1 #include <linux/module.h>
2 #include <linux/moduleparam.h>
3 #include <linux/types.h>
4 #include <linux/kernel.h>
5 #include <linux/fs_struct.h>
8 #include <linux/reboot.h>
9 #include <linux/delay.h>
10 #include <linux/proc_fs.h>
11 #include <asm/uaccess.h>
12 #include <linux/sysrq.h>
13 #include <linux/timer.h>
14 #include <linux/time.h>
15 #include <linux/lglock.h>
16 #include <linux/init.h>
17 #include <linux/idr.h>
18 #include <linux/namei.h>
19 #include <linux/bitops.h>
20 #include <linux/mount.h>
21 #include <linux/dcache.h>
22 #include <linux/spinlock.h>
23 #include <linux/completion.h>
24 #include <linux/sched.h>
25 #include <linux/seq_file.h>
26 #include <linux/kprobes.h>
27 #include <linux/kallsyms.h>
28 #include <linux/nsproxy.h>
30 #define VERSION_STR "0.0.1"
33 #error "This code does not support your architecture"
36 static char *aclpath __devinitdata = "procprotect";
37 static struct qstr aclqpath;
39 module_param(aclpath, charp, 0);
40 MODULE_PARM_DESC(aclpath, "Root of directory that stores acl tags for /proc files.");
42 MODULE_AUTHOR("Sapan Bhatia <sapanb@cs.princeton.edu>");
43 MODULE_DESCRIPTION("Lightweight ACLs for /proc.");
44 MODULE_LICENSE("GPL");
45 MODULE_VERSION(VERSION_STR);
47 struct procprotect_ctx {
56 struct hlist_node hlist;
59 #define HASH_SIZE (1<<16)
61 struct hlist_head procprotect_hash[HASH_SIZE];
63 struct proc_dir_entry *proc_entry;
65 static int run_acl(unsigned long ino) {
67 struct acl_entry *entry;
68 hlist_for_each_entry_rcu(entry,
69 n, &procprotect_hash[ino & (HASH_SIZE-1)],
71 if (entry->ino==ino) {
79 Entry point of intercepted call. We need to do two things here:
80 - Decide if we need the heavier return hook to be called
81 - Save the first argument, which is in a register, for consideration in the return hook
83 static int lookup_fast_entry(struct kretprobe_instance *ri, struct pt_regs *regs) {
85 struct procprotect_ctx *ctx;
86 struct nameidata *nd = (struct nameidata *) regs->di;
87 struct qstr *q = (struct qstr *) regs->si;
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->cx;
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 qstr *q = (struct qstr *) regs->si;
129 struct path *p = (struct path *) regs->dx;
131 struct dentry *parent = nd->path.dentry;
132 struct inode *pinode = parent->d_inode;
136 if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC
137 && current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {
139 ctx = (struct procprotect_ctx *) ri->data;
141 ctx->flags = nd->flags;
149 /* The entry hook ensures that the return hook is only called for
152 static int lookup_slow_ret(struct kretprobe_instance *ri, struct pt_regs *regs)
154 struct procprotect_ctx *ctx = (struct procprotect_ctx *) ri->data;
158 /* The kernel is going to honor the request. Here's where we step in */
159 /*struct qstr *q = ctx->q;
160 if (!strncmp(q->name,"sysrq-trigger",13)) {
161 printk(KERN_CRIT "lookup_slow sysrqtrigger");
163 struct path *p = ctx->path;
164 struct inode *inode = p->dentry->d_inode;
165 if (!run_acl(inode->i_ino)) {
180 static struct file *do_last_probe(struct nameidata *nd, struct path *path, struct file *file,
181 struct open_flags *op, const char *pathname) {
182 struct dentry *parent = nd->path.dentry;
183 struct inode *pinode = parent->d_inode;
184 struct qstr *q = &nd->last;
187 if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC && current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {
188 /*if (!strncmp(q->name,"sysrq-trigger",13)) {
189 printk(KERN_CRIT "do_last sysrqtrigger: %d",op->open_flag);
191 op->open_flag &= ~O_CREAT;
196 static struct jprobe dolast_probe = {
197 .entry = (kprobe_opcode_t *) do_last_probe
200 static struct kretprobe fast_probe = {
201 .entry_handler = (kprobe_opcode_t *) lookup_fast_entry,
202 .handler = (kprobe_opcode_t *) lookup_fast_ret,
204 .data_size = sizeof(struct procprotect_ctx)
207 static struct kretprobe slow_probe = {
208 .entry_handler = (kprobe_opcode_t *) lookup_slow_entry,
209 .handler = (kprobe_opcode_t *) lookup_slow_ret,
211 .data_size = sizeof(struct procprotect_ctx)
214 static void add_entry(char *pathname) {
216 if (kern_path(pathname, 0, &path)) {
217 printk(KERN_CRIT "Path lookup failed for %s",pathname);
220 unsigned int ino = path.dentry->d_inode->i_ino;
221 struct acl_entry *entry;
222 entry = kmalloc(GFP_KERNEL, sizeof(struct acl_entry));
226 printk(KERN_CRIT "Could not allocate memory for %s",pathname);
230 hlist_add_head_rcu(&entry->hlist,&procprotect_hash[ino&(HASH_SIZE-1)]);
231 printk(KERN_CRIT "Added inode %u",ino);
234 printk(KERN_CRIT "Did not add inode %u, already in list", ino);
241 static void __exit procprotect_exit(void)
243 unregister_kretprobe(&fast_probe);
244 unregister_kretprobe(&slow_probe);
245 unregister_jprobe(&dolast_probe);
246 struct hlist_node *n;
247 struct acl_entry *entry;
250 for (i=0;i<HASH_SIZE;i++) {
251 hlist_for_each_entry_rcu(entry,
252 n, &procprotect_hash[i],
258 remove_proc_entry("procprotect",NULL);
259 printk("Procprotect: Stopped procprotect.\n");
264 int procfile_write(struct file *file, const char *buffer, unsigned long count, void *data) {
265 char pathname[PATH_MAX];
267 if (current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns)
270 if (copy_from_user(pathname, buffer, count)) {
273 if (count && (pathname[count-1]==10 || pathname[count-1]==13)) {
274 pathname[count-1]='\0';
277 pathname[count]='\0';
280 printk(KERN_CRIT "Length of buffer=%d",strlen(pathname));
284 static int __init procprotect_init(void)
286 printk("Procprotect: starting procprotect version %s with ACLs at path %s.\n",
287 VERSION_STR, aclpath);
291 for(i=0;i<HASH_SIZE;i++) {
292 INIT_HLIST_HEAD(&procprotect_hash[i]);
295 aclqpath.name = aclpath;
296 aclqpath.len = strnlen(aclpath, PATH_MAX);
298 dolast_probe.kp.addr =
299 (kprobe_opcode_t *) kallsyms_lookup_name("do_last");
301 if (!dolast_probe.kp.addr) {
302 printk("Couldn't find %s to plant kretprobe\n", "do_last");
306 if ((ret = register_jprobe(&dolast_probe)) <0) {
307 printk("register_jprobe failed, returned %u\n", ret);
311 (kprobe_opcode_t *) kallsyms_lookup_name("lookup_fast");
312 if (!fast_probe.kp.addr) {
313 printk("Couldn't find %s to plant kretprobe\n", "lookup_fast");
318 (kprobe_opcode_t *) kallsyms_lookup_name("lookup_slow");
319 if (!slow_probe.kp.addr) {
320 printk("Couldn't find %s to plant kretprobe\n", "lookup_slow");
326 if ((ret = register_kretprobe(&fast_probe)) <0) {
327 printk("register_kretprobe failed, returned %d\n", ret);
331 printk("Planted kretprobe at %p, handler addr %p\n",
332 fast_probe.kp.addr, fast_probe.handler);
334 if ((ret = register_kretprobe(&slow_probe)) <0) {
335 printk("register_kretprobe failed, returned %d\n", ret);
338 printk("Planted kretprobe at %p, handler addr %p\n",
339 slow_probe.kp.addr, slow_probe.handler);
341 proc_entry = create_proc_entry("procprotect", 0644, NULL);
342 proc_entry->write_proc = procfile_write;
349 module_init(procprotect_init);
350 module_exit(procprotect_exit);