driver/helper.c

   1 #include <dbi_kprobes.h>
   2 #include <dbi_kprobes_deps.h>
   3 #include <ksyms.h>
   4 #include "us_proc_inst.h"
   5 #include "us_slot_manager.h"
   6 #include "storage.h"
   7 #include "sspt/sspt.h"
   8 #include "filters/filters_core.h"
   9
  10 /*
  11  ******************************************************************************
  12  *                               do_page_fault()                              *
  13  ******************************************************************************
  14  */
  15
  16 struct pf_data {
  17         unsigned long addr;
  18 };
  19
  20 static int entry_handler_pf(struct kretprobe_instance *ri, struct pt_regs *regs)
  21 {
  22         struct pf_data *data = (struct pf_data *)ri->data;
  23
  24 #if defined(CONFIG_X86)
  25         data->addr = read_cr2();
  26 #elif defined(CONFIG_ARM)
  27         data->addr = regs->ARM_r0;
  28 #else
  29 #error this architecture is not supported
  30 #endif
  31
  32         return 0;
  33 }
  34
  35 /* Detects when IPs are really loaded into phy mem and installs probes. */
  36 static int ret_handler_pf(struct kretprobe_instance *ri, struct pt_regs *regs)
  37 {
  38         struct task_struct *task;
  39         struct sspt_proc *proc;
  40
  41         /*
  42          * Because process threads have same address space
  43          * we instrument only group_leader of all this threads
  44          */
  45         task = current->group_leader;
  46         if (task->flags & PF_KTHREAD)
  47                 return 0;
  48
  49         if (!is_us_instrumentation())
  50                 return 0;
  51
  52         proc = sspt_proc_get_by_task(task);
  53         if (proc)
  54                 goto install_proc;
  55
  56         task = check_task(task);
  57         if (task) {
  58                 proc = sspt_proc_get_new(task);
  59                 goto install_proc;
  60         }
  61
  62         return 0;
  63
  64 install_proc:
  65         if (proc->first_install) {
  66                 unsigned long page;
  67                 page = ((struct pf_data *)ri->data)->addr & PAGE_MASK;
  68                 sspt_proc_install_page(proc, page);
  69         } else {
  70                 sspt_proc_install(proc);
  71         }
  72
  73         return 0;
  74 }
  75
  76 static struct kretprobe pf_kretprobe = {
  77         .entry_handler = entry_handler_pf,
  78         .handler = ret_handler_pf,
  79         .data_size = sizeof(struct pf_data)
  80 };
  81
  82
  83
  84 /*
  85  ******************************************************************************
  86  *                              copy_process()                                *
  87  ******************************************************************************
  88  */
  89
  90 static void recover_child(struct task_struct *child_task, struct sspt_proc *proc)
  91 {
  92         sspt_proc_uninstall(proc, child_task, US_DISARM);
  93         dbi_disarm_urp_inst_for_task(current, child_task);
  94 }
  95
  96 static void rm_uprobes_child(struct task_struct *task)
  97 {
  98         struct sspt_proc *proc = sspt_proc_get_by_task(current);
  99         if(proc) {
 100                 recover_child(task, proc);
 101         }
 102 }
 103
 104 /* Delete uprobs in children at fork */
 105 static int ret_handler_cp(struct kretprobe_instance *ri, struct pt_regs *regs)
 106 {
 107         struct task_struct *task = (struct task_struct *)regs_return_value(regs);
 108
 109         if(!task || IS_ERR(task))
 110                 goto out;
 111
 112         if(task->mm != current->mm) {   /* check flags CLONE_VM */
 113                 rm_uprobes_child(task);
 114
 115                 if (check_task(current)) {
 116                         struct sspt_proc *proc;
 117
 118                         proc = sspt_proc_get_new(task);
 119                         sspt_proc_install(proc);
 120                 }
 121         }
 122 out:
 123         return 0;
 124 }
 125
 126 static struct kretprobe cp_kretprobe = {
 127         .handler = ret_handler_cp,
 128 };
 129
 130
 131
 132 /*
 133  ******************************************************************************
 134  *                                mm_release()                                *
 135  ******************************************************************************
 136  */
 137
 138 /* Detects when target process removes IPs. */
 139 static int mr_pre_handler(struct kprobe *p, struct pt_regs *regs)
 140 {
 141         struct sspt_proc *proc = NULL;
 142         struct task_struct *task;
 143
 144 #if defined(CONFIG_X86)
 145         return 0;
 146 #elif defined(CONFIG_ARM)
 147         task = (struct task_struct *)regs->ARM_r0;
 148 #else
 149 #error this architecture is not supported
 150 #endif
 151
 152         if (!is_us_instrumentation() || task->tgid != task->pid) {
 153                 goto out;
 154         }
 155
 156         proc = sspt_proc_get_by_task(task);
 157         if (proc) {
 158                 int ret = sspt_proc_uninstall(proc, task, US_UNREGS_PROBE);
 159                 if (ret != 0) {
 160                         printk("failed to uninstall IPs (%d)!\n", ret);
 161                 }
 162
 163                 dbi_unregister_all_uprobes(task);
 164         }
 165
 166 out:
 167         return 0;
 168 }
 169
 170 static struct kprobe mr_kprobe = {
 171         .pre_handler = mr_pre_handler
 172 };
 173
 174
 175
 176 /*
 177  ******************************************************************************
 178  *                                 do_munmap()                                *
 179  ******************************************************************************
 180  */
 181
 182 static int remove_unmap_probes(struct task_struct *task, struct sspt_proc *proc, unsigned long start, size_t len)
 183 {
 184         struct mm_struct *mm = task->mm;
 185         struct vm_area_struct *vma;
 186
 187         if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE - start) {
 188                 return -EINVAL;
 189         }
 190
 191         if ((len = PAGE_ALIGN(len)) == 0) {
 192                 return -EINVAL;
 193         }
 194
 195         vma = find_vma(mm, start);
 196         if (vma && check_vma(vma)) {
 197                 struct sspt_file *file;
 198                 unsigned long end = start + len;
 199                 struct dentry *dentry = vma->vm_file->f_dentry;
 200
 201                 file = sspt_proc_find_file(proc, dentry);
 202                 if (file) {
 203                         if (vma->vm_start == start || vma->vm_end == end) {
 204                                 sspt_file_uninstall(file, task, US_UNREGS_PROBE);
 205                                 file->loaded = 0;
 206                         } else {
 207                                 unsigned long page_addr;
 208                                 struct sspt_page *page;
 209
 210                                 for (page_addr = vma->vm_start; page_addr < vma->vm_end; page_addr += PAGE_SIZE) {
 211                                         page = sspt_find_page_mapped(file, page_addr);
 212                                         if (page) {
 213                                                 sspt_unregister_page(page, US_UNREGS_PROBE, task);
 214                                         }
 215                                 }
 216
 217                                 if (sspt_file_check_install_pages(file)) {
 218                                         file->loaded = 0;
 219                                 }
 220                         }
 221                 }
 222         }
 223
 224         return 0;
 225 }
 226
 227 /* Detects when target removes IPs. */
 228 static int unmap_pre_handler(struct kprobe *p, struct pt_regs *regs)
 229 {
 230         /* for ARM */
 231         struct mm_struct *mm;
 232         unsigned long start;
 233         size_t len;
 234
 235 #if defined(CONFIG_X86)
 236         return 0;
 237 #elif defined(CONFIG_ARM)
 238         mm = (struct mm_struct *)regs->ARM_r0;
 239         start = regs->ARM_r1;
 240         len = (size_t)regs->ARM_r2;
 241 #else
 242 #error this architecture is not supported
 243 #endif
 244
 245         struct sspt_proc *proc = NULL;
 246         struct task_struct *task = current;
 247
 248         //if user-space instrumentation is not set
 249         if (!is_us_instrumentation()) {
 250                 goto out;
 251         }
 252
 253         proc = sspt_proc_get_by_task(task);
 254         if (proc) {
 255                 if (remove_unmap_probes(task, proc, start, len)) {
 256                         printk("ERROR do_munmap: start=%lx, len=%x\n", start, len);
 257                 }
 258         }
 259
 260 out:
 261         return 0;
 262 }
 263
 264 static struct kprobe unmap_kprobe = {
 265         .pre_handler = unmap_pre_handler
 266 };
 267
 268
 269
 270 int register_helper(void)
 271 {
 272         int ret = 0;
 273
 274         /* install kprobe on 'do_munmap' to detect when for remove user space probes */
 275         ret = dbi_register_kprobe(&unmap_kprobe);
 276         if (ret) {
 277                 printk("dbi_register_kprobe(do_munmap) result=%d!\n", ret);
 278                 return ret;
 279         }
 280
 281         /* install kprobe on 'mm_release' to detect when for remove user space probes */
 282         ret = dbi_register_kprobe(&mr_kprobe);
 283         if (ret != 0) {
 284                 printk("dbi_register_kprobe(mm_release) result=%d!\n", ret);
 285                 goto unregister_unmap;
 286         }
 287
 288
 289         /* install kretprobe on 'copy_process' */
 290         ret = dbi_register_kretprobe(&cp_kretprobe);
 291         if (ret) {
 292                 printk("dbi_register_kretprobe(copy_process) result=%d!\n", ret);
 293                 goto unregister_mr;
 294         }
 295
 296         /* install kretprobe on 'do_page_fault' to detect when they will be loaded */
 297         ret = dbi_register_kretprobe(&pf_kretprobe);
 298         if (ret) {
 299                 printk("dbi_register_kretprobe(do_page_fault) result=%d!\n", ret);
 300                 goto unregister_cp;
 301         }
 302
 303         return ret;
 304
 305 unregister_cp:
 306         dbi_unregister_kretprobe(&cp_kretprobe);
 307
 308 unregister_mr:
 309         dbi_unregister_kprobe(&mr_kprobe, NULL);
 310
 311 unregister_unmap:
 312         dbi_unregister_kprobe(&unmap_kprobe, NULL);
 313
 314         return ret;
 315 }
 316
 317 void unregister_helper(void)
 318 {
 319         /* uninstall kretprobe with 'do_page_fault' */
 320         dbi_unregister_kretprobe(&pf_kretprobe);
 321
 322         /* uninstall kretprobe with 'copy_process' */
 323         dbi_unregister_kretprobe(&cp_kretprobe);
 324
 325         /* uninstall kprobe with 'mm_release' */
 326         dbi_unregister_kprobe(&mr_kprobe, NULL);
 327
 328         /* uninstall kprobe with 'do_munmap' */
 329         dbi_unregister_kprobe(&unmap_kprobe, NULL);
 330 }
 331
 332 int init_helper(void)
 333 {
 334         unsigned long addr;
 335         addr = swap_ksyms("do_page_fault");
 336         if (addr == 0) {
 337                 printk("Cannot find address for page fault function!\n");
 338                 return -EINVAL;
 339         }
 340         pf_kretprobe.kp.addr = (kprobe_opcode_t *)addr;
 341
 342         addr = swap_ksyms("copy_process");
 343         if (addr == 0) {
 344                 printk("Cannot find address for copy_process function!\n");
 345                 return -EINVAL;
 346         }
 347         cp_kretprobe.kp.addr = (kprobe_opcode_t *)addr;
 348
 349         addr = swap_ksyms("mm_release");
 350         if (addr == 0) {
 351                 printk("Cannot find address for mm_release function!\n");
 352                 return -EINVAL;
 353         }
 354         mr_kprobe.addr = (kprobe_opcode_t *)addr;
 355
 356         addr = swap_ksyms("do_munmap");
 357         if (addr == 0) {
 358                 printk("Cannot find address for do_munmap function!\n");
 359                 return -EINVAL;
 360         }
 361         unmap_kprobe.addr = (kprobe_opcode_t *)addr;
 362
 363         return 0;
 364 }
 365
 366 void uninit_helper(void)
 367 {
 368 }