In preparation for refactoring kernel_read_file*(), remove the redundant
"size" argument which is not needed: it can be included in the return
code, with callers adjusted. (VFS reads already cannot be larger than
INT_MAX.)
Signed-off-by: Kees Cook <[email protected]>
---
drivers/base/firmware_loader/main.c | 8 ++++----
fs/kernel_read_file.c | 20 +++++++++-----------
include/linux/kernel_read_file.h | 8 ++++----
kernel/kexec_file.c | 13 ++++++-------
kernel/module.c | 7 +++----
security/integrity/digsig.c | 5 +++--
security/integrity/ima/ima_fs.c | 5 +++--
7 files changed, 32 insertions(+), 34 deletions(-)
diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
index d4a413ea48ce..ea419c7d3d34 100644
--- a/drivers/base/firmware_loader/main.c
+++ b/drivers/base/firmware_loader/main.c
@@ -462,7 +462,7 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
size_t in_size,
const void *in_buffer))
{
- loff_t size;
+ size_t size;
int i, len;
int rc = -ENOENT;
char *path;
@@ -494,10 +494,9 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
fw_priv->size = 0;
/* load firmware files from the mount namespace of init */
- rc = kernel_read_file_from_path_initns(path, &buffer,
- &size, msize,
+ rc = kernel_read_file_from_path_initns(path, &buffer, msize,
READING_FIRMWARE);
- if (rc) {
+ if (rc < 0) {
if (rc != -ENOENT)
dev_warn(device, "loading %s failed with error %d\n",
path, rc);
@@ -506,6 +505,7 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
path);
continue;
}
+ size = rc;
dev_dbg(device, "Loading firmware from %s\n", path);
if (decompress) {
dev_dbg(device, "f/w decompressing %s\n",
diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c
index 54d972d4befc..dc28a8def597 100644
--- a/fs/kernel_read_file.c
+++ b/fs/kernel_read_file.c
@@ -5,7 +5,7 @@
#include <linux/security.h>
#include <linux/vmalloc.h>
-int kernel_read_file(struct file *file, void **buf, loff_t *size,
+int kernel_read_file(struct file *file, void **buf,
loff_t max_size, enum kernel_read_file_id id)
{
loff_t i_size, pos;
@@ -29,7 +29,7 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
ret = -EINVAL;
goto out;
}
- if (i_size > SIZE_MAX || (max_size > 0 && i_size > max_size)) {
+ if (i_size > INT_MAX || (max_size > 0 && i_size > max_size)) {
ret = -EFBIG;
goto out;
}
@@ -59,8 +59,6 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
}
ret = security_kernel_post_read_file(file, *buf, i_size, id);
- if (!ret)
- *size = pos;
out_free:
if (ret < 0) {
@@ -72,11 +70,11 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
out:
allow_write_access(file);
- return ret;
+ return ret == 0 ? pos : ret;
}
EXPORT_SYMBOL_GPL(kernel_read_file);
-int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
+int kernel_read_file_from_path(const char *path, void **buf,
loff_t max_size, enum kernel_read_file_id id)
{
struct file *file;
@@ -89,14 +87,14 @@ int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
if (IS_ERR(file))
return PTR_ERR(file);
- ret = kernel_read_file(file, buf, size, max_size, id);
+ ret = kernel_read_file(file, buf, 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,
+ loff_t max_size,
enum kernel_read_file_id id)
{
struct file *file;
@@ -115,13 +113,13 @@ 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, size, max_size, id);
+ ret = kernel_read_file(file, buf, 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,
+int kernel_read_file_from_fd(int fd, void **buf, loff_t max_size,
enum kernel_read_file_id id)
{
struct fd f = fdget(fd);
@@ -130,7 +128,7 @@ int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
if (!f.file)
goto out;
- ret = kernel_read_file(f.file, buf, size, max_size, id);
+ ret = kernel_read_file(f.file, buf, max_size, id);
out:
fdput(f);
return ret;
diff --git a/include/linux/kernel_read_file.h b/include/linux/kernel_read_file.h
index 78cf3d7dc835..0ca0bdbed1bd 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 *size, loff_t max_size,
+ void **buf, loff_t max_size,
enum kernel_read_file_id id);
int kernel_read_file_from_path(const char *path,
- void **buf, loff_t *size, loff_t max_size,
+ void **buf, loff_t max_size,
enum kernel_read_file_id id);
int kernel_read_file_from_path_initns(const char *path,
- void **buf, loff_t *size, loff_t max_size,
+ void **buf, loff_t max_size,
enum kernel_read_file_id id);
int kernel_read_file_from_fd(int fd,
- void **buf, loff_t *size, loff_t max_size,
+ void **buf, loff_t max_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 1358069ce9e9..a201bbb19158 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -220,13 +220,12 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
{
int ret;
void *ldata;
- loff_t size;
ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf,
- &size, INT_MAX, READING_KEXEC_IMAGE);
- if (ret)
+ INT_MAX, READING_KEXEC_IMAGE);
+ if (ret < 0)
return ret;
- image->kernel_buf_len = size;
+ image->kernel_buf_len = ret;
/* Call arch image probe handlers */
ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
@@ -243,11 +242,11 @@ 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,
- &size, INT_MAX,
+ INT_MAX,
READING_KEXEC_INITRAMFS);
- if (ret)
+ if (ret < 0)
goto out;
- image->initrd_buf_len = size;
+ image->initrd_buf_len = ret;
}
if (cmdline_len) {
diff --git a/kernel/module.c b/kernel/module.c
index e9765803601b..b6fd4f51cc30 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3988,7 +3988,6 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
{
struct load_info info = { };
- loff_t size;
void *hdr = NULL;
int err;
@@ -4002,12 +4001,12 @@ 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, &size, INT_MAX,
+ err = kernel_read_file_from_fd(fd, &hdr, INT_MAX,
READING_MODULE);
- if (err)
+ if (err < 0)
return err;
info.hdr = hdr;
- info.len = size;
+ info.len = err;
return load_module(&info, uargs, flags);
}
diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index f8869be45d8f..97661ffabc4e 100644
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -171,16 +171,17 @@ int __init integrity_add_key(const unsigned int id, const void *data,
int __init integrity_load_x509(const unsigned int id, const char *path)
{
void *data = NULL;
- loff_t size;
+ size_t size;
int rc;
key_perm_t perm;
- rc = kernel_read_file_from_path(path, &data, &size, 0,
+ rc = kernel_read_file_from_path(path, &data, 0,
READING_X509_CERTIFICATE);
if (rc < 0) {
pr_err("Unable to open file: %s (%d)", path, rc);
return rc;
}
+ size = rc;
perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | KEY_USR_READ;
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index e13ffece3726..9ba145d3d6d9 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -275,7 +275,7 @@ static ssize_t ima_read_policy(char *path)
{
void *data = NULL;
char *datap;
- loff_t size;
+ size_t size;
int rc, pathlen = strlen(path);
char *p;
@@ -284,11 +284,12 @@ static ssize_t ima_read_policy(char *path)
datap = path;
strsep(&datap, "\n");
- rc = kernel_read_file_from_path(path, &data, &size, 0, READING_POLICY);
+ rc = kernel_read_file_from_path(path, &data, 0, READING_POLICY);
if (rc < 0) {
pr_err("Unable to open file: %s (%d)", path, rc);
return rc;
}
+ size = rc;
datap = data;
while (size > 0 && (p = strsep(&datap, "\n"))) {
--
2.25.1
Hi Kees,
On 2020-07-17 10:43 a.m., Kees Cook wrote:
> In preparation for refactoring kernel_read_file*(), remove the redundant
> "size" argument which is not needed: it can be included in the return
I don't think the size argument is redundant though.
The existing kernel_read_file functions always read the whole file.
Now, what happens if the file is bigger than the buffer.
How does kernel_read_file know it read the whole file by looking at the
return value?
> code, with callers adjusted. (VFS reads already cannot be larger than
> INT_MAX.)
>
> Signed-off-by: Kees Cook <[email protected]>
> ---
> drivers/base/firmware_loader/main.c | 8 ++++----
> fs/kernel_read_file.c | 20 +++++++++-----------
> include/linux/kernel_read_file.h | 8 ++++----
> kernel/kexec_file.c | 13 ++++++-------
> kernel/module.c | 7 +++----
> security/integrity/digsig.c | 5 +++--
> security/integrity/ima/ima_fs.c | 5 +++--
> 7 files changed, 32 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
> index d4a413ea48ce..ea419c7d3d34 100644
> --- a/drivers/base/firmware_loader/main.c
> +++ b/drivers/base/firmware_loader/main.c
> @@ -462,7 +462,7 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
> size_t in_size,
> const void *in_buffer))
> {
> - loff_t size;
> + size_t size;
> int i, len;
> int rc = -ENOENT;
> char *path;
> @@ -494,10 +494,9 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
> fw_priv->size = 0;
>
> /* load firmware files from the mount namespace of init */
> - rc = kernel_read_file_from_path_initns(path, &buffer,
> - &size, msize,
> + rc = kernel_read_file_from_path_initns(path, &buffer, msize,
> READING_FIRMWARE);
> - if (rc) {
> + if (rc < 0) {
> if (rc != -ENOENT)
> dev_warn(device, "loading %s failed with error %d\n",
> path, rc);
> @@ -506,6 +505,7 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
> path);
> continue;
> }
> + size = rc;
> dev_dbg(device, "Loading firmware from %s\n", path);
> if (decompress) {
> dev_dbg(device, "f/w decompressing %s\n",
> diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c
> index 54d972d4befc..dc28a8def597 100644
> --- a/fs/kernel_read_file.c
> +++ b/fs/kernel_read_file.c
> @@ -5,7 +5,7 @@
> #include <linux/security.h>
> #include <linux/vmalloc.h>
>
> -int kernel_read_file(struct file *file, void **buf, loff_t *size,
> +int kernel_read_file(struct file *file, void **buf,
> loff_t max_size, enum kernel_read_file_id id)
> {
> loff_t i_size, pos;
> @@ -29,7 +29,7 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
> ret = -EINVAL;
> goto out;
> }
> - if (i_size > SIZE_MAX || (max_size > 0 && i_size > max_size)) {
> + if (i_size > INT_MAX || (max_size > 0 && i_size > max_size)) {
Should this be SSIZE_MAX?
> ret = -EFBIG;
> goto out;
> }
> @@ -59,8 +59,6 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
> }
>
> ret = security_kernel_post_read_file(file, *buf, i_size, id);
> - if (!ret)
> - *size = pos;
>
> out_free:
> if (ret < 0) {
> @@ -72,11 +70,11 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
>
> out:
> allow_write_access(file);
> - return ret;
> + return ret == 0 ? pos : ret;
> }
> EXPORT_SYMBOL_GPL(kernel_read_file);
>
> -int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
> +int kernel_read_file_from_path(const char *path, void **buf,
> loff_t max_size, enum kernel_read_file_id id)
> {
> struct file *file;
> @@ -89,14 +87,14 @@ int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
> if (IS_ERR(file))
> return PTR_ERR(file);
>
> - ret = kernel_read_file(file, buf, size, max_size, id);
> + ret = kernel_read_file(file, buf, 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,
> + loff_t max_size,
> enum kernel_read_file_id id)
> {
> struct file *file;
> @@ -115,13 +113,13 @@ 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, size, max_size, id);
> + ret = kernel_read_file(file, buf, 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,
> +int kernel_read_file_from_fd(int fd, void **buf, loff_t max_size,
> enum kernel_read_file_id id)
> {
> struct fd f = fdget(fd);
> @@ -130,7 +128,7 @@ int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
> if (!f.file)
> goto out;
>
> - ret = kernel_read_file(f.file, buf, size, max_size, id);
> + ret = kernel_read_file(f.file, buf, max_size, id);
> out:
> fdput(f);
> return ret;
> diff --git a/include/linux/kernel_read_file.h b/include/linux/kernel_read_file.h
> index 78cf3d7dc835..0ca0bdbed1bd 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 *size, loff_t max_size,
> + void **buf, loff_t max_size,
> enum kernel_read_file_id id);
> int kernel_read_file_from_path(const char *path,
> - void **buf, loff_t *size, loff_t max_size,
> + void **buf, loff_t max_size,
> enum kernel_read_file_id id);
> int kernel_read_file_from_path_initns(const char *path,
> - void **buf, loff_t *size, loff_t max_size,
> + void **buf, loff_t max_size,
> enum kernel_read_file_id id);
> int kernel_read_file_from_fd(int fd,
> - void **buf, loff_t *size, loff_t max_size,
> + void **buf, loff_t max_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 1358069ce9e9..a201bbb19158 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -220,13 +220,12 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
> {
> int ret;
> void *ldata;
> - loff_t size;
>
> ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf,
> - &size, INT_MAX, READING_KEXEC_IMAGE);
> - if (ret)
> + INT_MAX, READING_KEXEC_IMAGE);
> + if (ret < 0)
> return ret;
> - image->kernel_buf_len = size;
> + image->kernel_buf_len = ret;
>
> /* Call arch image probe handlers */
> ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
> @@ -243,11 +242,11 @@ 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,
> - &size, INT_MAX,
> + INT_MAX,
> READING_KEXEC_INITRAMFS);
> - if (ret)
> + if (ret < 0)
> goto out;
> - image->initrd_buf_len = size;
> + image->initrd_buf_len = ret;
> }
>
> if (cmdline_len) {
> diff --git a/kernel/module.c b/kernel/module.c
> index e9765803601b..b6fd4f51cc30 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -3988,7 +3988,6 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
> SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
> {
> struct load_info info = { };
> - loff_t size;
> void *hdr = NULL;
> int err;
>
> @@ -4002,12 +4001,12 @@ 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, &size, INT_MAX,
> + err = kernel_read_file_from_fd(fd, &hdr, INT_MAX,
> READING_MODULE);
> - if (err)
> + if (err < 0)
> return err;
> info.hdr = hdr;
> - info.len = size;
> + info.len = err;
>
> return load_module(&info, uargs, flags);
> }
> diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
> index f8869be45d8f..97661ffabc4e 100644
> --- a/security/integrity/digsig.c
> +++ b/security/integrity/digsig.c
> @@ -171,16 +171,17 @@ int __init integrity_add_key(const unsigned int id, const void *data,
> int __init integrity_load_x509(const unsigned int id, const char *path)
> {
> void *data = NULL;
> - loff_t size;
> + size_t size;
> int rc;
> key_perm_t perm;
>
> - rc = kernel_read_file_from_path(path, &data, &size, 0,
> + rc = kernel_read_file_from_path(path, &data, 0,
> READING_X509_CERTIFICATE);
> if (rc < 0) {
> pr_err("Unable to open file: %s (%d)", path, rc);
> return rc;
> }
> + size = rc;
>
> perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | KEY_USR_READ;
>
> diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
> index e13ffece3726..9ba145d3d6d9 100644
> --- a/security/integrity/ima/ima_fs.c
> +++ b/security/integrity/ima/ima_fs.c
> @@ -275,7 +275,7 @@ static ssize_t ima_read_policy(char *path)
> {
> void *data = NULL;
> char *datap;
> - loff_t size;
> + size_t size;
> int rc, pathlen = strlen(path);
>
> char *p;
> @@ -284,11 +284,12 @@ static ssize_t ima_read_policy(char *path)
> datap = path;
> strsep(&datap, "\n");
>
> - rc = kernel_read_file_from_path(path, &data, &size, 0, READING_POLICY);
> + rc = kernel_read_file_from_path(path, &data, 0, READING_POLICY);
> if (rc < 0) {
> pr_err("Unable to open file: %s (%d)", path, rc);
> return rc;
> }
> + size = rc;
>
> datap = data;
> while (size > 0 && (p = strsep(&datap, "\n"))) {
On 2020-07-17 12:04 p.m., Scott Branden wrote:
> Hi Kees,
>
> On 2020-07-17 10:43 a.m., Kees Cook wrote:
>> In preparation for refactoring kernel_read_file*(), remove the redundant
>> "size" argument which is not needed: it can be included in the return
> I don't think the size argument is redundant though.
> The existing kernel_read_file functions always read the whole file.
> Now, what happens if the file is bigger than the buffer.
> How does kernel_read_file know it read the whole file by looking at
> the return value?
Actually, this change looks ok dealing with the size. I'll look at the
rest.
>
>> code, with callers adjusted. (VFS reads already cannot be larger than
>> INT_MAX.)
>>
>> Signed-off-by: Kees Cook <[email protected]>
>> ---
>> drivers/base/firmware_loader/main.c | 8 ++++----
>> fs/kernel_read_file.c | 20 +++++++++-----------
>> include/linux/kernel_read_file.h | 8 ++++----
>> kernel/kexec_file.c | 13 ++++++-------
>> kernel/module.c | 7 +++----
>> security/integrity/digsig.c | 5 +++--
>> security/integrity/ima/ima_fs.c | 5 +++--
>> 7 files changed, 32 insertions(+), 34 deletions(-)
>>
>> diff --git a/drivers/base/firmware_loader/main.c
>> b/drivers/base/firmware_loader/main.c
>> index d4a413ea48ce..ea419c7d3d34 100644
>> --- a/drivers/base/firmware_loader/main.c
>> +++ b/drivers/base/firmware_loader/main.c
>> @@ -462,7 +462,7 @@ fw_get_filesystem_firmware(struct device *device,
>> struct fw_priv *fw_priv,
>> size_t in_size,
>> const void *in_buffer))
>> {
>> - loff_t size;
>> + size_t size;
>> int i, len;
>> int rc = -ENOENT;
>> char *path;
>> @@ -494,10 +494,9 @@ fw_get_filesystem_firmware(struct device
>> *device, struct fw_priv *fw_priv,
>> fw_priv->size = 0;
>> /* load firmware files from the mount namespace of init */
>> - rc = kernel_read_file_from_path_initns(path, &buffer,
>> - &size, msize,
>> + rc = kernel_read_file_from_path_initns(path, &buffer, msize,
>> READING_FIRMWARE);
>> - if (rc) {
>> + if (rc < 0) {
>> if (rc != -ENOENT)
>> dev_warn(device, "loading %s failed with error %d\n",
>> path, rc);
>> @@ -506,6 +505,7 @@ fw_get_filesystem_firmware(struct device *device,
>> struct fw_priv *fw_priv,
>> path);
>> continue;
>> }
>> + size = rc;
>> dev_dbg(device, "Loading firmware from %s\n", path);
>> if (decompress) {
>> dev_dbg(device, "f/w decompressing %s\n",
>> diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c
>> index 54d972d4befc..dc28a8def597 100644
>> --- a/fs/kernel_read_file.c
>> +++ b/fs/kernel_read_file.c
>> @@ -5,7 +5,7 @@
>> #include <linux/security.h>
>> #include <linux/vmalloc.h>
>> -int kernel_read_file(struct file *file, void **buf, loff_t *size,
>> +int kernel_read_file(struct file *file, void **buf,
>> loff_t max_size, enum kernel_read_file_id id)
>> {
>> loff_t i_size, pos;
>> @@ -29,7 +29,7 @@ int kernel_read_file(struct file *file, void **buf,
>> loff_t *size,
>> ret = -EINVAL;
>> goto out;
>> }
>> - if (i_size > SIZE_MAX || (max_size > 0 && i_size > max_size)) {
>> + if (i_size > INT_MAX || (max_size > 0 && i_size > max_size)) {
> Should this be SSIZE_MAX?
>> ret = -EFBIG;
>> goto out;
>> }
>> @@ -59,8 +59,6 @@ int kernel_read_file(struct file *file, void **buf,
>> loff_t *size,
>> }
>> ret = security_kernel_post_read_file(file, *buf, i_size, id);
>> - if (!ret)
>> - *size = pos;
>> out_free:
>> if (ret < 0) {
>> @@ -72,11 +70,11 @@ int kernel_read_file(struct file *file, void
>> **buf, loff_t *size,
>> out:
>> allow_write_access(file);
>> - return ret;
>> + return ret == 0 ? pos : ret;
>> }
>> EXPORT_SYMBOL_GPL(kernel_read_file);
>> -int kernel_read_file_from_path(const char *path, void **buf,
>> loff_t *size,
>> +int kernel_read_file_from_path(const char *path, void **buf,
>> loff_t max_size, enum kernel_read_file_id id)
>> {
>> struct file *file;
>> @@ -89,14 +87,14 @@ int kernel_read_file_from_path(const char *path,
>> void **buf, loff_t *size,
>> if (IS_ERR(file))
>> return PTR_ERR(file);
>> - ret = kernel_read_file(file, buf, size, max_size, id);
>> + ret = kernel_read_file(file, buf, 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,
>> + loff_t max_size,
>> enum kernel_read_file_id id)
>> {
>> struct file *file;
>> @@ -115,13 +113,13 @@ 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, size, max_size, id);
>> + ret = kernel_read_file(file, buf, 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,
>> +int kernel_read_file_from_fd(int fd, void **buf, loff_t max_size,
>> enum kernel_read_file_id id)
>> {
>> struct fd f = fdget(fd);
>> @@ -130,7 +128,7 @@ int kernel_read_file_from_fd(int fd, void **buf,
>> loff_t *size, loff_t max_size,
>> if (!f.file)
>> goto out;
>> - ret = kernel_read_file(f.file, buf, size, max_size, id);
>> + ret = kernel_read_file(f.file, buf, max_size, id);
>> out:
>> fdput(f);
>> return ret;
>> diff --git a/include/linux/kernel_read_file.h
>> b/include/linux/kernel_read_file.h
>> index 78cf3d7dc835..0ca0bdbed1bd 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 *size, loff_t max_size,
>> + void **buf, loff_t max_size,
>> enum kernel_read_file_id id);
>> int kernel_read_file_from_path(const char *path,
>> - void **buf, loff_t *size, loff_t max_size,
>> + void **buf, loff_t max_size,
>> enum kernel_read_file_id id);
>> int kernel_read_file_from_path_initns(const char *path,
>> - void **buf, loff_t *size, loff_t max_size,
>> + void **buf, loff_t max_size,
>> enum kernel_read_file_id id);
>> int kernel_read_file_from_fd(int fd,
>> - void **buf, loff_t *size, loff_t max_size,
>> + void **buf, loff_t max_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 1358069ce9e9..a201bbb19158 100644
>> --- a/kernel/kexec_file.c
>> +++ b/kernel/kexec_file.c
>> @@ -220,13 +220,12 @@ kimage_file_prepare_segments(struct kimage
>> *image, int kernel_fd, int initrd_fd,
>> {
>> int ret;
>> void *ldata;
>> - loff_t size;
>> ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf,
>> - &size, INT_MAX, READING_KEXEC_IMAGE);
>> - if (ret)
>> + INT_MAX, READING_KEXEC_IMAGE);
>> + if (ret < 0)
>> return ret;
>> - image->kernel_buf_len = size;
>> + image->kernel_buf_len = ret;
>> /* Call arch image probe handlers */
>> ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
>> @@ -243,11 +242,11 @@ 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,
>> - &size, INT_MAX,
>> + INT_MAX,
>> READING_KEXEC_INITRAMFS);
>> - if (ret)
>> + if (ret < 0)
>> goto out;
>> - image->initrd_buf_len = size;
>> + image->initrd_buf_len = ret;
>> }
>> if (cmdline_len) {
>> diff --git a/kernel/module.c b/kernel/module.c
>> index e9765803601b..b6fd4f51cc30 100644
>> --- a/kernel/module.c
>> +++ b/kernel/module.c
>> @@ -3988,7 +3988,6 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
>> SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs,
>> int, flags)
>> {
>> struct load_info info = { };
>> - loff_t size;
>> void *hdr = NULL;
>> int err;
>> @@ -4002,12 +4001,12 @@ 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, &size, INT_MAX,
>> + err = kernel_read_file_from_fd(fd, &hdr, INT_MAX,
>> READING_MODULE);
>> - if (err)
>> + if (err < 0)
>> return err;
>> info.hdr = hdr;
>> - info.len = size;
>> + info.len = err;
>> return load_module(&info, uargs, flags);
>> }
>> diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
>> index f8869be45d8f..97661ffabc4e 100644
>> --- a/security/integrity/digsig.c
>> +++ b/security/integrity/digsig.c
>> @@ -171,16 +171,17 @@ int __init integrity_add_key(const unsigned int
>> id, const void *data,
>> int __init integrity_load_x509(const unsigned int id, const char
>> *path)
>> {
>> void *data = NULL;
>> - loff_t size;
>> + size_t size;
>> int rc;
>> key_perm_t perm;
>> - rc = kernel_read_file_from_path(path, &data, &size, 0,
>> + rc = kernel_read_file_from_path(path, &data, 0,
>> READING_X509_CERTIFICATE);
>> if (rc < 0) {
>> pr_err("Unable to open file: %s (%d)", path, rc);
>> return rc;
>> }
>> + size = rc;
>> perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW |
>> KEY_USR_READ;
>> diff --git a/security/integrity/ima/ima_fs.c
>> b/security/integrity/ima/ima_fs.c
>> index e13ffece3726..9ba145d3d6d9 100644
>> --- a/security/integrity/ima/ima_fs.c
>> +++ b/security/integrity/ima/ima_fs.c
>> @@ -275,7 +275,7 @@ static ssize_t ima_read_policy(char *path)
>> {
>> void *data = NULL;
>> char *datap;
>> - loff_t size;
>> + size_t size;
>> int rc, pathlen = strlen(path);
>> char *p;
>> @@ -284,11 +284,12 @@ static ssize_t ima_read_policy(char *path)
>> datap = path;
>> strsep(&datap, "\n");
>> - rc = kernel_read_file_from_path(path, &data, &size, 0,
>> READING_POLICY);
>> + rc = kernel_read_file_from_path(path, &data, 0, READING_POLICY);
>> if (rc < 0) {
>> pr_err("Unable to open file: %s (%d)", path, rc);
>> return rc;
>> }
>> + size = rc;
>> datap = data;
>> while (size > 0 && (p = strsep(&datap, "\n"))) {
>
On Fri, Jul 17, 2020 at 12:04:18PM -0700, Scott Branden wrote:
> On 2020-07-17 10:43 a.m., Kees Cook wrote:
> > In preparation for refactoring kernel_read_file*(), remove the redundant
> > "size" argument which is not needed: it can be included in the return
>
> I don't think the size argument is redundant though.
> The existing kernel_read_file functions always read the whole file.
> Now, what happens if the file is bigger than the buffer.
> How does kernel_read_file know it read the whole file by looking at the
> return value?
Yes; an entirely reasonable concern. This is why I add the file_size
output argument later in the series.
> > code, with callers adjusted. (VFS reads already cannot be larger than
> > INT_MAX.)
> > [...]
> > - if (i_size > SIZE_MAX || (max_size > 0 && i_size > max_size)) {
> > + if (i_size > INT_MAX || (max_size > 0 && i_size > max_size)) {
>
> Should this be SSIZE_MAX?
No, for two reasons: then we need to change the return value and likely
the callers need more careful checks, and more importantly, because the
VFS already limits single read actions to INT_MAX, so limits above this
make no sense. Win win! :)
--
Kees Cook
Hi Kees,
On 2020-07-17 3:06 p.m., Kees Cook wrote:
> On Fri, Jul 17, 2020 at 12:04:18PM -0700, Scott Branden wrote:
>> On 2020-07-17 10:43 a.m., Kees Cook wrote:
>>> In preparation for refactoring kernel_read_file*(), remove the redundant
>>> "size" argument which is not needed: it can be included in the return
>> I don't think the size argument is redundant though.
>> The existing kernel_read_file functions always read the whole file.
>> Now, what happens if the file is bigger than the buffer.
>> How does kernel_read_file know it read the whole file by looking at the
>> return value?
> Yes; an entirely reasonable concern. This is why I add the file_size
> output argument later in the series.
There is something wrong with this patch. I apply patches 1-5 and these
pass the kernel self test.
Patch 6 does not pass the kernel-selftest/firmware/fw_run_tests.sh
>>> code, with callers adjusted. (VFS reads already cannot be larger than
>>> INT_MAX.)
>>> [...]
>>> - if (i_size > SIZE_MAX || (max_size > 0 && i_size > max_size)) {
>>> + if (i_size > INT_MAX || (max_size > 0 && i_size > max_size)) {
>> Should this be SSIZE_MAX?
> No, for two reasons: then we need to change the return value and likely
> the callers need more careful checks, and more importantly, because the
> VFS already limits single read actions to INT_MAX, so limits above this
> make no sense. Win win! :)
>
Hi Kees,
On 2020-07-17 10:43 a.m., Kees Cook wrote:
> In preparation for refactoring kernel_read_file*(), remove the redundant
> "size" argument which is not needed: it can be included in the return
> code, with callers adjusted. (VFS reads already cannot be larger than
> INT_MAX.)
>
> Signed-off-by: Kees Cook <[email protected]>
> ---
> drivers/base/firmware_loader/main.c | 8 ++++----
> fs/kernel_read_file.c | 20 +++++++++-----------
> include/linux/kernel_read_file.h | 8 ++++----
> kernel/kexec_file.c | 13 ++++++-------
> kernel/module.c | 7 +++----
> security/integrity/digsig.c | 5 +++--
> security/integrity/ima/ima_fs.c | 5 +++--
> 7 files changed, 32 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
> index d4a413ea48ce..ea419c7d3d34 100644
> --- a/drivers/base/firmware_loader/main.c
> +++ b/drivers/base/firmware_loader/main.c
> @@ -462,7 +462,7 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
> size_t in_size,
> const void *in_buffer))
> {
> - loff_t size;
> + size_t size;
> int i, len;
> int rc = -ENOENT;
> char *path;
> @@ -494,10 +494,9 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
> fw_priv->size = 0;
>
> /* load firmware files from the mount namespace of init */
> - rc = kernel_read_file_from_path_initns(path, &buffer,
> - &size, msize,
> + rc = kernel_read_file_from_path_initns(path, &buffer, msize,
> READING_FIRMWARE);
> - if (rc) {
> + if (rc < 0) {
> if (rc != -ENOENT)
> dev_warn(device, "loading %s failed with error %d\n",
> path, rc);
> @@ -506,6 +505,7 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
> path);
> continue;
> }
> + size = rc;
Change fails to return 0. Need rc = 0; here.
> dev_dbg(device, "Loading firmware from %s\n", path);
> if (decompress) {
> dev_dbg(device, "f/w decompressing %s\n",
>
On Tue, Jul 21, 2020 at 02:43:07PM -0700, Scott Branden wrote:
> On 2020-07-17 10:43 a.m., Kees Cook wrote:
> > In preparation for refactoring kernel_read_file*(), remove the redundant
> > "size" argument which is not needed: it can be included in the return
> > code, with callers adjusted. (VFS reads already cannot be larger than
> > INT_MAX.)
> >
> > Signed-off-by: Kees Cook <[email protected]>
> > ---
> > drivers/base/firmware_loader/main.c | 8 ++++----
> > fs/kernel_read_file.c | 20 +++++++++-----------
> > include/linux/kernel_read_file.h | 8 ++++----
> > kernel/kexec_file.c | 13 ++++++-------
> > kernel/module.c | 7 +++----
> > security/integrity/digsig.c | 5 +++--
> > security/integrity/ima/ima_fs.c | 5 +++--
> > 7 files changed, 32 insertions(+), 34 deletions(-)
> >
> > diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
> > index d4a413ea48ce..ea419c7d3d34 100644
> > --- a/drivers/base/firmware_loader/main.c
> > +++ b/drivers/base/firmware_loader/main.c
> > @@ -462,7 +462,7 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
> > size_t in_size,
> > const void *in_buffer))
> > {
> > - loff_t size;
> > + size_t size;
> > int i, len;
> > int rc = -ENOENT;
> > char *path;
> > @@ -494,10 +494,9 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
> > fw_priv->size = 0;
> > /* load firmware files from the mount namespace of init */
> > - rc = kernel_read_file_from_path_initns(path, &buffer,
> > - &size, msize,
> > + rc = kernel_read_file_from_path_initns(path, &buffer, msize,
> > READING_FIRMWARE);
> > - if (rc) {
> > + if (rc < 0) {
> > if (rc != -ENOENT)
> > dev_warn(device, "loading %s failed with error %d\n",
> > path, rc);
> > @@ -506,6 +505,7 @@ fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
> > path);
> > continue;
> > }
> > + size = rc;
> Change fails to return 0.? Need rc = 0; here.
Oh nice; good catch! I'll fix this.
--
Kees Cook