1 #include <linux/module.h>
2 #include <linux/moduleparam.h>
3 #include <linux/types.h>
4 #include <linux/kernel.h>
5 #include <linux/version.h>
6 #include <linux/fs_struct.h>
9 #include <linux/reboot.h>
10 #include <linux/delay.h>
11 #include <linux/proc_fs.h>
12 #include <asm/uaccess.h>
13 #include <linux/sysrq.h>
14 #include <linux/timer.h>
15 #include <linux/time.h>
16 #include <linux/lglock.h>
17 #include <linux/init.h>
18 #include <linux/idr.h>
19 #include <linux/namei.h>
20 #include <linux/bitops.h>
21 #include <linux/mount.h>
22 #include <linux/dcache.h>
23 #include <linux/spinlock.h>
24 #include <linux/completion.h>
25 #include <linux/sched.h>
26 #include <linux/seq_file.h>
27 #include <linux/kprobes.h>
28 #include <linux/kallsyms.h>
29 #include <linux/nsproxy.h>
31 #define VERSION_STR "0.0.1"
34 #error "This code does not support your architecture"
37 static char *aclpath = "procprotect";
39 static struct qstr aclqpath;
41 module_param(aclpath, charp, 0);
42 MODULE_PARM_DESC(aclpath, "Root of directory that stores acl tags for /proc files.");
44 MODULE_AUTHOR("Sapan Bhatia <sapanb@cs.princeton.edu>");
45 MODULE_DESCRIPTION("Lightweight ACLs for /proc.");
46 MODULE_LICENSE("GPL");
47 MODULE_VERSION(VERSION_STR);
49 struct procprotect_ctx {
58 struct hlist_node hlist;
61 #define HASH_SIZE (1<<16)
63 struct hlist_head procprotect_hash[HASH_SIZE];
65 struct proc_dir_entry *proc_entry;
67 static int run_acl(unsigned long ino) {
68 struct acl_entry *entry;
69 hlist_for_each_entry_rcu(entry,
70 &procprotect_hash[ino & (HASH_SIZE-1)],
72 if (entry->ino==ino) {
80 Entry point of intercepted call. We need to do two things here:
81 - Decide if we need the heavier return hook to be called
82 - Save the first argument, which is in a register, for consideration in the return hook
84 static int lookup_fast_entry(struct kretprobe_instance *ri, struct pt_regs *regs) {
86 struct procprotect_ctx *ctx;
87 struct nameidata *nd = (struct nameidata *) regs->di;
88 struct dentry *parent = nd->path.dentry;
89 struct inode *pinode = parent->d_inode;
91 if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC
92 && current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {
93 ctx = (struct procprotect_ctx *) ri->data;
94 ctx->inode = regs->dx;
95 ctx->flags = nd->flags;
102 /* The entry hook ensures that the return hook is only called for
107 static int lookup_fast_ret(struct kretprobe_instance *ri, struct pt_regs *regs)
109 struct procprotect_ctx *ctx = (struct procprotect_ctx *) ri->data;
113 /* The kernel is going to honor the request. Here's where we step in */
114 struct inode *inode = *(ctx->inode);
115 if (!run_acl(inode->i_ino)) {
124 static int lookup_slow_entry(struct kretprobe_instance *ri, struct pt_regs *regs) {
126 struct procprotect_ctx *ctx;
127 struct nameidata *nd = (struct nameidata *) regs->di;
128 struct path *p = (struct path *) regs->si;
130 struct dentry *parent = nd->path.dentry;
131 struct inode *pinode = parent->d_inode;
135 if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC
136 && current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {
138 ctx = (struct procprotect_ctx *) ri->data;
140 ctx->flags = nd->flags;
148 /* The entry hook ensures that the return hook is only called for
151 static int print_once = 0;
153 static int lookup_slow_ret(struct kretprobe_instance *ri, struct pt_regs *regs)
155 struct procprotect_ctx *ctx;
158 if (!ri || !ri->data) {return 0;}
159 ctx = (struct procprotect_ctx *) ri->data;
164 struct path *p = ctx->path;
165 if (!p || !p->dentry || !p->dentry->d_inode /* This last check was responsible for the f18 bug*/) {
168 struct inode *inode = p->dentry->d_inode;
169 if (!run_acl(inode->i_ino)) {
184 static struct file *do_last_probe(struct nameidata *nd, struct path *path, struct file *file,
185 struct open_flags *op, const char *pathname) {
186 struct dentry *parent = nd->path.dentry;
187 struct inode *pinode = parent->d_inode;
188 struct qstr *q = &nd->last;
191 if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC && current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {
192 /*if (!strncmp(q->name,"sysrq-trigger",13)) {
193 printk(KERN_CRIT "do_last sysrqtrigger: %d",op->open_flag);
195 op->open_flag &= ~O_CREAT;
200 static struct jprobe dolast_probe = {
201 .entry = (kprobe_opcode_t *) do_last_probe
204 static struct kretprobe fast_probe = {
205 .entry_handler = (kprobe_opcode_t *) lookup_fast_entry,
206 .handler = (kprobe_opcode_t *) lookup_fast_ret,
208 .data_size = sizeof(struct procprotect_ctx)
211 static struct kretprobe slow_probe = {
212 .entry_handler = (kprobe_opcode_t *) lookup_slow_entry,
213 .handler = (kprobe_opcode_t *) lookup_slow_ret,
215 .data_size = sizeof(struct procprotect_ctx)
218 static void add_entry(char *pathname) {
220 if (kern_path(pathname, 0, &path)) {
221 printk(KERN_CRIT "Path lookup failed for %s",pathname);
224 unsigned int ino = path.dentry->d_inode->i_ino;
225 struct acl_entry *entry;
226 entry = kmalloc(GFP_KERNEL, sizeof(struct acl_entry));
230 printk(KERN_CRIT "Could not allocate memory for %s",pathname);
234 hlist_add_head_rcu(&entry->hlist,&procprotect_hash[ino&(HASH_SIZE-1)]);
235 printk(KERN_CRIT "Added inode %u",ino);
238 printk(KERN_CRIT "Did not add inode %u, already in list", ino);
245 static void __exit procprotect_exit(void)
247 unregister_kretprobe(&fast_probe);
248 unregister_kretprobe(&slow_probe);
249 unregister_jprobe(&dolast_probe);
250 struct acl_entry *entry;
253 for (i=0;i<HASH_SIZE;i++) {
254 hlist_for_each_entry_rcu(entry,
255 &procprotect_hash[i],
261 remove_proc_entry("procprotect",NULL);
262 printk("Procprotect: Stopped procprotect.\n");
267 int procfile_write(struct file *file, const char *buffer, unsigned long count, void *data) {
268 char pathname[PATH_MAX];
270 if (current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns)
273 if (copy_from_user(pathname, buffer, count)) {
276 if (count && (pathname[count-1]==10 || pathname[count-1]==13)) {
277 pathname[count-1]='\0';
280 pathname[count]='\0';
283 printk(KERN_CRIT "Length of buffer=%d",strlen(pathname));
287 static int __init procprotect_init(void)
292 printk("Procprotect: starting procprotect version %s with ACLs at path %s.\n",
293 VERSION_STR, aclpath);
295 for(i=0;i<HASH_SIZE;i++) {
296 INIT_HLIST_HEAD(&procprotect_hash[i]);
299 aclqpath.name = aclpath;
300 aclqpath.len = strnlen(aclpath, PATH_MAX);
302 dolast_probe.kp.addr =
303 (kprobe_opcode_t *) kallsyms_lookup_name("do_last");
305 if (!dolast_probe.kp.addr) {
306 printk("Couldn't find %s to plant kretprobe\n", "do_last");
310 if ((ret = register_jprobe(&dolast_probe)) <0) {
311 printk("register_jprobe failed, returned %u\n", ret);
315 (kprobe_opcode_t *) kallsyms_lookup_name("lookup_fast");
316 if (!fast_probe.kp.addr) {
317 printk("Couldn't find %s to plant kretprobe\n", "lookup_fast");
322 (kprobe_opcode_t *) kallsyms_lookup_name("lookup_slow");
323 if (!slow_probe.kp.addr) {
324 printk("Couldn't find %s to plant kretprobe\n", "lookup_slow");
330 if ((ret = register_kretprobe(&fast_probe)) <0) {
331 printk("register_kretprobe failed, returned %d\n", ret);
335 printk("Planted kretprobe at %p, handler addr %p\n",
336 fast_probe.kp.addr, fast_probe.handler);
338 if ((ret = register_kretprobe(&slow_probe)) <0) {
339 printk("register_kretprobe failed, returned %d\n", ret);
342 printk("Planted kretprobe at %p, handler addr %p\n",
343 slow_probe.kp.addr, slow_probe.handler);
345 proc_entry = create_proc_entry("procprotect", 0644, NULL);
346 proc_entry->write_proc = procfile_write;
353 module_init(procprotect_init);
354 module_exit(procprotect_exit);