cdrom: Make device operations read-only
Since function tables are a common target for attackers, it's best to keep
them in read-only memory. As such, this makes the CDROM device ops tables
const. This drops additionally n_minors, since it isn't used meaningfully,
and sets the only user of cdrom_dummy_generic_packet explicitly so the
variables can all be const.
Inspired by similar changes in grsecurity/PaX.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index 59cca72..bbbd3ca 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -342,8 +342,8 @@ static void cdrom_sysctl_register(void);
static LIST_HEAD(cdrom_list);
-static int cdrom_dummy_generic_packet(struct cdrom_device_info *cdi,
- struct packet_command *cgc)
+int cdrom_dummy_generic_packet(struct cdrom_device_info *cdi,
+ struct packet_command *cgc)
{
if (cgc->sense) {
cgc->sense->sense_key = 0x05;
@@ -354,6 +354,7 @@ static int cdrom_dummy_generic_packet(struct cdrom_device_info *cdi,
cgc->stat = -EIO;
return -EIO;
}
+EXPORT_SYMBOL(cdrom_dummy_generic_packet);
static int cdrom_flush_cache(struct cdrom_device_info *cdi)
{
@@ -371,7 +372,7 @@ static int cdrom_flush_cache(struct cdrom_device_info *cdi)
static int cdrom_get_disc_info(struct cdrom_device_info *cdi,
disc_information *di)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
struct packet_command cgc;
int ret, buflen;
@@ -586,7 +587,7 @@ static int cdrom_mrw_set_lba_space(struct cdrom_device_info *cdi, int space)
int register_cdrom(struct cdrom_device_info *cdi)
{
static char banner_printed;
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
int *change_capability = (int *)&cdo->capability; /* hack */
cd_dbg(CD_OPEN, "entering register_cdrom\n");
@@ -610,7 +611,6 @@ int register_cdrom(struct cdrom_device_info *cdi)
ENSURE(reset, CDC_RESET);
ENSURE(generic_packet, CDC_GENERIC_PACKET);
cdi->mc_flags = 0;
- cdo->n_minors = 0;
cdi->options = CDO_USE_FFLAGS;
if (autoclose == 1 && CDROM_CAN(CDC_CLOSE_TRAY))
@@ -630,8 +630,7 @@ int register_cdrom(struct cdrom_device_info *cdi)
else
cdi->cdda_method = CDDA_OLD;
- if (!cdo->generic_packet)
- cdo->generic_packet = cdrom_dummy_generic_packet;
+ WARN_ON(!cdo->generic_packet);
cd_dbg(CD_REG_UNREG, "drive \"/dev/%s\" registered\n", cdi->name);
mutex_lock(&cdrom_mutex);
@@ -652,7 +651,6 @@ void unregister_cdrom(struct cdrom_device_info *cdi)
if (cdi->exit)
cdi->exit(cdi);
- cdi->ops->n_minors--;
cd_dbg(CD_REG_UNREG, "drive \"/dev/%s\" unregistered\n", cdi->name);
}
@@ -1036,7 +1034,7 @@ static
int open_for_data(struct cdrom_device_info *cdi)
{
int ret;
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
tracktype tracks;
cd_dbg(CD_OPEN, "entering open_for_data\n");
/* Check if the driver can report drive status. If it can, we
@@ -1198,8 +1196,8 @@ int cdrom_open(struct cdrom_device_info *cdi, struct block_device *bdev,
/* This code is similar to that in open_for_data. The routine is called
whenever an audio play operation is requested.
*/
-static int check_for_audio_disc(struct cdrom_device_info * cdi,
- struct cdrom_device_ops * cdo)
+static int check_for_audio_disc(struct cdrom_device_info *cdi,
+ const struct cdrom_device_ops *cdo)
{
int ret;
tracktype tracks;
@@ -1254,7 +1252,7 @@ static int check_for_audio_disc(struct cdrom_device_info * cdi,
void cdrom_release(struct cdrom_device_info *cdi, fmode_t mode)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
int opened_for_data;
cd_dbg(CD_CLOSE, "entering cdrom_release\n");
@@ -1294,7 +1292,7 @@ static int cdrom_read_mech_status(struct cdrom_device_info *cdi,
struct cdrom_changer_info *buf)
{
struct packet_command cgc;
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
int length;
/*
@@ -1643,7 +1641,7 @@ static int dvd_do_auth(struct cdrom_device_info *cdi, dvd_authinfo *ai)
int ret;
u_char buf[20];
struct packet_command cgc;
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
rpc_state_t rpc_state;
memset(buf, 0, sizeof(buf));
@@ -1791,7 +1789,7 @@ static int dvd_read_physical(struct cdrom_device_info *cdi, dvd_struct *s,
{
unsigned char buf[21], *base;
struct dvd_layer *layer;
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
int ret, layer_num = s->physical.layer_num;
if (layer_num >= DVD_LAYERS)
@@ -1842,7 +1840,7 @@ static int dvd_read_copyright(struct cdrom_device_info *cdi, dvd_struct *s,
{
int ret;
u_char buf[8];
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
init_cdrom_command(cgc, buf, sizeof(buf), CGC_DATA_READ);
cgc->cmd[0] = GPCMD_READ_DVD_STRUCTURE;
@@ -1866,7 +1864,7 @@ static int dvd_read_disckey(struct cdrom_device_info *cdi, dvd_struct *s,
{
int ret, size;
u_char *buf;
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
size = sizeof(s->disckey.value) + 4;
@@ -1894,7 +1892,7 @@ static int dvd_read_bca(struct cdrom_device_info *cdi, dvd_struct *s,
{
int ret, size = 4 + 188;
u_char *buf;
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
buf = kmalloc(size, GFP_KERNEL);
if (!buf)
@@ -1928,7 +1926,7 @@ static int dvd_read_manufact(struct cdrom_device_info *cdi, dvd_struct *s,
{
int ret = 0, size;
u_char *buf;
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
size = sizeof(s->manufact.value) + 4;
@@ -1995,7 +1993,7 @@ int cdrom_mode_sense(struct cdrom_device_info *cdi,
struct packet_command *cgc,
int page_code, int page_control)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
memset(cgc->cmd, 0, sizeof(cgc->cmd));
@@ -2010,7 +2008,7 @@ int cdrom_mode_sense(struct cdrom_device_info *cdi,
int cdrom_mode_select(struct cdrom_device_info *cdi,
struct packet_command *cgc)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
memset(cgc->cmd, 0, sizeof(cgc->cmd));
memset(cgc->buffer, 0, 2);
@@ -2025,7 +2023,7 @@ int cdrom_mode_select(struct cdrom_device_info *cdi,
static int cdrom_read_subchannel(struct cdrom_device_info *cdi,
struct cdrom_subchnl *subchnl, int mcn)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
struct packet_command cgc;
char buffer[32];
int ret;
@@ -2073,7 +2071,7 @@ static int cdrom_read_cd(struct cdrom_device_info *cdi,
struct packet_command *cgc, int lba,
int blocksize, int nblocks)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
memset(&cgc->cmd, 0, sizeof(cgc->cmd));
cgc->cmd[0] = GPCMD_READ_10;
@@ -2093,7 +2091,7 @@ static int cdrom_read_block(struct cdrom_device_info *cdi,
struct packet_command *cgc,
int lba, int nblocks, int format, int blksize)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
memset(&cgc->cmd, 0, sizeof(cgc->cmd));
cgc->cmd[0] = GPCMD_READ_CD;
@@ -2764,7 +2762,7 @@ static int cdrom_ioctl_audioctl(struct cdrom_device_info *cdi,
*/
static int cdrom_switch_blocksize(struct cdrom_device_info *cdi, int size)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
struct packet_command cgc;
struct modesel_head mh;
@@ -2790,7 +2788,7 @@ static int cdrom_switch_blocksize(struct cdrom_device_info *cdi, int size)
static int cdrom_get_track_info(struct cdrom_device_info *cdi,
__u16 track, __u8 type, track_information *ti)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
struct packet_command cgc;
int ret, buflen;
@@ -3049,7 +3047,7 @@ static noinline int mmc_ioctl_cdrom_play_msf(struct cdrom_device_info *cdi,
void __user *arg,
struct packet_command *cgc)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
struct cdrom_msf msf;
cd_dbg(CD_DO_IOCTL, "entering CDROMPLAYMSF\n");
if (copy_from_user(&msf, (struct cdrom_msf __user *)arg, sizeof(msf)))
@@ -3069,7 +3067,7 @@ static noinline int mmc_ioctl_cdrom_play_blk(struct cdrom_device_info *cdi,
void __user *arg,
struct packet_command *cgc)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
struct cdrom_blk blk;
cd_dbg(CD_DO_IOCTL, "entering CDROMPLAYBLK\n");
if (copy_from_user(&blk, (struct cdrom_blk __user *)arg, sizeof(blk)))
@@ -3164,7 +3162,7 @@ static noinline int mmc_ioctl_cdrom_start_stop(struct cdrom_device_info *cdi,
struct packet_command *cgc,
int cmd)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
cd_dbg(CD_DO_IOCTL, "entering CDROMSTART/CDROMSTOP\n");
cgc->cmd[0] = GPCMD_START_STOP_UNIT;
cgc->cmd[1] = 1;
@@ -3177,7 +3175,7 @@ static noinline int mmc_ioctl_cdrom_pause_resume(struct cdrom_device_info *cdi,
struct packet_command *cgc,
int cmd)
{
- struct cdrom_device_ops *cdo = cdi->ops;
+ const struct cdrom_device_ops *cdo = cdi->ops;
cd_dbg(CD_DO_IOCTL, "entering CDROMPAUSE/CDROMRESUME\n");
cgc->cmd[0] = GPCMD_PAUSE_RESUME;
cgc->cmd[8] = (cmd == CDROMRESUME) ? 1 : 0;