Merge branch 'serge-next-2' of git://git.kernel.org/pub/scm/linux/kernel/git/sergeh/linux-security

Pull more security layer updates from Serge Hallyn:
 "A few more commits had previously failed to make it through
  security-next into linux-next but this week made it into linux-next.
  At least commit "ima: introduce ima_kernel_read()" was deemed critical
  by Mimi to make this merge window.

  This is a temporary tree just for this request.  Mimi has pointed me
  to some previous threads about keeping maintainer trees at the
  previous release, which I'll certainly do for anything long-term,
  after talking with James"

* 'serge-next-2' of git://git.kernel.org/pub/scm/linux/kernel/git/sergeh/linux-security:
  ima: introduce ima_kernel_read()
  evm: prohibit userspace writing 'security.evm' HMAC value
  ima: check inode integrity cache in violation check
  ima: prevent unnecessary policy checking
  evm: provide option to protect additional SMACK xattrs
  evm: replace HMAC version with attribute mask
  ima: prevent new digsig xattr from being replaced

7 files changed, 114 insertions, 28 deletions

diff --git a/security/integrity/evm/Kconfig b/security/integrity/evm/Kconfig
index d35b4915b00d..d606f3d12d6b 100644
--- a/security/integrity/evm/Kconfig
+++ b/security/integrity/evm/Kconfig
@@ -12,15 +12,41 @@ config EVM
 
           If you are unsure how to answer this question, answer N.
 
-config EVM_HMAC_VERSION
-        int "EVM HMAC version"
+if EVM
+
+menu "EVM options"
+
+config EVM_ATTR_FSUUID
+        bool "FSUUID (version 2)"
+        default y
         depends on EVM
-        default 2
         help
-          This options adds EVM HMAC version support.
-          1 - original version
-          2 - add per filesystem unique identifier (UUID) (default)
+          Include filesystem UUID for HMAC calculation.
+
+          Default value is 'selected', which is former version 2.
+          if 'not selected', it is former version 1
 
-          WARNING: changing the HMAC calculation method or adding 
+          WARNING: changing the HMAC calculation method or adding
           additional info to the calculation, requires existing EVM
-          labeled file systems to be relabeled.  
+          labeled file systems to be relabeled.
+
+config EVM_EXTRA_SMACK_XATTRS
+        bool "Additional SMACK xattrs"
+        depends on EVM && SECURITY_SMACK
+        default n
+        help
+          Include additional SMACK xattrs for HMAC calculation.
+
+          In addition to the original security xattrs (eg. security.selinux,
+          security.SMACK64, security.capability, and security.ima) included
+          in the HMAC calculation, enabling this option includes newly defined
+          Smack xattrs: security.SMACK64EXEC, security.SMACK64TRANSMUTE and
+          security.SMACK64MMAP.
+
+          WARNING: changing the HMAC calculation method or adding
+          additional info to the calculation, requires existing EVM
+          labeled file systems to be relabeled.
+
+endmenu
+
+endif
diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h
index 37c88ddb3cfe..88bfe77efa1c 100644
--- a/security/integrity/evm/evm.h
+++ b/security/integrity/evm/evm.h
@@ -24,7 +24,10 @@
 extern int evm_initialized;
 extern char *evm_hmac;
 extern char *evm_hash;
-extern int evm_hmac_version;
+
+#define EVM_ATTR_FSUUID         0x0001
+
+extern int evm_hmac_attrs;
 
 extern struct crypto_shash *hmac_tfm;
 extern struct crypto_shash *hash_tfm;
diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index 6b540f1822e0..5e9687f02e1b 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -112,7 +112,7 @@ static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
         hmac_misc.gid = from_kgid(&init_user_ns, inode->i_gid);
         hmac_misc.mode = inode->i_mode;
         crypto_shash_update(desc, (const u8 *)&hmac_misc, sizeof(hmac_misc));
-        if (evm_hmac_version > 1)
+        if (evm_hmac_attrs & EVM_ATTR_FSUUID)
                 crypto_shash_update(desc, inode->i_sb->s_uuid,
                                     sizeof(inode->i_sb->s_uuid));
         crypto_shash_final(desc, digest);
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 6e0bd933b6a9..3bcb80df4d01 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -32,7 +32,7 @@ static char *integrity_status_msg[] = {
 };
 char *evm_hmac = "hmac(sha1)";
 char *evm_hash = "sha1";
-int evm_hmac_version = CONFIG_EVM_HMAC_VERSION;
+int evm_hmac_attrs;
 
 char *evm_config_xattrnames[] = {
 #ifdef CONFIG_SECURITY_SELINUX
@@ -40,6 +40,11 @@ char *evm_config_xattrnames[] = {
 #endif
 #ifdef CONFIG_SECURITY_SMACK
         XATTR_NAME_SMACK,
+#ifdef CONFIG_EVM_EXTRA_SMACK_XATTRS
+        XATTR_NAME_SMACKEXEC,
+        XATTR_NAME_SMACKTRANSMUTE,
+        XATTR_NAME_SMACKMMAP,
+#endif
 #endif
 #ifdef CONFIG_IMA_APPRAISE
         XATTR_NAME_IMA,
@@ -57,6 +62,14 @@ static int __init evm_set_fixmode(char *str)
 }
 __setup("evm=", evm_set_fixmode);
 
+static void __init evm_init_config(void)
+{
+#ifdef CONFIG_EVM_ATTR_FSUUID
+        evm_hmac_attrs |= EVM_ATTR_FSUUID;
+#endif
+        pr_info("HMAC attrs: 0x%x\n", evm_hmac_attrs);
+}
+
 static int evm_find_protected_xattrs(struct dentry *dentry)
 {
         struct inode *inode = dentry->d_inode;
@@ -287,12 +300,20 @@ out:
  * @xattr_value: pointer to the new extended attribute value
  * @xattr_value_len: pointer to the new extended attribute value length
  *
- * Updating 'security.evm' requires CAP_SYS_ADMIN privileges and that
- * the current value is valid.
+ * Before allowing the 'security.evm' protected xattr to be updated,
+ * verify the existing value is valid.  As only the kernel should have
+ * access to the EVM encrypted key needed to calculate the HMAC, prevent
+ * userspace from writing HMAC value.  Writing 'security.evm' requires
+ * requires CAP_SYS_ADMIN privileges.
  */
 int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name,
                        const void *xattr_value, size_t xattr_value_len)
 {
+        const struct evm_ima_xattr_data *xattr_data = xattr_value;
+
+        if ((strcmp(xattr_name, XATTR_NAME_EVM) == 0)
+            && (xattr_data->type == EVM_XATTR_HMAC))
+                return -EPERM;
         return evm_protect_xattr(dentry, xattr_name, xattr_value,
                                  xattr_value_len);
 }
@@ -432,6 +453,8 @@ static int __init init_evm(void)
 {
         int error;
 
+        evm_init_config();
+
         error = evm_init_secfs();
         if (error < 0) {
                 pr_info("Error registering secfs\n");
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 291bf0f3a46d..d3113d4aaa3c 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -341,7 +341,7 @@ static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name,
         return 0;
 }
 
-static void ima_reset_appraise_flags(struct inode *inode)
+static void ima_reset_appraise_flags(struct inode *inode, int digsig)
 {
         struct integrity_iint_cache *iint;
 
@@ -353,18 +353,22 @@ static void ima_reset_appraise_flags(struct inode *inode)
                 return;
 
         iint->flags &= ~IMA_DONE_MASK;
+        if (digsig)
+                iint->flags |= IMA_DIGSIG;
         return;
 }
 
 int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
                        const void *xattr_value, size_t xattr_value_len)
 {
+        const struct evm_ima_xattr_data *xvalue = xattr_value;
         int result;
 
         result = ima_protect_xattr(dentry, xattr_name, xattr_value,
                                    xattr_value_len);
         if (result == 1) {
-                ima_reset_appraise_flags(dentry->d_inode);
+                ima_reset_appraise_flags(dentry->d_inode,
+                         (xvalue->type == EVM_IMA_XATTR_DIGSIG) ? 1 : 0);
                 result = 0;
         }
         return result;
@@ -376,7 +380,7 @@ int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name)
 
         result = ima_protect_xattr(dentry, xattr_name, NULL, 0);
         if (result == 1) {
-                ima_reset_appraise_flags(dentry->d_inode);
+                ima_reset_appraise_flags(dentry->d_inode, 0);
                 result = 0;
         }
         return result;
diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index 1bde8e627766..ccd0ac8fa9a0 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -27,6 +27,36 @@
 
 static struct crypto_shash *ima_shash_tfm;
 
+/**
+ * ima_kernel_read - read file content
+ *
+ * This is a function for reading file content instead of kernel_read().
+ * It does not perform locking checks to ensure it cannot be blocked.
+ * It does not perform security checks because it is irrelevant for IMA.
+ *
+ */
+static int ima_kernel_read(struct file *file, loff_t offset,
+                           char *addr, unsigned long count)
+{
+        mm_segment_t old_fs;
+        char __user *buf = addr;
+        ssize_t ret;
+
+        if (!(file->f_mode & FMODE_READ))
+                return -EBADF;
+        if (!file->f_op->read && !file->f_op->aio_read)
+                return -EINVAL;
+
+        old_fs = get_fs();
+        set_fs(get_ds());
+        if (file->f_op->read)
+                ret = file->f_op->read(file, buf, count, &offset);
+        else
+                ret = do_sync_read(file, buf, count, &offset);
+        set_fs(old_fs);
+        return ret;
+}
+
 int ima_init_crypto(void)
 {
         long rc;
@@ -104,7 +134,7 @@ static int ima_calc_file_hash_tfm(struct file *file,
         while (offset < i_size) {
                 int rbuf_len;
 
-                rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE);
+                rbuf_len = ima_kernel_read(file, offset, rbuf, PAGE_SIZE);
                 if (rbuf_len < 0) {
                         rc = rbuf_len;
                         break;
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index dcc98cf542d8..09baa335ebc7 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -81,7 +81,6 @@ static void ima_rdwr_violation_check(struct file *file)
 {
         struct inode *inode = file_inode(file);
         fmode_t mode = file->f_mode;
-        int must_measure;
         bool send_tomtou = false, send_writers = false;
         char *pathbuf = NULL;
         const char *pathname;
@@ -92,18 +91,19 @@ static void ima_rdwr_violation_check(struct file *file)
         mutex_lock(&inode->i_mutex);    /* file metadata: permissions, xattr */
 
         if (mode & FMODE_WRITE) {
-                if (atomic_read(&inode->i_readcount) && IS_IMA(inode))
-                        send_tomtou = true;
-                goto out;
+                if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
+                        struct integrity_iint_cache *iint;
+                        iint = integrity_iint_find(inode);
+                        /* IMA_MEASURE is set from reader side */
+                        if (iint && (iint->flags & IMA_MEASURE))
+                                send_tomtou = true;
+                }
+        } else {
+                if ((atomic_read(&inode->i_writecount) > 0) &&
+                    ima_must_measure(inode, MAY_READ, FILE_CHECK))
+                        send_writers = true;
         }
 
-        must_measure = ima_must_measure(inode, MAY_READ, FILE_CHECK);
-        if (!must_measure)
-                goto out;
-
-        if (atomic_read(&inode->i_writecount) > 0)
-                send_writers = true;
-out:
         mutex_unlock(&inode->i_mutex);
 
         if (!send_tomtou && !send_writers)