[TOMOYO 09/15] Argv[0] access control functions.

[Kentaro Takeda <k.takeda26@gmail.com>]

argv[0] check functions for TOMOYO Linux.
If the executed program name and argv[0] is different,
TOMOYO Linux checks permission.

Each permission can be automatically accumulated into
the policy of each domain using 'learning mode'.

Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
 security/tomoyo/exec.c |  230 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 230 insertions(+)

--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/security/tomoyo/exec.c	2007-08-24 15:51:37.000000000 +0900
@@ -0,0 +1,230 @@
+/*
+ * security/tomoyo/exec.c
+ *
+ * Argv0 access control functions for TOMOYO Linux.
+ */
+
+#include "tomoyo.h"
+#include "realpath.h"
+
+/*************************  AUDIT FUNCTIONS  *************************/
+
+static int tmy_audit_argv0_log(const struct path_info *filename,
+			       const char *argv0,
+			       const int is_granted,
+			       const int is_enforce)
+{
+	char *buf;
+	int len;
+
+	if (is_granted) {
+		if (!tmy_audit_grant())
+			return 0;
+	} else {
+		if (!tmy_audit_reject())
+			return 0;
+	}
+
+	len = filename->total_len + strlen(argv0) + 8;
+	buf = tmy_init_audit_log(&len);
+
+	if (!buf)
+		return -ENOMEM;
+
+	snprintf(buf + strlen(buf),
+		 len - strlen(buf) - 1,
+		 TMY_ALLOW_ARGV0 "%s %s",
+		 filename->name,
+		 argv0);
+
+	return tmy_write_audit_log(buf, is_granted, is_enforce);
+}
+
+/*************************  ARGV0 MISMATCH HANDLER  *************************/
+
+/*
+ * @is_add:   1  add this entry if not quota exceeded
+ *           -1  always add this entry
+ *            0  remove this entry
+ */
+static int tmy_add_argv0_entry(const char *filename,
+			       const char *argv0,
+			       struct domain_info *domain,
+			       const struct condition_list *cond,
+			       const u8 is_add)
+{
+	struct acl_info *ptr;
+	const struct path_info *saved_filename;
+	const struct path_info *saved_argv0;
+	int error = -ENOMEM;
+
+	if (!tmy_correct_path(filename, 1, 0, -1, __FUNCTION__) ||
+	    !tmy_correct_path(argv0, -1, 0, -1, __FUNCTION__) ||
+	    strchr(argv0, '/'))
+		return -EINVAL;
+
+	saved_filename = tmy_save_name(filename);
+	saved_argv0 = tmy_save_name(argv0);
+	if (!saved_filename || !saved_argv0)
+		return -ENOMEM;
+
+	down(&domain_acl_lock);
+
+	if (!is_add)
+		goto remove;
+
+	ptr = domain->first_acl_ptr;
+	if (!ptr)
+		goto first_entry;
+	while (1) {
+		struct argv0_acl *acl = (struct argv0_acl *) ptr;
+
+		if (ptr->type == TMY_TYPE_ARGV0_ACL && ptr->cond == cond &&
+		    acl->filename == saved_filename &&
+		    acl->argv0 == saved_argv0) {
+			ptr->is_deleted = 0;
+			/* Found. Nothing to do. */
+			error = 0;
+			break;
+		}
+
+		if (ptr->next) {
+			ptr = ptr->next;
+			continue;
+		}
+
+first_entry: ;
+		if (is_add == 1 && tmy_too_many_acl(domain))
+			break;
+
+		/* Not found. Append it to the tail. */
+		acl = tmy_alloc_element(sizeof(*acl));
+		if (!acl)
+			break;
+
+		acl->head.type = TMY_TYPE_ARGV0_ACL;
+		acl->head.cond = cond;
+		acl->filename = saved_filename;
+		acl->argv0 = saved_argv0;
+		error = tmy_add_acl(ptr, domain,
+				    (struct acl_info *) acl);
+
+		break;
+	}
+	goto ok;
+remove: ;
+	error = -ENOENT;
+	for (ptr = domain->first_acl_ptr; ptr; ptr = ptr->next) {
+		struct argv0_acl *acl = (struct argv0_acl *) ptr;
+
+		if (ptr->type != TMY_TYPE_ARGV0_ACL ||
+		    ptr->cond != cond || ptr->is_deleted ||
+		    acl->filename != saved_filename ||
+		    acl->argv0 != saved_argv0)
+			continue;
+
+		error = tmy_del_acl(ptr);
+		break;
+	}
+ok: ;
+	up(&domain_acl_lock);
+
+	return error;
+}
+
+static int tmy_argv0_acl(const struct path_info *filename,
+			 const char *argv0_)
+{
+	const struct domain_info *domain = TMY_SECURITY->domain;
+	int error = -EPERM;
+	struct acl_info *ptr;
+	struct path_info argv0;
+
+	if (!tmy_flags(TMY_MAC_FOR_ARGV0))
+		return 0;
+
+	argv0.name = argv0_;
+	tmy_fill_path_info(&argv0);
+
+	for (ptr = domain->first_acl_ptr; ptr; ptr = ptr->next) {
+		struct argv0_acl *acl = (struct argv0_acl *) ptr;
+
+		if (ptr->type == TMY_TYPE_ARGV0_ACL &&
+		    ptr->is_deleted == 0 &&
+		    tmy_check_condition(ptr->cond, NULL) == 0 &&
+		    tmy_path_match(filename, acl->filename) &&
+		    tmy_path_match(&argv0, acl->argv0)) {
+			error = 0;
+			break;
+		}
+	}
+
+	return error;
+}
+
+/**
+ * tmy_argv0_perm - check for argv[0] permission.
+ * @filename: pointer to filename.
+ * @argv0:    pointer to basename of argv[0].
+ *
+ * Returns zero if permission granted.
+ * Returns nonzero if permission denied.
+ */
+int tmy_argv0_perm(const struct path_info *filename, const char *argv0)
+{
+	int error = 0;
+	const int is_enforce = tmy_enforce(TMY_MAC_FOR_ARGV0);
+
+	if (!tmy_flags(TMY_MAC_FOR_ARGV0))
+		return 0;
+	if (!filename || !argv0 || !*argv0)
+		return 0;
+
+	error = tmy_argv0_acl(filename, argv0);
+
+	tmy_audit_argv0_log(filename, argv0, !error, is_enforce);
+
+	if (error) {
+		struct domain_info * const domain = TMY_SECURITY->domain;
+
+		if (is_enforce)
+			error = tmy_supervisor("%s\n" TMY_ALLOW_ARGV0 "%s %s\n",
+					       domain->domainname->name,
+					       filename->name, argv0);
+
+		else if (tmy_accept(TMY_MAC_FOR_ARGV0))
+			tmy_add_argv0_entry(filename->name, argv0, domain,
+					    NULL, 1);
+
+		if (!is_enforce)
+			error = 0;
+	}
+
+	return error;
+}
+
+/**
+ * tmy_add_argv0_policy - add or delete argv[0] policy.
+ * @data:      a line to parse.
+ * @domain:    pointer to "struct domain_info".
+ * @cond:      pointer to "struct condition_list". May be NULL.
+ * @is_delete: is this delete request?
+ *
+ * Returns zero on success.
+ * Returns nonzero on failure.
+ */
+int tmy_add_argv0_policy(char *data,
+			 struct domain_info *domain,
+			 const struct condition_list *cond,
+			 const int is_delete)
+{
+	char *argv0 = strchr(data, ' ');
+
+	if (!argv0)
+		return -EINVAL;
+
+	*argv0++ = '\0';
+
+	return tmy_add_argv0_entry(data, argv0, domain, cond,
+				   is_delete ? 0 : -1);
+}