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 {
54 struct hlist_node hlist;
57 #define HASH_SIZE (1<<16)
59 struct hlist_head procprotect_hash[HASH_SIZE];
61 struct proc_dir_entry *proc_entry;
64 Entry point of intercepted call. We need to do two things here:
65 - Decide if we need the heavier return hook to be called
66 - Save the first argument, which is in a register, for consideration in the return hook
68 static int do_lookup_entry(struct kretprobe_instance *ri, struct pt_regs *regs) {
70 struct procprotect_ctx *ctx;
71 struct nameidata *nd = (struct nameidata *) regs->di;
72 struct qstr *q = (struct qstr *) regs->si;
73 struct dentry *parent = nd->path.dentry;
74 struct inode *pinode = parent->d_inode;
76 if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC
77 && current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {
78 ctx = (struct procprotect_ctx *) ri->data;
79 ctx->inode = regs->cx;
80 ctx->flags = nd->flags;
87 static int run_acl(unsigned long ino) {
89 struct acl_entry *entry;
90 hlist_for_each_entry_rcu(entry,
91 n, &procprotect_hash[ino & (HASH_SIZE-1)],
93 if (entry->ino==ino) {
100 /* The entry hook ensures that the return hook is only called for
103 static int do_lookup_ret(struct kretprobe_instance *ri, struct pt_regs *regs)
105 struct procprotect_ctx *ctx = (struct procprotect_ctx *) ri->data;
109 /* The kernel is going to honor the request. Here's where we step in */
110 struct inode *inode = *(ctx->inode);
111 if (!run_acl(inode->i_ino)) {
112 if (current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {
128 static struct file *do_last_probe(struct nameidata *nd, struct path *path,
129 struct open_flags *op, const char *pathname) {
130 struct dentry *parent = nd->path.dentry;
131 struct inode *pinode = parent->d_inode;
133 if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC && current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {
134 op->open_flag &= ~O_CREAT;
139 static struct jprobe dolast_probe = {
140 .entry = (kprobe_opcode_t *) do_last_probe
143 static struct kretprobe proc_probe = {
144 .entry_handler = (kprobe_opcode_t *) do_lookup_entry,
145 .handler = (kprobe_opcode_t *) do_lookup_ret,
147 .data_size = sizeof(struct procprotect_ctx)
150 static void add_entry(char *pathname) {
152 if (kern_path(pathname, 0, &path)) {
153 printk(KERN_CRIT "Path lookup failed for %s",pathname);
156 unsigned int ino = path.dentry->d_inode->i_ino;
157 struct acl_entry *entry;
158 entry = kmalloc(GFP_KERNEL, sizeof(struct acl_entry));
162 printk(KERN_CRIT "Could not allocate memory for %s",pathname);
166 hlist_add_head_rcu(&entry->hlist,&procprotect_hash[ino&(HASH_SIZE-1)]);
167 printk(KERN_CRIT "Added inode %u",ino);
170 printk(KERN_CRIT "Did not add inode %u, already in list", ino);
177 static void __exit procprotect_exit(void)
179 unregister_kretprobe(&proc_probe);
180 unregister_jprobe(&dolast_probe);
181 struct hlist_node *n;
182 struct acl_entry *entry;
185 for (i=0;i<HASH_SIZE;i++) {
186 hlist_for_each_entry_rcu(entry,
187 n, &procprotect_hash[i],
193 remove_proc_entry("procprotect",NULL);
194 printk("Procprotect: Stopped procprotect.\n");
199 int procfile_write(struct file *file, const char *buffer, unsigned long count, void *data) {
200 char pathname[PATH_MAX];
202 if (current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns)
205 if (copy_from_user(pathname, buffer, count)) {
208 if (count && (pathname[count-1]==10 || pathname[count-1]==13)) {
209 pathname[count-1]='\0';
212 pathname[count]='\0';
214 printk(KERN_CRIT "Length of buffer=%d",strlen(pathname));
218 static int __init procprotect_init(void)
220 printk("Procprotect: starting procprotect version %s with ACLs at path %s.\n",
221 VERSION_STR, aclpath);
225 for(i=0;i<HASH_SIZE;i++) {
226 INIT_HLIST_HEAD(&procprotect_hash[i]);
229 aclqpath.name = aclpath;
230 aclqpath.len = strnlen(aclpath, PATH_MAX);
233 (kprobe_opcode_t *) kallsyms_lookup_name("do_lookup");
234 if (!proc_probe.kp.addr) {
235 printk("Couldn't find %s to plant kretprobe\n", "do_execve");
239 dolast_probe.kp.addr =
240 (kprobe_opcode_t *) kallsyms_lookup_name("do_last");
242 if (!dolast_probe.kp.addr) {
243 printk("Couldn't find %s to plant kretprobe\n", "do_last");
247 if ((ret = register_jprobe(&dolast_probe)) <0) {
248 printk("register_jprobe failed, returned %u\n", ret);
252 if ((ret = register_kretprobe(&proc_probe)) <0) {
253 printk("register_kretprobe failed, returned %d\n", ret);
256 printk("Planted kretprobe at %p, handler addr %p\n",
257 proc_probe.kp.addr, proc_probe.handler);
259 proc_entry = create_proc_entry("procprotect", 0644, NULL);
260 proc_entry->write_proc = procfile_write;
267 module_init(procprotect_init);
268 module_exit(procprotect_exit);