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Message-ID: <b574b926-58f3-0f4c-0bbc-1ca978836917@broadcom.com>
Date: Fri, 17 Jul 2020 12:11:24 -0700
From: Scott Branden <scott.branden@...adcom.com>
To: Kees Cook <keescook@...omium.org>
Cc: Mimi Zohar <zohar@...ux.ibm.com>,
Matthew Wilcox <willy@...radead.org>,
James Morris <jmorris@...ei.org>,
Luis Chamberlain <mcgrof@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Alexander Viro <viro@...iv.linux.org.uk>,
Jessica Yu <jeyu@...nel.org>,
Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
"Serge E. Hallyn" <serge@...lyn.com>,
Casey Schaufler <casey@...aufler-ca.com>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Peter Zijlstra <peterz@...radead.org>,
Matthew Garrett <matthewgarrett@...gle.com>,
David Howells <dhowells@...hat.com>,
Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
Randy Dunlap <rdunlap@...radead.org>,
"Joel Fernandes (Google)" <joel@...lfernandes.org>,
KP Singh <kpsingh@...gle.com>, Dave Olsthoorn <dave@...aar.me>,
Hans de Goede <hdegoede@...hat.com>,
Peter Jones <pjones@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Stephen Boyd <stephen.boyd@...aro.org>,
Paul Moore <paul@...l-moore.com>,
Stephen Smalley <stephen.smalley.work@...il.com>,
linux-security-module@...r.kernel.org,
linux-integrity@...r.kernel.org, selinux@...r.kernel.org,
linux-fsdevel@...r.kernel.org, kexec@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/13] fs/kernel_read_file: Split into separate source
file
On 2020-07-17 10:43 a.m., Kees Cook wrote:
> These routines are used in places outside of exec(2), so in preparation
> for refactoring them, move them into a separate source file,
> fs/kernel_read_file.c.
>
> Signed-off-by: Kees Cook <keescook@...omium.org>
Acked-by: Scott Branden <scott.branden@...adcom.com>
> ---
> fs/Makefile | 3 +-
> fs/exec.c | 132 ----------------------------------------
> fs/kernel_read_file.c | 138 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 140 insertions(+), 133 deletions(-)
> create mode 100644 fs/kernel_read_file.c
>
> diff --git a/fs/Makefile b/fs/Makefile
> index 2ce5112b02c8..a05fc247b2a7 100644
> --- a/fs/Makefile
> +++ b/fs/Makefile
> @@ -13,7 +13,8 @@ obj-y := open.o read_write.o file_table.o super.o \
> seq_file.o xattr.o libfs.o fs-writeback.o \
> pnode.o splice.o sync.o utimes.o d_path.o \
> stack.o fs_struct.o statfs.o fs_pin.o nsfs.o \
> - fs_types.o fs_context.o fs_parser.o fsopen.o
> + fs_types.o fs_context.o fs_parser.o fsopen.o \
> + kernel_read_file.o
>
> ifeq ($(CONFIG_BLOCK),y)
> obj-y += buffer.o block_dev.o direct-io.o mpage.o
> diff --git a/fs/exec.c b/fs/exec.c
> index 07a7fe9ac5be..d619b79aab30 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -923,138 +923,6 @@ struct file *open_exec(const char *name)
> }
> EXPORT_SYMBOL(open_exec);
>
> -int kernel_read_file(struct file *file, void **buf, loff_t *size,
> - loff_t max_size, enum kernel_read_file_id id)
> -{
> - loff_t i_size, pos;
> - ssize_t bytes = 0;
> - void *allocated = NULL;
> - int ret;
> -
> - if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0)
> - return -EINVAL;
> -
> - ret = deny_write_access(file);
> - if (ret)
> - return ret;
> -
> - ret = security_kernel_read_file(file, id);
> - if (ret)
> - goto out;
> -
> - i_size = i_size_read(file_inode(file));
> - if (i_size <= 0) {
> - ret = -EINVAL;
> - goto out;
> - }
> - if (i_size > SIZE_MAX || (max_size > 0 && i_size > max_size)) {
> - ret = -EFBIG;
> - goto out;
> - }
> -
> - if (!*buf)
> - *buf = allocated = vmalloc(i_size);
> - if (!*buf) {
> - ret = -ENOMEM;
> - goto out;
> - }
> -
> - pos = 0;
> - while (pos < i_size) {
> - bytes = kernel_read(file, *buf + pos, i_size - pos, &pos);
> - if (bytes < 0) {
> - ret = bytes;
> - goto out_free;
> - }
> -
> - if (bytes == 0)
> - break;
> - }
> -
> - if (pos != i_size) {
> - ret = -EIO;
> - goto out_free;
> - }
> -
> - ret = security_kernel_post_read_file(file, *buf, i_size, id);
> - if (!ret)
> - *size = pos;
> -
> -out_free:
> - if (ret < 0) {
> - if (allocated) {
> - vfree(*buf);
> - *buf = NULL;
> - }
> - }
> -
> -out:
> - allow_write_access(file);
> - return ret;
> -}
> -EXPORT_SYMBOL_GPL(kernel_read_file);
> -
> -int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
> - loff_t max_size, enum kernel_read_file_id id)
> -{
> - struct file *file;
> - int ret;
> -
> - if (!path || !*path)
> - return -EINVAL;
> -
> - file = filp_open(path, O_RDONLY, 0);
> - if (IS_ERR(file))
> - return PTR_ERR(file);
> -
> - ret = kernel_read_file(file, buf, size, max_size, id);
> - fput(file);
> - return ret;
> -}
> -EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
> -
> -int kernel_read_file_from_path_initns(const char *path, void **buf,
> - loff_t *size, loff_t max_size,
> - enum kernel_read_file_id id)
> -{
> - struct file *file;
> - struct path root;
> - int ret;
> -
> - if (!path || !*path)
> - return -EINVAL;
> -
> - task_lock(&init_task);
> - get_fs_root(init_task.fs, &root);
> - task_unlock(&init_task);
> -
> - file = file_open_root(root.dentry, root.mnt, path, O_RDONLY, 0);
> - path_put(&root);
> - if (IS_ERR(file))
> - return PTR_ERR(file);
> -
> - ret = kernel_read_file(file, buf, size, max_size, id);
> - fput(file);
> - return ret;
> -}
> -EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns);
> -
> -int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
> - enum kernel_read_file_id id)
> -{
> - struct fd f = fdget(fd);
> - int ret = -EBADF;
> -
> - if (!f.file)
> - goto out;
> -
> - ret = kernel_read_file(f.file, buf, size, max_size, id);
> -out:
> - fdput(f);
> - return ret;
> -}
> -EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
> -
> #if defined(CONFIG_HAVE_AOUT) || defined(CONFIG_BINFMT_FLAT) || \
> defined(CONFIG_BINFMT_ELF_FDPIC)
> ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
> diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c
> new file mode 100644
> index 000000000000..54d972d4befc
> --- /dev/null
> +++ b/fs/kernel_read_file.c
> @@ -0,0 +1,138 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <linux/fs.h>
> +#include <linux/fs_struct.h>
> +#include <linux/kernel_read_file.h>
> +#include <linux/security.h>
> +#include <linux/vmalloc.h>
> +
> +int kernel_read_file(struct file *file, void **buf, loff_t *size,
> + loff_t max_size, enum kernel_read_file_id id)
> +{
> + loff_t i_size, pos;
> + ssize_t bytes = 0;
> + void *allocated = NULL;
> + int ret;
> +
> + if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0)
> + return -EINVAL;
> +
> + ret = deny_write_access(file);
> + if (ret)
> + return ret;
> +
> + ret = security_kernel_read_file(file, id);
> + if (ret)
> + goto out;
> +
> + i_size = i_size_read(file_inode(file));
> + if (i_size <= 0) {
> + ret = -EINVAL;
> + goto out;
> + }
> + if (i_size > SIZE_MAX || (max_size > 0 && i_size > max_size)) {
> + ret = -EFBIG;
> + goto out;
> + }
> +
> + if (!*buf)
> + *buf = allocated = vmalloc(i_size);
> + if (!*buf) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + pos = 0;
> + while (pos < i_size) {
> + bytes = kernel_read(file, *buf + pos, i_size - pos, &pos);
> + if (bytes < 0) {
> + ret = bytes;
> + goto out_free;
> + }
> +
> + if (bytes == 0)
> + break;
> + }
> +
> + if (pos != i_size) {
> + ret = -EIO;
> + goto out_free;
> + }
> +
> + ret = security_kernel_post_read_file(file, *buf, i_size, id);
> + if (!ret)
> + *size = pos;
> +
> +out_free:
> + if (ret < 0) {
> + if (allocated) {
> + vfree(*buf);
> + *buf = NULL;
> + }
> + }
> +
> +out:
> + allow_write_access(file);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(kernel_read_file);
> +
> +int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
> + loff_t max_size, enum kernel_read_file_id id)
> +{
> + struct file *file;
> + int ret;
> +
> + if (!path || !*path)
> + return -EINVAL;
> +
> + file = filp_open(path, O_RDONLY, 0);
> + if (IS_ERR(file))
> + return PTR_ERR(file);
> +
> + ret = kernel_read_file(file, buf, size, max_size, id);
> + fput(file);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
> +
> +int kernel_read_file_from_path_initns(const char *path, void **buf,
> + loff_t *size, loff_t max_size,
> + enum kernel_read_file_id id)
> +{
> + struct file *file;
> + struct path root;
> + int ret;
> +
> + if (!path || !*path)
> + return -EINVAL;
> +
> + task_lock(&init_task);
> + get_fs_root(init_task.fs, &root);
> + task_unlock(&init_task);
> +
> + file = file_open_root(root.dentry, root.mnt, path, O_RDONLY, 0);
> + path_put(&root);
> + if (IS_ERR(file))
> + return PTR_ERR(file);
> +
> + ret = kernel_read_file(file, buf, size, max_size, id);
> + fput(file);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns);
> +
> +int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
> + enum kernel_read_file_id id)
> +{
> + struct fd f = fdget(fd);
> + int ret = -EBADF;
> +
> + if (!f.file)
> + goto out;
> +
> + ret = kernel_read_file(f.file, buf, size, max_size, id);
> +out:
> + fdput(f);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
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