linux-fsdevel@vger.kernel.org, Tycho Andersen <tycho@tycho.ws>,
Alexander Viro <viro@zeniv.linux.org.uk>
Subject: [PATCH v7 4/6] files: add a replace_fd_files() function
Date: Thu, 27 Sep 2018 09:11:17 -0600 [thread overview]
Message-ID: <20180927151119.9989-5-tycho@tycho.ws> (raw)
In-Reply-To: <20180927151119.9989-1-tycho@tycho.ws>
Similar to fd_install/__fd_install, we want to be able to replace an fd of
an arbitrary struct files_struct, not just current's. We'll use this in the
next patch to implement the seccomp ioctl that allows inserting fds into a
stopped process' context.
v7: new in v7
Signed-off-by: Tycho Andersen <tycho@tycho.ws>
CC: Alexander Viro <viro@zeniv.linux.org.uk>
CC: Kees Cook <keescook@chromium.org>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Eric W. Biederman <ebiederm@xmission.com>
CC: "Serge E. Hallyn" <serge@hallyn.com>
CC: Christian Brauner <christian.brauner@ubuntu.com>
CC: Tyler Hicks <tyhicks@canonical.com>
CC: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
---
fs/file.c | 22 +++++++++++++++-------
include/linux/file.h | 8 ++++++++
2 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/fs/file.c b/fs/file.c
index 7ffd6e9d103d..3b3c5aadaadb 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -850,24 +850,32 @@ __releases(&files->file_lock)
}
int replace_fd(unsigned fd, struct file *file, unsigned flags)
+{
+ return replace_fd_task(current, fd, file, flags);
+}
+
+/*
+ * Same warning as __alloc_fd()/__fd_install() here.
+ */
+int replace_fd_task(struct task_struct *task, unsigned fd,
+ struct file *file, unsigned flags)
{
int err;
- struct files_struct *files = current->files;
if (!file)
- return __close_fd(files, fd);
+ return __close_fd(task->files, fd);
- if (fd >= rlimit(RLIMIT_NOFILE))
+ if (fd >= task_rlimit(task, RLIMIT_NOFILE))
return -EBADF;
- spin_lock(&files->file_lock);
- err = expand_files(files, fd);
+ spin_lock(&task->files->file_lock);
+ err = expand_files(task->files, fd);
if (unlikely(err < 0))
goto out_unlock;
- return do_dup2(files, file, fd, flags);
+ return do_dup2(task->files, file, fd, flags);
out_unlock:
- spin_unlock(&files->file_lock);
+ spin_unlock(&task->files->file_lock);
return err;
}
diff --git a/include/linux/file.h b/include/linux/file.h
index 6b2fb032416c..f94277fee038 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -11,6 +11,7 @@
#include <linux/posix_types.h>
struct file;
+struct task_struct;
extern void fput(struct file *);
@@ -79,6 +80,13 @@ static inline void fdput_pos(struct fd f)
extern int f_dupfd(unsigned int from, struct file *file, unsigned flags);
extern int replace_fd(unsigned fd, struct file *file, unsigned flags);
+/*
+ * Warning! This is only safe if you know the owner of the files_struct is
+ * stopped outside syscall context. It's a very bad idea to use this unless you
+ * have similar guarantees in your code.
+ */
+extern int replace_fd_task(struct task_struct *task, unsigned fd,
+ struct file *file, unsigned flags);
extern void set_close_on_exec(unsigned int fd, int flag);
extern bool get_close_on_exec(unsigned int fd);
extern int get_unused_fd_flags(unsigned flags);
--
2.17.1
next prev parent reply other threads:[~2018-09-27 21:30 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-27 15:11 [PATCH v7 0/6] seccomp trap to userspace Tycho Andersen
2018-09-27 15:11 ` [PATCH v7 1/6] seccomp: add a return code to " Tycho Andersen
2018-09-27 21:31 ` Kees Cook
2018-09-27 22:48 ` Tycho Andersen
2018-09-27 23:10 ` Kees Cook
2018-09-28 14:39 ` Tycho Andersen
2018-10-08 14:58 ` Christian Brauner
2018-10-09 14:28 ` Tycho Andersen
2018-10-09 16:24 ` Christian Brauner
2018-10-09 16:29 ` Tycho Andersen
2018-10-17 20:29 ` Tycho Andersen
2018-10-17 22:21 ` Kees Cook
2018-10-17 22:33 ` Tycho Andersen
2018-10-21 16:04 ` Tycho Andersen
2018-10-22 9:42 ` Christian Brauner
2018-09-27 21:51 ` Jann Horn
2018-09-27 22:45 ` Kees Cook
2018-09-27 23:08 ` Tycho Andersen
2018-09-27 23:04 ` Tycho Andersen
2018-09-27 23:37 ` Jann Horn
2018-09-29 0:28 ` Aleksa Sarai
2018-09-27 15:11 ` [PATCH v7 2/6] seccomp: make get_nth_filter available outside of CHECKPOINT_RESTORE Tycho Andersen
2018-09-27 16:51 ` Jann Horn
2018-09-27 21:42 ` Kees Cook
2018-10-08 13:55 ` Christian Brauner
2018-09-27 15:11 ` [PATCH v7 3/6] seccomp: add a way to get a listener fd from ptrace Tycho Andersen
2018-09-27 16:20 ` Jann Horn
2018-09-27 16:34 ` Tycho Andersen
2018-09-27 17:35 ` Jann Horn
2018-09-27 18:09 ` Tycho Andersen
2018-09-27 21:53 ` Kees Cook
2018-10-08 15:16 ` Christian Brauner
2018-10-08 15:33 ` Jann Horn
2018-10-08 16:21 ` Christian Brauner
2018-10-08 16:42 ` Jann Horn
2018-10-08 18:18 ` Christian Brauner
2018-10-09 12:39 ` Jann Horn
2018-10-09 13:28 ` Christian Brauner
2018-10-09 13:36 ` Jann Horn
2018-10-09 13:49 ` Christian Brauner
2018-10-09 13:50 ` Jann Horn
2018-10-09 14:09 ` Christian Brauner
2018-10-09 15:26 ` Jann Horn
2018-10-09 16:20 ` Christian Brauner
2018-10-09 16:26 ` Jann Horn
2018-10-10 12:54 ` Christian Brauner
2018-10-10 13:09 ` Christian Brauner
2018-10-10 13:10 ` Jann Horn
2018-10-10 13:18 ` Christian Brauner
2018-10-10 15:31 ` Paul Moore
2018-10-10 15:33 ` Jann Horn
2018-10-10 15:39 ` Christian Brauner
2018-10-10 16:54 ` Tycho Andersen
2018-10-10 17:15 ` Christian Brauner
2018-10-10 17:26 ` Tycho Andersen
2018-10-10 18:28 ` Christian Brauner
2018-10-11 7:24 ` Paul Moore
2018-10-11 13:39 ` Jann Horn
2018-10-11 23:10 ` Paul Moore
2018-10-12 1:02 ` Andy Lutomirski
2018-10-12 20:02 ` Tycho Andersen
2018-10-12 20:06 ` Jann Horn
2018-10-12 20:11 ` Christian Brauner
2018-10-08 18:00 ` Tycho Andersen
2018-10-08 18:41 ` Christian Brauner
2018-10-10 17:45 ` Andy Lutomirski
2018-10-10 18:26 ` Christian Brauner
2018-09-27 15:11 ` Tycho Andersen [this message]
2018-09-27 16:49 ` [PATCH v7 4/6] files: add a replace_fd_files() function Jann Horn
2018-09-27 18:04 ` Tycho Andersen
2018-09-27 21:59 ` Kees Cook
2018-09-28 2:20 ` Kees Cook
2018-09-28 2:46 ` Jann Horn
2018-09-28 5:23 ` Tycho Andersen
2018-09-27 15:11 ` [PATCH v7 5/6] seccomp: add a way to pass FDs via a notification fd Tycho Andersen
2018-09-27 16:39 ` Jann Horn
2018-09-27 22:13 ` Tycho Andersen
2018-09-27 19:28 ` Jann Horn
2018-09-27 22:14 ` Tycho Andersen
2018-09-27 22:17 ` Jann Horn
2018-09-27 22:49 ` Tycho Andersen
2018-09-27 22:09 ` Kees Cook
2018-09-27 22:15 ` Tycho Andersen
2018-09-27 15:11 ` [PATCH v7 6/6] samples: add an example of seccomp user trap Tycho Andersen
2018-09-27 22:11 ` Kees Cook
2018-09-28 21:57 ` [PATCH v7 0/6] seccomp trap to userspace Michael Kerrisk (man-opages)
2018-09-28 22:03 ` Tycho Andersen
2018-09-28 22:16 ` Michael Kerrisk (man-pages)
2018-09-28 22:34 ` Kees Cook
2018-09-28 22:46 ` Michael Kerrisk (man-pages)
2018-09-28 22:48 ` Jann Horn
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