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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id s13sm784326pfc.136.2020.06.17.15.03.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Jun 2020 15:03:34 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , Sargun Dhillon , Christian Brauner , Tycho Andersen , David Laight , Christoph Hellwig , "David S. Miller" , Jakub Kicinski , Alexander Viro , Aleksa Sarai , Matt Denton , Jann Horn , Chris Palmer , Robert Sesek , Giuseppe Scrivano , Greg Kroah-Hartman , Andy Lutomirski , Will Drewry , Shuah Khan , netdev@vger.kernel.org, containers@lists.linux-foundation.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v5 5/7] fs: Expand __fd_install_received() to accept fd Date: Wed, 17 Jun 2020 15:03:25 -0700 Message-Id: <20200617220327.3731559-6-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200617220327.3731559-1-keescook@chromium.org> References: <20200617220327.3731559-1-keescook@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Expand __fd_install_received() with support for replace_fd() for the coming seccomp "addfd" ioctl(). Add new wrapper fd_replace_received() for the new mode and update existing wrappers to retain old mode. Signed-off-by: Kees Cook --- fs/file.c | 22 +++++++++++++++++----- include/linux/file.h | 10 +++++++--- 2 files changed, 24 insertions(+), 8 deletions(-) diff --git a/fs/file.c b/fs/file.c index de85a42defe2..9568bcfd1f44 100644 --- a/fs/file.c +++ b/fs/file.c @@ -937,6 +937,7 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags) /** * __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: __user pointer to write new fd number to * @o_flags: the O_* flags to apply to the new fd entry @@ -947,7 +948,8 @@ int replace_fd(unsigned fd, struct file *file, unsigned flags) * * Returns newly install fd or -ve on error. */ -int __fd_install_received(struct file *file, int __user *ufd, unsigned int o_flags) +int __fd_install_received(int fd, struct file *file, int __user *ufd, + unsigned int o_flags) { struct socket *sock; int new_fd; @@ -957,9 +959,11 @@ int __fd_install_received(struct file *file, int __user *ufd, unsigned int o_fla if (error) return error; - new_fd = get_unused_fd_flags(o_flags); - if (new_fd < 0) - return new_fd; + if (fd < 0) { + new_fd = get_unused_fd_flags(o_flags); + if (new_fd < 0) + return new_fd; + } if (ufd) { error = put_user(new_fd, ufd); @@ -969,6 +973,15 @@ int __fd_install_received(struct file *file, int __user *ufd, unsigned int o_fla } } + if (fd < 0) + fd_install(new_fd, get_file(file)); + else { + new_fd = fd; + error = replace_fd(new_fd, file, o_flags); + if (error) + return error; + } + /* 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. @@ -978,7 +991,6 @@ int __fd_install_received(struct file *file, int __user *ufd, unsigned int o_fla sock_update_netprioidx(&sock->sk->sk_cgrp_data); sock_update_classid(&sock->sk->sk_cgrp_data); } - fd_install(new_fd, get_file(file)); return new_fd; } diff --git a/include/linux/file.h b/include/linux/file.h index e19974ed9322..04389b0da11b 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -92,18 +92,22 @@ 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, +extern int __fd_install_received(int fd, 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) { if (ufd == NULL) return -EFAULT; - return __fd_install_received(file, ufd, o_flags); + return __fd_install_received(-1, file, ufd, o_flags); } static inline int fd_install_received(struct file *file, unsigned int o_flags) { - return __fd_install_received(file, NULL, o_flags); + return __fd_install_received(-1, file, NULL, o_flags); +} +static inline int fd_replace_received(int fd, struct file *file, unsigned int o_flags) +{ + return __fd_install_received(fd, file, NULL, o_flags); } extern void flush_delayed_fput(void); -- 2.25.1