| Message ID | 20200428073010.25631-1-roberto.sassu@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | None | expand |
From: Roberto Sassu > Sent: 28 April 2020 08:30 > 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. > > 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 first two bytes of the digest with the number of slots. > Also reduce the depth of the hash table by doubling the number of slots. > > Changelog > > v2: directly access the first two bytes of the digest to avoid memory > access issues on big endian systems (suggested by David Laight) > > Cc: stable@vger.kernel.org > Fixes: 3323eec921ef ("integrity: IMA as an integrity service provider") > Co-developed-by: Roberto Sassu <roberto.sassu@huawei.com> > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> > Signed-off-by: Krzysztof Struczynski <krzysztof.struczynski@huawei.com> Acked-by: David.Laight@aculab.com > --- > security/integrity/ima/ima.h | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h > index 467dfdbea25c..02796473238b 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 +179,10 @@ 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); > + /* there is no point in taking a hash of part of a digest */ > + return (digest[0] | digest[1] << 8) % IMA_MEASURE_HTABLE_SIZE; > } > > #define __ima_hooks(hook) \ > -- > 2.17.1 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 467dfdbea25c..02796473238b 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 +179,10 @@ 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); + /* there is no point in taking a hash of part of a digest */ + return (digest[0] | digest[1] << 8) % IMA_MEASURE_HTABLE_SIZE; } #define __ima_hooks(hook) \