[PATCH ghak96 v3] audit: issue CWD record to accompany LSM_AUDIT_DATA_* records

[Richard Guy Briggs <rgb@redhat.com>]

The LSM_AUDIT_DATA_* records for PATH, FILE, IOCTL_OP, DENTRY and INODE
are incomplete without the task context of the AUDIT Current Working
Directory record.  Add it.

This record addition can't use audit_dummy_context to determine whether
or not to store the record information since the LSM_AUDIT_DATA_*
records are initiated by various LSMs independent of any audit rules.
context->in_syscall is used to determine if it was called in user
context like audit_getname.

Please see the upstream issue
https://github.com/linux-audit/audit-kernel/issues/96

Adapted from Vladis Dronov's v2 patch.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
---
Passes audit-testsuite.

Changelog:
v3
- adapt and refactor__audit_getname, don't key on dummy

v2
2020-04-02 vdronov https://www.redhat.com/archives/linux-audit/2020-April/msg00004.html
- convert to standalone CWD record

v1:
2020-03-24 vdronov https://github.com/nefigtut/audit-kernel/commit/df0b55b7ab84e1c9faa588b08e547e604bf25c87
- add cwd= field to LSM record

 include/linux/audit.h |  9 ++++++++-
 kernel/auditsc.c      | 17 +++++++++++++++--
 security/lsm_audit.c  |  5 +++++
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 03c4035a532b..bb850d588e1c 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -292,7 +292,7 @@ extern void __audit_syscall_entry(int major, unsigned long a0, unsigned long a1,
 extern void __audit_syscall_exit(int ret_success, long ret_value);
 extern struct filename *__audit_reusename(const __user char *uptr);
 extern void __audit_getname(struct filename *name);
-
+extern void __audit_getcwd(void);
 extern void __audit_inode(struct filename *name, const struct dentry *dentry,
 				unsigned int flags);
 extern void __audit_file(const struct file *);
@@ -351,6 +351,11 @@ static inline void audit_getname(struct filename *name)
 	if (unlikely(!audit_dummy_context()))
 		__audit_getname(name);
 }
+static inline void audit_getcwd(void)
+{
+	if (unlikely(audit_context()))
+		__audit_getcwd();
+}
 static inline void audit_inode(struct filename *name,
 				const struct dentry *dentry,
 				unsigned int aflags) {
@@ -579,6 +584,8 @@ static inline struct filename *audit_reusename(const __user char *name)
 }
 static inline void audit_getname(struct filename *name)
 { }
+static inline void audit_getcwd(void)
+{ }
 static inline void audit_inode(struct filename *name,
 				const struct dentry *dentry,
 				unsigned int aflags)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 3a9100e95fda..934ab5b8c1c5 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1891,6 +1891,20 @@ struct filename *
 	return NULL;
 }
 
+inline void _audit_getcwd(struct audit_context *context)
+{
+	if (!context->pwd.dentry)
+		get_fs_pwd(current->fs, &context->pwd);
+}
+
+void __audit_getcwd(void)
+{
+	struct audit_context *context = audit_context();
+
+	if (context->in_syscall)
+		_audit_getcwd(context);
+}
+
 /**
  * __audit_getname - add a name to the list
  * @name: name to add
@@ -1915,8 +1929,7 @@ void __audit_getname(struct filename *name)
 	name->aname = n;
 	name->refcnt++;
 
-	if (!context->pwd.dentry)
-		get_fs_pwd(current->fs, &context->pwd);
+	_audit_getcwd(context);
 }
 
 static inline int audit_copy_fcaps(struct audit_names *name,
diff --git a/security/lsm_audit.c b/security/lsm_audit.c
index 2d2bf49016f4..7c555621c2bd 100644
--- a/security/lsm_audit.c
+++ b/security/lsm_audit.c
@@ -241,6 +241,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 			audit_log_untrustedstring(ab, inode->i_sb->s_id);
 			audit_log_format(ab, " ino=%lu", inode->i_ino);
 		}
+		audit_getcwd();
 		break;
 	}
 	case LSM_AUDIT_DATA_FILE: {
@@ -254,6 +255,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 			audit_log_untrustedstring(ab, inode->i_sb->s_id);
 			audit_log_format(ab, " ino=%lu", inode->i_ino);
 		}
+		audit_getcwd();
 		break;
 	}
 	case LSM_AUDIT_DATA_IOCTL_OP: {
@@ -269,6 +271,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 		}
 
 		audit_log_format(ab, " ioctlcmd=0x%hx", a->u.op->cmd);
+		audit_getcwd();
 		break;
 	}
 	case LSM_AUDIT_DATA_DENTRY: {
@@ -283,6 +286,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 			audit_log_untrustedstring(ab, inode->i_sb->s_id);
 			audit_log_format(ab, " ino=%lu", inode->i_ino);
 		}
+		audit_getcwd();
 		break;
 	}
 	case LSM_AUDIT_DATA_INODE: {
@@ -300,6 +304,7 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 		audit_log_format(ab, " dev=");
 		audit_log_untrustedstring(ab, inode->i_sb->s_id);
 		audit_log_format(ab, " ino=%lu", inode->i_ino);
+		audit_getcwd();
 		break;
 	}
 	case LSM_AUDIT_DATA_TASK: {
-- 
1.8.3.1