diff options
| author | Kees Cook <keescook@chromium.org> | 2020-06-10 20:47:45 -0700 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2020-07-13 11:03:44 -0700 |
| commit | deefa7f3505ae2fb6a7cb75f50134b65a1dd1494 (patch) | |
| tree | 4147bf6aa14904b8e7cf4e1aaf9f39ac6a82a149 /fs/file.c | |
| parent | 6659061045cc93f609e100b128f30581e5f012e9 (diff) | |
fs: Add receive_fd() wrapper for __receive_fd()
For both pidfd and seccomp, the __user pointer is not used. Update
__receive_fd() to make writing to ufd optional via a NULL check. However,
for the receive_fd_user() wrapper, ufd is NULL checked so an -EFAULT
can be returned to avoid changing the SCM_RIGHTS interface behavior. Add
new wrapper receive_fd() for pidfd and seccomp that does not use the ufd
argument. For the new helper, the allocated fd needs to be returned on
success. Update the existing callers to handle it.
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Sargun Dhillon <sargun@sargun.me>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'fs/file.c')
| -rw-r--r-- | fs/file.c | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/fs/file.c b/fs/file.c index 0cd598cab476..56d96d5c0c9f 100644 --- a/fs/file.c +++ b/fs/file.c @@ -944,12 +944,13 @@ out_unlock: * @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. Writes the fd number to userspace. + * checks and count updates. Optionally writes the fd number to userspace, if + * @ufd is non-NULL. * * This helper handles its own reference counting of the incoming * struct file. * - * Returns -ve on error. + * Returns newly install fd or -ve on error. */ int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags) { @@ -964,16 +965,18 @@ int __receive_fd(struct file *file, int __user *ufd, unsigned 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 sock usage counts, if any. */ __receive_sock(file); fd_install(new_fd, get_file(file)); - return 0; + return new_fd; } static int ksys_dup3(unsigned int oldfd, unsigned int newfd, int flags) |