/*
* analyze_object
* Look at a library loaded into the current process, and determine as much as
* possible about it. The disassembling, allocations are initiated here.
*
* This is a callback function, passed to dl_iterate_phdr(3).
* data and size are just unused callback arguments.
*
*
* From dl_iterate_phdr(3) man page:
*
* struct dl_phdr_info
* {
* ElfW(Addr) dlpi_addr; Base address of object
* const char *dlpi_name; (Null-terminated) name of object
* const ElfW(Phdr) *dlpi_phdr; Pointer to array of ELF program headers
* ElfW(Half) dlpi_phnum; # of items in dlpi_phdr
* ...
* }
*
*/
static int
analyze_object(struct dl_phdr_info *info, size_t size, void *data)
{
(void) data;
(void) size;
const char *path;
debug_dump("analyze_object called on \"%s\" at 0x%016" PRIxPTR "\n",
info->dlpi_name, info->dlpi_addr);
if ((path = get_object_path(info)) == NULL)
return 0;
debug_dump("analyze %s\n", path);
if (!should_patch_object(info->dlpi_addr, path))
return 0;
struct intercept_desc *patches = allocate_next_obj_desc();
patches->base_addr = (unsigned char *)info->dlpi_addr;
patches->path = path;
find_syscalls(patches);
allocate_trampoline_table(patches);
create_patch_wrappers(patches);
return 0;
}
static int __init init_ugidctl(void)
{
dev_t dev;
int rc;
rc = find_syscalls();
if (rc)
return rc;
dprintk("found sys_setuid() 0x%p", ugidctl_sys_setuid);
dprintk("found sys_setgid() 0x%p", ugidctl_sys_setgid);
dprintk("found sys_setgroups() 0x%p\n", ugidctl_sys_setgroups);
rc = -ENOMEM;
uid_cache = KMEM_CACHE(ugidctl_uid_node, 0);
if (!uid_cache) {
printk(KERN_ERR "%s: cannot allocate uid cache\n", MOD_NAME);
goto out;
}
gid_cache = KMEM_CACHE(ugidctl_gid_node, 0);
if (!gid_cache) {
printk(KERN_ERR "%s: cannot allocate gid cache\n", MOD_NAME);
goto out_uid_cache;
}
rc = alloc_chrdev_region(&dev, 0, 1, DEV_NAME);
if (rc) {
printk(KERN_ERR "%s: failed to register chrdev region\n", MOD_NAME);
goto out_gid_cache;
}
ugidctl_major = MAJOR(dev);
ugidctl_class = class_create(THIS_MODULE, DEV_NAME);
if (IS_ERR(ugidctl_class)) {
printk(KERN_ERR "%s: failed to register with sysfs\n", MOD_NAME);
rc = PTR_ERR(ugidctl_class);
goto out_region;
}
cdev_init(&ugidctl_cdev, &ugidctl_fops);
rc = cdev_add(&ugidctl_cdev, dev, 1);
if (rc) {
printk(KERN_ERR "%s: failed to add char device\n", MOD_NAME);
goto out_class;
}
device_create(ugidctl_class, NULL, dev, NULL, DEV_NAME);
// printk(KERN_INFO "%s: v" MOD_VERSION " loaded\n", MOD_NAME);
return 0;
out_class:
class_destroy(ugidctl_class);
out_region:
unregister_chrdev_region(dev, 1);
out_gid_cache:
kmem_cache_destroy(gid_cache);
out_uid_cache:
kmem_cache_destroy(uid_cache);
out:
return rc;
}
