cregit-Linux how code gets into the kernel

Release 4.7 kernel/audit_fsnotify.c

Directory: kernel
/* audit_fsnotify.c -- tracking inodes
 *
 * Copyright 2003-2009,2014-2015 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.
 */

#include <linux/kernel.h>
#include <linux/audit.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/fs.h>
#include <linux/fsnotify_backend.h>
#include <linux/namei.h>
#include <linux/netlink.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/security.h>
#include "audit.h"

/*
 * this mark lives on the parent directory of the inode in question.
 * but dev, ino, and path are about the child
 */

struct audit_fsnotify_mark {
	
dev_t dev;		/* associated superblock device */
	
unsigned long ino;	/* associated inode number */
	
char *path;		/* insertion path */
	
struct fsnotify_mark mark; /* fsnotify mark on the inode */
	
struct audit_krule *rule;
};

/* fsnotify handle. */

static struct fsnotify_group *audit_fsnotify_group;

/* fsnotify events we care about. */

#define AUDIT_FS_EVENTS (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\
                         FS_MOVE_SELF | FS_EVENT_ON_CHILD)


static void audit_fsnotify_mark_free(struct audit_fsnotify_mark *audit_mark) { kfree(audit_mark->path); kfree(audit_mark); }

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static void audit_fsnotify_free_mark(struct fsnotify_mark *mark) { struct audit_fsnotify_mark *audit_mark; audit_mark = container_of(mark, struct audit_fsnotify_mark, mark); audit_fsnotify_mark_free(audit_mark); }

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char *audit_mark_path(struct audit_fsnotify_mark *mark) { return mark->path; }

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int audit_mark_compare(struct audit_fsnotify_mark *mark, unsigned long ino, dev_t dev) { if (mark->ino == AUDIT_INO_UNSET) return 0; return (mark->ino == ino) && (mark->dev == dev); }

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static void audit_update_mark(struct audit_fsnotify_mark *audit_mark, struct inode *inode) { audit_mark->dev = inode ? inode->i_sb->s_dev : AUDIT_DEV_UNSET; audit_mark->ino = inode ? inode->i_ino : AUDIT_INO_UNSET; }

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struct audit_fsnotify_mark *audit_alloc_mark(struct audit_krule *krule, char *pathname, int len) { struct audit_fsnotify_mark *audit_mark; struct path path; struct dentry *dentry; struct inode *inode; int ret; if (pathname[0] != '/' || pathname[len-1] == '/') return ERR_PTR(-EINVAL); dentry = kern_path_locked(pathname, &path); if (IS_ERR(dentry)) return (void *)dentry; /* returning an error */ inode = path.dentry->d_inode; inode_unlock(inode); audit_mark = kzalloc(sizeof(*audit_mark), GFP_KERNEL); if (unlikely(!audit_mark)) { audit_mark = ERR_PTR(-ENOMEM); goto out; } fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_free_mark); audit_mark->mark.mask = AUDIT_FS_EVENTS; audit_mark->path = pathname; audit_update_mark(audit_mark, dentry->d_inode); audit_mark->rule = krule; ret = fsnotify_add_mark(&audit_mark->mark, audit_fsnotify_group, inode, NULL, true); if (ret < 0) { audit_fsnotify_mark_free(audit_mark); audit_mark = ERR_PTR(ret); } out: dput(dentry); path_put(&path); return audit_mark; }

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static void audit_mark_log_rule_change(struct audit_fsnotify_mark *audit_mark, char *op) { struct audit_buffer *ab; struct audit_krule *rule = audit_mark->rule; if (!audit_enabled) return; ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE); if (unlikely(!ab)) return; audit_log_format(ab, "auid=%u ses=%u op=", from_kuid(&init_user_ns, audit_get_loginuid(current)), audit_get_sessionid(current)); audit_log_string(ab, op); audit_log_format(ab, " path="); audit_log_untrustedstring(ab, audit_mark->path); audit_log_key(ab, rule->filterkey); audit_log_format(ab, " list=%d res=1", rule->listnr); audit_log_end(ab); }

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void audit_remove_mark(struct audit_fsnotify_mark *audit_mark) { fsnotify_destroy_mark(&audit_mark->mark, audit_fsnotify_group); fsnotify_put_mark(&audit_mark->mark); }

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void audit_remove_mark_rule(struct audit_krule *krule) { struct audit_fsnotify_mark *mark = krule->exe; audit_remove_mark(mark); }

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static void audit_autoremove_mark_rule(struct audit_fsnotify_mark *audit_mark) { struct audit_krule *rule = audit_mark->rule; struct audit_entry *entry = container_of(rule, struct audit_entry, rule); audit_mark_log_rule_change(audit_mark, "autoremove_rule"); audit_del_rule(entry); }

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/* Update mark data in audit rules based on fsnotify events. */
static int audit_mark_handle_event(struct fsnotify_group *group, struct inode *to_tell, struct fsnotify_mark *inode_mark, struct fsnotify_mark *vfsmount_mark, u32 mask, void *data, int data_type, const unsigned char *dname, u32 cookie) { struct audit_fsnotify_mark *audit_mark; struct inode *inode = NULL; audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark); BUG_ON(group != audit_fsnotify_group); switch (data_type) { case (FSNOTIFY_EVENT_PATH): inode = ((struct path *)data)->dentry->d_inode; break; case (FSNOTIFY_EVENT_INODE): inode = (struct inode *)data; break; default: BUG(); return 0; }; if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) { if (audit_compare_dname_path(dname, audit_mark->path, AUDIT_NAME_FULL)) return 0; audit_update_mark(audit_mark, inode); } else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF)) audit_autoremove_mark_rule(audit_mark); return 0; }

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static const struct fsnotify_ops audit_mark_fsnotify_ops = { .handle_event = audit_mark_handle_event, };
static int __init audit_fsnotify_init(void) { audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops); if (IS_ERR(audit_fsnotify_group)) { audit_fsnotify_group = NULL; audit_panic("cannot create audit fsnotify group"); } return 0; }

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device_initcall(audit_fsnotify_init);

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Directory: kernel
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