ima: Collect modsig

Obtain the modsig and calculate its corresponding hash in
ima_collect_measurement().

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index ed8e19d38805200d55164b3b18906edcc4a5cb0b..0bc764c80327bccbb1c3d15e4e22908119d19a3b 100644 (file)
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -207,7 +207,7 @@ int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid,
 int ima_must_measure(struct inode *inode, int mask, enum ima_hooks func);
 int ima_collect_measurement(struct integrity_iint_cache *iint,
                            struct file *file, void *buf, loff_t size,
-                           enum hash_algo algo);
+                           enum hash_algo algo, struct modsig *modsig);
 void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
                           const unsigned char *filename,
                           struct evm_ima_xattr_data *xattr_value,
@@ -311,6 +311,7 @@ static inline int ima_read_xattr(struct dentry *dentry,
 bool ima_hook_supports_modsig(enum ima_hooks func);
 int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len,
                    struct modsig **modsig);
+void ima_collect_modsig(struct modsig *modsig, const void *buf, loff_t size);
 void ima_free_modsig(struct modsig *modsig);
 #else
 static inline bool ima_hook_supports_modsig(enum ima_hooks func)
@@ -324,6 +325,11 @@ static inline int ima_read_modsig(enum ima_hooks func, const void *buf,
        return -EOPNOTSUPP;
 }
 
+static inline void ima_collect_modsig(struct modsig *modsig, const void *buf,
+                                     loff_t size)
+{
+}
+
 static inline void ima_free_modsig(struct modsig *modsig)
 {
 }

diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index f614e22bf39f47134c5124ce0d003ce5343abcbf..ff8b7fb03ea02284e1a899c86205ab9ce06ebe27 100644 (file)
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -205,7 +205,7 @@ int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid,
  */
 int ima_collect_measurement(struct integrity_iint_cache *iint,
                            struct file *file, void *buf, loff_t size,
-                           enum hash_algo algo)
+                           enum hash_algo algo, struct modsig *modsig)
 {
        const char *audit_cause = "failed";
        struct inode *inode = file_inode(file);
@@ -252,6 +252,9 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
        memcpy(iint->ima_hash, &hash, length);
        iint->version = i_version;
 
+       if (modsig)
+               ima_collect_modsig(modsig, buf, size);
+
        /* Possibly temporary failure due to type of read (eg. O_DIRECT) */
        if (!result)
                iint->flags |= IMA_COLLECTED;

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index d21e40eaba426a1782062d93ec2d1374b2522647..136ae4e0ee92124c219e9c031060db439f1b4d54 100644 (file)
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -435,7 +435,7 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
            !(iint->flags & IMA_HASH))
                return;
 
-       rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo);
+       rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo, NULL);
        if (rc < 0)
                return;
 

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index d8672e850615f07a950075758770a700b470a17e..7c8d92cf27559a6e6f8ed6326eead516188ff00e 100644 (file)
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -314,7 +314,7 @@ static int process_measurement(struct file *file, const struct cred *cred,
 
        hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
 
-       rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
+       rc = ima_collect_measurement(iint, file, buf, size, hash_algo, modsig);
        if (rc != 0 && rc != -EBADF && rc != -EINVAL)
                goto out_locked;
 

diff --git a/security/integrity/ima/ima_modsig.c b/security/integrity/ima/ima_modsig.c
index f41ebe370fa07c725ab8c6c36b73b91fd3400d84..257387ce3b70418ada9e9529bd48e43ed15f7906 100644 (file)
--- a/security/integrity/ima/ima_modsig.c
+++ b/security/integrity/ima/ima_modsig.c
@@ -17,6 +17,19 @@
 
 struct modsig {
        struct pkcs7_message *pkcs7_msg;
+
+       enum hash_algo hash_algo;
+
+       /* This digest will go in the 'd-modsig' field of the IMA template. */
+       const u8 *digest;
+       u32 digest_size;
+
+       /*
+        * This is what will go to the measurement list if the template requires
+        * storing the signature.
+        */
+       int raw_pkcs7_len;
+       u8 raw_pkcs7[];
 };
 
 /**
@@ -71,7 +84,8 @@ int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len,
        sig_len = be32_to_cpu(sig->sig_len);
        buf_len -= sig_len + sizeof(*sig);
 
-       hdr = kmalloc(sizeof(*hdr), GFP_KERNEL);
+       /* Allocate sig_len additional bytes to hold the raw PKCS#7 data. */
+       hdr = kzalloc(sizeof(*hdr) + sig_len, GFP_KERNEL);
        if (!hdr)
                return -ENOMEM;
 
@@ -81,11 +95,43 @@ int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len,
                return PTR_ERR(hdr->pkcs7_msg);
        }
 
+       memcpy(hdr->raw_pkcs7, buf + buf_len, sig_len);
+       hdr->raw_pkcs7_len = sig_len;
+
+       /* We don't know the hash algorithm yet. */
+       hdr->hash_algo = HASH_ALGO__LAST;
+
        *modsig = hdr;
 
        return 0;
 }
 
+/**
+ * ima_collect_modsig - Calculate the file hash without the appended signature.
+ *
+ * Since the modsig is part of the file contents, the hash used in its signature
+ * isn't the same one ordinarily calculated by IMA. Therefore PKCS7 code
+ * calculates a separate one for signature verification.
+ */
+void ima_collect_modsig(struct modsig *modsig, const void *buf, loff_t size)
+{
+       int rc;
+
+       /*
+        * Provide the file contents (minus the appended sig) so that the PKCS7
+        * code can calculate the file hash.
+        */
+       size -= modsig->raw_pkcs7_len + strlen(MODULE_SIG_STRING) +
+               sizeof(struct module_signature);
+       rc = pkcs7_supply_detached_data(modsig->pkcs7_msg, buf, size);
+       if (rc)
+               return;
+
+       /* Ask the PKCS7 code to calculate the file hash. */
+       rc = pkcs7_get_digest(modsig->pkcs7_msg, &modsig->digest,
+                             &modsig->digest_size, &modsig->hash_algo);
+}
+
 int ima_modsig_verify(struct key *keyring, const struct modsig *modsig)
 {
        return verify_pkcs7_message_sig(NULL, 0, modsig->pkcs7_msg, keyring,