fs/kernel_file_read: Add "offset" arg for partial reads
To perform partial reads, callers of kernel_read_file*() must have a
non-NULL file_size argument and a preallocated buffer. The new "offset"
argument can then be used to seek to specific locations in the file to
fill the buffer to, at most, "buf_size" per call.
Where possible, the LSM hooks can report whether a full file has been
read or not so that the contents can be reasoned about.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201002173828.2099543-14-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 5fc56cc..ea8ff8a 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -284,7 +284,8 @@ static ssize_t ima_read_policy(char *path)
datap = path;
strsep(&datap, "\n");
- rc = kernel_read_file_from_path(path, &data, INT_MAX, NULL, READING_POLICY);
+ rc = kernel_read_file_from_path(path, 0, &data, INT_MAX, NULL,
+ READING_POLICY);
if (rc < 0) {
pr_err("Unable to open file: %s (%d)", path, rc);
return rc;