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 #if LINUX_VERSION_CODE >= KERNEL_VERSION(3,8,0)
38 static char *aclpath = "procprotect";
40 static char *aclpath __devinitdata = "procprotect";
43 static struct qstr aclqpath;
45 module_param(aclpath, charp, 0);
46 MODULE_PARM_DESC(aclpath, "Root of directory that stores acl tags for /proc files.");
48 MODULE_AUTHOR("Sapan Bhatia <sapanb@cs.princeton.edu>");
49 MODULE_DESCRIPTION("Lightweight ACLs for /proc.");
50 MODULE_LICENSE("GPL");
51 MODULE_VERSION(VERSION_STR);
53 struct procprotect_ctx {
62 struct hlist_node hlist;
65 #define HASH_SIZE (1<<16)
67 struct hlist_head procprotect_hash[HASH_SIZE];
69 struct proc_dir_entry *proc_entry;
71 static int run_acl(unsigned long ino) {
73 struct acl_entry *entry;
74 hlist_for_each_entry_rcu(entry,
75 n, &procprotect_hash[ino & (HASH_SIZE-1)],
77 if (entry->ino==ino) {
85 Entry point of intercepted call. We need to do two things here:
86 - Decide if we need the heavier return hook to be called
87 - Save the first argument, which is in a register, for consideration in the return hook
89 static int lookup_fast_entry(struct kretprobe_instance *ri, struct pt_regs *regs) {
91 struct procprotect_ctx *ctx;
92 struct nameidata *nd = (struct nameidata *) regs->di;
93 struct qstr *q = (struct qstr *) regs->si;
94 struct dentry *parent = nd->path.dentry;
95 struct inode *pinode = parent->d_inode;
97 if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC
98 && current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {
99 ctx = (struct procprotect_ctx *) ri->data;
100 ctx->inode = regs->cx;
101 ctx->flags = nd->flags;
108 /* The entry hook ensures that the return hook is only called for
113 static int lookup_fast_ret(struct kretprobe_instance *ri, struct pt_regs *regs)
115 struct procprotect_ctx *ctx = (struct procprotect_ctx *) ri->data;
119 /* The kernel is going to honor the request. Here's where we step in */
120 struct inode *inode = *(ctx->inode);
121 if (!run_acl(inode->i_ino)) {
130 static int lookup_slow_entry(struct kretprobe_instance *ri, struct pt_regs *regs) {
132 struct procprotect_ctx *ctx;
133 struct nameidata *nd = (struct nameidata *) regs->di;
134 struct qstr *q = (struct qstr *) regs->si;
135 struct path *p = (struct path *) regs->dx;
137 struct dentry *parent = nd->path.dentry;
138 struct inode *pinode = parent->d_inode;
142 if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC
143 && current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {
145 ctx = (struct procprotect_ctx *) ri->data;
147 ctx->flags = nd->flags;
155 /* The entry hook ensures that the return hook is only called for
158 static int lookup_slow_ret(struct kretprobe_instance *ri, struct pt_regs *regs)
160 struct procprotect_ctx *ctx = (struct procprotect_ctx *) ri->data;
164 /* The kernel is going to honor the request. Here's where we step in */
165 /*struct qstr *q = ctx->q;
166 if (!strncmp(q->name,"sysrq-trigger",13)) {
167 printk(KERN_CRIT "lookup_slow sysrqtrigger");
169 struct path *p = ctx->path;
170 struct inode *inode = p->dentry->d_inode;
171 if (!run_acl(inode->i_ino)) {
186 static struct file *do_last_probe(struct nameidata *nd, struct path *path, struct file *file,
187 struct open_flags *op, const char *pathname) {
188 struct dentry *parent = nd->path.dentry;
189 struct inode *pinode = parent->d_inode;
190 struct qstr *q = &nd->last;
193 if (pinode->i_sb->s_magic == PROC_SUPER_MAGIC && current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns) {
194 /*if (!strncmp(q->name,"sysrq-trigger",13)) {
195 printk(KERN_CRIT "do_last sysrqtrigger: %d",op->open_flag);
197 op->open_flag &= ~O_CREAT;
202 static struct jprobe dolast_probe = {
203 .entry = (kprobe_opcode_t *) do_last_probe
206 static struct kretprobe fast_probe = {
207 .entry_handler = (kprobe_opcode_t *) lookup_fast_entry,
208 .handler = (kprobe_opcode_t *) lookup_fast_ret,
210 .data_size = sizeof(struct procprotect_ctx)
213 static struct kretprobe slow_probe = {
214 .entry_handler = (kprobe_opcode_t *) lookup_slow_entry,
215 .handler = (kprobe_opcode_t *) lookup_slow_ret,
217 .data_size = sizeof(struct procprotect_ctx)
220 static void add_entry(char *pathname) {
222 if (kern_path(pathname, 0, &path)) {
223 printk(KERN_CRIT "Path lookup failed for %s",pathname);
226 unsigned int ino = path.dentry->d_inode->i_ino;
227 struct acl_entry *entry;
228 entry = kmalloc(GFP_KERNEL, sizeof(struct acl_entry));
232 printk(KERN_CRIT "Could not allocate memory for %s",pathname);
236 hlist_add_head_rcu(&entry->hlist,&procprotect_hash[ino&(HASH_SIZE-1)]);
237 printk(KERN_CRIT "Added inode %u",ino);
240 printk(KERN_CRIT "Did not add inode %u, already in list", ino);
247 static void __exit procprotect_exit(void)
249 unregister_kretprobe(&fast_probe);
250 unregister_kretprobe(&slow_probe);
251 unregister_jprobe(&dolast_probe);
252 struct hlist_node *n;
253 struct acl_entry *entry;
256 for (i=0;i<HASH_SIZE;i++) {
257 hlist_for_each_entry_rcu(entry,
258 n, &procprotect_hash[i],
264 remove_proc_entry("procprotect",NULL);
265 printk("Procprotect: Stopped procprotect.\n");
270 int procfile_write(struct file *file, const char *buffer, unsigned long count, void *data) {
271 char pathname[PATH_MAX];
273 if (current->nsproxy->mnt_ns!=init_task.nsproxy->mnt_ns)
276 if (copy_from_user(pathname, buffer, count)) {
279 if (count && (pathname[count-1]==10 || pathname[count-1]==13)) {
280 pathname[count-1]='\0';
283 pathname[count]='\0';
286 printk(KERN_CRIT "Length of buffer=%d",strlen(pathname));
290 static int __init procprotect_init(void)
295 printk("Procprotect: starting procprotect version %s with ACLs at path %s.\n",
296 VERSION_STR, aclpath);
298 for(i=0;i<HASH_SIZE;i++) {
299 INIT_HLIST_HEAD(&procprotect_hash[i]);
302 aclqpath.name = aclpath;
303 aclqpath.len = strnlen(aclpath, PATH_MAX);
305 dolast_probe.kp.addr =
306 (kprobe_opcode_t *) kallsyms_lookup_name("do_last");
308 if (!dolast_probe.kp.addr) {
309 printk("Couldn't find %s to plant kretprobe\n", "do_last");
313 if ((ret = register_jprobe(&dolast_probe)) <0) {
314 printk("register_jprobe failed, returned %u\n", ret);
318 (kprobe_opcode_t *) kallsyms_lookup_name("lookup_fast");
319 if (!fast_probe.kp.addr) {
320 printk("Couldn't find %s to plant kretprobe\n", "lookup_fast");
325 (kprobe_opcode_t *) kallsyms_lookup_name("lookup_slow");
326 if (!slow_probe.kp.addr) {
327 printk("Couldn't find %s to plant kretprobe\n", "lookup_slow");
333 if ((ret = register_kretprobe(&fast_probe)) <0) {
334 printk("register_kretprobe failed, returned %d\n", ret);
338 printk("Planted kretprobe at %p, handler addr %p\n",
339 fast_probe.kp.addr, fast_probe.handler);
341 if ((ret = register_kretprobe(&slow_probe)) <0) {
342 printk("register_kretprobe failed, returned %d\n", ret);
345 printk("Planted kretprobe at %p, handler addr %p\n",
346 slow_probe.kp.addr, slow_probe.handler);
348 proc_entry = create_proc_entry("procprotect", 0644, NULL);
349 proc_entry->write_proc = procfile_write;
356 module_init(procprotect_init);
357 module_exit(procprotect_exit);