LSM: Add "contents" flag to kernel_read_file hook

As with the kernel_load_data LSM hook, add a "contents" flag to the
kernel_read_file LSM hook that indicates whether the LSM can expect
a matching call to the kernel_post_read_file LSM hook with the full
contents of the file. With the coming addition of partial file read
support for kernel_read_file*() API, the LSM will no longer be able
to always see the entire contents of a file during the read calls.

For cases where the LSM must read examine the complete file contents,
it will need to do so on its own every time the kernel_read_file
hook is called with contents=false (or reject such cases). Adjust all
existing LSMs to retain existing behavior.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-12-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kees Cook 2020-10-02 10:38:23 -07:00 committed by Greg Kroah-Hartman
parent 38f901735a
commit 2039bda1fa
9 changed files with 41 additions and 14 deletions

View file

@ -23,7 +23,8 @@ extern int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot);
extern int ima_load_data(enum kernel_load_data_id id, bool contents);
extern int ima_post_load_data(char *buf, loff_t size,
enum kernel_load_data_id id, char *description);
extern int ima_read_file(struct file *file, enum kernel_read_file_id id);
extern int ima_read_file(struct file *file, enum kernel_read_file_id id,
bool contents);
extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
enum kernel_read_file_id id);
extern void ima_post_path_mknod(struct dentry *dentry);
@ -92,7 +93,8 @@ static inline int ima_post_load_data(char *buf, loff_t size,
return 0;
}
static inline int ima_read_file(struct file *file, enum kernel_read_file_id id)
static inline int ima_read_file(struct file *file, enum kernel_read_file_id id,
bool contents)
{
return 0;
}