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 {
53 struct hlist_node hlist;
56 #define HASH_SIZE (1<<16)
58 struct hlist_head procprotect_hash[HASH_SIZE];
60 struct proc_dir_entry *proc_entry;
63 Entry point of intercepted call. We need to do two things here:
64 - Decide if we need the heavier return hook to be called
65 - Save the first argument, which is in a register, for consideration in the return hook
67 static int do_lookup_entry(struct kretprobe_instance *ri, struct pt_regs *regs) {
69 struct procprotect_ctx *ctx;
70 struct nameidata *nd = (struct nameidata *) regs->di;
71 struct qstr *q = (struct qstr *) regs->si;
72 struct dentry *parent = nd->path.dentry;
73 struct inode *pinode = parent->d_inode;
75 if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC) {
76 ctx = (struct procprotect_ctx *) ri->data;
77 ctx->inode = (struct inode **) regs->cx;
84 static int run_acl(unsigned long ino) {
86 struct acl_entry *entry;
87 hlist_for_each_entry_rcu(entry,
88 n, &procprotect_hash[ino & (HASH_SIZE-1)],
90 if (entry->ino==ino) {
97 /* The entry hook ensures that the return hook is only called for
100 static int do_lookup_ret(struct kretprobe_instance *ri, struct pt_regs *regs)
102 struct procprotect_ctx *ctx = (struct procprotect_ctx *) ri->data;
106 /* The kernel is going to honor the request. Here's where we step in */
107 struct inode *inode = *(ctx->inode);
108 //printk(KERN_CRIT "Checking inode %x number %u",inode,inode->i_ino);
109 if (!run_acl(inode->i_ino)) {
110 if (current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns)
118 static struct kretprobe proc_probe = {
119 .entry_handler = (kprobe_opcode_t *) do_lookup_entry,
120 .handler = (kprobe_opcode_t *) do_lookup_ret,
122 .data_size = sizeof(struct procprotect_ctx)
125 static void add_entry(char *pathname) {
127 if (kern_path(pathname, 0, &path)) {
128 printk(KERN_CRIT "Path lookup failed for %s",pathname);
131 unsigned int ino = path.dentry->d_inode->i_ino;
132 struct acl_entry *entry;
133 entry = kmalloc(GFP_KERNEL, sizeof(struct acl_entry));
137 printk(KERN_CRIT "Could not allocate memory for %s",pathname);
141 hlist_add_head_rcu(&entry->hlist,&procprotect_hash[ino&(HASH_SIZE-1)]);
142 printk(KERN_CRIT "Added inode %u",ino);
145 printk(KERN_CRIT "Did not add inode %u, already in list", ino);
152 static void __exit procprotect_exit(void)
154 unregister_kretprobe(&proc_probe);
155 struct hlist_node *n;
156 struct acl_entry *entry;
159 for (i=0;i<HASH_SIZE;i++) {
160 hlist_for_each_entry_rcu(entry,
161 n, &procprotect_hash[i],
167 remove_proc_entry("procprotect",NULL);
168 printk("Procprotect: Stopped procprotect.\n");
173 int procfile_write(struct file *file, const char *buffer, unsigned long count, void *data) {
174 char pathname[PATH_MAX];
176 if (current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns)
179 if (copy_from_user(pathname, buffer, count)) {
182 if (count && (pathname[count-1]==10 || pathname[count-1]==13)) {
183 pathname[count-1]='\0';
186 pathname[count]='\0';
188 printk(KERN_CRIT "Length of buffer=%d",strlen(pathname));
192 static int __init procprotect_init(void)
194 printk("Procprotect: starting procprotect version %s with ACLs at path %s.\n",
195 VERSION_STR, aclpath);
199 for(i=0;i<HASH_SIZE;i++) {
200 INIT_HLIST_HEAD(&procprotect_hash[i]);
203 aclqpath.name = aclpath;
204 aclqpath.len = strnlen(aclpath, PATH_MAX);
207 (kprobe_opcode_t *) kallsyms_lookup_name("do_lookup");
208 if (!proc_probe.kp.addr) {
209 printk("Couldn't find %s to plant kretprobe\n", "do_execve");
213 if ((ret = register_kretprobe(&proc_probe)) <0) {
214 printk("register_kretprobe failed, returned %d\n", ret);
217 printk("Planted kretprobe at %p, handler addr %p\n",
218 proc_probe.kp.addr, proc_probe.handler);
220 proc_entry = create_proc_entry("procprotect", 0644, NULL);
221 proc_entry->write_proc = procfile_write;
227 module_init(procprotect_init);
228 module_exit(procprotect_exit);