> -----Original Message----- > From: David Laight [mailto:David.Laight@xxxxxxxxxx] > Sent: Monday, April 27, 2020 1:00 PM > To: Roberto Sassu <roberto.sassu@xxxxxxxxxx>; zohar@xxxxxxxxxxxxx; > rgoldwyn@xxxxxxx > Cc: linux-integrity@xxxxxxxxxxxxxxx; linux-security-module@xxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; Silviu Vlasceanu > <Silviu.Vlasceanu@xxxxxxxxxx>; Krzysztof Struczynski > <krzysztof.struczynski@xxxxxxxxxx>; stable@xxxxxxxxxxxxxxx > Subject: RE: [PATCH v2 3/6] ima: Fix ima digest hash table key calculation > > From: Roberto Sassu > > Sent: 27 April 2020 11:29 > > Function hash_long() accepts unsigned long, while currently only one byte > > is passed from ima_hash_key(), which calculates a key for ima_htable. > > > > Given that hashing the digest does not give clear benefits compared to > > using the digest itself, remove hash_long() and return the modulus > > calculated on the beginning of the digest with the number of slots. Also > > reduce the depth of the hash table by doubling the number of slots. > > > > Cc: stable@xxxxxxxxxxxxxxx > > Fixes: 3323eec921ef ("integrity: IMA as an integrity service provider") > > Co-developed-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx> > > Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx> > > Signed-off-by: Krzysztof Struczynski <krzysztof.struczynski@xxxxxxxxxx> > > --- > > security/integrity/ima/ima.h | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h > > index 467dfdbea25c..6ee458cf124a 100644 > > --- a/security/integrity/ima/ima.h > > +++ b/security/integrity/ima/ima.h > > @@ -36,7 +36,7 @@ enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 }; > > #define IMA_DIGEST_SIZE SHA1_DIGEST_SIZE > > #define IMA_EVENT_NAME_LEN_MAX 255 > > > > -#define IMA_HASH_BITS 9 > > +#define IMA_HASH_BITS 10 > > #define IMA_MEASURE_HTABLE_SIZE (1 << IMA_HASH_BITS) > > > > #define IMA_TEMPLATE_FIELD_ID_MAX_LEN 16 > > @@ -179,9 +179,9 @@ struct ima_h_table { > > }; > > extern struct ima_h_table ima_htable; > > > > -static inline unsigned long ima_hash_key(u8 *digest) > > +static inline unsigned int ima_hash_key(u8 *digest) > > { > > - return hash_long(*digest, IMA_HASH_BITS); > > + return (*(unsigned int *)digest % IMA_MEASURE_HTABLE_SIZE); > > That almost certainly isn't right. > It falls foul of the *(integer_type *)ptr being almost always wrong. I didn't find the problem. Can you please explain? Thanks Roberto HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063 Managing Director: Li Peng, Li Jian, Shi Yanli > David > > - > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, > MK1 1PT, UK > Registration No: 1397386 (Wales)
