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[104.198.60.80]) by smtp.gmail.com with ESMTPSA id z16sm9204945ilz.64.2020.06.15.22.29.43 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Mon, 15 Jun 2020 22:29:43 -0700 (PDT) Date: Tue, 16 Jun 2020 05:29:41 +0000 From: Sargun Dhillon To: Kees Cook Cc: linux-kernel@vger.kernel.org, Christian Brauner , "David S. Miller" , Christoph Hellwig , Tycho Andersen , 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: Re: [PATCH v4 02/11] fs: Move __scm_install_fd() to __fd_install_received() Message-ID: <20200616052941.GB16032@ircssh-2.c.rugged-nimbus-611.internal> References: <20200616032524.460144-1-keescook@chromium.org> <20200616032524.460144-3-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200616032524.460144-3-keescook@chromium.org> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org 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 > --- > 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 > #include > #include > +#include > #include > #include > #include > @@ -18,6 +19,8 @@ > #include > #include > #include > +#include > +#include > > 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 Probably doesn't matter, but this function doesn't take the fd, or ufd_required argument in this patch. > + * > + * Installs a received file into the file descriptor table, with appropriate > + * checks and count updates. Optionally writes the fd number to userspace. ufd does not apppear options here. > + * > + * 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); > +} > + > extern void flush_delayed_fput(void); > extern void __fput_sync(struct file *); > > diff --git a/include/net/scm.h b/include/net/scm.h > index 581a94d6c613..1ce365f4c256 100644 > --- a/include/net/scm.h > +++ b/include/net/scm.h > @@ -37,7 +37,6 @@ struct scm_cookie { > #endif > }; > > -int __scm_install_fd(struct file *file, int __user *ufd, unsigned int o_flags); > void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm); > void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm); > int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm); > diff --git a/net/compat.c b/net/compat.c > index 27d477fdcaa0..94f288e8dac5 100644 > --- a/net/compat.c > +++ b/net/compat.c > @@ -298,7 +298,7 @@ void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm) > int err = 0, i; > > for (i = 0; i < fdmax; i++) { > - err = __scm_install_fd(scm->fp->fp[i], cmsg_data + i, o_flags); > + err = fd_install_received_user(scm->fp->fp[i], cmsg_data + i, o_flags); > if (err) > break; > } > diff --git a/net/core/scm.c b/net/core/scm.c > index 6151678c73ed..df190f1fdd28 100644 > --- a/net/core/scm.c > +++ b/net/core/scm.c > @@ -280,36 +280,6 @@ void put_cmsg_scm_timestamping(struct msghdr *msg, struct scm_timestamping_inter > } > EXPORT_SYMBOL(put_cmsg_scm_timestamping); > > -int __scm_install_fd(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 scm_max_fds(struct msghdr *msg) > { > if (msg->msg_controllen <= sizeof(struct cmsghdr)) > @@ -336,7 +306,7 @@ 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); > + err = fd_install_received_user(scm->fp->fp[i], cmsg_data + i, o_flags); > if (err) > break; > } > -- > 2.25.1 >