[TOMOYO #7 25/30] Signal operation restriction part.

[Tetsuo Handa]

This file controls signal transmission operations.

Signed-off-by: Kentaro Takeda <takedakn@xxxxxxxxxxxxx>
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Toshiharu Harada <haradats@xxxxxxxxxxxxx>
---
 fs/tomoyo_signal.c |  227 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 227 insertions(+)

--- /dev/null
+++ linux-2.6.25-rc8-mm1/fs/tomoyo_signal.c
@@ -0,0 +1,227 @@
+/*
+ * fs/tomoyo_signal.c
+ *
+ * Implementation of the Domain-Based Mandatory Access Control.
+ *
+ * Copyright (C) 2005-2008  NTT DATA CORPORATION
+ *
+ * Version: 1.6.0   2008/04/01
+ *
+ */
+
+#include <linux/ccs_common.h>
+#include <linux/tomoyo.h>
+#include <linux/realpath.h>
+
+/**
+ * audit_signal_log - Audit signal log.
+ *
+ * @signal:      Signal number.
+ * @dest_domain: Destination domainname.
+ * @is_granted:  True if this is a granted log.
+ * @profile:     Profile number used.
+ * @mode:        Access control mode used.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int audit_signal_log(const int signal,
+			    const struct path_info *dest_domain,
+			    const bool is_granted, const u8 profile,
+			    const u8 mode)
+{
+	char *buf;
+	int len;
+	int len2;
+	if (ccs_can_save_audit_log(is_granted) < 0)
+		return -ENOMEM;
+	len = dest_domain->total_len + 64;
+	buf = ccs_init_audit_log(&len, profile, mode, NULL);
+	if (!buf)
+		return -ENOMEM;
+	len2 = strlen(buf);
+	snprintf(buf + len2, len - len2 - 1, KEYWORD_ALLOW_SIGNAL "%d %s\n",
+		 signal, dest_domain->name);
+	return ccs_write_audit_log(buf, is_granted);
+}
+
+/**
+ * update_signal_acl - Update "struct signal_acl_record" list.
+ *
+ * @sig:          Signal number.
+ * @dest_pattern: Destination domainname.
+ * @domain:       Pointer to "struct domain_info".
+ * @condition:    Pointer to "struct condition_list". May be NULL.
+ * @is_delete:    True if it is a delete request.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int update_signal_acl(const int sig, const char *dest_pattern,
+			     struct domain_info *domain,
+			     const struct condition_list *condition,
+			     const bool is_delete)
+{
+	struct acl_info *ptr;
+	struct signal_acl_record *acl;
+	const struct path_info *saved_dest_pattern;
+	const u16 hash = sig;
+	int error = -ENOMEM;
+	if (!domain)
+		return -EINVAL;
+	if (!dest_pattern || !ccs_is_correct_domain(dest_pattern, __func__))
+		return -EINVAL;
+	saved_dest_pattern = ccs_save_name(dest_pattern);
+	if (!saved_dest_pattern)
+		return -ENOMEM;
+	mutex_lock(&domain_acl_lock);
+	if (is_delete)
+		goto delete;
+	list1_for_each_entry(ptr, &domain->acl_info_list, list) {
+		if (ccs_acl_type1(ptr) != TYPE_SIGNAL_ACL)
+			continue;
+		if (ccs_get_condition_part(ptr) != condition)
+			continue;
+		acl = container_of(ptr, struct signal_acl_record, head);
+		if (acl->sig != hash ||
+		    ccs_pathcmp(acl->domainname, saved_dest_pattern))
+			continue;
+		error = ccs_add_domain_acl(NULL, ptr);
+		goto out;
+	}
+	/* Not found. Append it to the tail. */
+	acl = ccs_alloc_acl_element(TYPE_SIGNAL_ACL, condition);
+	if (!acl)
+		goto out;
+	acl->sig = hash;
+	acl->domainname = saved_dest_pattern;
+	error = ccs_add_domain_acl(domain, &acl->head);
+	goto out;
+ delete:
+	error = -ENOENT;
+	list1_for_each_entry(ptr, &domain->acl_info_list, list) {
+		if (ccs_acl_type2(ptr) != TYPE_SIGNAL_ACL)
+			continue;
+		if (ccs_get_condition_part(ptr) != condition)
+			continue;
+		acl = container_of(ptr, struct signal_acl_record, head);
+		if (acl->sig != hash ||
+		    ccs_pathcmp(acl->domainname, saved_dest_pattern))
+			continue;
+		error = ccs_del_domain_acl(ptr);
+		break;
+	}
+ out:
+	mutex_unlock(&domain_acl_lock);
+	return error;
+}
+
+/**
+ * ccs_check_signal_acl - Check permission for signal.
+ *
+ * @sig: Signal number.
+ * @pid: Target's PID.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int ccs_check_signal_acl(const int sig, const int pid)
+{
+	struct domain_info *domain = current->domain_info;
+	struct domain_info *dest = NULL;
+	const char *dest_pattern;
+	struct acl_info *ptr;
+	const u16 hash = sig;
+	const u8 profile = current->domain_info->profile;
+	const u8 mode = ccs_check_flags(CCS_TOMOYO_MAC_FOR_SIGNAL);
+	const bool is_enforce = (mode == 3);
+	bool found = false;
+	if (!mode)
+		return 0;
+	if (!sig)
+		return 0;                /* No check for NULL signal. */
+	if (current->pid == pid) {
+		audit_signal_log(sig, domain->domainname, true, profile, mode);
+		return 0;                /* No check for self process. */
+	}
+	{ /* Simplified checking. */
+		struct task_struct *p = NULL;
+		/***** CRITICAL SECTION START *****/
+		read_lock(&tasklist_lock);
+		if (pid > 0)
+			p = find_task_by_vpid((pid_t) pid);
+		else if (pid == 0)
+			p = current;
+		else if (pid == -1)
+			dest = &KERNEL_DOMAIN;
+		else
+			p = find_task_by_vpid((pid_t) -pid);
+		if (p)
+			dest = p->domain_info;
+		read_unlock(&tasklist_lock);
+		/***** CRITICAL SECTION END *****/
+		if (!dest)
+			return 0; /* I can't find destinatioin. */
+	}
+	if (domain == dest) {
+		audit_signal_log(sig, dest->domainname, true, profile, mode);
+		return 0;                /* No check for self domain. */
+	}
+	dest_pattern = dest->domainname->name;
+	list1_for_each_entry(ptr, &domain->acl_info_list, list) {
+		struct signal_acl_record *acl;
+		if (ccs_acl_type2(ptr) != TYPE_SIGNAL_ACL)
+			continue;
+		acl = container_of(ptr, struct signal_acl_record, head);
+		if (acl->sig == hash && ccs_check_condition(ptr, NULL)) {
+			const int len = acl->domainname->total_len;
+			if (strncmp(acl->domainname->name, dest_pattern, len))
+				continue;
+			switch (dest_pattern[len]) {
+			case ' ':
+			case '\0':
+				break;
+			default:
+				continue;
+			}
+			ccs_update_condition(ptr);
+			found = true;
+			break;
+		}
+	}
+	audit_signal_log(sig, dest->domainname, found, profile, mode);
+	if (found)
+		return 0;
+	if (ccs_verbose_mode())
+		printk(KERN_WARNING "TOMOYO-%s: Signal %d "
+		       "to %s denied for %s\n", ccs_get_msg(is_enforce), sig,
+		       ccs_get_last_name(dest), ccs_get_last_name(domain));
+	if (is_enforce)
+		return ccs_check_supervisor("%s\n"
+					    KEYWORD_ALLOW_SIGNAL "%d %s\n",
+					    domain->domainname->name,
+					    sig, dest_pattern);
+	if (mode == 1 && ccs_check_domain_quota(domain))
+		update_signal_acl(sig, dest_pattern, domain, NULL, false);
+	return 0;
+}
+
+/**
+ * ccs_write_signal_policy - Write "struct signal_acl_record" list.
+ *
+ * @data:      String to parse.
+ * @domain:    Pointer to "struct domain_info".
+ * @condition: Pointer to "struct condition_list". May be NULL.
+ * @is_delete: True if it is a delete request.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int ccs_write_signal_policy(char *data, struct domain_info *domain,
+			    const struct condition_list *condition,
+			    const bool is_delete)
+{
+	int sig;
+	char *domainname = strchr(data, ' ');
+	if (sscanf(data, "%d", &sig) == 1 && domainname &&
+	    ccs_is_domain_def(domainname + 1))
+		return update_signal_acl(sig, domainname + 1, domain,
+					 condition, is_delete);
+	return -EINVAL;
+}

-- 
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