ima: don't allow control characters in policy path

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I409K9


CVE: NA

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Expected error message `ima: Unable to open file:` can be overwritten
when the uploaded path contains control characters like `\r` or `\b`.
Therefore, When an invalid path (which contains control characters) is
uploaded through SecurityFS, unexpected logs can be printed to dmesg.

This patch rejects policy paths with control characters.

Signed-off-by: Zhang Tianxing <zhangtianxing3@huawei.com>
Reviewed-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>