[PATCH v3 10/19] fs/kernel_read_file: Add file_size output argument

Kees Cook
2020-07-24T21:37:42Z

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.

Acked-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
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 f80c0d102be8..bd199404935f 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 eda19ca256a3..878ca684a3a1 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 692b83e82edf..5fc56ccb6678 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