syscalls/open.c

   1 #include <sys/types.h>
   2 #include <sys/stat.h>
   3 #include <fcntl.h>
   4 #include <stdlib.h>
   5 #include "files.h"
   6 #include "sanitise.h"
   7 #include "shm.h"
   8 #include "utils.h"
   9 #include "compat.h"
  10
  11 static const unsigned long o_flags[] = {
  12         O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
  13         O_NONBLOCK, O_SYNC, O_ASYNC, O_DIRECTORY,
  14         O_NOFOLLOW, O_CLOEXEC, O_DIRECT, O_NOATIME,
  15         O_PATH, O_DSYNC, O_LARGEFILE, O_TMPFILE,
  16 };
  17
  18 /*
  19  * Choose a random number of file flags to OR into the mask.
  20  * also used in files.c:open_file()
  21  */
  22 unsigned long get_o_flags(void)
  23 {
  24         unsigned long mask;
  25
  26         mask = set_rand_bitmask(ARRAY_SIZE(o_flags), o_flags);
  27
  28         return mask;
  29 }
  30
  31 /*
  32  * SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, int, mode)
  33  */
  34 static void sanitise_open(int childno);
  35
  36 struct syscallentry syscall_open = {
  37         .name = "open",
  38         .num_args = 3,
  39         .arg1name = "filename",
  40         .arg1type = ARG_PATHNAME,
  41         .arg2name = "flags",
  42         .arg2type = ARG_OP,
  43         .arg2list = {
  44                 .num = 4,
  45                 .values = { O_RDONLY, O_WRONLY, O_RDWR, O_CREAT, },
  46         },
  47         .arg3name = "mode",
  48         .arg3type = ARG_MODE_T,
  49         .sanitise = sanitise_open,
  50 };
  51
  52 static void sanitise_open(int childno)
  53 {
  54         unsigned long flags;
  55
  56         flags = get_o_flags();
  57
  58         shm->syscall[childno].a2 |= flags;
  59 }
  60
  61 /*
  62  * SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, int, mode)
  63  */
  64 static void sanitise_openat(int childno);
  65
  66 struct syscallentry syscall_openat = {
  67         .name = "openat",
  68         .num_args = 4,
  69         .arg1name = "dfd",
  70         .arg1type = ARG_FD,
  71         .arg2name = "filename",
  72         .arg2type = ARG_PATHNAME,
  73         .arg3name = "flags",
  74         .arg3type = ARG_OP,
  75         .arg3list = {
  76                 .num = 4,
  77                 .values = { O_RDONLY, O_WRONLY, O_RDWR, O_CREAT, },
  78         },
  79         .arg4name = "mode",
  80         .arg4type = ARG_MODE_T,
  81         .flags = NEED_ALARM,
  82         .sanitise = sanitise_openat,
  83 };
  84
  85 static void sanitise_openat(int childno)
  86 {
  87         unsigned long flags;
  88
  89         flags = get_o_flags();
  90
  91         shm->syscall[childno].a3 |= flags;
  92 }
  93
  94 /*
  95  * SYSCALL_DEFINE3(open_by_handle_at, int, mountdirfd,
  96  *               struct file_handle __user *, handle,
  97  *               int, flags)
  98  */
  99 struct syscallentry syscall_open_by_handle_at = {
 100         .name = "open_by_handle_at",
 101         .num_args = 3,
 102         .arg1name = "mountdirfd",
 103         .arg1type = ARG_FD,
 104         .arg2name = "handle",
 105         .arg2type = ARG_ADDRESS,
 106         .arg3name = "flags",
 107         .arg3type = ARG_OP,
 108         .arg3list = {
 109                 .num = 4,
 110                 .values = { O_RDONLY, O_WRONLY, O_RDWR, O_CREAT, },
 111         },
 112         .flags = NEED_ALARM,
 113         .sanitise = sanitise_openat,    // For now we only sanitise .flags, which is also arg3
 114 };