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authorMimi Zohar <zohar@linux.vnet.ibm.com>2016-02-29 19:52:05 -0500
committerMimi Zohar <zohar@linux.vnet.ibm.com>2016-05-01 09:23:52 -0400
commit05d1a717ec0430c916a749b94eb90ab74bbfa356 (patch)
treed5283278e18669da5c76e41d1d33d58787dc61bc /security
parent42a4c603198f0d45b7aa936d3ac6ba1b8bd14a1b (diff)
downloadlinux-05d1a717ec0430c916a749b94eb90ab74bbfa356.tar.bz2
ima: add support for creating files using the mknodat syscall
Commit 3034a14 "ima: pass 'opened' flag to identify newly created files" stopped identifying empty files as new files. However new empty files can be created using the mknodat syscall. On systems with IMA-appraisal enabled, these empty files are not labeled with security.ima extended attributes properly, preventing them from subsequently being opened in order to write the file data contents. This patch defines a new hook named ima_post_path_mknod() to mark these empty files, created using mknodat, as new in order to allow the file data contents to be written. In addition, files with security.ima xattrs containing a file signature are considered "immutable" and can not be modified. The file contents need to be written, before signing the file. This patch relaxes this requirement for new files, allowing the file signature to be written before the file contents. Changelog: - defer identifying files with signatures stored as security.ima (based on Dmitry Rozhkov's comments) - removing tests (eg. dentry, dentry->d_inode, inode->i_size == 0) (based on Al's review) Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: Al Viro <<viro@zeniv.linux.org.uk> Tested-by: Dmitry Rozhkov <dmitry.rozhkov@linux.intel.com>
Diffstat (limited to 'security')
-rw-r--r--security/integrity/ima/ima_appraise.c5
-rw-r--r--security/integrity/ima/ima_main.c25
2 files changed, 29 insertions, 1 deletions
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index d2f28a0c8614..1bcbc12e03d9 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -275,6 +275,11 @@ out:
xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
if (!ima_fix_xattr(dentry, iint))
status = INTEGRITY_PASS;
+ } else if ((inode->i_size == 0) &&
+ (iint->flags & IMA_NEW_FILE) &&
+ (xattr_value &&
+ xattr_value->type == EVM_IMA_XATTR_DIGSIG)) {
+ status = INTEGRITY_PASS;
}
integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
op, cause, rc, 0);
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 391f41751021..68b26c340acd 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -246,7 +246,8 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
ima_audit_measurement(iint, pathname);
out_digsig:
- if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG))
+ if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG) &&
+ !(iint->flags & IMA_NEW_FILE))
rc = -EACCES;
kfree(xattr_value);
out_free:
@@ -316,6 +317,28 @@ int ima_file_check(struct file *file, int mask, int opened)
EXPORT_SYMBOL_GPL(ima_file_check);
/**
+ * ima_post_path_mknod - mark as a new inode
+ * @dentry: newly created dentry
+ *
+ * Mark files created via the mknodat syscall as new, so that the
+ * file data can be written later.
+ */
+void ima_post_path_mknod(struct dentry *dentry)
+{
+ struct integrity_iint_cache *iint;
+ struct inode *inode = dentry->d_inode;
+ int must_appraise;
+
+ must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
+ if (!must_appraise)
+ return;
+
+ iint = integrity_inode_get(inode);
+ if (iint)
+ iint->flags |= IMA_NEW_FILE;
+}
+
+/**
* ima_read_file - pre-measure/appraise hook decision based on policy
* @file: pointer to the file to be measured/appraised/audit
* @read_id: caller identifier