[PATCH 1/3] audit: implement audit by executable

Eric Paris
2014-05-13T22:11:22Z

This patch implements the ability to filter on the executable. It is
clearly incomplete! This patch adds the inode/dev of the executable at
the moment the rule is loaded. It does not update if the executable is
updated/moved/whatever. That should be added. But at this moment, this
patch works.

Based-on-user-interface-by: Richard Guy Briggs <rgb@redhat.com>
Cc: rgb@redhat.com
Based-on-idea-by: Peter Moody <pmoody@google.com>
Cc: pmoody@google.com
Signed-off-by: Eric Paris <eparis@redhat.com>
---
include/linux/audit.h | 1 +
include/uapi/linux/audit.h | 2 +
kernel/Makefile | 2 +-
kernel/audit.h | 27 +++++++++++
kernel/audit_exe.c | 113 +++++++++++++++++++++++++++++++++++++++++++++
kernel/auditfilter.c | 43 +++++++++++++++++
kernel/auditsc.c | 16 +++++++
7 files changed, 203 insertions(+), 1 deletion(-)
create mode 100644 kernel/audit_exe.c

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 1ae0089..84e7bc4 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -59,6 +59,7 @@ struct audit_krule {
struct audit_field *inode_f; /* quick access to an inode field */
struct audit_watch *watch; /* associated watch */
struct audit_tree *tree; /* associated watched tree */
+ struct audit_exe *exe;
struct list_head rlist; /* entry in audit_{watch,tree}.rules list */
struct list_head list; /* for AUDIT_LIST* purposes only */
u64 prio;
diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index d95eba0..e916088 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -266,6 +266,8 @@
#define AUDIT_OBJ_UID 109
#define AUDIT_OBJ_GID 110
#define AUDIT_FIELD_COMPARE 111
+#define AUDIT_EXE 112
+#define AUDIT_EXE_CHILDREN 113

#define AUDIT_ARG0 200
#define AUDIT_ARG1 (AUDIT_ARG0+1)
diff --git a/kernel/Makefile b/kernel/Makefile
index bc010ee..a1d5715 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -61,7 +61,7 @@ obj-$(CONFIG_SMP) += stop_machine.o
obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
obj-$(CONFIG_AUDIT) += audit.o auditfilter.o
obj-$(CONFIG_AUDITSYSCALL) += auditsc.o
-obj-$(CONFIG_AUDIT_WATCH) += audit_watch.o
+obj-$(CONFIG_AUDIT_WATCH) += audit_watch.o audit_exe.o
obj-$(CONFIG_AUDIT_TREE) += audit_tree.o
obj-$(CONFIG_GCOV_KERNEL) += gcov/
obj-$(CONFIG_KPROBES) += kprobes.o
diff --git a/kernel/audit.h b/kernel/audit.h
index 7bb6573..58ed955 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -56,6 +56,7 @@ enum audit_state {

/* Rule lists */
struct audit_watch;
+struct audit_exe;
struct audit_tree;
struct audit_chunk;

@@ -280,6 +281,13 @@ extern int audit_add_watch(struct audit_krule *krule, struct list_head **list);
extern void audit_remove_watch_rule(struct audit_krule *krule);
extern char *audit_watch_path(struct audit_watch *watch);
extern int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev);
+
+int audit_make_exe_rule(struct audit_krule *krule, char *pathname, int len, u32 op);
+void audit_remove_exe_rule(struct audit_krule *krule);
+char *audit_exe_path(struct audit_exe *exe);
+int audit_dup_exe(struct audit_krule *new, struct audit_krule *old);
+int audit_exe_compare(struct task_struct *tsk, struct audit_exe *exe);
+
#else
#define audit_put_watch(w) {}
#define audit_get_watch(w) {}
@@ -289,6 +297,25 @@ extern int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev
#define audit_watch_path(w) ""
#define audit_watch_compare(w, i, d) 0

+static inline int audit_make_exe_rule(struct audit_krule *krule, char *pathname, int len, u32 op) {
+ return -EINVAL;
+}
+static inline void audit_remove_exe_rule(struct audit_krule *krule) {
+ BUG();
+ return 0;
+}
+static inline char *audit_exe_path(struct audit_exe *exe) {
+ BUG();
+ return "";
+}
+static inline int audit_dup_exe(struct audit_krule *new, struct audit_krule *old) {
+ BUG();
+ return -EINVAL
+}
+static inline int audit_exe_compare(struct task_struct *tsk, struct audit_exe *exe) {
+ BUG();
+ return 0;
+}
#endif /* CONFIG_AUDIT_WATCH */

#ifdef CONFIG_AUDIT_TREE
diff --git a/kernel/audit_exe.c b/kernel/audit_exe.c
new file mode 100644
index 0000000..09c436c
--- /dev/null
+++ b/kernel/audit_exe.c
@@ -0,0 +1,113 @@
+/* audit_exe.c -- filtering of audit events
+ *
+ * Copyright 2014 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/audit.h>
+#include <linux/mutex.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/slab.h>
+#include "audit.h"
+
+struct audit_exe {
+ char *pathname;
+ unsigned long ino;
+ dev_t dev;
+};
+
+/* Translate a watch string to kernel respresentation. */
+int audit_make_exe_rule(struct audit_krule *krule, char *pathname, int len, u32 op)
+{
+ struct audit_exe *exe;
+ struct path path;
+ struct dentry *dentry;
+ unsigned long ino;
+ dev_t dev;
+
+ if (pathname[0] != '/' || pathname[len-1] == '/')
+ return -EINVAL;
+
+ dentry = kern_path_locked(pathname, &path);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+ mutex_unlock(&path.dentry->d_inode->i_mutex);
+
+ if (!dentry->d_inode)
+ return -ENOENT;
+ dev = dentry->d_inode->i_sb->s_dev;
+ ino = dentry->d_inode->i_ino;
+ dput(dentry);
+
+ exe = kmalloc(sizeof(*exe), GFP_KERNEL);
+ if (!exe)
+ return -ENOMEM;
+ exe->ino = ino;
+ exe->dev = dev;
+ exe->pathname = pathname;
+ krule->exe = exe;
+
+ return 0;
+}
+
+void audit_remove_exe_rule(struct audit_krule *krule)
+{
+ struct audit_exe *exe;
+
+ exe = krule->exe;
+ krule->exe = NULL;
+ kfree(exe->pathname);
+ kfree(exe);
+}
+
+char *audit_exe_path(struct audit_exe *exe)
+{
+ return exe->pathname;
+}
+
+int audit_dup_exe(struct audit_krule *new, struct audit_krule *old)
+{
+ struct audit_exe *exe;
+
+ exe = kmalloc(sizeof(*exe), GFP_KERNEL);
+ if (!exe)
+ return -ENOMEM;
+
+ exe->pathname = kstrdup(old->exe->pathname, GFP_KERNEL);
+ if (!exe->pathname) {
+ kfree(exe);
+ return -ENOMEM;
+ }
+
+ exe->ino = old->exe->ino;
+ exe->dev = old->exe->dev;
+ new->exe = exe;
+
+ return 0;
+}
+
+int audit_exe_compare(struct task_struct *tsk, struct audit_exe *exe)
+{
+ if (tsk->mm->exe_file->f_inode->i_ino != exe->ino)
+ return 0;
+ if (tsk->mm->exe_file->f_inode->i_sb->s_dev != exe->dev)
+ return 0;
+ return 1;
+}
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 8e9bc9c..9caeaf5 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -390,6 +390,13 @@ static int audit_field_valid(struct audit_entry *entry, struct audit_field *f)
if (f->val > AUDIT_MAX_FIELD_COMPARE)
return -EINVAL;
break;
+ case AUDIT_EXE:
+ case AUDIT_EXE_CHILDREN:
+ if (f->op != Audit_equal)
+ return -EINVAL;
+ if (entry->rule.listnr != AUDIT_FILTER_EXIT)
+ return -EINVAL;
+ break;
};
return 0;
}
@@ -541,6 +548,23 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
entry->rule.buflen += f->val;
entry->rule.filterkey = str;
break;
+ case AUDIT_EXE:
+ case AUDIT_EXE_CHILDREN:
+ if (entry->rule.exe || f->val > PATH_MAX)
+ goto exit_free;
+ str = audit_unpack_string(&bufp, &remain, f->val);
+ if (IS_ERR(str)) {
+ err = PTR_ERR(str);
+ goto exit_free;
+ }
+ entry->rule.buflen += f->val;
+
+ err = audit_make_exe_rule(&entry->rule, str, f->val, f->op);
+ if (err) {
+ kfree(str);
+ goto exit_free;
+ }
+ break;
}
}

@@ -619,6 +643,11 @@ static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
data->buflen += data->values[i] =
audit_pack_string(&bufp, krule->filterkey);
break;
+ case AUDIT_EXE:
+ case AUDIT_EXE_CHILDREN:
+ data->buflen += data->values[i] =
+ audit_pack_string(&bufp, audit_exe_path(krule->exe));
+ break;
default:
data->values[i] = f->val;
}
@@ -674,6 +703,13 @@ static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
if (strcmp(a->filterkey, b->filterkey))
return 1;
break;
+ case AUDIT_EXE:
+ case AUDIT_EXE_CHILDREN:
+ /* both paths exist based on above type compare */
+ if (strcmp(audit_exe_path(a->exe),
+ audit_exe_path(b->exe)))
+ return 1;
+ break;
case AUDIT_UID:
case AUDIT_EUID:
case AUDIT_SUID:
@@ -795,6 +831,11 @@ struct audit_entry *audit_dupe_rule(struct audit_krule *old)
err = -ENOMEM;
else
new->filterkey = fk;
+ break;
+ case AUDIT_EXE:
+ case AUDIT_EXE_CHILDREN:
+ err = audit_dup_exe(new, old);
+ break;
}
if (err) {
audit_free_rule(entry);
@@ -966,6 +1007,8 @@ static inline int audit_del_rule(struct audit_entry *entry)
if (e->rule.tree)
audit_remove_tree_rule(&e->rule);

+ if (e->rule.exe)
+ audit_remove_exe_rule(&e->rule);
list_del_rcu(&e->list);
list_del(&e->rule.list);
call_rcu(&e->rcu, audit_free_rule_rcu);
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index b12a712..fa11362 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -48,6 +48,7 @@
#include <asm/types.h>
#include <linux/atomic.h>
#include <linux/fs.h>
+#include <linux/dcache.h>
#include <linux/namei.h>
#include <linux/mm.h>
#include <linux/export.h>
@@ -71,6 +72,7 @@
#include <linux/capability.h>
#include <linux/fs_struct.h>
#include <linux/compat.h>
+#include <linux/sched.h>
#include <linux/ctype.h>

#include "audit.h"
@@ -472,6 +474,20 @@ static int audit_filter_rules(struct task_struct *tsk,
result = audit_comparator(ctx->ppid, f->op, f->val);
}
break;
+ case AUDIT_EXE:
+ result = audit_exe_compare(tsk, rule->exe);
+ break;
+ case AUDIT_EXE_CHILDREN:
+ {
+ struct task_struct *ptsk;
+ for (ptsk = tsk; ptsk->parent->pid > 0; ptsk = find_task_by_vpid(ptsk->parent->pid)) {
+ if (audit_exe_compare(ptsk, rule->exe)) {
+ ++result;
+ break;
+ }
+ }
+ }
+ break;
case AUDIT_UID:
result = audit_uid_comparator(cred->uid, f->op, f->uid);
break;
--
1.9.0