TOMOYO: Add auditing interface.

Add /sys/kernel/security/tomoyo/audit interface. This interface generates audit
logs in the form of domain policy so that /usr/sbin/tomoyo-auditd can reuse
audit logs for appending to /sys/kernel/security/tomoyo/domain_policy
interface.

Signed-off-by: Tetsuo Handa <[email protected]>
Signed-off-by: James Morris <[email protected]>

security/tomoyo/Makefile

@@ -1 +1 @@
-obj-y = common.o domain.o file.o gc.o group.o load_policy.o memory.o mount.o realpath.o securityfs_if.o tomoyo.o util.o
+obj-y = audit.o common.o domain.o file.o gc.o group.o load_policy.o memory.o mount.o realpath.o securityfs_if.o tomoyo.o util.o

security/tomoyo/audit.c

@@ -0,0 +1,300 @@
+/*
+ * security/tomoyo/audit.c
+ *
+ * Pathname restriction functions.
+ *
+ * Copyright (C) 2005-2010  NTT DATA CORPORATION
+ */
+
+#include "common.h"
+#include <linux/slab.h>
+
+/**
+ * tomoyo_convert_time - Convert time_t to YYYY/MM/DD hh/mm/ss.
+ *
+ * @time:  Seconds since 1970/01/01 00:00:00.
+ * @stamp: Pointer to "struct tomoyo_time".
+ *
+ * Returns nothing.
+ *
+ * This function does not handle Y2038 problem.
+ */
+static void tomoyo_convert_time(time_t time, struct tomoyo_time *stamp)
+{
+	static const u16 tomoyo_eom[2][12] = {
+		{ 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
+		{ 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
+	};
+	u16 y;
+	u8 m;
+	bool r;
+	stamp->sec = time % 60;
+	time /= 60;
+	stamp->min = time % 60;
+	time /= 60;
+	stamp->hour = time % 24;
+	time /= 24;
+	for (y = 1970; ; y++) {
+		const unsigned short days = (y & 3) ? 365 : 366;
+		if (time < days)
+			break;
+		time -= days;
+	}
+	r = (y & 3) == 0;
+	for (m = 0; m < 11 && time >= tomoyo_eom[r][m]; m++)
+		;
+	if (m)
+		time -= tomoyo_eom[r][m - 1];
+	stamp->year = y;
+	stamp->month = ++m;
+	stamp->day = ++time;
+}
+
+/**
+ * tomoyo_print_header - Get header line of audit log.
+ *
+ * @r: Pointer to "struct tomoyo_request_info".
+ *
+ * Returns string representation.
+ *
+ * This function uses kmalloc(), so caller must kfree() if this function
+ * didn't return NULL.
+ */
+static char *tomoyo_print_header(struct tomoyo_request_info *r)
+{
+	struct tomoyo_time stamp;
+	const pid_t gpid = task_pid_nr(current);
+	static const int tomoyo_buffer_len = 4096;
+	char *buffer = kmalloc(tomoyo_buffer_len, GFP_NOFS);
+	pid_t ppid;
+	if (!buffer)
+		return NULL;
+	{
+		struct timeval tv;
+		do_gettimeofday(&tv);
+		tomoyo_convert_time(tv.tv_sec, &stamp);
+	}
+	rcu_read_lock();
+	ppid = task_tgid_vnr(current->real_parent);
+	rcu_read_unlock();
+	snprintf(buffer, tomoyo_buffer_len - 1,
+		 "#%04u/%02u/%02u %02u:%02u:%02u# profile=%u mode=%s "
+		 "granted=%s (global-pid=%u) task={ pid=%u ppid=%u "
+		 "uid=%u gid=%u euid=%u egid=%u suid=%u sgid=%u "
+		 "fsuid=%u fsgid=%u }",
+		 stamp.year, stamp.month, stamp.day, stamp.hour,
+		 stamp.min, stamp.sec, r->profile, tomoyo_mode[r->mode],
+		 tomoyo_yesno(r->granted), gpid, task_tgid_vnr(current), ppid,
+		 current_uid(), current_gid(), current_euid(), current_egid(),
+		 current_suid(), current_sgid(), current_fsuid(),
+		 current_fsgid());
+	return buffer;
+}
+
+/**
+ * tomoyo_init_log - Allocate buffer for audit logs.
+ *
+ * @r:    Pointer to "struct tomoyo_request_info".
+ * @len:  Buffer size needed for @fmt and @args.
+ * @fmt:  The printf()'s format string.
+ * @args: va_list structure for @fmt.
+ *
+ * Returns pointer to allocated memory.
+ *
+ * This function uses kzalloc(), so caller must kfree() if this function
+ * didn't return NULL.
+ */
+char *tomoyo_init_log(struct tomoyo_request_info *r, int len, const char *fmt,
+		      va_list args)
+{
+	char *buf = NULL;
+	const char *header = NULL;
+	int pos;
+	const char *domainname = tomoyo_domain()->domainname->name;
+	header = tomoyo_print_header(r);
+	if (!header)
+		return NULL;
+	/* +10 is for '\n' etc. and '\0'. */
+	len += strlen(domainname) + strlen(header) + 10;
+	len = tomoyo_round2(len);
+	buf = kzalloc(len, GFP_NOFS);
+	if (!buf)
+		goto out;
+	len--;
+	pos = snprintf(buf, len, "%s", header);
+	pos += snprintf(buf + pos, len - pos, "\n%s\n", domainname);
+	vsnprintf(buf + pos, len - pos, fmt, args);
+out:
+	kfree(header);
+	return buf;
+}
+
+/* Wait queue for /sys/kernel/security/tomoyo/audit. */
+static DECLARE_WAIT_QUEUE_HEAD(tomoyo_log_wait);
+
+/* Structure for audit log. */
+struct tomoyo_log {
+	struct list_head list;
+	char *log;
+	int size;
+};
+
+/* The list for "struct tomoyo_log". */
+static LIST_HEAD(tomoyo_log);
+
+/* Lock for "struct list_head tomoyo_log". */
+static DEFINE_SPINLOCK(tomoyo_log_lock);
+
+/* Length of "stuct list_head tomoyo_log". */
+static unsigned int tomoyo_log_count;
+
+/**
+ * tomoyo_get_audit - Get audit mode.
+ *
+ * @profile:     Profile number.
+ * @index:       Index number of functionality.
+ * @is_granted:  True if granted log, false otherwise.
+ *
+ * Returns true if this request should be audited, false otherwise.
+ */
+static bool tomoyo_get_audit(const u8 profile, const u8 index,
+			     const bool is_granted)
+{
+	u8 mode;
+	const u8 category = TOMOYO_MAC_CATEGORY_FILE + TOMOYO_MAX_MAC_INDEX;
+	struct tomoyo_profile *p;
+	if (!tomoyo_policy_loaded)
+		return false;
+	p = tomoyo_profile(profile);
+	if (tomoyo_log_count >= p->pref[TOMOYO_PREF_MAX_AUDIT_LOG])
+		return false;
+	mode = p->config[index];
+	if (mode == TOMOYO_CONFIG_USE_DEFAULT)
+		mode = p->config[category];
+	if (mode == TOMOYO_CONFIG_USE_DEFAULT)
+		mode = p->default_config;
+	if (is_granted)
+		return mode & TOMOYO_CONFIG_WANT_GRANT_LOG;
+	return mode & TOMOYO_CONFIG_WANT_REJECT_LOG;
+}
+
+/**
+ * tomoyo_write_log2 - Write an audit log.
+ *
+ * @r:    Pointer to "struct tomoyo_request_info".
+ * @len:  Buffer size needed for @fmt and @args.
+ * @fmt:  The printf()'s format string.
+ * @args: va_list structure for @fmt.
+ *
+ * Returns nothing.
+ */
+void tomoyo_write_log2(struct tomoyo_request_info *r, int len, const char *fmt,
+		       va_list args)
+{
+	char *buf;
+	struct tomoyo_log *entry;
+	bool quota_exceeded = false;
+	if (!tomoyo_get_audit(r->profile, r->type, r->granted))
+		goto out;
+	buf = tomoyo_init_log(r, len, fmt, args);
+	if (!buf)
+		goto out;
+	entry = kzalloc(sizeof(*entry), GFP_NOFS);
+	if (!entry) {
+		kfree(buf);
+		goto out;
+	}
+	entry->log = buf;
+	len = tomoyo_round2(strlen(buf) + 1);
+	/*
+	 * The entry->size is used for memory quota checks.
+	 * Don't go beyond strlen(entry->log).
+	 */
+	entry->size = len + tomoyo_round2(sizeof(*entry));
+	spin_lock(&tomoyo_log_lock);
+	if (tomoyo_memory_quota[TOMOYO_MEMORY_AUDIT] &&
+	    tomoyo_memory_used[TOMOYO_MEMORY_AUDIT] + entry->size >=
+	    tomoyo_memory_quota[TOMOYO_MEMORY_AUDIT]) {
+		quota_exceeded = true;
+	} else {
+		tomoyo_memory_used[TOMOYO_MEMORY_AUDIT] += entry->size;
+		list_add_tail(&entry->list, &tomoyo_log);
+		tomoyo_log_count++;
+	}
+	spin_unlock(&tomoyo_log_lock);
+	if (quota_exceeded) {
+		kfree(buf);
+		kfree(entry);
+		goto out;
+	}
+	wake_up(&tomoyo_log_wait);
+out:
+	return;
+}
+
+/**
+ * tomoyo_write_log - Write an audit log.
+ *
+ * @r:   Pointer to "struct tomoyo_request_info".
+ * @fmt: The printf()'s format string, followed by parameters.
+ *
+ * Returns nothing.
+ */
+void tomoyo_write_log(struct tomoyo_request_info *r, const char *fmt, ...)
+{
+	va_list args;
+	int len;
+	va_start(args, fmt);
+	len = vsnprintf((char *) &len, 1, fmt, args) + 1;
+	va_end(args);
+	va_start(args, fmt);
+	tomoyo_write_log2(r, len, fmt, args);
+	va_end(args);
+}
+
+/**
+ * tomoyo_read_log - Read an audit log.
+ *
+ * @head: Pointer to "struct tomoyo_io_buffer".
+ *
+ * Returns nothing.
+ */
+void tomoyo_read_log(struct tomoyo_io_buffer *head)
+{
+	struct tomoyo_log *ptr = NULL;
+	if (head->r.w_pos)
+		return;
+	kfree(head->read_buf);
+	head->read_buf = NULL;
+	spin_lock(&tomoyo_log_lock);
+	if (!list_empty(&tomoyo_log)) {
+		ptr = list_entry(tomoyo_log.next, typeof(*ptr), list);
+		list_del(&ptr->list);
+		tomoyo_log_count--;
+		tomoyo_memory_used[TOMOYO_MEMORY_AUDIT] -= ptr->size;
+	}
+	spin_unlock(&tomoyo_log_lock);
+	if (ptr) {
+		head->read_buf = ptr->log;
+		head->r.w[head->r.w_pos++] = head->read_buf;
+		kfree(ptr);
+	}
+}
+
+/**
+ * tomoyo_poll_log - Wait for an audit log.
+ *
+ * @file: Pointer to "struct file".
+ * @wait: Pointer to "poll_table".
+ *
+ * Returns POLLIN | POLLRDNORM when ready to read an audit log.
+ */
+int tomoyo_poll_log(struct file *file, poll_table *wait)
+{
+	if (tomoyo_log_count)
+		return POLLIN | POLLRDNORM;
+	poll_wait(file, &tomoyo_log_wait, wait);
+	if (tomoyo_log_count)
+		return POLLIN | POLLRDNORM;
+	return 0;
+}