[RFC,v2,03/13] integrity/digest_cache: Add functions to populate and search
Commit Message
From: Roberto Sassu <roberto.sassu@huawei.com>
Add digest_cache_init_htable(), to size a hash table depending on the
number of digests to be added to the cache.
Add digest_cache_add() and digest_cache_lookup() to respectively add and
lookup a digest in the digest cache.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/digest_cache.c | 131 ++++++++++++++++++++++++++++++
security/integrity/digest_cache.h | 24 ++++++
2 files changed, 155 insertions(+)
Comments
On Sat Aug 12, 2023 at 1:46 PM EEST, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> Add digest_cache_init_htable(), to size a hash table depending on the
> number of digests to be added to the cache.
>
> Add digest_cache_add() and digest_cache_lookup() to respectively add and
> lookup a digest in the digest cache.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
> security/integrity/digest_cache.c | 131 ++++++++++++++++++++++++++++++
> security/integrity/digest_cache.h | 24 ++++++
> 2 files changed, 155 insertions(+)
>
> diff --git a/security/integrity/digest_cache.c b/security/integrity/digest_cache.c
> index 4201c68171a..d14d84b804b 100644
> --- a/security/integrity/digest_cache.c
> +++ b/security/integrity/digest_cache.c
> @@ -315,3 +315,134 @@ struct digest_cache *digest_cache_get(struct dentry *dentry,
>
> return iint->dig_user;
> }
> +
> +/**
> + * digest_cache_init_htable - Allocate and initialize the hash table
> + * @digest_cache: Digest cache
> + * @num_digests: Number of digests to add to the digest cache
> + *
> + * This function allocates and initializes the hash table. Its size is
> + * determined by the number of digests to add to the digest cache, known
> + * at this point by the parser calling this function.
> + *
> + * Return: Zero on success, a negative value otherwise.
> + */
> +int digest_cache_init_htable(struct digest_cache *digest_cache,
> + u64 num_digests)
> +{
> + int i;
> +
> + if (!digest_cache)
> + return 0;
> +
> + digest_cache->num_slots = num_digests / DIGEST_CACHE_HTABLE_DEPTH;
> + if (!digest_cache->num_slots)
> + digest_cache->num_slots = 1;
> +
> + digest_cache->slots = kmalloc_array(num_digests,
> + sizeof(*digest_cache->slots),
> + GFP_KERNEL);
> + if (!digest_cache->slots)
> + return -ENOMEM;
> +
> + for (i = 0; i < digest_cache->num_slots; i++)
> + INIT_HLIST_HEAD(&digest_cache->slots[i]);
> +
> + pr_debug("Initialized %d hash table slots for digest list %s\n",
> + digest_cache->num_slots, digest_cache->path_str);
> + return 0;
> +}
> +
> +/**
> + * digest_cache_add - Add a new digest to the digest cache
> + * @digest_cache: Digest cache
> + * @digest: Digest to add
> + *
> + * This function, invoked by a digest list parser, adds a digest extracted
> + * from a digest list to the digest cache.
> + *
> + * Return: Zero on success, a negative value on error.
Nit: previous had a different phrasing "a negative value otherwise".
I would suggest "a POSIX error code otherwise" for both.
> + */
> +int digest_cache_add(struct digest_cache *digest_cache, u8 *digest)
> +{
> + struct digest_cache_entry *entry;
> + unsigned int key;
> + int digest_len;
> +
> + if (!digest_cache)
> + return 0;
> +
> + digest_len = hash_digest_size[digest_cache->algo];
> +
> + entry = kmalloc(sizeof(*entry) + digest_len, GFP_KERNEL);
> + if (!entry)
> + return -ENOMEM;
> +
> + memcpy(entry->digest, digest, digest_len);
> +
> + key = digest_cache_hash_key(digest, digest_cache->num_slots);
> + hlist_add_head(&entry->hnext, &digest_cache->slots[key]);
> + pr_debug("Add digest %s:%*phN from digest list %s\n",
> + hash_algo_name[digest_cache->algo], digest_len, digest,
> + digest_cache->path_str);
> + return 0;
> +}
> +
> +/**
> + * digest_cache_lookup - Searches a digest in the digest cache
> + * @digest_cache: Digest cache
> + * @digest: Digest to search
> + * @algo: Algorithm of the digest to search
> + * @pathname: Path of the file whose digest is looked up
> + *
> + * This function, invoked by IMA or EVM, searches the calculated digest of
> + * a file or file metadata in the digest cache acquired with
> + * digest_cache_get().
> + *
> + * Return: Zero if the digest is found, a negative value if not.
> + */
> +int digest_cache_lookup(struct digest_cache *digest_cache, u8 *digest,
> + enum hash_algo algo, const char *pathname)
> +{
> + struct digest_cache_entry *entry;
> + unsigned int key;
> + int digest_len;
> + int search_depth = 0;
> +
> + if (!digest_cache)
> + return -ENOENT;
> +
> + if (digest_cache->algo == HASH_ALGO__LAST) {
> + pr_debug("Algorithm not set for digest list %s\n",
> + digest_cache->path_str);
> + return -ENOENT;
> + }
> +
> + digest_len = hash_digest_size[digest_cache->algo];
> +
> + if (algo != digest_cache->algo) {
> + pr_debug("Algo mismatch for file %s, digest %s:%*phN in digest list %s (%s)\n",
> + pathname, hash_algo_name[algo], digest_len, digest,
> + digest_cache->path_str,
> + hash_algo_name[digest_cache->algo]);
> + return -ENOENT;
> + }
> +
> + key = digest_cache_hash_key(digest, digest_cache->num_slots);
> +
> + hlist_for_each_entry_rcu(entry, &digest_cache->slots[key], hnext) {
> + if (!memcmp(entry->digest, digest, digest_len)) {
> + pr_debug("Cache hit at depth %d for file %s, digest %s:%*phN in digest list %s\n",
> + search_depth, pathname, hash_algo_name[algo],
> + digest_len, digest, digest_cache->path_str);
> + return 0;
> + }
> +
> + search_depth++;
> + }
> +
> + pr_debug("Cache miss for file %s, digest %s:%*phN in digest list %s\n",
> + pathname, hash_algo_name[algo], digest_len, digest,
> + digest_cache->path_str);
> + return -ENOENT;
> +}
> diff --git a/security/integrity/digest_cache.h b/security/integrity/digest_cache.h
> index ff88e8593c6..01cd70f9850 100644
> --- a/security/integrity/digest_cache.h
> +++ b/security/integrity/digest_cache.h
> @@ -66,6 +66,11 @@ static inline unsigned int digest_cache_hash_key(u8 *digest,
> void digest_cache_free(struct digest_cache *digest_cache);
> struct digest_cache *digest_cache_get(struct dentry *dentry,
> struct integrity_iint_cache *iint);
> +int digest_cache_init_htable(struct digest_cache *digest_cache,
> + u64 num_digests);
> +int digest_cache_add(struct digest_cache *digest_cache, u8 *digest);
> +int digest_cache_lookup(struct digest_cache *digest_cache, u8 *digest,
> + enum hash_algo algo, const char *pathname);
> #else
> static inline void digest_cache_free(struct digest_cache *digest_cache)
> {
> @@ -77,5 +82,24 @@ digest_cache_get(struct dentry *dentry, struct integrity_iint_cache *iint)
> return NULL;
> }
>
> +static inline int digest_cache_init_htable(struct digest_cache *digest_cache,
> + u64 num_digests)
> +{
> + return -EOPNOTSUPP;
> +}
> +
> +static inline int digest_cache_add(struct digest_cache *digest_cache,
> + u8 *digest)
> +{
> + return -EOPNOTSUPP;
> +}
> +
> +static inline int digest_cache_lookup(struct digest_cache *digest_cache,
> + u8 *digest, enum hash_algo algo,
> + const char *pathname)
> +{
> + return -ENOENT;
> +}
> +
> #endif /* CONFIG_INTEGRITY_DIGEST_CACHE */
> #endif /* _DIGEST_CACHE_H */
> --
> 2.34.1
Why all this complexity instead of using xarray?
https://docs.kernel.org/core-api/xarray.html
BR, Jarkko
On 8/14/2023 7:13 PM, Jarkko Sakkinen wrote:
> On Sat Aug 12, 2023 at 1:46 PM EEST, Roberto Sassu wrote:
>> From: Roberto Sassu <roberto.sassu@huawei.com>
>>
>> Add digest_cache_init_htable(), to size a hash table depending on the
>> number of digests to be added to the cache.
>>
>> Add digest_cache_add() and digest_cache_lookup() to respectively add and
>> lookup a digest in the digest cache.
>>
>> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
>> ---
>> security/integrity/digest_cache.c | 131 ++++++++++++++++++++++++++++++
>> security/integrity/digest_cache.h | 24 ++++++
>> 2 files changed, 155 insertions(+)
>>
>> diff --git a/security/integrity/digest_cache.c b/security/integrity/digest_cache.c
>> index 4201c68171a..d14d84b804b 100644
>> --- a/security/integrity/digest_cache.c
>> +++ b/security/integrity/digest_cache.c
>> @@ -315,3 +315,134 @@ struct digest_cache *digest_cache_get(struct dentry *dentry,
>>
>> return iint->dig_user;
>> }
>> +
>> +/**
>> + * digest_cache_init_htable - Allocate and initialize the hash table
>> + * @digest_cache: Digest cache
>> + * @num_digests: Number of digests to add to the digest cache
>> + *
>> + * This function allocates and initializes the hash table. Its size is
>> + * determined by the number of digests to add to the digest cache, known
>> + * at this point by the parser calling this function.
>> + *
>> + * Return: Zero on success, a negative value otherwise.
>> + */
>> +int digest_cache_init_htable(struct digest_cache *digest_cache,
>> + u64 num_digests)
>> +{
>> + int i;
>> +
>> + if (!digest_cache)
>> + return 0;
>> +
>> + digest_cache->num_slots = num_digests / DIGEST_CACHE_HTABLE_DEPTH;
>> + if (!digest_cache->num_slots)
>> + digest_cache->num_slots = 1;
>> +
>> + digest_cache->slots = kmalloc_array(num_digests,
>> + sizeof(*digest_cache->slots),
>> + GFP_KERNEL);
>> + if (!digest_cache->slots)
>> + return -ENOMEM;
>> +
>> + for (i = 0; i < digest_cache->num_slots; i++)
>> + INIT_HLIST_HEAD(&digest_cache->slots[i]);
>> +
>> + pr_debug("Initialized %d hash table slots for digest list %s\n",
>> + digest_cache->num_slots, digest_cache->path_str);
>> + return 0;
>> +}
>> +
>> +/**
>> + * digest_cache_add - Add a new digest to the digest cache
>> + * @digest_cache: Digest cache
>> + * @digest: Digest to add
>> + *
>> + * This function, invoked by a digest list parser, adds a digest extracted
>> + * from a digest list to the digest cache.
>> + *
>> + * Return: Zero on success, a negative value on error.
>
> Nit: previous had a different phrasing "a negative value otherwise".
>
> I would suggest "a POSIX error code otherwise" for both.
Ok.
>> + */
>> +int digest_cache_add(struct digest_cache *digest_cache, u8 *digest)
>> +{
>> + struct digest_cache_entry *entry;
>> + unsigned int key;
>> + int digest_len;
>> +
>> + if (!digest_cache)
>> + return 0;
>> +
>> + digest_len = hash_digest_size[digest_cache->algo];
>> +
>> + entry = kmalloc(sizeof(*entry) + digest_len, GFP_KERNEL);
>> + if (!entry)
>> + return -ENOMEM;
>> +
>> + memcpy(entry->digest, digest, digest_len);
>> +
>> + key = digest_cache_hash_key(digest, digest_cache->num_slots);
>> + hlist_add_head(&entry->hnext, &digest_cache->slots[key]);
>> + pr_debug("Add digest %s:%*phN from digest list %s\n",
>> + hash_algo_name[digest_cache->algo], digest_len, digest,
>> + digest_cache->path_str);
>> + return 0;
>> +}
>> +
>> +/**
>> + * digest_cache_lookup - Searches a digest in the digest cache
>> + * @digest_cache: Digest cache
>> + * @digest: Digest to search
>> + * @algo: Algorithm of the digest to search
>> + * @pathname: Path of the file whose digest is looked up
>> + *
>> + * This function, invoked by IMA or EVM, searches the calculated digest of
>> + * a file or file metadata in the digest cache acquired with
>> + * digest_cache_get().
>> + *
>> + * Return: Zero if the digest is found, a negative value if not.
>> + */
>> +int digest_cache_lookup(struct digest_cache *digest_cache, u8 *digest,
>> + enum hash_algo algo, const char *pathname)
>> +{
>> + struct digest_cache_entry *entry;
>> + unsigned int key;
>> + int digest_len;
>> + int search_depth = 0;
>> +
>> + if (!digest_cache)
>> + return -ENOENT;
>> +
>> + if (digest_cache->algo == HASH_ALGO__LAST) {
>> + pr_debug("Algorithm not set for digest list %s\n",
>> + digest_cache->path_str);
>> + return -ENOENT;
>> + }
>> +
>> + digest_len = hash_digest_size[digest_cache->algo];
>> +
>> + if (algo != digest_cache->algo) {
>> + pr_debug("Algo mismatch for file %s, digest %s:%*phN in digest list %s (%s)\n",
>> + pathname, hash_algo_name[algo], digest_len, digest,
>> + digest_cache->path_str,
>> + hash_algo_name[digest_cache->algo]);
>> + return -ENOENT;
>> + }
>> +
>> + key = digest_cache_hash_key(digest, digest_cache->num_slots);
>> +
>> + hlist_for_each_entry_rcu(entry, &digest_cache->slots[key], hnext) {
>> + if (!memcmp(entry->digest, digest, digest_len)) {
>> + pr_debug("Cache hit at depth %d for file %s, digest %s:%*phN in digest list %s\n",
>> + search_depth, pathname, hash_algo_name[algo],
>> + digest_len, digest, digest_cache->path_str);
>> + return 0;
>> + }
>> +
>> + search_depth++;
>> + }
>> +
>> + pr_debug("Cache miss for file %s, digest %s:%*phN in digest list %s\n",
>> + pathname, hash_algo_name[algo], digest_len, digest,
>> + digest_cache->path_str);
>> + return -ENOENT;
>> +}
>> diff --git a/security/integrity/digest_cache.h b/security/integrity/digest_cache.h
>> index ff88e8593c6..01cd70f9850 100644
>> --- a/security/integrity/digest_cache.h
>> +++ b/security/integrity/digest_cache.h
>> @@ -66,6 +66,11 @@ static inline unsigned int digest_cache_hash_key(u8 *digest,
>> void digest_cache_free(struct digest_cache *digest_cache);
>> struct digest_cache *digest_cache_get(struct dentry *dentry,
>> struct integrity_iint_cache *iint);
>> +int digest_cache_init_htable(struct digest_cache *digest_cache,
>> + u64 num_digests);
>> +int digest_cache_add(struct digest_cache *digest_cache, u8 *digest);
>> +int digest_cache_lookup(struct digest_cache *digest_cache, u8 *digest,
>> + enum hash_algo algo, const char *pathname);
>> #else
>> static inline void digest_cache_free(struct digest_cache *digest_cache)
>> {
>> @@ -77,5 +82,24 @@ digest_cache_get(struct dentry *dentry, struct integrity_iint_cache *iint)
>> return NULL;
>> }
>>
>> +static inline int digest_cache_init_htable(struct digest_cache *digest_cache,
>> + u64 num_digests)
>> +{
>> + return -EOPNOTSUPP;
>> +}
>> +
>> +static inline int digest_cache_add(struct digest_cache *digest_cache,
>> + u8 *digest)
>> +{
>> + return -EOPNOTSUPP;
>> +}
>> +
>> +static inline int digest_cache_lookup(struct digest_cache *digest_cache,
>> + u8 *digest, enum hash_algo algo,
>> + const char *pathname)
>> +{
>> + return -ENOENT;
>> +}
>> +
>> #endif /* CONFIG_INTEGRITY_DIGEST_CACHE */
>> #endif /* _DIGEST_CACHE_H */
>> --
>> 2.34.1
>
> Why all this complexity instead of using xarray?
>
> https://docs.kernel.org/core-api/xarray.html
Uhm, did I get correctly from the documentation that it isn't the
optimal solution for hash tables?
Thanks
Roberto
On Wed Aug 16, 2023 at 11:35 AM EEST, Roberto Sassu wrote:
> On 8/14/2023 7:13 PM, Jarkko Sakkinen wrote:
> > On Sat Aug 12, 2023 at 1:46 PM EEST, Roberto Sassu wrote:
> >> From: Roberto Sassu <roberto.sassu@huawei.com>
> >>
> >> Add digest_cache_init_htable(), to size a hash table depending on the
> >> number of digests to be added to the cache.
> >>
> >> Add digest_cache_add() and digest_cache_lookup() to respectively add and
> >> lookup a digest in the digest cache.
> >>
> >> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> >> ---
> >> security/integrity/digest_cache.c | 131 ++++++++++++++++++++++++++++++
> >> security/integrity/digest_cache.h | 24 ++++++
> >> 2 files changed, 155 insertions(+)
> >>
> >> diff --git a/security/integrity/digest_cache.c b/security/integrity/digest_cache.c
> >> index 4201c68171a..d14d84b804b 100644
> >> --- a/security/integrity/digest_cache.c
> >> +++ b/security/integrity/digest_cache.c
> >> @@ -315,3 +315,134 @@ struct digest_cache *digest_cache_get(struct dentry *dentry,
> >>
> >> return iint->dig_user;
> >> }
> >> +
> >> +/**
> >> + * digest_cache_init_htable - Allocate and initialize the hash table
> >> + * @digest_cache: Digest cache
> >> + * @num_digests: Number of digests to add to the digest cache
> >> + *
> >> + * This function allocates and initializes the hash table. Its size is
> >> + * determined by the number of digests to add to the digest cache, known
> >> + * at this point by the parser calling this function.
> >> + *
> >> + * Return: Zero on success, a negative value otherwise.
> >> + */
> >> +int digest_cache_init_htable(struct digest_cache *digest_cache,
> >> + u64 num_digests)
> >> +{
> >> + int i;
> >> +
> >> + if (!digest_cache)
> >> + return 0;
> >> +
> >> + digest_cache->num_slots = num_digests / DIGEST_CACHE_HTABLE_DEPTH;
> >> + if (!digest_cache->num_slots)
> >> + digest_cache->num_slots = 1;
> >> +
> >> + digest_cache->slots = kmalloc_array(num_digests,
> >> + sizeof(*digest_cache->slots),
> >> + GFP_KERNEL);
> >> + if (!digest_cache->slots)
> >> + return -ENOMEM;
> >> +
> >> + for (i = 0; i < digest_cache->num_slots; i++)
> >> + INIT_HLIST_HEAD(&digest_cache->slots[i]);
> >> +
> >> + pr_debug("Initialized %d hash table slots for digest list %s\n",
> >> + digest_cache->num_slots, digest_cache->path_str);
> >> + return 0;
> >> +}
> >> +
> >> +/**
> >> + * digest_cache_add - Add a new digest to the digest cache
> >> + * @digest_cache: Digest cache
> >> + * @digest: Digest to add
> >> + *
> >> + * This function, invoked by a digest list parser, adds a digest extracted
> >> + * from a digest list to the digest cache.
> >> + *
> >> + * Return: Zero on success, a negative value on error.
> >
> > Nit: previous had a different phrasing "a negative value otherwise".
> >
> > I would suggest "a POSIX error code otherwise" for both.
>
> Ok.
>
> >> + */
> >> +int digest_cache_add(struct digest_cache *digest_cache, u8 *digest)
> >> +{
> >> + struct digest_cache_entry *entry;
> >> + unsigned int key;
> >> + int digest_len;
> >> +
> >> + if (!digest_cache)
> >> + return 0;
> >> +
> >> + digest_len = hash_digest_size[digest_cache->algo];
> >> +
> >> + entry = kmalloc(sizeof(*entry) + digest_len, GFP_KERNEL);
> >> + if (!entry)
> >> + return -ENOMEM;
> >> +
> >> + memcpy(entry->digest, digest, digest_len);
> >> +
> >> + key = digest_cache_hash_key(digest, digest_cache->num_slots);
> >> + hlist_add_head(&entry->hnext, &digest_cache->slots[key]);
> >> + pr_debug("Add digest %s:%*phN from digest list %s\n",
> >> + hash_algo_name[digest_cache->algo], digest_len, digest,
> >> + digest_cache->path_str);
> >> + return 0;
> >> +}
> >> +
> >> +/**
> >> + * digest_cache_lookup - Searches a digest in the digest cache
> >> + * @digest_cache: Digest cache
> >> + * @digest: Digest to search
> >> + * @algo: Algorithm of the digest to search
> >> + * @pathname: Path of the file whose digest is looked up
> >> + *
> >> + * This function, invoked by IMA or EVM, searches the calculated digest of
> >> + * a file or file metadata in the digest cache acquired with
> >> + * digest_cache_get().
> >> + *
> >> + * Return: Zero if the digest is found, a negative value if not.
> >> + */
> >> +int digest_cache_lookup(struct digest_cache *digest_cache, u8 *digest,
> >> + enum hash_algo algo, const char *pathname)
> >> +{
> >> + struct digest_cache_entry *entry;
> >> + unsigned int key;
> >> + int digest_len;
> >> + int search_depth = 0;
> >> +
> >> + if (!digest_cache)
> >> + return -ENOENT;
> >> +
> >> + if (digest_cache->algo == HASH_ALGO__LAST) {
> >> + pr_debug("Algorithm not set for digest list %s\n",
> >> + digest_cache->path_str);
> >> + return -ENOENT;
> >> + }
> >> +
> >> + digest_len = hash_digest_size[digest_cache->algo];
> >> +
> >> + if (algo != digest_cache->algo) {
> >> + pr_debug("Algo mismatch for file %s, digest %s:%*phN in digest list %s (%s)\n",
> >> + pathname, hash_algo_name[algo], digest_len, digest,
> >> + digest_cache->path_str,
> >> + hash_algo_name[digest_cache->algo]);
> >> + return -ENOENT;
> >> + }
> >> +
> >> + key = digest_cache_hash_key(digest, digest_cache->num_slots);
> >> +
> >> + hlist_for_each_entry_rcu(entry, &digest_cache->slots[key], hnext) {
> >> + if (!memcmp(entry->digest, digest, digest_len)) {
> >> + pr_debug("Cache hit at depth %d for file %s, digest %s:%*phN in digest list %s\n",
> >> + search_depth, pathname, hash_algo_name[algo],
> >> + digest_len, digest, digest_cache->path_str);
> >> + return 0;
> >> + }
> >> +
> >> + search_depth++;
> >> + }
> >> +
> >> + pr_debug("Cache miss for file %s, digest %s:%*phN in digest list %s\n",
> >> + pathname, hash_algo_name[algo], digest_len, digest,
> >> + digest_cache->path_str);
> >> + return -ENOENT;
> >> +}
> >> diff --git a/security/integrity/digest_cache.h b/security/integrity/digest_cache.h
> >> index ff88e8593c6..01cd70f9850 100644
> >> --- a/security/integrity/digest_cache.h
> >> +++ b/security/integrity/digest_cache.h
> >> @@ -66,6 +66,11 @@ static inline unsigned int digest_cache_hash_key(u8 *digest,
> >> void digest_cache_free(struct digest_cache *digest_cache);
> >> struct digest_cache *digest_cache_get(struct dentry *dentry,
> >> struct integrity_iint_cache *iint);
> >> +int digest_cache_init_htable(struct digest_cache *digest_cache,
> >> + u64 num_digests);
> >> +int digest_cache_add(struct digest_cache *digest_cache, u8 *digest);
> >> +int digest_cache_lookup(struct digest_cache *digest_cache, u8 *digest,
> >> + enum hash_algo algo, const char *pathname);
> >> #else
> >> static inline void digest_cache_free(struct digest_cache *digest_cache)
> >> {
> >> @@ -77,5 +82,24 @@ digest_cache_get(struct dentry *dentry, struct integrity_iint_cache *iint)
> >> return NULL;
> >> }
> >>
> >> +static inline int digest_cache_init_htable(struct digest_cache *digest_cache,
> >> + u64 num_digests)
> >> +{
> >> + return -EOPNOTSUPP;
> >> +}
> >> +
> >> +static inline int digest_cache_add(struct digest_cache *digest_cache,
> >> + u8 *digest)
> >> +{
> >> + return -EOPNOTSUPP;
> >> +}
> >> +
> >> +static inline int digest_cache_lookup(struct digest_cache *digest_cache,
> >> + u8 *digest, enum hash_algo algo,
> >> + const char *pathname)
> >> +{
> >> + return -ENOENT;
> >> +}
> >> +
> >> #endif /* CONFIG_INTEGRITY_DIGEST_CACHE */
> >> #endif /* _DIGEST_CACHE_H */
> >> --
> >> 2.34.1
> >
> > Why all this complexity instead of using xarray?
> >
> > https://docs.kernel.org/core-api/xarray.html
>
> Uhm, did I get correctly from the documentation that it isn't the
> optimal solution for hash tables?
I think you are correct with xarray that it is not a great fit here
(I overlooked).
BR, Jarkko
@@ -315,3 +315,134 @@ struct digest_cache *digest_cache_get(struct dentry *dentry,
return iint->dig_user;
}
+
+/**
+ * digest_cache_init_htable - Allocate and initialize the hash table
+ * @digest_cache: Digest cache
+ * @num_digests: Number of digests to add to the digest cache
+ *
+ * This function allocates and initializes the hash table. Its size is
+ * determined by the number of digests to add to the digest cache, known
+ * at this point by the parser calling this function.
+ *
+ * Return: Zero on success, a negative value otherwise.
+ */
+int digest_cache_init_htable(struct digest_cache *digest_cache,
+ u64 num_digests)
+{
+ int i;
+
+ if (!digest_cache)
+ return 0;
+
+ digest_cache->num_slots = num_digests / DIGEST_CACHE_HTABLE_DEPTH;
+ if (!digest_cache->num_slots)
+ digest_cache->num_slots = 1;
+
+ digest_cache->slots = kmalloc_array(num_digests,
+ sizeof(*digest_cache->slots),
+ GFP_KERNEL);
+ if (!digest_cache->slots)
+ return -ENOMEM;
+
+ for (i = 0; i < digest_cache->num_slots; i++)
+ INIT_HLIST_HEAD(&digest_cache->slots[i]);
+
+ pr_debug("Initialized %d hash table slots for digest list %s\n",
+ digest_cache->num_slots, digest_cache->path_str);
+ return 0;
+}
+
+/**
+ * digest_cache_add - Add a new digest to the digest cache
+ * @digest_cache: Digest cache
+ * @digest: Digest to add
+ *
+ * This function, invoked by a digest list parser, adds a digest extracted
+ * from a digest list to the digest cache.
+ *
+ * Return: Zero on success, a negative value on error.
+ */
+int digest_cache_add(struct digest_cache *digest_cache, u8 *digest)
+{
+ struct digest_cache_entry *entry;
+ unsigned int key;
+ int digest_len;
+
+ if (!digest_cache)
+ return 0;
+
+ digest_len = hash_digest_size[digest_cache->algo];
+
+ entry = kmalloc(sizeof(*entry) + digest_len, GFP_KERNEL);
+ if (!entry)
+ return -ENOMEM;
+
+ memcpy(entry->digest, digest, digest_len);
+
+ key = digest_cache_hash_key(digest, digest_cache->num_slots);
+ hlist_add_head(&entry->hnext, &digest_cache->slots[key]);
+ pr_debug("Add digest %s:%*phN from digest list %s\n",
+ hash_algo_name[digest_cache->algo], digest_len, digest,
+ digest_cache->path_str);
+ return 0;
+}
+
+/**
+ * digest_cache_lookup - Searches a digest in the digest cache
+ * @digest_cache: Digest cache
+ * @digest: Digest to search
+ * @algo: Algorithm of the digest to search
+ * @pathname: Path of the file whose digest is looked up
+ *
+ * This function, invoked by IMA or EVM, searches the calculated digest of
+ * a file or file metadata in the digest cache acquired with
+ * digest_cache_get().
+ *
+ * Return: Zero if the digest is found, a negative value if not.
+ */
+int digest_cache_lookup(struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo, const char *pathname)
+{
+ struct digest_cache_entry *entry;
+ unsigned int key;
+ int digest_len;
+ int search_depth = 0;
+
+ if (!digest_cache)
+ return -ENOENT;
+
+ if (digest_cache->algo == HASH_ALGO__LAST) {
+ pr_debug("Algorithm not set for digest list %s\n",
+ digest_cache->path_str);
+ return -ENOENT;
+ }
+
+ digest_len = hash_digest_size[digest_cache->algo];
+
+ if (algo != digest_cache->algo) {
+ pr_debug("Algo mismatch for file %s, digest %s:%*phN in digest list %s (%s)\n",
+ pathname, hash_algo_name[algo], digest_len, digest,
+ digest_cache->path_str,
+ hash_algo_name[digest_cache->algo]);
+ return -ENOENT;
+ }
+
+ key = digest_cache_hash_key(digest, digest_cache->num_slots);
+
+ hlist_for_each_entry_rcu(entry, &digest_cache->slots[key], hnext) {
+ if (!memcmp(entry->digest, digest, digest_len)) {
+ pr_debug("Cache hit at depth %d for file %s, digest %s:%*phN in digest list %s\n",
+ search_depth, pathname, hash_algo_name[algo],
+ digest_len, digest, digest_cache->path_str);
+ return 0;
+ }
+
+ search_depth++;
+ }
+
+ pr_debug("Cache miss for file %s, digest %s:%*phN in digest list %s\n",
+ pathname, hash_algo_name[algo], digest_len, digest,
+ digest_cache->path_str);
+ return -ENOENT;
+}
@@ -66,6 +66,11 @@ static inline unsigned int digest_cache_hash_key(u8 *digest,
void digest_cache_free(struct digest_cache *digest_cache);
struct digest_cache *digest_cache_get(struct dentry *dentry,
struct integrity_iint_cache *iint);
+int digest_cache_init_htable(struct digest_cache *digest_cache,
+ u64 num_digests);
+int digest_cache_add(struct digest_cache *digest_cache, u8 *digest);
+int digest_cache_lookup(struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo, const char *pathname);
#else
static inline void digest_cache_free(struct digest_cache *digest_cache)
{
@@ -77,5 +82,24 @@ digest_cache_get(struct dentry *dentry, struct integrity_iint_cache *iint)
return NULL;
}
+static inline int digest_cache_init_htable(struct digest_cache *digest_cache,
+ u64 num_digests)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int digest_cache_add(struct digest_cache *digest_cache,
+ u8 *digest)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int digest_cache_lookup(struct digest_cache *digest_cache,
+ u8 *digest, enum hash_algo algo,
+ const char *pathname)
+{
+ return -ENOENT;
+}
+
#endif /* CONFIG_INTEGRITY_DIGEST_CACHE */
#endif /* _DIGEST_CACHE_H */