auditsc.c

linux 2.6.19 kernel source code before patching

/* auditsc.c -- System-call auditing support
 * Handles all system-call specific auditing features.
 *
 * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
 * Copyright 2005 Hewlett-Packard Development Company, L.P.
 * Copyright (C) 2005, 2006 IBM Corporation
 * All Rights Reserved.
 *
 * 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
 *
 * Written by Rickard E. (Rik) Faith <[e-mail]>
 *
 * Many of the ideas implemented here are from Stephen C. Tweedie,
 * especially the idea of avoiding a copy by using getname.
 *
 * The method for actual interception of syscall entry and exit (not in
 * this file -- see entry.S) is based on a GPL'd patch written by
 * [e-mail] and Copyright 2003 SuSE Linux AG.
 *
 * POSIX message queue support added by George Wilson <[e-mail]>,
 * 2006.
 *
 * The support of additional filter rules compares (>, <, >=, <=) was
 * added by Dustin Kirkland <[e-mail]>, 2005.
 *
 * Modified by Amy Griffis <[e-mail]> to collect additional
 * filesystem information.
 *
 * Subject and object context labeling support added by <[e-mail]>
 * and <[e-mail]> for LSPP certification compliance.
 */

#include <linux/init.h>
#include <asm/types.h>
#include <asm/atomic.h>
#include <asm/types.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/socket.h>
#include <linux/mqueue.h>
#include <linux/audit.h>
#include <linux/personality.h>
#include <linux/time.h>
#include <linux/netlink.h>
#include <linux/compiler.h>
#include <asm/unistd.h>
#include <linux/security.h>
#include <linux/list.h>
#include <linux/tty.h>
#include <linux/selinux.h>
#include <linux/binfmts.h>
#include <linux/highmem.h>
#include <linux/syscalls.h>

#include "audit.h"

extern struct list_head audit_filter_list[];

/* No syscall auditing will take place unless audit_enabled != 0. */
extern int audit_enabled;

/* AUDIT_NAMES is the number of slots we reserve in the audit_context
 * for saving names from getname(). */
#define AUDIT_NAMES    20

/* Indicates that audit should log the full pathname. */
#define AUDIT_NAME_FULL -1

/* number of audit rules */
int audit_n_rules;

/* determines whether we collect data for signals sent */
int audit_signals;

/* When fs/namei.c:getname() is called, we store the pointer in name and
 * we don't let putname() free it (instead we free all of the saved
 * pointers at syscall exit time).
 *
 * Further, in fs/namei.c:path_lookup() we store the inode and device. */
struct audit_names {
	const char	*name;
	int		name_len;	/* number of name's characters to log */
	unsigned	name_put;	/* call __putname() for this name */
	unsigned long	ino;
	dev_t		dev;
	umode_t		mode;
	uid_t		uid;
	gid_t		gid;
	dev_t		rdev;
	u32		osid;
};

struct audit_aux_data {
	struct audit_aux_data	*next;
	int			type;
};

#define AUDIT_AUX_IPCPERM	0

/* Number of target pids per aux struct. */
#define AUDIT_AUX_PIDS	16

struct audit_aux_data_mq_open {
	struct audit_aux_data	d;
	int			oflag;
	mode_t			mode;
	struct mq_attr		attr;
};

struct audit_aux_data_mq_sendrecv {
	struct audit_aux_data	d;
	mqd_t			mqdes;
	size_t			msg_len;
	unsigned int		msg_prio;
	struct timespec		abs_timeout;
};

struct audit_aux_data_mq_notify {
	struct audit_aux_data	d;
	mqd_t			mqdes;
	struct sigevent 	notification;
};

struct audit_aux_data_mq_getsetattr {
	struct audit_aux_data	d;
	mqd_t			mqdes;
	struct mq_attr 		mqstat;
};

struct audit_aux_data_ipcctl {
	struct audit_aux_data	d;
	struct ipc_perm		p;
	unsigned long		qbytes;
	uid_t			uid;
	gid_t			gid;
	mode_t			mode;
	u32			osid;
};

struct audit_aux_data_execve {
	struct audit_aux_data	d;
	int argc;
	int envc;
	char mem[0];
};

struct audit_aux_data_socketcall {
	struct audit_aux_data	d;
	int			nargs;
	unsigned long		args[0];
};

struct audit_aux_data_sockaddr {
	struct audit_aux_data	d;
	int			len;
	char			a[0];
};

struct audit_aux_data_fd_pair {
	struct	audit_aux_data d;
	int	fd[2];
};

struct audit_aux_data_path {
	struct audit_aux_data	d;
	struct dentry		*dentry;
	struct vfsmount		*mnt;
};

struct audit_aux_data_pids {
	struct audit_aux_data	d;
	pid_t			target_pid[AUDIT_AUX_PIDS];
	u32			target_sid[AUDIT_AUX_PIDS];
	int			pid_count;
};

/* The per-task audit context. */
struct audit_context {
	int		    dummy;	/* must be the first element */
	int		    in_syscall;	/* 1 if task is in a syscall */
	enum audit_state    state;
	unsigned int	    serial;     /* serial number for record */
	struct timespec	    ctime;      /* time of syscall entry */
	uid_t		    loginuid;   /* login uid (identity) */
	int		    major;      /* syscall number */
	unsigned long	    argv[4];    /* syscall arguments */
	int		    return_valid; /* return code is valid */
	long		    return_code;/* syscall return code */
	int		    auditable;  /* 1 if record should be written */
	int		    name_count;
	struct audit_names  names[AUDIT_NAMES];
	char *		    filterkey;	/* key for rule that triggered record */
	struct dentry *	    pwd;
	struct vfsmount *   pwdmnt;
	struct audit_context *previous; /* For nested syscalls */
	struct audit_aux_data *aux;
	struct audit_aux_data *aux_pids;

				/* Save things to print about task_struct */
	pid_t		    pid, ppid;
	uid_t		    uid, euid, suid, fsuid;
	gid_t		    gid, egid, sgid, fsgid;
	unsigned long	    personality;
	int		    arch;

	pid_t		    target_pid;
	u32		    target_sid;

#if AUDIT_DEBUG
	int		    put_count;
	int		    ino_count;
#endif
};

#define ACC_MODE(x) ("\004\002\006\006"[(x)&O_ACCMODE])
static inline int open_arg(int flags, int mask)
{
	int n = ACC_MODE(flags);
	if (flags & (O_TRUNC | O_CREAT))
		n |= AUDIT_PERM_WRITE;
	return n & mask;
}

static int audit_match_perm(struct audit_context *ctx, int mask)
{
	unsigned n = ctx->major;
	switch (audit_classify_syscall(ctx->arch, n)) {
	case 0:	/* native */
		if ((mask & AUDIT_PERM_WRITE) &&
		     audit_match_class(AUDIT_CLASS_WRITE, n))
			return 1;
		if ((mask & AUDIT_PERM_READ) &&
		     audit_match_class(AUDIT_CLASS_READ, n))
			return 1;
		if ((mask & AUDIT_PERM_ATTR) &&
		     audit_match_class(AUDIT_CLASS_CHATTR, n))
			return 1;
		return 0;
	case 1: /* 32bit on biarch */
		if ((mask & AUDIT_PERM_WRITE) &&
		     audit_match_class(AUDIT_CLASS_WRITE_32, n))
			return 1;
		if ((mask & AUDIT_PERM_READ) &&
		     audit_match_class(AUDIT_CLASS_READ_32, n))
			return 1;
		if ((mask & AUDIT_PERM_ATTR) &&
		     audit_match_class(AUDIT_CLASS_CHATTR_32, n))
			return 1;
		return 0;
	case 2: /* open */
		return mask & ACC_MODE(ctx->argv[1]);
	case 3: /* openat */
		return mask & ACC_MODE(ctx->argv[2]);
	case 4: /* socketcall */
		return ((mask & AUDIT_PERM_WRITE) && ctx->argv[0] == SYS_BIND);
	case 5: /* execve */
		return mask & AUDIT_PERM_EXEC;
	default:
		return 0;
	}
}

/* Determine if any context name data matches a rule's watch data */
/* Compare a task_struct with an audit_rule.  Return 1 on match, 0
 * otherwise. */
static int audit_filter_rules(struct task_struct *tsk,
			      struct audit_krule *rule,
			      struct audit_context *ctx,
			      struct audit_names *name,
			      enum audit_state *state)
{
	int i, j, need_sid = 1;
	u32 sid;

	for (i = 0; i < rule->field_count; i++) {
		struct audit_field *f = &rule->fields[i];
		int result = 0;

		switch (f->type) {
		case AUDIT_PID:
			result = audit_comparator(tsk->pid, f->op, f->val);
			break;
		case AUDIT_PPID:
			if (ctx) {
				if (!ctx->ppid)
					ctx->ppid = sys_getppid();
				result = audit_comparator(ctx->ppid, f->op, f->val);
			}
			break;
		case AUDIT_UID:
			result = audit_comparator(tsk->uid, f->op, f->val);
			break;
		case AUDIT_EUID:
			result = audit_comparator(tsk->euid, f->op, f->val);
			break;
		case AUDIT_SUID:
			result = audit_comparator(tsk->suid, f->op, f->val);
			break;
		case AUDIT_FSUID:
			result = audit_comparator(tsk->fsuid, f->op, f->val);
			break;
		case AUDIT_GID:
			result = audit_comparator(tsk->gid, f->op, f->val);
			break;
		case AUDIT_EGID:
			result = audit_comparator(tsk->egid, f->op, f->val);
			break;
		case AUDIT_SGID:
			result = audit_comparator(tsk->sgid, f->op, f->val);
			break;
		case AUDIT_FSGID:
			result = audit_comparator(tsk->fsgid, f->op, f->val);
			break;
		case AUDIT_PERS:
			result = audit_comparator(tsk->personality, f->op, f->val);
			break;
		case AUDIT_ARCH:
 			if (ctx)
				result = audit_comparator(ctx->arch, f->op, f->val);
			break;

		case AUDIT_EXIT:
			if (ctx && ctx->return_valid)
				result = audit_comparator(ctx->return_code, f->op, f->val);
			break;
		case AUDIT_SUCCESS:
			if (ctx && ctx->return_valid) {
				if (f->val)
					result = audit_comparator(ctx->return_valid, f->op, AUDITSC_SUCCESS);
				else
					result = audit_comparator(ctx->return_valid, f->op, AUDITSC_FAILURE);
			}
			break;
		case AUDIT_DEVMAJOR:
			if (name)
				result = audit_comparator(MAJOR(name->dev),
							  f->op, f->val);
			else if (ctx) {
				for (j = 0; j < ctx->name_count; j++) {
					if (audit_comparator(MAJOR(ctx->names[j].dev),	f->op, f->val)) {
						++result;
						break;
					}
				}
			}
			break;
		case AUDIT_DEVMINOR:
			if (name)
				result = audit_comparator(MINOR(name->dev),
							  f->op, f->val);
			else if (ctx) {
				for (j = 0; j < ctx->name_count; j++) {
					if (audit_comparator(MINOR(ctx->names[j].dev), f->op, f->val)) {
						++result;
						break;
					}
				}
			}
			break;
		case AUDIT_INODE:
			if (name)
				result = (name->ino == f->val);
			else if (ctx) {
				for (j = 0; j < ctx->name_count; j++) {
					if (audit_comparator(ctx->names[j].ino, f->op, f->val)) {
						++result;
						break;
					}
				}
			}
			break;
		case AUDIT_WATCH:
			if (name && rule->watch->ino != (unsigned long)-1)
				result = (name->dev == rule->watch->dev &&
					  name->ino == rule->watch->ino);
			break;
		case AUDIT_LOGINUID:
			result = 0;
			if (ctx)
				result = audit_comparator(ctx->loginuid, f->op, f->val);
			break;
		case AUDIT_SUBJ_USER:
		case AUDIT_SUBJ_ROLE:
		case AUDIT_SUBJ_TYPE:
		case AUDIT_SUBJ_SEN:
		case AUDIT_SUBJ_CLR:
			/* NOTE: this may return negative values indicating
			   a temporary error.  We simply treat this as a
			   match for now to avoid losing information that
			   may be wanted.   An error message will also be
			   logged upon error */
			if (f->se_rule) {
				if (need_sid) {
					selinux_get_task_sid(tsk, &sid);
					need_sid = 0;
				}
				result = selinux_audit_rule_match(sid, f->type,
				                                  f->op,
				                                  f->se_rule,
				                                  ctx);
			}
			break;
		case AUDIT_OBJ_USER:
		case AUDIT_OBJ_ROLE:
		case AUDIT_OBJ_TYPE:
		case AUDIT_OBJ_LEV_LOW:
		case AUDIT_OBJ_LEV_HIGH:
			/* The above note for AUDIT_SUBJ_USER...AUDIT_SUBJ_CLR
			   also applies here */
			if (f->se_rule) {
				/* Find files that match */
				if (name) {
					result = selinux_audit_rule_match(
					           name->osid, f->type, f->op,
					           f->se_rule, ctx);
				} else if (ctx) {
					for (j = 0; j < ctx->name_count; j++) {
						if (selinux_audit_rule_match(
						      ctx->names[j].osid,
						      f->type, f->op,
						      f->se_rule, ctx)) {
							++result;
							break;
						}
					}
				}
				/* Find ipc objects that match */
				if (ctx) {
					struct audit_aux_data *aux;
					for (aux = ctx->aux; aux;
					     aux = aux->next) {
						if (aux->type == AUDIT_IPC) {
							struct audit_aux_data_ipcctl *axi = (void *)aux;
							if (selinux_audit_rule_match(axi->osid, f->type, f->op, f->se_rule, ctx)) {
								++result;
								break;
							}
						}
					}
				}
			}
			break;
		case AUDIT_ARG0:
		case AUDIT_ARG1:
		case AUDIT_ARG2:
		case AUDIT_ARG3:
			if (ctx)
				result = audit_comparator(ctx->argv[f->type-AUDIT_ARG0], f->op, f->val);
			break;
		case AUDIT_FILTERKEY:
			/* ignore this field for filtering */
			result = 1;
			break;
		case AUDIT_PERM:
			result = audit_match_perm(ctx, f->val);
			break;
		}

		if (!result)
			return 0;
	}
	if (rule->filterkey)
		ctx->filterkey = kstrdup(rule->filterkey, GFP_ATOMIC);
	switch (rule->action) {
	case AUDIT_NEVER:    *state = AUDIT_DISABLED;	    break;
	case AUDIT_ALWAYS:   *state = AUDIT_RECORD_CONTEXT; break;
	}
	return 1;
}

/* At process creation time, we can determine if system-call auditing is
 * completely disabled for this task.  Since we only have the task
 * structure at this point, we can only check uid and gid.
 */
static enum audit_state audit_filter_task(struct task_struct *tsk)
{
	struct audit_entry *e;
	enum audit_state   state;

	rcu_read_lock();
	list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TASK], list) {
		if (audit_filter_rules(tsk, &e->rule, NULL, NULL, &state)) {
			rcu_read_unlock();
			return state;
		}
	}
	rcu_read_unlock();
	return AUDIT_BUILD_CONTEXT;
}

/* At syscall entry and exit time, this filter is called if the
 * audit_state is not low enough that auditing cannot take place, but is
 * also not high enough that we already know we have to write an audit
 * record (i.e., the state is AUDIT_SETUP_CONTEXT or AUDIT_BUILD_CONTEXT).
 */
static enum audit_state audit_filter_syscall(struct task_struct *tsk,
					     struct audit_context *ctx,
					     struct list_head *list)
{
	struct audit_entry *e;
	enum audit_state state;

	if (audit_pid && tsk->tgid == audit_pid)
		return AUDIT_DISABLED;