ima: provide support for arbitrary hash algorithms

In preparation of supporting more hash algorithms with larger hash sizes
needed for signature verification, this patch replaces the 20 byte sized
digest, with a more flexible structure.  The new structure includes the
hash algorithm, digest size, and digest.

Changelog:
- recalculate filedata hash for the measurement list, if the signature
  hash digest size is greater than 20 bytes.
- use generic HASH_ALGO_
- make ima_calc_file_hash static
- scripts lindent and checkpatch fixes

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

7 files changed, 98 insertions, 32 deletions

diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 39196abaff0d..e6628e783df1 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -9,6 +9,7 @@ config IMA
         select CRYPTO_HMAC
         select CRYPTO_MD5
         select CRYPTO_SHA1
+        select CRYPTO_HASH_INFO
         select TCG_TPM if HAS_IOMEM && !UML
         select TCG_TIS if TCG_TPM && X86
         select TCG_IBMVTPM if TCG_TPM && PPC64
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index b3dd616560f7..eb86032f4f1e 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -39,7 +39,7 @@ enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 };
 /* set during initialization */
 extern int ima_initialized;
 extern int ima_used_chip;
-extern char *ima_hash;
+extern int ima_hash_algo;
 extern int ima_appraise;
 
 /* IMA inode template definition */
@@ -70,8 +70,9 @@ void ima_fs_cleanup(void);
 int ima_inode_alloc(struct inode *inode);
 int ima_add_template_entry(struct ima_template_entry *entry, int violation,
                            const char *op, struct inode *inode);
-int ima_calc_file_hash(struct file *file, char *digest);
-int ima_calc_buffer_hash(const void *data, int len, char *digest);
+int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash);
+int ima_calc_buffer_hash(const void *data, int len,
+                         struct ima_digest_data *hash);
 int ima_calc_boot_aggregate(char *digest);
 void ima_add_violation(struct inode *inode, const unsigned char *filename,
                        const char *op, const char *cause);
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 1c03e8f1e0e1..e531fe22e582 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -44,6 +44,7 @@ int ima_store_template(struct ima_template_entry *entry,
         const char *op = "add_template_measure";
         const char *audit_cause = "hashing_error";
         int result;
+        struct ima_digest_data hash;
 
         memset(entry->digest, 0, sizeof(entry->digest));
         entry->template_name = IMA_TEMPLATE_NAME;
@@ -51,14 +52,14 @@ int ima_store_template(struct ima_template_entry *entry,
 
         if (!violation) {
                 result = ima_calc_buffer_hash(&entry->template,
-                                                entry->template_len,
-                                                entry->digest);
+                                              entry->template_len, &hash);
                 if (result < 0) {
                         integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
                                             entry->template_name, op,
                                             audit_cause, result, 0);
                         return result;
                 }
+                memcpy(entry->digest, hash.digest, hash.length);
         }
         result = ima_add_template_entry(entry, violation, op, inode);
         return result;
@@ -147,8 +148,9 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
         if (!(iint->flags & IMA_COLLECTED)) {
                 u64 i_version = file_inode(file)->i_version;
 
-                iint->ima_xattr.type = IMA_XATTR_DIGEST;
-                result = ima_calc_file_hash(file, iint->ima_xattr.digest);
+                /* use default hash algorithm */
+                iint->ima_hash.algo = ima_hash_algo;
+                result = ima_calc_file_hash(file, &iint->ima_hash);
                 if (!result) {
                         iint->version = i_version;
                         iint->flags |= IMA_COLLECTED;
@@ -196,7 +198,21 @@ void ima_store_measurement(struct integrity_iint_cache *iint,
                 return;
         }
         memset(&entry->template, 0, sizeof(entry->template));
-        memcpy(entry->template.digest, iint->ima_xattr.digest, IMA_DIGEST_SIZE);
+        if (iint->ima_hash.algo != ima_hash_algo) {
+                struct ima_digest_data hash;
+
+                hash.algo = ima_hash_algo;
+                result = ima_calc_file_hash(file, &hash);
+                if (result)
+                        integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
+                                            filename, "collect_data", "failed",
+                                            result, 0);
+                else
+                        memcpy(entry->template.digest, hash.digest,
+                               hash.length);
+        } else
+                memcpy(entry->template.digest, iint->ima_hash.digest,
+                       iint->ima_hash.length);
         strcpy(entry->template.file_name,
                (strlen(filename) > IMA_EVENT_NAME_LEN_MAX) ?
                file->f_dentry->d_name.name : filename);
@@ -212,14 +228,14 @@ void ima_audit_measurement(struct integrity_iint_cache *iint,
                            const unsigned char *filename)
 {
         struct audit_buffer *ab;
-        char hash[(IMA_DIGEST_SIZE * 2) + 1];
+        char hash[(iint->ima_hash.length * 2) + 1];
         int i;
 
         if (iint->flags & IMA_AUDITED)
                 return;
 
-        for (i = 0; i < IMA_DIGEST_SIZE; i++)
-                hex_byte_pack(hash + (i * 2), iint->ima_xattr.digest[i]);
+        for (i = 0; i < iint->ima_hash.length; i++)
+                hex_byte_pack(hash + (i * 2), iint->ima_hash.digest[i]);
         hash[i * 2] = '\0';
 
         ab = audit_log_start(current->audit_context, GFP_KERNEL,
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index e3230d6a8d96..3833b0fa7108 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -43,12 +43,12 @@ int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func)
 }
 
 static int ima_fix_xattr(struct dentry *dentry,
-                          struct integrity_iint_cache *iint)
+                         struct integrity_iint_cache *iint)
 {
-        iint->ima_xattr.type = IMA_XATTR_DIGEST;
+        iint->ima_hash.type = IMA_XATTR_DIGEST;
         return __vfs_setxattr_noperm(dentry, XATTR_NAME_IMA,
-                                     (u8 *)&iint->ima_xattr,
-                                      sizeof(iint->ima_xattr), 0);
+                                     &iint->ima_hash.type,
+                                     1 + iint->ima_hash.length, 0);
 }
 
 /* Return specific func appraised cached result */
@@ -159,8 +159,12 @@ int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
                         status = INTEGRITY_FAIL;
                         break;
                 }
-                rc = memcmp(xattr_value->digest, iint->ima_xattr.digest,
-                            IMA_DIGEST_SIZE);
+                if (rc - 1 == iint->ima_hash.length)
+                        rc = memcmp(xattr_value->digest,
+                                    iint->ima_hash.digest,
+                                    iint->ima_hash.length);
+                else
+                        rc = -EINVAL;
                 if (rc) {
                         cause = "invalid-hash";
                         status = INTEGRITY_FAIL;
@@ -172,8 +176,8 @@ int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
                 iint->flags |= IMA_DIGSIG;
                 rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
                                              xattr_value->digest, rc - 1,
-                                             iint->ima_xattr.digest,
-                                             IMA_DIGEST_SIZE);
+                                             iint->ima_hash.digest,
+                                             iint->ima_hash.length);
                 if (rc == -EOPNOTSUPP) {
                         status = INTEGRITY_UNKNOWN;
                 } else if (rc) {
diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index a02e0791cf15..2fd178651467 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -20,6 +20,7 @@
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <crypto/hash.h>
+#include <crypto/hash_info.h>
 #include "ima.h"
 
 static struct crypto_shash *ima_shash_tfm;
@@ -28,10 +29,11 @@ int ima_init_crypto(void)
 {
         long rc;
 
-        ima_shash_tfm = crypto_alloc_shash(ima_hash, 0, 0);
+        ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0);
         if (IS_ERR(ima_shash_tfm)) {
                 rc = PTR_ERR(ima_shash_tfm);
-                pr_err("Can not allocate %s (reason: %ld)\n", ima_hash, rc);
+                pr_err("Can not allocate %s (reason: %ld)\n",
+                       hash_algo_name[ima_hash_algo], rc);
                 return rc;
         }
         return 0;
@@ -40,17 +42,19 @@ int ima_init_crypto(void)
 /*
  * Calculate the MD5/SHA1 file digest
  */
-int ima_calc_file_hash(struct file *file, char *digest)
+static int ima_calc_file_hash_tfm(struct file *file,
+                                  struct ima_digest_data *hash,
+                                  struct crypto_shash *tfm)
 {
         loff_t i_size, offset = 0;
         char *rbuf;
         int rc, read = 0;
         struct {
                 struct shash_desc shash;
-                char ctx[crypto_shash_descsize(ima_shash_tfm)];
+                char ctx[crypto_shash_descsize(tfm)];
         } desc;
 
-        desc.shash.tfm = ima_shash_tfm;
+        desc.shash.tfm = tfm;
         desc.shash.flags = 0;
 
         rc = crypto_shash_init(&desc.shash);
@@ -85,17 +89,42 @@ int ima_calc_file_hash(struct file *file, char *digest)
         }
         kfree(rbuf);
         if (!rc)
-                rc = crypto_shash_final(&desc.shash, digest);
+                rc = crypto_shash_final(&desc.shash, hash->digest);
         if (read)
                 file->f_mode &= ~FMODE_READ;
 out:
         return rc;
 }
 
+int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
+{
+        struct crypto_shash *tfm = ima_shash_tfm;
+        int rc;
+
+        if (hash->algo != ima_hash_algo && hash->algo < HASH_ALGO__LAST) {
+                tfm = crypto_alloc_shash(hash_algo_name[hash->algo], 0, 0);
+                if (IS_ERR(tfm)) {
+                        rc = PTR_ERR(tfm);
+                        pr_err("Can not allocate %s (reason: %d)\n",
+                               hash_algo_name[hash->algo], rc);
+                        return rc;
+                }
+        }
+
+        hash->length = crypto_shash_digestsize(tfm);
+
+        rc = ima_calc_file_hash_tfm(file, hash, tfm);
+
+        if (tfm != ima_shash_tfm)
+                crypto_free_shash(tfm);
+
+        return rc;
+}
+
 /*
  * Calculate the hash of a given buffer
  */
-int ima_calc_buffer_hash(const void *data, int len, char *digest)
+int ima_calc_buffer_hash(const void *buf, int len, struct ima_digest_data *hash)
 {
         struct {
                 struct shash_desc shash;
@@ -105,7 +134,11 @@ int ima_calc_buffer_hash(const void *data, int len, char *digest)
         desc.shash.tfm = ima_shash_tfm;
         desc.shash.flags = 0;
 
-        return crypto_shash_digest(&desc.shash, data, len, digest);
+        /* this function uses default algo */
+        hash->algo = ima_hash_algo;
+        hash->length = crypto_shash_digestsize(ima_shash_tfm);
+
+        return crypto_shash_digest(&desc.shash, buf, len, hash->digest);
 }
 
 static void __init ima_pcrread(int idx, u8 *pcr)
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 0f359df6344c..7708c2120d9c 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -24,6 +24,7 @@
 #include <linux/slab.h>
 #include <linux/xattr.h>
 #include <linux/ima.h>
+#include <crypto/hash_info.h>
 
 #include "ima.h"
 
@@ -35,11 +36,12 @@ int ima_appraise = IMA_APPRAISE_ENFORCE;
 int ima_appraise;
 #endif
 
-char *ima_hash = "sha1";
+int ima_hash_algo = HASH_ALGO_SHA1;
+
 static int __init hash_setup(char *str)
 {
         if (strncmp(str, "md5", 3) == 0)
-                ima_hash = "md5";
+                ima_hash_algo = HASH_ALGO_MD5;
         return 1;
 }
 __setup("ima_hash=", hash_setup);
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index f86731649f54..0b02ea868e30 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -59,20 +59,29 @@ enum evm_ima_xattr_type {
 struct evm_ima_xattr_data {
         u8 type;
         u8 digest[SHA1_DIGEST_SIZE];
-}  __attribute__((packed));
+} __packed;
+
+#define IMA_MAX_DIGEST_SIZE     64
+
+struct ima_digest_data {
+        u8 algo;
+        u8 length;
+        u8 type;
+        u8 digest[IMA_MAX_DIGEST_SIZE];
+} __packed;
 
 /* integrity data associated with an inode */
 struct integrity_iint_cache {
-        struct rb_node rb_node; /* rooted in integrity_iint_tree */
+        struct rb_node rb_node; /* rooted in integrity_iint_tree */
         struct inode *inode;    /* back pointer to inode in question */
         u64 version;            /* track inode changes */
         unsigned long flags;
-        struct evm_ima_xattr_data ima_xattr;
         enum integrity_status ima_file_status:4;
         enum integrity_status ima_mmap_status:4;
         enum integrity_status ima_bprm_status:4;
         enum integrity_status ima_module_status:4;
         enum integrity_status evm_status:4;
+        struct ima_digest_data ima_hash;
 };
 
 /* rbtree tree calls to lookup, insert, delete