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compat_ioctl: don't look up the fd twice
In code in fs/compat_ioctl.c that translates ioctl arguments into a in-kernel structure, then performs sys_ioctl, possibly under set_fs(KERNEL_DS), this commit changes the sys_ioctl calls to do_ioctl calls. do_ioctl is a new function that does the same thing as sys_ioctl, but doesn't look up the fd again. This change is made to avoid (potential) security issues because of ioctl handlers that accept one of the ioctl commands I2C_FUNCS, VIDEO_GET_EVENT, MTIOCPOS, MTIOCGET, TIOCGSERIAL, TIOCSSERIAL, RTC_IRQP_READ, RTC_EPOCH_READ. This can happen for multiple reasons: - The ioctl command number could be reused. - The ioctl handler might not check the full ioctl command. This is e.g. true for drm_ioctl. - The ioctl handler is very special, e.g. cuse_file_ioctl The real issue is that set_fs(KERNEL_DS) is used here, but that's fixed in a separate commit "compat_ioctl: don't call do_ioctl under set_fs(KERNEL_DS)". This change mitigates potential security issues by preventing a race that permits invocation of unlocked_ioctl handlers under KERNEL_DS through compat code even if a corresponding compat_ioctl handler exists. So far, no way has been identified to use this to damage kernel memory without having CAP_SYS_ADMIN in the init ns (with the capability, doing reads/writes at arbitrary kernel addresses should be easy through CUSE's ioctl handler with FUSE_IOCTL_UNRESTRICTED set). [AV: two missed sys_ioctl() taken care of] Signed-off-by: Jann Horn <jann@thejh.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Jann Horn
Al Viro
parent
168309855a
commit
b43417216e
@ -115,15 +115,27 @@
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#include <asm/fbio.h>
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#endif
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static int w_long(unsigned int fd, unsigned int cmd,
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compat_ulong_t __user *argp)
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static int do_ioctl(struct file *file, unsigned int fd,
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unsigned int cmd, unsigned long arg)
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{
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int err;
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err = security_file_ioctl(file, cmd, arg);
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if (err)
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return err;
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return do_vfs_ioctl(file, fd, cmd, arg);
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}
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static int w_long(struct file *file, unsigned int fd,
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unsigned int cmd, compat_ulong_t __user *argp)
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{
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mm_segment_t old_fs = get_fs();
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int err;
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unsigned long val;
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set_fs (KERNEL_DS);
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err = sys_ioctl(fd, cmd, (unsigned long)&val);
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err = do_ioctl(file, fd, cmd, (unsigned long)&val);
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set_fs (old_fs);
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if (!err && put_user(val, argp))
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return -EFAULT;
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@ -139,15 +151,15 @@ struct compat_video_event {
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} u;
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};
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static int do_video_get_event(unsigned int fd, unsigned int cmd,
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struct compat_video_event __user *up)
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static int do_video_get_event(struct file *file, unsigned int fd,
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unsigned int cmd, struct compat_video_event __user *up)
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{
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struct video_event kevent;
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mm_segment_t old_fs = get_fs();
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int err;
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set_fs(KERNEL_DS);
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err = sys_ioctl(fd, cmd, (unsigned long) &kevent);
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err = do_ioctl(file, fd, cmd, (unsigned long) &kevent);
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set_fs(old_fs);
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if (!err) {
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@ -169,8 +181,8 @@ struct compat_video_still_picture {
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int32_t size;
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};
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static int do_video_stillpicture(unsigned int fd, unsigned int cmd,
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struct compat_video_still_picture __user *up)
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static int do_video_stillpicture(struct file *file, unsigned int fd,
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unsigned int cmd, struct compat_video_still_picture __user *up)
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{
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struct video_still_picture __user *up_native;
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compat_uptr_t fp;
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@ -190,7 +202,7 @@ static int do_video_stillpicture(unsigned int fd, unsigned int cmd,
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if (err)
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return -EFAULT;
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err = sys_ioctl(fd, cmd, (unsigned long) up_native);
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err = do_ioctl(file, fd, cmd, (unsigned long) up_native);
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return err;
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}
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@ -200,8 +212,8 @@ struct compat_video_spu_palette {
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compat_uptr_t palette;
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};
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static int do_video_set_spu_palette(unsigned int fd, unsigned int cmd,
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struct compat_video_spu_palette __user *up)
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static int do_video_set_spu_palette(struct file *file, unsigned int fd,
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unsigned int cmd, struct compat_video_spu_palette __user *up)
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{
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struct video_spu_palette __user *up_native;
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compat_uptr_t palp;
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@ -218,7 +230,7 @@ static int do_video_set_spu_palette(unsigned int fd, unsigned int cmd,
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if (err)
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return -EFAULT;
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err = sys_ioctl(fd, cmd, (unsigned long) up_native);
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err = do_ioctl(file, fd, cmd, (unsigned long) up_native);
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return err;
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}
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@ -276,7 +288,7 @@ static int sg_build_iovec(sg_io_hdr_t __user *sgio, void __user *dxferp, u16 iov
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return 0;
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}
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static int sg_ioctl_trans(unsigned int fd, unsigned int cmd,
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static int sg_ioctl_trans(struct file *file, unsigned int fd, unsigned int cmd,
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sg_io_hdr32_t __user *sgio32)
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{
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sg_io_hdr_t __user *sgio;
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@ -289,7 +301,7 @@ static int sg_ioctl_trans(unsigned int fd, unsigned int cmd,
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if (get_user(interface_id, &sgio32->interface_id))
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return -EFAULT;
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if (interface_id != 'S')
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return sys_ioctl(fd, cmd, (unsigned long)sgio32);
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return do_ioctl(file, fd, cmd, (unsigned long)sgio32);
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if (get_user(iovec_count, &sgio32->iovec_count))
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return -EFAULT;
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@ -349,7 +361,7 @@ static int sg_ioctl_trans(unsigned int fd, unsigned int cmd,
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if (put_user(compat_ptr(data), &sgio->usr_ptr))
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return -EFAULT;
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err = sys_ioctl(fd, cmd, (unsigned long) sgio);
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err = do_ioctl(file, fd, cmd, (unsigned long) sgio);
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if (err >= 0) {
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void __user *datap;
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@ -380,13 +392,13 @@ struct compat_sg_req_info { /* used by SG_GET_REQUEST_TABLE ioctl() */
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int unused;
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};
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static int sg_grt_trans(unsigned int fd, unsigned int cmd, struct
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compat_sg_req_info __user *o)
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static int sg_grt_trans(struct file *file, unsigned int fd,
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unsigned int cmd, struct compat_sg_req_info __user *o)
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{
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int err, i;
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sg_req_info_t __user *r;
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r = compat_alloc_user_space(sizeof(sg_req_info_t)*SG_MAX_QUEUE);
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err = sys_ioctl(fd,cmd,(unsigned long)r);
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err = do_ioctl(file, fd, cmd, (unsigned long)r);
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if (err < 0)
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return err;
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for (i = 0; i < SG_MAX_QUEUE; i++) {
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@ -412,8 +424,8 @@ struct sock_fprog32 {
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#define PPPIOCSPASS32 _IOW('t', 71, struct sock_fprog32)
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#define PPPIOCSACTIVE32 _IOW('t', 70, struct sock_fprog32)
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static int ppp_sock_fprog_ioctl_trans(unsigned int fd, unsigned int cmd,
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struct sock_fprog32 __user *u_fprog32)
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static int ppp_sock_fprog_ioctl_trans(struct file *file, unsigned int fd,
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unsigned int cmd, struct sock_fprog32 __user *u_fprog32)
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{
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struct sock_fprog __user *u_fprog64 = compat_alloc_user_space(sizeof(struct sock_fprog));
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void __user *fptr64;
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@ -435,7 +447,7 @@ static int ppp_sock_fprog_ioctl_trans(unsigned int fd, unsigned int cmd,
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else
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cmd = PPPIOCSACTIVE;
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return sys_ioctl(fd, cmd, (unsigned long) u_fprog64);
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return do_ioctl(file, fd, cmd, (unsigned long) u_fprog64);
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}
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struct ppp_option_data32 {
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@ -451,7 +463,7 @@ struct ppp_idle32 {
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};
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#define PPPIOCGIDLE32 _IOR('t', 63, struct ppp_idle32)
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static int ppp_gidle(unsigned int fd, unsigned int cmd,
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static int ppp_gidle(struct file *file, unsigned int fd, unsigned int cmd,
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struct ppp_idle32 __user *idle32)
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{
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struct ppp_idle __user *idle;
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@ -460,7 +472,7 @@ static int ppp_gidle(unsigned int fd, unsigned int cmd,
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idle = compat_alloc_user_space(sizeof(*idle));
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err = sys_ioctl(fd, PPPIOCGIDLE, (unsigned long) idle);
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err = do_ioctl(file, fd, PPPIOCGIDLE, (unsigned long) idle);
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if (!err) {
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if (get_user(xmit, &idle->xmit_idle) ||
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@ -472,7 +484,7 @@ static int ppp_gidle(unsigned int fd, unsigned int cmd,
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return err;
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}
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static int ppp_scompress(unsigned int fd, unsigned int cmd,
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static int ppp_scompress(struct file *file, unsigned int fd, unsigned int cmd,
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struct ppp_option_data32 __user *odata32)
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{
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struct ppp_option_data __user *odata;
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@ -492,7 +504,7 @@ static int ppp_scompress(unsigned int fd, unsigned int cmd,
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sizeof(__u32) + sizeof(int)))
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return -EFAULT;
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return sys_ioctl(fd, PPPIOCSCOMPRESS, (unsigned long) odata);
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return do_ioctl(file, fd, PPPIOCSCOMPRESS, (unsigned long) odata);
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}
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#ifdef CONFIG_BLOCK
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@ -512,7 +524,8 @@ struct mtpos32 {
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};
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#define MTIOCPOS32 _IOR('m', 3, struct mtpos32)
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static int mt_ioctl_trans(unsigned int fd, unsigned int cmd, void __user *argp)
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static int mt_ioctl_trans(struct file *file, unsigned int fd,
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unsigned int cmd, void __user *argp)
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{
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mm_segment_t old_fs = get_fs();
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struct mtget get;
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@ -534,7 +547,7 @@ static int mt_ioctl_trans(unsigned int fd, unsigned int cmd, void __user *argp)
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break;
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}
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set_fs (KERNEL_DS);
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err = sys_ioctl (fd, kcmd, (unsigned long)karg);
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err = do_ioctl(file, fd, kcmd, (unsigned long)karg);
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set_fs (old_fs);
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if (err)
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return err;
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@ -605,8 +618,8 @@ struct serial_struct32 {
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compat_int_t reserved[1];
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};
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static int serial_struct_ioctl(unsigned fd, unsigned cmd,
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struct serial_struct32 __user *ss32)
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static int serial_struct_ioctl(struct file *file, unsigned fd,
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unsigned cmd, struct serial_struct32 __user *ss32)
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{
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typedef struct serial_struct32 SS32;
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int err;
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@ -629,7 +642,7 @@ static int serial_struct_ioctl(unsigned fd, unsigned cmd,
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ss.iomap_base = 0UL;
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}
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set_fs(KERNEL_DS);
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err = sys_ioctl(fd,cmd,(unsigned long)(&ss));
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err = do_ioctl(file, fd, cmd, (unsigned long)&ss);
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set_fs(oldseg);
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if (cmd == TIOCGSERIAL && err >= 0) {
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if (!access_ok(VERIFY_WRITE, ss32, sizeof(SS32)))
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@ -674,8 +687,8 @@ struct i2c_rdwr_aligned {
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struct i2c_msg msgs[0];
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};
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static int do_i2c_rdwr_ioctl(unsigned int fd, unsigned int cmd,
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struct i2c_rdwr_ioctl_data32 __user *udata)
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static int do_i2c_rdwr_ioctl(struct file *file, unsigned int fd,
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unsigned int cmd, struct i2c_rdwr_ioctl_data32 __user *udata)
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{
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struct i2c_rdwr_aligned __user *tdata;
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struct i2c_msg __user *tmsgs;
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@ -708,11 +721,11 @@ static int do_i2c_rdwr_ioctl(unsigned int fd, unsigned int cmd,
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put_user(compat_ptr(datap), &tmsgs[i].buf))
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return -EFAULT;
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}
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return sys_ioctl(fd, cmd, (unsigned long)tdata);
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return do_ioctl(file, fd, cmd, (unsigned long)tdata);
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}
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static int do_i2c_smbus_ioctl(unsigned int fd, unsigned int cmd,
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struct i2c_smbus_ioctl_data32 __user *udata)
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static int do_i2c_smbus_ioctl(struct file *file, unsigned int fd,
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unsigned int cmd, struct i2c_smbus_ioctl_data32 __user *udata)
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{
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struct i2c_smbus_ioctl_data __user *tdata;
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compat_caddr_t datap;
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@ -734,7 +747,7 @@ static int do_i2c_smbus_ioctl(unsigned int fd, unsigned int cmd,
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__put_user(compat_ptr(datap), &tdata->data))
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return -EFAULT;
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return sys_ioctl(fd, cmd, (unsigned long)tdata);
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return do_ioctl(file, fd, cmd, (unsigned long)tdata);
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}
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#define RTC_IRQP_READ32 _IOR('p', 0x0b, compat_ulong_t)
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@ -742,7 +755,8 @@ static int do_i2c_smbus_ioctl(unsigned int fd, unsigned int cmd,
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#define RTC_EPOCH_READ32 _IOR('p', 0x0d, compat_ulong_t)
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#define RTC_EPOCH_SET32 _IOW('p', 0x0e, compat_ulong_t)
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static int rtc_ioctl(unsigned fd, unsigned cmd, void __user *argp)
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static int rtc_ioctl(struct file *file, unsigned fd,
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unsigned cmd, void __user *argp)
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{
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mm_segment_t oldfs = get_fs();
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compat_ulong_t val32;
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@ -753,7 +767,7 @@ static int rtc_ioctl(unsigned fd, unsigned cmd, void __user *argp)
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case RTC_IRQP_READ32:
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case RTC_EPOCH_READ32:
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set_fs(KERNEL_DS);
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ret = sys_ioctl(fd, (cmd == RTC_IRQP_READ32) ?
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ret = do_ioctl(file, fd, (cmd == RTC_IRQP_READ32) ?
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RTC_IRQP_READ : RTC_EPOCH_READ,
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(unsigned long)&kval);
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set_fs(oldfs);
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@ -762,9 +776,9 @@ static int rtc_ioctl(unsigned fd, unsigned cmd, void __user *argp)
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val32 = kval;
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return put_user(val32, (unsigned int __user *)argp);
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case RTC_IRQP_SET32:
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return sys_ioctl(fd, RTC_IRQP_SET, (unsigned long)argp);
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return do_ioctl(file, fd, RTC_IRQP_SET, (unsigned long)argp);
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case RTC_EPOCH_SET32:
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return sys_ioctl(fd, RTC_EPOCH_SET, (unsigned long)argp);
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return do_ioctl(file, fd, RTC_EPOCH_SET, (unsigned long)argp);
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}
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return -ENOIOCTLCMD;
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@ -1443,46 +1457,46 @@ static long do_ioctl_trans(int fd, unsigned int cmd,
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switch (cmd) {
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case PPPIOCGIDLE32:
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return ppp_gidle(fd, cmd, argp);
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return ppp_gidle(file, fd, cmd, argp);
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case PPPIOCSCOMPRESS32:
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return ppp_scompress(fd, cmd, argp);
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return ppp_scompress(file, fd, cmd, argp);
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case PPPIOCSPASS32:
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case PPPIOCSACTIVE32:
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return ppp_sock_fprog_ioctl_trans(fd, cmd, argp);
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return ppp_sock_fprog_ioctl_trans(file, fd, cmd, argp);
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#ifdef CONFIG_BLOCK
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case SG_IO:
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return sg_ioctl_trans(fd, cmd, argp);
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return sg_ioctl_trans(file, fd, cmd, argp);
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case SG_GET_REQUEST_TABLE:
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return sg_grt_trans(fd, cmd, argp);
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return sg_grt_trans(file, fd, cmd, argp);
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case MTIOCGET32:
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case MTIOCPOS32:
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return mt_ioctl_trans(fd, cmd, argp);
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return mt_ioctl_trans(file, fd, cmd, argp);
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#endif
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/* Serial */
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case TIOCGSERIAL:
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case TIOCSSERIAL:
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return serial_struct_ioctl(fd, cmd, argp);
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return serial_struct_ioctl(file, fd, cmd, argp);
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/* i2c */
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case I2C_FUNCS:
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return w_long(fd, cmd, argp);
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return w_long(file, fd, cmd, argp);
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case I2C_RDWR:
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return do_i2c_rdwr_ioctl(fd, cmd, argp);
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return do_i2c_rdwr_ioctl(file, fd, cmd, argp);
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case I2C_SMBUS:
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return do_i2c_smbus_ioctl(fd, cmd, argp);
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return do_i2c_smbus_ioctl(file, fd, cmd, argp);
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/* Not implemented in the native kernel */
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case RTC_IRQP_READ32:
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case RTC_IRQP_SET32:
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case RTC_EPOCH_READ32:
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case RTC_EPOCH_SET32:
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return rtc_ioctl(fd, cmd, argp);
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return rtc_ioctl(file, fd, cmd, argp);
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/* dvb */
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case VIDEO_GET_EVENT:
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return do_video_get_event(fd, cmd, argp);
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return do_video_get_event(file, fd, cmd, argp);
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case VIDEO_STILLPICTURE:
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return do_video_stillpicture(fd, cmd, argp);
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return do_video_stillpicture(file, fd, cmd, argp);
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case VIDEO_SET_SPU_PALETTE:
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return do_video_set_spu_palette(fd, cmd, argp);
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return do_video_set_spu_palette(file, fd, cmd, argp);
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}
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/*
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