Hi Roberto, Krsysztof,
On Wed, 2020-03-25 at 17:11 +0100, Roberto Sassu wrote:
From: Krzysztof Struczynski krzysztof.struczynski@huawei.com
Function hash_long() accepts unsigned long, while currently only one byte is passed from ima_hash_key(), which calculates a key for ima_htable. Use more bytes to avoid frequent collisions.
Length of the buffer is not explicitly passed as a function parameter, because this function expects a digest whose length is greater than the size of unsigned long.
Somehow I missed the original report of this problem https://lore.kern el.org/patchwork/patch/674684/. This patch is definitely better, but how many unique keys are actually being used? Is it anywhere near IMA_MEASURE_HTABLE_SIZE(512)?
Do we need a new securityfs entry to display the number used?
Mimi
Cc: stable@vger.kernel.org Fixes: 3323eec921ef ("integrity: IMA as an integrity service provider") Signed-off-by: Krzysztof Struczynski krzysztof.struczynski@huawei.com
security/integrity/ima/ima.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 64317d95363e..cf0022c2bc14 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -177,7 +177,7 @@ extern struct ima_h_table ima_htable; static inline unsigned long ima_hash_key(u8 *digest) {
- return hash_long(*digest, IMA_HASH_BITS);
- return hash_long(*((unsigned long *)digest), IMA_HASH_BITS);
} #define __ima_hooks(hook) \