linux-kernel - [PATCH ghak96] audit: set cwd in audit context for file-related LSM audit records

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Message-Id: <20200402141319.28714-1-vdronov@redhat.com>
Date:   Thu,  2 Apr 2020 16:13:19 +0200
From:   Vladis Dronov <vdronov@...hat.com>
To:     Paul Moore <paul@...l-moore.com>, Eric Paris <eparis@...hat.com>,
        linux-audit@...hat.com, James Morris <jmorris@...ei.org>,
        "Serge E . Hallyn" <serge@...lyn.com>,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH ghak96] audit: set cwd in audit context for file-related LSM audit records

Set a current working directory in an audit context for the following record
types in dump_common_audit_data(): LSM_AUDIT_DATA_PATH, LSM_AUDIT_DATA_FILE,
LSM_AUDIT_DATA_IOCTL_OP, LSM_AUDIT_DATA_DENTRY, LSM_AUDIT_DATA_INODE so a
separate CWD record is emitted later.

Link: https://github.com/linux-audit/audit-kernel/issues/96
Signed-off-by: Vladis Dronov <vdronov@...hat.com>
---
out-of-commit-message-note:

Hello,
Honestly, I'm not sure about "if (!context->in_syscall)" check in
__audit_getcwd(). It was copied from __audit_getname() and I do
not quite understand why it is there and if __audit_getcwd() needs
it. If you have an idea on this, could you please, tell?

 include/linux/audit.h |  9 ++++++++-
 kernel/auditsc.c      | 17 +++++++++++++++++
 security/lsm_audit.c  |  5 +++++
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index f9ceae57ca8d..b4306abc5891 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -268,7 +268,7 @@ 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 *);
@@ -327,6 +327,11 @@ 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_dummy_context()))
+		__audit_getcwd();
+}
 static inline void audit_inode(struct filename *name,
 				const struct dentry *dentry,
 				unsigned int aflags) {
@@ -545,6 +550,8 @@ 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 flags)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 814406a35db1..16316032ef9f 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1890,6 +1890,23 @@ void __audit_getname(struct filename *name)
 		get_fs_pwd(current->fs, &context->pwd);
 }
 
+/**
+ * __audit_getcwd - set a current working directory
+ *
+ * Set a current working directory of an audited process for this context.
+ * Called from security/lsm_audit.c:dump_common_audit_data().
+ */
+void __audit_getcwd(void)
+{
+	struct audit_context *context = audit_context();
+
+	if (!context->in_syscall)
+		return;
+
+	if (!context->pwd.dentry)
+		get_fs_pwd(current->fs, &context->pwd);
+}
+
 static inline int audit_copy_fcaps(struct audit_names *name,
 				   const struct dentry *dentry)
 {
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: {
-- 
2.20.1