/* here we test to make sure that the task passed in valid pointers
* to syscalls that have pointers are arguments, so that we make sure
* we only ever modify user-space data when we think we're modifying
* user-space data. */
int check_pointers(volatile registers_t *regs)
{
switch(SYSCALL_NUM_AND_RET) {
case SYS_READ: case SYS_FSTAT: case SYS_STAT: case SYS_GETPATH:
case SYS_READLINK: case SYS_GETNODESTR:
case SYS_POSFSSTAT:
return __is_valid_user_ptr(SYSCALL_NUM_AND_RET, (void *)_B_, 0);
case SYS_TIMES: case SYS_GETPWD: case SYS_PIPE:
case SYS_MEMSTAT: case SYS_GETTIME: case SYS_GETHOSTNAME:
case SYS_UNAME:
return __is_valid_user_ptr(SYSCALL_NUM_AND_RET, (void *)_A_, 0);
case SYS_SETSIG: case SYS_WAITPID:
return __is_valid_user_ptr(SYSCALL_NUM_AND_RET, (void *)_B_, 1);
case SYS_SELECT:
if(!__is_valid_user_ptr(SYSCALL_NUM_AND_RET, (void *)_B_, 1))
return 0;
if(!__is_valid_user_ptr(SYSCALL_NUM_AND_RET, (void *)_C_, 1))
return 0;
if(!__is_valid_user_ptr(SYSCALL_NUM_AND_RET, (void *)_D_, 1))
return 0;
if(!__is_valid_user_ptr(SYSCALL_NUM_AND_RET, (void *)_E_, 1))
return 0;
break;
case SYS_DIRSTAT:
if(!__is_valid_user_ptr(SYSCALL_NUM_AND_RET, (void *)_C_, 0))
return 0;
if(!__is_valid_user_ptr(SYSCALL_NUM_AND_RET, (void *)_D_, 0))
return 0;
break;
case SYS_SIGACT: case SYS_SIGPROCMASK:
return __is_valid_user_ptr(SYSCALL_NUM_AND_RET, (void *)_C_, 1);
case SYS_CHOWN: case SYS_CHMOD:
return __is_valid_user_ptr(SYSCALL_NUM_AND_RET, (void *)_A_, 1);
}
return 1;
}
int do_exec(task_t *t, char *path, char **argv, char **env)
{
unsigned int i=0;
addr_t end, eip;
unsigned int argc=0, envc=0;
int desc;
char **backup_argv=0, **backup_env=0;
/* Sanity */
if(!t) panic(PANIC_NOSYNC, "Tried to execute with empty task");
if(t == kernel_task) panic(0, "Kernel is being executed at the gallows!");
if(t != current_task)
panic(0, "I don't know, was really drunk at the time");
if(t->magic != TASK_MAGIC)
panic(0, "Invalid task in exec (%d)", t->pid);
if(!path || !*path)
return -EINVAL;
/* Load the file, and make sure that it is valid and accessable */
if(EXEC_LOG == 2)
printk(0, "[%d]: Checking executable file (%s)\n", t->pid, path);
struct file *efil;
int err_open, num;
efil=d_sys_open(path, O_RDONLY, 0, &err_open, &num);
if(efil)
desc = num;
else
desc = err_open;
if(desc < 0 || !efil)
return -ENOENT;
if(!permissions(efil->inode, MAY_EXEC))
{
sys_close(desc);
return -EACCES;
}
/* Detirmine if the file is a valid ELF */
int header_size = 0;
#if CONFIG_ARCH == TYPE_ARCH_X86_64
header_size = sizeof(elf64_header_t);
#elif CONFIG_ARCH == TYPE_ARCH_X86
header_size = sizeof(elf32_header_t);
#endif
char mem[header_size];
read_data(desc, mem, 0, header_size);
int other_bitsize=0;
#if CONFIG_ARCH == TYPE_ARCH_X86_64
if(is_valid_elf32_otherarch(mem, 2))
other_bitsize = 1;
#endif
if(!is_valid_elf(mem, 2) && !other_bitsize) {
sys_close(desc);
return -ENOEXEC;
}
if(EXEC_LOG == 2)
printk(0, "[%d]: Copy data\n", t->pid);
/* okay, lets back up argv and env so that we can
* clear out the address space and not lose data..*/
if(__is_valid_user_ptr(SYS_EXECVE, argv, 0)) {
while(__is_valid_user_ptr(SYS_EXECVE, argv[argc], 0) && *argv[argc]) argc++;
backup_argv = (char **)kmalloc(sizeof(addr_t) * argc);
for(i=0;i<argc;i++) {
backup_argv[i] = (char *)kmalloc(strlen(argv[i]) + 1);
_strcpy(backup_argv[i], argv[i]);
}
}
if(__is_valid_user_ptr(SYS_EXECVE, env, 0)) {
while(__is_valid_user_ptr(SYS_EXECVE, env[envc], 0) && *env[envc]) envc++;
backup_env = (char **)kmalloc(sizeof(addr_t) * envc);
for(i=0;i<envc;i++) {
backup_env[i] = (char *)kmalloc(strlen(env[i]) + 1);
_strcpy(backup_env[i], env[i]);
}
}
/* and the path too! */
char *path_backup = (char *)kmalloc(strlen(path) + 1);
_strcpy((char *)path_backup, path);
path = path_backup;
if(pd_cur_data->count > 1)
printk(0, "[exec]: Not sure what to do here...\n");
/* Preexec - This is the point of no return. Here we close out unneeded
* file descs, free up the page directory and clear up the resources
* of the task */
if(EXEC_LOG)
printk(0, "Executing (task %d, cpu %d, tty %d, cwd=%s): %s\n", t->pid, ((cpu_t *)t->cpu)->apicid, t->tty, current_task->thread->pwd->name, path);
preexec(t, desc);
strncpy((char *)t->command, path, 128);
if(other_bitsize)
{
#if CONFIG_ARCH == TYPE_ARCH_X86_64
if(!process_elf_other(mem, desc, &eip, &end))
eip=0;
#endif
} else if(!process_elf(mem, desc, &eip, &end))
eip=0;
sys_close(desc);
if(!eip) {
printk(5, "[exec]: Tried to execute an invalid ELF file!\n");
free_dp(backup_argv, argc);
free_dp(backup_env, envc);
#if DEBUG
panic(0, "");
#endif
exit(0);
}
if(EXEC_LOG == 2)
printk(0, "[%d]: Updating task values\n", t->pid);
/* Setup the task with the proper values (libc malloc stack) */
addr_t end_l = end;
end = (end&PAGE_MASK);
user_map_if_not_mapped_noclear(end);
/* now we need to copy back the args and env into userspace
* writeable memory...yippie. */
addr_t args_start = end + PAGE_SIZE;
addr_t env_start = args_start;
addr_t alen = 0;
if(backup_argv) {
for(i=0;i<(sizeof(addr_t) * (argc+1))/PAGE_SIZE + 2;i++)
user_map_if_not_mapped_noclear(args_start + i * PAGE_SIZE);
memcpy((void *)args_start, backup_argv, sizeof(addr_t) * argc);
alen += sizeof(addr_t) * argc;
*(addr_t *)(args_start + alen) = 0; /* set last argument value to zero */
alen += sizeof(addr_t);
argv = (char **)args_start;
for(i=0;i<argc;i++)
{
char *old = argv[i];
char *new = (char *)(args_start+alen);
user_map_if_not_mapped_noclear((addr_t)new);
unsigned len = strlen(old) + 4;
user_map_if_not_mapped_noclear((addr_t)new + len + 1);
argv[i] = new;
_strcpy(new, old);
kfree(old);
alen += len;
}
kfree(backup_argv);
}
env_start = args_start + alen;
alen = 0;
if(backup_env) {
for(i=0;i<(((sizeof(addr_t) * (envc+1))/PAGE_SIZE) + 2);i++)
user_map_if_not_mapped_noclear(env_start + i * PAGE_SIZE);
memcpy((void *)env_start, backup_env, sizeof(addr_t) * envc);
alen += sizeof(addr_t) * envc;
*(addr_t *)(env_start + alen) = 0; /* set last argument value to zero */
alen += sizeof(addr_t);
env = (char **)env_start;
for(i=0;i<envc;i++)
{
char *old = env[i];
char *new = (char *)(env_start+alen);
user_map_if_not_mapped_noclear((addr_t)new);
unsigned len = strlen(old) + 1;
user_map_if_not_mapped_noclear((addr_t)new + len + 1);
env[i] = new;
_strcpy(new, old);
kfree(old);
alen += len;
}
kfree(backup_env);
}
end = (env_start + alen) & PAGE_MASK;
t->env = env;
t->argv = argv;
kfree(path);
t->heap_start = t->heap_end = end + PAGE_SIZE;
if(other_bitsize)
raise_task_flag(t, TF_OTHERBS);
user_map_if_not_mapped_noclear(t->heap_start);
/* Zero the heap and stack */
memset((void *)end_l, 0, PAGE_SIZE-(end_l%PAGE_SIZE));
memset((void *)(end+PAGE_SIZE), 0, PAGE_SIZE);
memset((void *)(STACK_LOCATION - STACK_SIZE), 0, STACK_SIZE);
/* Release everything */
if(EXEC_LOG == 2)
printk(0, "[%d]: Performing call\n", t->pid);
set_int(0);
lower_task_flag(t, TF_SCHED);
if(!(kernel_state_flags & KSF_HAVEEXECED))
set_ksf(KSF_HAVEEXECED);
arch_specific_exec_initializer(t, argc, eip);
return 0;
}