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From: Kees Cook <keescook@chromium.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Kees Cook <keescook@chromium.org>,
	Scott Branden <scott.branden@broadcom.com>,
	Mimi Zohar <zohar@linux.ibm.com>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Jessica Yu <jeyu@kernel.org>, SeongJae Park <sjpark@amazon.de>,
	KP Singh <kpsingh@chromium.org>,
	linux-efi@vger.kernel.org, linux-security-module@vger.kernel.org,
	linux-integrity@vger.kernel.org, selinux@vger.kernel.org,
	linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v3 09/19] fs/kernel_read_file: Switch buffer size arg to size_t
Date: Fri, 24 Jul 2020 14:36:30 -0700
Message-ID: <20200724213640.389191-10-keescook@chromium.org> (raw)
In-Reply-To: <20200724213640.389191-1-keescook@chromium.org>

In preparation for further refactoring of kernel_read_file*(), rename
the "max_size" argument to the more accurate "buf_size", and correct
its type to size_t. Add kerndoc to explain the specifics of how the
arguments will be used. Note that with buf_size now size_t, it can no
longer be negative (and was never called with a negative value). Adjust
callers to use it as a "maximum size" when *buf is NULL.

Acked-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 fs/kernel_read_file.c            | 34 +++++++++++++++++++++++---------
 include/linux/kernel_read_file.h |  8 ++++----
 security/integrity/digsig.c      |  2 +-
 security/integrity/ima/ima_fs.c  |  2 +-
 4 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c
index dc28a8def597..e21a76001fff 100644
--- a/fs/kernel_read_file.c
+++ b/fs/kernel_read_file.c
@@ -5,15 +5,31 @@
 #include <linux/security.h>
 #include <linux/vmalloc.h>
 
+/**
+ * kernel_read_file() - read file contents into a kernel buffer
+ *
+ * @file	file to read from
+ * @buf		pointer to a "void *" buffer for reading into (if
+ *		*@buf is NULL, a buffer will be allocated, and
+ *		@buf_size will be ignored)
+ * @buf_size	size of buf, if already allocated. If @buf not
+ *		allocated, this is the largest size to allocate.
+ * @id		the kernel_read_file_id identifying the type of
+ *		file contents being read (for LSMs to examine)
+ *
+ * Returns number of bytes read (no single read will be bigger
+ * than INT_MAX), or negative on error.
+ *
+ */
 int kernel_read_file(struct file *file, void **buf,
-		     loff_t max_size, enum kernel_read_file_id id)
+		     size_t buf_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)
+	if (!S_ISREG(file_inode(file)->i_mode))
 		return -EINVAL;
 
 	ret = deny_write_access(file);
@@ -29,7 +45,7 @@ int kernel_read_file(struct file *file, void **buf,
 		ret = -EINVAL;
 		goto out;
 	}
-	if (i_size > INT_MAX || (max_size > 0 && i_size > max_size)) {
+	if (i_size > INT_MAX || i_size > buf_size) {
 		ret = -EFBIG;
 		goto out;
 	}
@@ -75,7 +91,7 @@ int kernel_read_file(struct file *file, void **buf,
 EXPORT_SYMBOL_GPL(kernel_read_file);
 
 int kernel_read_file_from_path(const char *path, void **buf,
-			       loff_t max_size, enum kernel_read_file_id id)
+			       size_t buf_size, enum kernel_read_file_id id)
 {
 	struct file *file;
 	int ret;
@@ -87,14 +103,14 @@ int kernel_read_file_from_path(const char *path, void **buf,
 	if (IS_ERR(file))
 		return PTR_ERR(file);
 
-	ret = kernel_read_file(file, buf, max_size, id);
+	ret = kernel_read_file(file, buf, buf_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 max_size,
+				      size_t buf_size,
 				      enum kernel_read_file_id id)
 {
 	struct file *file;
@@ -113,13 +129,13 @@ int kernel_read_file_from_path_initns(const char *path, void **buf,
 	if (IS_ERR(file))
 		return PTR_ERR(file);
 
-	ret = kernel_read_file(file, buf, max_size, id);
+	ret = kernel_read_file(file, buf, buf_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 max_size,
+int kernel_read_file_from_fd(int fd, void **buf, size_t buf_size,
 			     enum kernel_read_file_id id)
 {
 	struct fd f = fdget(fd);
@@ -128,7 +144,7 @@ int kernel_read_file_from_fd(int fd, void **buf, loff_t max_size,
 	if (!f.file)
 		goto out;
 
-	ret = kernel_read_file(f.file, buf, max_size, id);
+	ret = kernel_read_file(f.file, buf, buf_size, id);
 out:
 	fdput(f);
 	return ret;
diff --git a/include/linux/kernel_read_file.h b/include/linux/kernel_read_file.h
index 0ca0bdbed1bd..910039e7593e 100644
--- a/include/linux/kernel_read_file.h
+++ b/include/linux/kernel_read_file.h
@@ -36,16 +36,16 @@ static inline const char *kernel_read_file_id_str(enum kernel_read_file_id id)
 }
 
 int kernel_read_file(struct file *file,
-		     void **buf, loff_t max_size,
+		     void **buf, size_t buf_size,
 		     enum kernel_read_file_id id);
 int kernel_read_file_from_path(const char *path,
-			       void **buf, loff_t max_size,
+			       void **buf, size_t buf_size,
 			       enum kernel_read_file_id id);
 int kernel_read_file_from_path_initns(const char *path,
-				      void **buf, loff_t max_size,
+				      void **buf, size_t buf_size,
 				      enum kernel_read_file_id id);
 int kernel_read_file_from_fd(int fd,
-			     void **buf, loff_t max_size,
+			     void **buf, size_t buf_size,
 			     enum kernel_read_file_id id);
 
 #endif /* _LINUX_KERNEL_READ_FILE_H */
diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index 97661ffabc4e..04f779c4f5ed 100644
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -175,7 +175,7 @@ int __init integrity_load_x509(const unsigned int id, const char *path)
 	int rc;
 	key_perm_t perm;
 
-	rc = kernel_read_file_from_path(path, &data, 0,
+	rc = kernel_read_file_from_path(path, &data, INT_MAX,
 					READING_X509_CERTIFICATE);
 	if (rc < 0) {
 		pr_err("Unable to open file: %s (%d)", path, rc);
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 602f52717757..692b83e82edf 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -284,7 +284,7 @@ static ssize_t ima_read_policy(char *path)
 	datap = path;
 	strsep(&datap, "\n");
 
-	rc = kernel_read_file_from_path(path, &data, 0, READING_POLICY);
+	rc = kernel_read_file_from_path(path, &data, INT_MAX, READING_POLICY);
 	if (rc < 0) {
 		pr_err("Unable to open file: %s (%d)", path, rc);
 		return rc;
-- 
2.25.1


  parent reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-24 21:36 [PATCH v3 00/19] Introduce partial kernel_read_file() support Kees Cook
2020-07-24 21:36 ` [PATCH v3 01/19] test_firmware: Test platform fw loading on non-EFI systems Kees Cook
2020-07-24 21:36 ` [PATCH v3 02/19] selftest/firmware: Add selftest timeout in settings Kees Cook
2020-07-24 21:36 ` [PATCH v3 03/19] firmware_loader: EFI firmware loader must handle pre-allocated buffer Kees Cook
2020-07-25 10:07   ` Greg Kroah-Hartman
2020-07-25 15:50     ` Kees Cook
2020-07-25 17:20       ` Greg Kroah-Hartman
2020-07-24 21:36 ` [PATCH v3 04/19] fs/kernel_read_file: Remove FIRMWARE_PREALLOC_BUFFER enum Kees Cook
2020-07-27 13:35   ` Mimi Zohar
2020-07-24 21:36 ` [PATCH v3 05/19] fs/kernel_read_file: Remove FIRMWARE_EFI_EMBEDDED enum Kees Cook
2020-07-24 21:36 ` [PATCH v3 06/19] fs/kernel_read_file: Split into separate include file Kees Cook
2020-07-27 14:41   ` Mimi Zohar
2020-07-24 21:36 ` [PATCH v3 07/19] fs/kernel_read_file: Split into separate source file Kees Cook
2020-07-27 14:53   ` Mimi Zohar
2020-07-24 21:36 ` [PATCH v3 08/19] fs/kernel_read_file: Remove redundant size argument Kees Cook
2020-07-27 16:29   ` Mimi Zohar
2020-07-24 21:36 ` Kees Cook [this message]
2020-07-27 16:29   ` [PATCH v3 09/19] fs/kernel_read_file: Switch buffer size arg to size_t Mimi Zohar
2020-07-24 21:36 ` [PATCH v3 10/19] fs/kernel_read_file: Add file_size output argument Kees Cook
2020-07-27 16:29   ` Mimi Zohar
2020-07-24 21:36 ` [PATCH v3 11/19] LSM: Introduce kernel_post_load_data() hook Kees Cook
2020-07-27 10:49   ` Mimi Zohar
2020-07-28 19:41     ` Kees Cook
2020-07-24 21:36 ` [PATCH v3 12/19] firmware_loader: Use security_post_load_data() Kees Cook
2020-07-27 10:57   ` Mimi Zohar
2020-07-28 19:43     ` Kees Cook
2020-07-29 16:29       ` Mimi Zohar
2020-07-29 18:10         ` Mimi Zohar
2020-07-29 19:13           ` Kees Cook
2020-07-24 21:36 ` [PATCH v3 13/19] module: Call security_kernel_post_load_data() Kees Cook
2020-07-24 21:36 ` [PATCH v3 14/19] LSM: Add "contents" flag to kernel_read_file hook Kees Cook
2020-07-24 21:36 ` [PATCH v3 15/19] IMA: Add support for file reads without contents Kees Cook
2020-07-27 13:23   ` Mimi Zohar
2020-07-28 19:44     ` Kees Cook
2020-07-28 19:56       ` Greg Kroah-Hartman
2020-07-28 20:12         ` Kees Cook
2020-07-24 21:36 ` [PATCH v3 16/19] fs/kernel_file_read: Add "offset" arg for partial reads Kees Cook
2020-07-24 21:36 ` [PATCH v3 17/19] firmware: Store opt_flags in fw_priv Kees Cook
2020-07-24 21:36 ` [PATCH v3 18/19] firmware: Add request_partial_firmware_into_buf() Kees Cook
2020-07-29  1:17   ` Luis Chamberlain
2020-07-29  6:22     ` Takashi Iwai
2020-07-29 17:43       ` Kees Cook
2020-07-24 21:36 ` [PATCH v3 19/19] test_firmware: Test partial read support Kees Cook
2020-07-25  5:14 ` [PATCH v3 00/19] Introduce partial kernel_read_file() support Scott Branden
2020-07-25 10:05 ` Greg Kroah-Hartman
2020-07-25 15:48   ` Kees Cook
2020-07-27 11:16 ` Mimi Zohar
2020-07-27 19:18   ` Scott Branden
2020-07-28 18:48     ` Mimi Zohar
2020-07-28 19:56       ` Scott Branden
2020-07-29  1:19 ` Luis Chamberlain

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