[PATCH 08/13] fs/kernel_read_file: Add file_size output argument

From: Kees Cook <hidden>
Date: 2020-07-17 17:43:29
Also in: kexec, linux-fsdevel, linux-integrity, lkml, selinux
Subsystem: driver core, kobjects, debugfs and sysfs, extended verification module (evm), filesystems (vfs and infrastructure), firmware loader (request_firmware), integrity measurement architecture (ima), kexec, security subsystem, the rest · Maintainers: Greg Kroah-Hartman, "Rafael J. Wysocki", Danilo Krummrich, Mimi Zohar, Roberto Sassu, Alexander Viro, Christian Brauner, Luis Chamberlain, Russ Weight, Dmitry Kasatkin, Andrew Morton, Baoquan He, Mike Rapoport, Pasha Tatashin, Pratyush Yadav, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds

In preparation for adding partial read support, add an optional output
argument to kernel_read_file*() that reports the file size so callers
can reason more easily about their reading progress.

Signed-off-by: Kees Cook <redacted>
---
 drivers/base/firmware_loader/main.c |  1 +
 fs/kernel_read_file.c               | 19 +++++++++++++------
 include/linux/kernel_read_file.h    |  4 ++++
 kernel/kexec_file.c                 |  4 ++--
 kernel/module.c                     |  2 +-
 security/integrity/digsig.c         |  2 +-
 security/integrity/ima/ima_fs.c     |  2 +-
 7 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
index ea419c7d3d34..3439a533927c 100644
--- a/drivers/base/firmware_loader/main.c
+++ b/drivers/base/firmware_loader/main.c

@@ -495,6 +495,7 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
 
 		/* load firmware files from the mount namespace of init */
 		rc = kernel_read_file_from_path_initns(path, &buffer, msize,
+						       NULL,
 						       READING_FIRMWARE);
 		if (rc < 0) {
 			if (rc != -ENOENT)

diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c
index e21a76001fff..2e29c38eb4df 100644
--- a/fs/kernel_read_file.c
+++ b/fs/kernel_read_file.c

@@ -14,6 +14,8 @@
  *		@buf_size will be ignored)
  * @buf_size	size of buf, if already allocated. If @buf not
  *		allocated, this is the largest size to allocate.
+ * @file_size	if non-NULL, the full size of @file will be
+ *		written here.
  * @id		the kernel_read_file_id identifying the type of
  *		file contents being read (for LSMs to examine)
  *

@@ -22,7 +24,8 @@
  *
  */
 int kernel_read_file(struct file *file, void **buf,
-		     size_t buf_size, enum kernel_read_file_id id)
+		     size_t buf_size, size_t *file_size,
+		     enum kernel_read_file_id id)
 {
 	loff_t i_size, pos;
 	ssize_t bytes = 0;

@@ -49,6 +52,8 @@ int kernel_read_file(struct file *file, void **buf,
 		ret = -EFBIG;
 		goto out;
 	}
+	if (file_size)
+		*file_size = i_size;
 
 	if (!*buf)
 		*buf = allocated = vmalloc(i_size);

@@ -91,7 +96,8 @@ 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,
-			       size_t buf_size, enum kernel_read_file_id id)
+			       size_t buf_size, size_t *file_size,
+			       enum kernel_read_file_id id)
 {
 	struct file *file;
 	int ret;

@@ -103,14 +109,14 @@ 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, buf_size, id);
+	ret = kernel_read_file(file, buf, buf_size, file_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,
-				      size_t buf_size,
+				      size_t buf_size, size_t *file_size,
 				      enum kernel_read_file_id id)
 {
 	struct file *file;

@@ -129,13 +135,14 @@ 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, buf_size, id);
+	ret = kernel_read_file(file, buf, buf_size, file_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, size_t buf_size,
+			     size_t *file_size,
 			     enum kernel_read_file_id id)
 {
 	struct fd f = fdget(fd);

@@ -144,7 +151,7 @@ int kernel_read_file_from_fd(int fd, void **buf, size_t buf_size,
 	if (!f.file)
 		goto out;
 
-	ret = kernel_read_file(f.file, buf, buf_size, id);
+	ret = kernel_read_file(f.file, buf, buf_size, file_size, id);
 out:
 	fdput(f);
 	return ret;

diff --git a/include/linux/kernel_read_file.h b/include/linux/kernel_read_file.h
index 910039e7593e..023293eaf948 100644
--- a/include/linux/kernel_read_file.h
+++ b/include/linux/kernel_read_file.h

@@ -37,15 +37,19 @@ static inline const char *kernel_read_file_id_str(enum kernel_read_file_id id)
 
 int kernel_read_file(struct file *file,
 		     void **buf, size_t buf_size,
+		     size_t *file_size,
 		     enum kernel_read_file_id id);
 int kernel_read_file_from_path(const char *path,
 			       void **buf, size_t buf_size,
+			       size_t *file_size,
 			       enum kernel_read_file_id id);
 int kernel_read_file_from_path_initns(const char *path,
 				      void **buf, size_t buf_size,
+				      size_t *file_size,
 				      enum kernel_read_file_id id);
 int kernel_read_file_from_fd(int fd,
 			     void **buf, size_t buf_size,
+			     size_t *file_size,
 			     enum kernel_read_file_id id);
 
 #endif /* _LINUX_KERNEL_READ_FILE_H */

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index a201bbb19158..7b0ecdc621aa 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c

@@ -222,7 +222,7 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 	void *ldata;
 
 	ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf,
-				       INT_MAX, READING_KEXEC_IMAGE);
+				       INT_MAX, NULL, READING_KEXEC_IMAGE);
 	if (ret < 0)
 		return ret;
 	image->kernel_buf_len = ret;

@@ -242,7 +242,7 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 	/* It is possible that there no initramfs is being loaded */
 	if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
 		ret = kernel_read_file_from_fd(initrd_fd, &image->initrd_buf,
-					       INT_MAX,
+					       INT_MAX, NULL,
 					       READING_KEXEC_INITRAMFS);
 		if (ret < 0)
 			goto out;

diff --git a/kernel/module.c b/kernel/module.c
index b6fd4f51cc30..860d713dd910 100644
--- a/kernel/module.c
+++ b/kernel/module.c

@@ -4001,7 +4001,7 @@ SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
 		      |MODULE_INIT_IGNORE_VERMAGIC))
 		return -EINVAL;
 
-	err = kernel_read_file_from_fd(fd, &hdr, INT_MAX,
+	err = kernel_read_file_from_fd(fd, &hdr, INT_MAX, NULL,
 				       READING_MODULE);
 	if (err < 0)
 		return err;

diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index 04f779c4f5ed..8a523dfd7fd7 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, INT_MAX,
+	rc = kernel_read_file_from_path(path, &data, INT_MAX, NULL,
 					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 8695170d0e5c..cff04083e598 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, INT_MAX, READING_POLICY);
+	rc = kernel_read_file_from_path(path, &data, INT_MAX, NULL, READING_POLICY);
 	if (rc < 0) {
 		pr_err("Unable to open file: %s (%d)", path, rc);
 		return rc;

-- 
2.25.1

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