cregit-Linux how code gets into the kernel

Release 4.15 kernel/auditfilter.c

Directory: kernel
/* auditfilter.c -- filtering of audit events
 *
 * Copyright 2003-2004 Red Hat, Inc.
 * Copyright 2005 Hewlett-Packard Development Company, L.P.
 * Copyright 2005 IBM Corporation
 *
 * 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/kthread.h>
#include <linux/mutex.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/netlink.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/security.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include "audit.h"

/*
 * Locking model:
 *
 * audit_filter_mutex:
 *              Synchronizes writes and blocking reads of audit's filterlist
 *              data.  Rcu is used to traverse the filterlist and access
 *              contents of structs audit_entry, audit_watch and opaque
 *              LSM rules during filtering.  If modified, these structures
 *              must be copied and replace their counterparts in the filterlist.
 *              An audit_parent struct is not accessed during filtering, so may
 *              be written directly provided audit_filter_mutex is held.
 */

/* Audit filter lists, defined in <linux/audit.h> */

struct list_head audit_filter_list[AUDIT_NR_FILTERS] = {
	LIST_HEAD_INIT(audit_filter_list[0]),
	LIST_HEAD_INIT(audit_filter_list[1]),
	LIST_HEAD_INIT(audit_filter_list[2]),
	LIST_HEAD_INIT(audit_filter_list[3]),
	LIST_HEAD_INIT(audit_filter_list[4]),
	LIST_HEAD_INIT(audit_filter_list[5]),
	LIST_HEAD_INIT(audit_filter_list[6]),
#if AUDIT_NR_FILTERS != 7
#error Fix audit_filter_list initialiser
#endif
};

static struct list_head audit_rules_list[AUDIT_NR_FILTERS] = {
	LIST_HEAD_INIT(audit_rules_list[0]),
	LIST_HEAD_INIT(audit_rules_list[1]),
	LIST_HEAD_INIT(audit_rules_list[2]),
	LIST_HEAD_INIT(audit_rules_list[3]),
	LIST_HEAD_INIT(audit_rules_list[4]),
	LIST_HEAD_INIT(audit_rules_list[5]),
	LIST_HEAD_INIT(audit_rules_list[6]),
};


DEFINE_MUTEX(audit_filter_mutex);




static void audit_free_lsm_field(struct audit_field *f)
{
	switch (f->type) {
	case AUDIT_SUBJ_USER:
	case AUDIT_SUBJ_ROLE:
	case AUDIT_SUBJ_TYPE:
	case AUDIT_SUBJ_SEN:
	case AUDIT_SUBJ_CLR:
	case AUDIT_OBJ_USER:
	case AUDIT_OBJ_ROLE:
	case AUDIT_OBJ_TYPE:
	case AUDIT_OBJ_LEV_LOW:
	case AUDIT_OBJ_LEV_HIGH:
		kfree(f->lsm_str);
		security_audit_rule_free(f->lsm_rule);
	}
}


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static inline void audit_free_rule(struct audit_entry *e)
{
	int i;
	struct audit_krule *erule = &e->rule;

	/* some rules don't have associated watches */
	if (erule->watch)
		audit_put_watch(erule->watch);
	if (erule->fields)
		for (i = 0; i < erule->field_count; i++)
			audit_free_lsm_field(&erule->fields[i]);
	kfree(erule->fields);
	kfree(erule->filterkey);
	kfree(e);
}


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Darrel Goeddel3033.33%116.67%


Zhenwen Xu1718.89%116.67%


Richard Guy Briggs22.22%116.67%


Total90100.00%6100.00%






void audit_free_rule_rcu(struct rcu_head *head)
{
	struct audit_entry *e = container_of(head, struct audit_entry, rcu);
	audit_free_rule(e);
}


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David Woodhouse310.00%150.00%


Total30100.00%2100.00%



/* Initialize an audit filterlist entry. */



static inline struct audit_entry *audit_init_entry(u32 field_count)
{
	struct audit_entry *entry;
	struct audit_field *fields;

	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (unlikely(!entry))
		return NULL;

	fields = kcalloc(field_count, sizeof(*fields), GFP_KERNEL);
	if (unlikely(!fields)) {
		kfree(entry);
		return NULL;
	}
	entry->rule.fields = fields;

	return entry;
}


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Darrel Goeddel4044.44%120.00%


Eric Paris2831.11%120.00%


Amy Griffis1921.11%240.00%


Fabian Frederick33.33%120.00%


Total90100.00%5100.00%



/* Unpack a filter field's string representation from user-space
 * buffer. */



char *audit_unpack_string(void **bufp, size_t *remain, size_t len)
{
	char *str;

	if (!*bufp || (len == 0) || (len > *remain))
		return ERR_PTR(-EINVAL);

	/* Of the currently implemented string fields, PATH_MAX
         * defines the longest valid length.
         */
	if (len > PATH_MAX)
		return ERR_PTR(-ENAMETOOLONG);

	str = kmalloc(len + 1, GFP_KERNEL);
	if (unlikely(!str))
		return ERR_PTR(-ENOMEM);

	memcpy(str, *bufp, len);
	str[len] = 0;
	*bufp += len;
	*remain -= len;

	return str;
}


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Amy Griffis9983.90%150.00%


Darrel Goeddel1916.10%150.00%


Total118100.00%2100.00%



/* Translate an inode field to kernel representation. */



static inline int audit_to_inode(struct audit_krule *krule,
				 struct audit_field *f)
{
	if (krule->listnr != AUDIT_FILTER_EXIT ||
	    krule->inode_f || krule->watch || krule->tree ||
	    (f->op != Audit_equal && f->op != Audit_not_equal))
		return -EINVAL;

	krule->inode_f = f;
	return 0;
}


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Amy Griffis3960.94%228.57%


Al Viro1828.12%228.57%


David Woodhouse46.25%114.29%


Richard Guy Briggs23.12%114.29%


Darrel Goeddel11.56%114.29%


Total64100.00%7100.00%




static __u32 *classes[AUDIT_SYSCALL_CLASSES];




int __init audit_register_class(int class, unsigned *list)
{
	__u32 *p = kcalloc(AUDIT_BITMASK_SIZE, sizeof(__u32), GFP_KERNEL);
	if (!p)
		return -ENOMEM;
	while (*list != ~0U) {
		unsigned n = *list++;
		if (n >= AUDIT_BITMASK_SIZE * 32 - AUDIT_SYSCALL_CLASSES) {
			kfree(p);
			return -EINVAL;
		}
		p[AUDIT_WORD(n)] |= AUDIT_BIT(n);
	}
	if (class >= AUDIT_SYSCALL_CLASSES || classes[class]) {
		kfree(p);
		return -EINVAL;
	}
	classes[class] = p;
	return 0;
}


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Al Viro8066.12%125.00%


Eric Paris2319.01%125.00%


Amy Griffis1613.22%125.00%


Fabian Frederick21.65%125.00%


Total121100.00%4100.00%






int audit_match_class(int class, unsigned syscall)
{
	if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32))
		return 0;
	if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class]))
		return 0;
	return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall);
}


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Klaus Weidner11.67%150.00%


Total60100.00%2100.00%



#ifdef CONFIG_AUDITSYSCALL



static inline int audit_match_class_bits(int class, u32 *mask)
{
	int i;

	if (classes[class]) {
		for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
			if (mask[i] & classes[class][i])
				return 0;
	}
	return 1;
}


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static int audit_match_signal(struct audit_entry *entry)
{
	struct audit_field *arch = entry->rule.arch_f;

	if (!arch) {
		/* When arch is unspecified, we must check both masks on biarch
                 * as syscall number alone is ambiguous. */
		return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
					       entry->rule.mask) &&
			audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
					       entry->rule.mask));
	}

	switch(audit_classify_arch(arch->val)) {
	case 0: /* native */
		return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
					       entry->rule.mask));
	case 1: /* 32bit on biarch */
		return (audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
					       entry->rule.mask));
	default:
		return 1;
	}
}

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Total106100.00%1100.00%



#endif

/* Common user-space to kernel rule translation. */



static inline struct audit_entry *audit_to_entry_common(struct audit_rule_data *rule)
{
	unsigned listnr;
	struct audit_entry *entry;
	int i, err;

	err = -EINVAL;
	listnr = rule->flags & ~AUDIT_FILTER_PREPEND;
	switch(listnr) {
	default:
		goto exit_err;
#ifdef CONFIG_AUDITSYSCALL
	case AUDIT_FILTER_ENTRY:
		if (rule->action == AUDIT_ALWAYS)
			goto exit_err;
	case AUDIT_FILTER_EXIT:
	case AUDIT_FILTER_TASK:
#endif
	case AUDIT_FILTER_USER:
	case AUDIT_FILTER_TYPE:
	case AUDIT_FILTER_FS:
		;
	}
	if (unlikely(rule->action == AUDIT_POSSIBLE)) {
		pr_err("AUDIT_POSSIBLE is deprecated\n");
		goto exit_err;
	}
	if (rule->action != AUDIT_NEVER && rule->action != AUDIT_ALWAYS)
		goto exit_err;
	if (rule->field_count > AUDIT_MAX_FIELDS)
		goto exit_err;

	err = -ENOMEM;
	entry = audit_init_entry(rule->field_count);
	if (!entry)
		goto exit_err;

	entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND;
	entry->rule.listnr = listnr;
	entry->rule.action = rule->action;
	entry->rule.field_count = rule->field_count;

	for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
		entry->rule.mask[i] = rule->mask[i];

	for (i = 0; i < AUDIT_SYSCALL_CLASSES; i++) {
		int bit = AUDIT_BITMASK_SIZE * 32 - i - 1;
		__u32 *p = &entry->rule.mask[AUDIT_WORD(bit)];
		__u32 *class;

		if (!(*p & AUDIT_BIT(bit)))
			continue;
		*p &= ~AUDIT_BIT(bit);
		class = classes[i];
		if (class) {
			int j;
			for (j = 0; j < AUDIT_BITMASK_SIZE; j++)
				entry->rule.mask[j] |= class[j];
		}
	}

	return entry;

exit_err:
	return ERR_PTR(err);
}


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Amy Griffis15845.14%220.00%


Al Viro13137.43%220.00%


David Woodhouse216.00%110.00%


Eric Paris185.14%220.00%


Darrel Goeddel185.14%110.00%


Richard Guy Briggs41.14%220.00%


Total350100.00%10100.00%




static u32 audit_ops[] =
{
	[Audit_equal] = AUDIT_EQUAL,
	[Audit_not_equal] = AUDIT_NOT_EQUAL,
	[Audit_bitmask] = AUDIT_BIT_MASK,
	[Audit_bittest] = AUDIT_BIT_TEST,
	[Audit_lt] = AUDIT_LESS_THAN,
	[Audit_gt] = AUDIT_GREATER_THAN,
	[Audit_le] = AUDIT_LESS_THAN_OR_EQUAL,
	[Audit_ge] = AUDIT_GREATER_THAN_OR_EQUAL,
};




static u32 audit_to_op(u32 op)
{
	u32 n;
	for (n = Audit_equal; n < Audit_bad && audit_ops[n] != op; n++)
		;
	return n;
}


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Al Viro36100.00%1100.00%


Total36100.00%1100.00%



/* check if an audit field is valid */



static int audit_field_valid(struct audit_entry *entry, struct audit_field *f)
{
	switch(f->type) {
	case AUDIT_MSGTYPE:
		if (entry->rule.listnr != AUDIT_FILTER_TYPE &&
		    entry->rule.listnr != AUDIT_FILTER_USER)
			return -EINVAL;
		break;
	case AUDIT_FSTYPE:
		if (entry->rule.listnr != AUDIT_FILTER_FS)
			return -EINVAL;
		break;
	}

	switch(entry->rule.listnr) {
	case AUDIT_FILTER_FS:
		switch(f->type) {
		case AUDIT_FSTYPE:
		case AUDIT_FILTERKEY:
			break;
		default:
			return -EINVAL;
		}
	}

	switch(f->type) {
	default:
		return -EINVAL;
	case AUDIT_UID:
	case AUDIT_EUID:
	case AUDIT_SUID:
	case AUDIT_FSUID:
	case AUDIT_LOGINUID:
	case AUDIT_OBJ_UID:
	case AUDIT_GID:
	case AUDIT_EGID:
	case AUDIT_SGID:
	case AUDIT_FSGID:
	case AUDIT_OBJ_GID:
	case AUDIT_PID:
	case AUDIT_PERS:
	case AUDIT_MSGTYPE:
	case AUDIT_PPID:
	case AUDIT_DEVMAJOR:
	case AUDIT_DEVMINOR:
	case AUDIT_EXIT:
	case AUDIT_SUCCESS:
	case AUDIT_INODE:
	case AUDIT_SESSIONID:
		/* bit ops are only useful on syscall args */
		if (f->op == Audit_bitmask || f->op == Audit_bittest)
			return -EINVAL;
		break;
	case AUDIT_ARG0:
	case AUDIT_ARG1:
	case AUDIT_ARG2:
	case AUDIT_ARG3:
	case AUDIT_SUBJ_USER:
	case AUDIT_SUBJ_ROLE:
	case AUDIT_SUBJ_TYPE:
	case AUDIT_SUBJ_SEN:
	case AUDIT_SUBJ_CLR:
	case AUDIT_OBJ_USER:
	case AUDIT_OBJ_ROLE:
	case AUDIT_OBJ_TYPE:
	case AUDIT_OBJ_LEV_LOW:
	case AUDIT_OBJ_LEV_HIGH:
	case AUDIT_WATCH:
	case AUDIT_DIR:
	case AUDIT_FILTERKEY:
		break;
	case AUDIT_LOGINUID_SET:
		if ((f->val != 0) && (f->val != 1))
			return -EINVAL;
	/* FALL THROUGH */
	case AUDIT_ARCH:
	case AUDIT_FSTYPE:
		if (f->op != Audit_not_equal && f->op != Audit_equal)
			return -EINVAL;
		break;
	case AUDIT_PERM:
		if (f->val & ~15)
			return -EINVAL;
		break;
	case AUDIT_FILETYPE:
		if (f->val & ~S_IFMT)
			return -EINVAL;
		break;
	case AUDIT_FIELD_COMPARE:
		if (f->val > AUDIT_MAX_FIELD_COMPARE)
			return -EINVAL;
		break;
	case AUDIT_EXE:
		if (f->op != Audit_equal)
			return -EINVAL;
		if (entry->rule.listnr != AUDIT_FILTER_EXIT)
			return -EINVAL;
		break;
	}
	return 0;
}


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Eric Paris13735.77%423.53%


Richard Guy Briggs8722.72%317.65%


Al Viro7519.58%423.53%


Eric W. Biedermann4411.49%211.76%


Amy Griffis348.88%211.76%


Darrel Goeddel41.04%15.88%


Steve Grubb20.52%15.88%


Total383100.00%17100.00%



/* Translate struct audit_rule_data to kernel's rule representation. */



static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
					       size_t datasz)
{
	int err = 0;
	struct audit_entry *entry;
	void *bufp;
	size_t remain = datasz - sizeof(struct audit_rule_data);
	int i;
	char *str;
	struct audit_fsnotify_mark *audit_mark;

	entry = audit_to_entry_common(data);
	if (IS_ERR(entry))
		goto exit_nofree;

	bufp = data->buf;
	for (i = 0; i < data->field_count; i++) {
		struct audit_field *f = &entry->rule.fields[i];

		err = -EINVAL;

		f->op = audit_to_op(data->fieldflags[i]);
		if (f->op == Audit_bad)
			goto exit_free;

		f->type = data->fields[i];
		f->val = data->values[i];

		/* Support legacy tests for a valid loginuid */
		if ((f->type == AUDIT_LOGINUID) && (f->val == AUDIT_UID_UNSET)) {
			f->type = AUDIT_LOGINUID_SET;
			f->val = 0;
			entry->rule.pflags |= AUDIT_LOGINUID_LEGACY;
		}

		err = audit_field_valid(entry, f);
		if (err)
			goto exit_free;

		err = -EINVAL;
		switch (f->type) {
		case AUDIT_LOGINUID:
		case AUDIT_UID:
		case AUDIT_EUID:
		case AUDIT_SUID:
		case AUDIT_FSUID:
		case AUDIT_OBJ_UID:
			f->uid = make_kuid(current_user_ns(), f->val);
			if (!uid_valid(f->uid))
				goto exit_free;
			break;
		case AUDIT_GID:
		case AUDIT_EGID:
		case AUDIT_SGID:
		case AUDIT_FSGID:
		case AUDIT_OBJ_GID:
			f->gid = make_kgid(current_user_ns(), f->val);
			if (!gid_valid(f->gid))
				goto exit_free;
			break;
		case AUDIT_SESSIONID:
		case AUDIT_ARCH:
			entry->rule.arch_f = f;
			break;
		case AUDIT_SUBJ_USER:
		case AUDIT_SUBJ_ROLE:
		case AUDIT_SUBJ_TYPE:
		case AUDIT_SUBJ_SEN:
		case AUDIT_SUBJ_CLR:
		case AUDIT_OBJ_USER:
		case AUDIT_OBJ_ROLE:
		case AUDIT_OBJ_TYPE:
		case AUDIT_OBJ_LEV_LOW:
		case AUDIT_OBJ_LEV_HIGH:
			str = audit_unpack_string(&bufp, &remain, f->val);
			if (IS_ERR(str))
				goto exit_free;
			entry->rule.buflen += f->val;

			err = security_audit_rule_init(f->type, f->op, str,
						       (void **)&f->lsm_rule);
			/* Keep currently invalid fields around in case they
                         * become valid after a policy reload. */
			if (err == -EINVAL) {
				pr_warn("audit rule for LSM \'%s\' is invalid\n",
					str);
				err = 0;
			}
			if (err) {
				kfree(str);
				goto exit_free;
			} else
				f->lsm_str = str;
			break;
		case AUDIT_WATCH:
			str = audit_unpack_string(&bufp, &remain, f->val);
			if (IS_ERR(str))
				goto exit_free;
			entry->rule.buflen += f->val;

			err = audit_to_watch(&entry->rule, str, f->val, f->op);
			if (err) {
				kfree(str);
				goto exit_free;
			}
			break;
		case AUDIT_DIR:
			str = audit_unpack_string(&bufp, &remain, f->val);
			if (IS_ERR(str))
				goto exit_free;
			entry->rule.buflen += f->val;

			err = audit_make_tree(&entry->rule, str, f->op);
			kfree(str);
			if (err)
				goto exit_free;
			break;
		case AUDIT_INODE:
			err = audit_to_inode(&entry->rule, f);
			if (err)
				goto exit_free;
			break;
		case AUDIT_FILTERKEY:
			if (entry->rule.filterkey || f->val > AUDIT_MAX_KEY_LEN)
				goto exit_free;
			str = audit_unpack_string(&bufp, &remain, f->val);
			if (IS_ERR(str))
				goto exit_free;
			entry->rule.buflen += f->val;
			entry->rule.filterkey = str;
			break;
		case AUDIT_EXE:
			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;

			audit_mark = audit_alloc_mark(&entry->rule, str, f->val);
			if (IS_ERR(audit_mark)) {
				kfree(str);
				err = PTR_ERR(audit_mark);
				goto exit_free;
			}
			entry->rule.exe = audit_mark;
			break;
		}
	}

	if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
		entry->rule.inode_f = NULL;

exit_nofree:
	return entry;

exit_free:
	if (entry->rule.tree)
		audit_put_tree(entry->rule.tree); /* that's the temporary one */
	if (entry->rule.exe)
		audit_remove_mark(entry->rule.exe); /* that's the template one */
	audit_free_rule(entry);
	return ERR_PTR(err);
}


Contributors
PersonTokensPropCommitsCommitProp
Amy Griffis34038.33%417.39%


Richard Guy Briggs15117.02%626.09%


Darrel Goeddel14316.12%313.04%


Al Viro11512.97%313.04%


Eric W. Biedermann9610.82%28.70%


Eric Paris171.92%14.35%


Linus Torvalds111.24%14.35%


Ahmed S. Darwish80.90%28.70%


Chen Gang S60.68%14.35%


Total887100.00%23100.00%



/* Pack a filter field's string representation into data block. */



static inline size_t audit_pack_string(void **bufp, const char *str)
{
	size_t len = strlen(str);

	memcpy(*bufp, str, len);
	*bufp += len;

	return len;
}


Contributors
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Eric Paris3274.42%150.00%


Amy Griffis1125.58%150.00%


Total43100.00%2100.00%



/* Translate kernel rule representation to struct audit_rule_data. */



static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
{
	struct audit_rule_data *data;
	void *bufp;
	int i;

	data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL);
	if (unlikely(!data))
		return NULL;
	memset(data, 0, sizeof(*data));

	data->flags = krule->flags | krule->listnr;
	data->action =