| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
| 2 | /* audit_fsnotify.c -- tracking inodes |
| 3 | * |
| 4 | * Copyright 2003-2009,2014-2015 Red Hat, Inc. |
| 5 | * Copyright 2005 Hewlett-Packard Development Company, L.P. |
| 6 | * Copyright 2005 IBM Corporation |
| 7 | */ |
| 8 | |
| 9 | #include <linux/kernel.h> |
| 10 | #include <linux/audit.h> |
| 11 | #include <linux/kthread.h> |
| 12 | #include <linux/mutex.h> |
| 13 | #include <linux/fs.h> |
| 14 | #include <linux/fsnotify_backend.h> |
| 15 | #include <linux/namei.h> |
| 16 | #include <linux/netlink.h> |
| 17 | #include <linux/sched.h> |
| 18 | #include <linux/slab.h> |
| 19 | #include <linux/security.h> |
| 20 | #include "audit.h" |
| 21 | |
| 22 | /* |
| 23 | * this mark lives on the parent directory of the inode in question. |
| 24 | * but dev, ino, and path are about the child |
| 25 | */ |
| 26 | struct audit_fsnotify_mark { |
| 27 | dev_t dev; /* associated superblock device */ |
| 28 | unsigned long ino; /* associated inode number */ |
| 29 | char *path; /* insertion path */ |
| 30 | struct fsnotify_mark mark; /* fsnotify mark on the inode */ |
| 31 | struct audit_krule *rule; |
| 32 | }; |
| 33 | |
| 34 | /* fsnotify handle. */ |
| 35 | static struct fsnotify_group *audit_fsnotify_group; |
| 36 | |
| 37 | /* fsnotify events we care about. */ |
| 38 | #define AUDIT_FS_EVENTS (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\ |
| 39 | FS_MOVE_SELF) |
| 40 | |
| 41 | static void audit_fsnotify_mark_free(struct audit_fsnotify_mark *audit_mark) |
| 42 | { |
| 43 | kfree(audit_mark->path); |
| 44 | kfree(audit_mark); |
| 45 | } |
| 46 | |
| 47 | static void audit_fsnotify_free_mark(struct fsnotify_mark *mark) |
| 48 | { |
| 49 | struct audit_fsnotify_mark *audit_mark; |
| 50 | |
| 51 | audit_mark = container_of(mark, struct audit_fsnotify_mark, mark); |
| 52 | audit_fsnotify_mark_free(audit_mark); |
| 53 | } |
| 54 | |
| 55 | char *audit_mark_path(struct audit_fsnotify_mark *mark) |
| 56 | { |
| 57 | return mark->path; |
| 58 | } |
| 59 | |
| 60 | int audit_mark_compare(struct audit_fsnotify_mark *mark, unsigned long ino, dev_t dev) |
| 61 | { |
| 62 | if (mark->ino == AUDIT_INO_UNSET) |
| 63 | return 0; |
| 64 | return (mark->ino == ino) && (mark->dev == dev); |
| 65 | } |
| 66 | |
| 67 | static void audit_update_mark(struct audit_fsnotify_mark *audit_mark, |
| 68 | const struct inode *inode) |
| 69 | { |
| 70 | audit_mark->dev = inode ? inode->i_sb->s_dev : AUDIT_DEV_UNSET; |
| 71 | audit_mark->ino = inode ? inode->i_ino : AUDIT_INO_UNSET; |
| 72 | } |
| 73 | |
| 74 | struct audit_fsnotify_mark *audit_alloc_mark(struct audit_krule *krule, char *pathname, int len) |
| 75 | { |
| 76 | struct audit_fsnotify_mark *audit_mark; |
| 77 | struct path path; |
| 78 | struct dentry *dentry; |
| 79 | struct inode *inode; |
| 80 | int ret; |
| 81 | |
| 82 | if (pathname[0] != '/' || pathname[len-1] == '/') |
| 83 | return ERR_PTR(-EINVAL); |
| 84 | |
| 85 | dentry = kern_path_locked(pathname, &path); |
| 86 | if (IS_ERR(dentry)) |
| 87 | return ERR_CAST(dentry); /* returning an error */ |
| 88 | inode = path.dentry->d_inode; |
| 89 | inode_unlock(inode); |
| 90 | |
| 91 | audit_mark = kzalloc(sizeof(*audit_mark), GFP_KERNEL); |
| 92 | if (unlikely(!audit_mark)) { |
| 93 | audit_mark = ERR_PTR(-ENOMEM); |
| 94 | goto out; |
| 95 | } |
| 96 | |
| 97 | fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_group); |
| 98 | audit_mark->mark.mask = AUDIT_FS_EVENTS; |
| 99 | audit_mark->path = pathname; |
| 100 | audit_update_mark(audit_mark, dentry->d_inode); |
| 101 | audit_mark->rule = krule; |
| 102 | |
| 103 | ret = fsnotify_add_inode_mark(&audit_mark->mark, inode, 0); |
| 104 | if (ret < 0) { |
| 105 | audit_mark->path = NULL; |
| 106 | fsnotify_put_mark(&audit_mark->mark); |
| 107 | audit_mark = ERR_PTR(ret); |
| 108 | } |
| 109 | out: |
| 110 | dput(dentry); |
| 111 | path_put(&path); |
| 112 | return audit_mark; |
| 113 | } |
| 114 | |
| 115 | static void audit_mark_log_rule_change(struct audit_fsnotify_mark *audit_mark, char *op) |
| 116 | { |
| 117 | struct audit_buffer *ab; |
| 118 | struct audit_krule *rule = audit_mark->rule; |
| 119 | |
| 120 | if (!audit_enabled) |
| 121 | return; |
| 122 | ab = audit_log_start(audit_context(), GFP_NOFS, AUDIT_CONFIG_CHANGE); |
| 123 | if (unlikely(!ab)) |
| 124 | return; |
| 125 | audit_log_session_info(ab); |
| 126 | audit_log_format(ab, " op=%s path=", op); |
| 127 | audit_log_untrustedstring(ab, audit_mark->path); |
| 128 | audit_log_key(ab, rule->filterkey); |
| 129 | audit_log_format(ab, " list=%d res=1", rule->listnr); |
| 130 | audit_log_end(ab); |
| 131 | } |
| 132 | |
| 133 | void audit_remove_mark(struct audit_fsnotify_mark *audit_mark) |
| 134 | { |
| 135 | fsnotify_destroy_mark(&audit_mark->mark, audit_fsnotify_group); |
| 136 | fsnotify_put_mark(&audit_mark->mark); |
| 137 | } |
| 138 | |
| 139 | void audit_remove_mark_rule(struct audit_krule *krule) |
| 140 | { |
| 141 | struct audit_fsnotify_mark *mark = krule->exe; |
| 142 | |
| 143 | audit_remove_mark(mark); |
| 144 | } |
| 145 | |
| 146 | static void audit_autoremove_mark_rule(struct audit_fsnotify_mark *audit_mark) |
| 147 | { |
| 148 | struct audit_krule *rule = audit_mark->rule; |
| 149 | struct audit_entry *entry = container_of(rule, struct audit_entry, rule); |
| 150 | |
| 151 | audit_mark_log_rule_change(audit_mark, "autoremove_rule"); |
| 152 | audit_del_rule(entry); |
| 153 | } |
| 154 | |
| 155 | /* Update mark data in audit rules based on fsnotify events. */ |
| 156 | static int audit_mark_handle_event(struct fsnotify_mark *inode_mark, u32 mask, |
| 157 | struct inode *inode, struct inode *dir, |
| 158 | const struct qstr *dname, u32 cookie) |
| 159 | { |
| 160 | struct audit_fsnotify_mark *audit_mark; |
| 161 | |
| 162 | audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark); |
| 163 | |
| 164 | if (WARN_ON_ONCE(inode_mark->group != audit_fsnotify_group)) |
| 165 | return 0; |
| 166 | |
| 167 | if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) { |
| 168 | if (audit_compare_dname_path(dname, audit_mark->path, AUDIT_NAME_FULL)) |
| 169 | return 0; |
| 170 | audit_update_mark(audit_mark, inode); |
| 171 | } else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF)) { |
| 172 | audit_autoremove_mark_rule(audit_mark); |
| 173 | } |
| 174 | |
| 175 | return 0; |
| 176 | } |
| 177 | |
| 178 | static const struct fsnotify_ops audit_mark_fsnotify_ops = { |
| 179 | .handle_inode_event = audit_mark_handle_event, |
| 180 | .free_mark = audit_fsnotify_free_mark, |
| 181 | }; |
| 182 | |
| 183 | static int __init audit_fsnotify_init(void) |
| 184 | { |
| 185 | audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops, |
| 186 | FSNOTIFY_GROUP_DUPS); |
| 187 | if (IS_ERR(audit_fsnotify_group)) { |
| 188 | audit_fsnotify_group = NULL; |
| 189 | audit_panic("cannot create audit fsnotify group"); |
| 190 | } |
| 191 | return 0; |
| 192 | } |
| 193 | device_initcall(audit_fsnotify_init); |