compat_ioctl: reimplement SG_IO handling

There are two code locations that implement the SG_IO ioctl: the old
sg.c driver, and the generic scsi_ioctl helper that is in turn used by
multiple drivers.

To eradicate the old compat_ioctl conversion handler for the SG_IO
command, I implement a readable pair of put_sg_io_hdr() /get_sg_io_hdr()
helper functions that can be used for both compat and native mode,
and then I call this from both drivers.

For the iovec handling, there is already a compat_import_iovec() function
that can simply be called in place of import_iovec().

To avoid having to pass the compat/native state through multiple
indirections, I mark the SG_IO command itself as compatible in
fs/compat_ioctl.c and use in_compat_syscall() to figure out where
we are called from.

As a side-effect of this, the sg.c driver now also accepts the 32-bit
sg_io_hdr format in compat mode using the read/write interface, not
just ioctl. This should improve compatiblity with old 32-bit binaries,
but it would break if any application intentionally passes the 64-bit
data structure in compat mode here.

Steffen Maier helped debug an issue in an earlier version of this patch.

Cc: Steffen Maier <maier@linux.ibm.com>
Cc: linux-scsi@vger.kernel.org
Cc: Doug Gilbert <dgilbert@interlog.com>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 1 insertions, 147 deletions

diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index 10ba2d9e20bc..f279e77df256 100644
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -64,151 +64,6 @@ static int do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 }
 
 #ifdef CONFIG_BLOCK
-typedef struct sg_io_hdr32 {
-	compat_int_t interface_id;	/* [i] 'S' for SCSI generic (required) */
-	compat_int_t dxfer_direction;	/* [i] data transfer direction  */
-	unsigned char cmd_len;		/* [i] SCSI command length ( <= 16 bytes) */
-	unsigned char mx_sb_len;		/* [i] max length to write to sbp */
-	unsigned short iovec_count;	/* [i] 0 implies no scatter gather */
-	compat_uint_t dxfer_len;		/* [i] byte count of data transfer */
-	compat_uint_t dxferp;		/* [i], [*io] points to data transfer memory
-					      or scatter gather list */
-	compat_uptr_t cmdp;		/* [i], [*i] points to command to perform */
-	compat_uptr_t sbp;		/* [i], [*o] points to sense_buffer memory */
-	compat_uint_t timeout;		/* [i] MAX_UINT->no timeout (unit: millisec) */
-	compat_uint_t flags;		/* [i] 0 -> default, see SG_FLAG... */
-	compat_int_t pack_id;		/* [i->o] unused internally (normally) */
-	compat_uptr_t usr_ptr;		/* [i->o] unused internally */
-	unsigned char status;		/* [o] scsi status */
-	unsigned char masked_status;	/* [o] shifted, masked scsi status */
-	unsigned char msg_status;		/* [o] messaging level data (optional) */
-	unsigned char sb_len_wr;		/* [o] byte count actually written to sbp */
-	unsigned short host_status;	/* [o] errors from host adapter */
-	unsigned short driver_status;	/* [o] errors from software driver */
-	compat_int_t resid;		/* [o] dxfer_len - actual_transferred */
-	compat_uint_t duration;		/* [o] time taken by cmd (unit: millisec) */
-	compat_uint_t info;		/* [o] auxiliary information */
-} sg_io_hdr32_t;  /* 64 bytes long (on sparc32) */
-
-typedef struct sg_iovec32 {
-	compat_uint_t iov_base;
-	compat_uint_t iov_len;
-} sg_iovec32_t;
-
-static int sg_build_iovec(sg_io_hdr_t __user *sgio, void __user *dxferp, u16 iovec_count)
-{
-	sg_iovec_t __user *iov = (sg_iovec_t __user *) (sgio + 1);
-	sg_iovec32_t __user *iov32 = dxferp;
-	int i;
-
-	for (i = 0; i < iovec_count; i++) {
-		u32 base, len;
-
-		if (get_user(base, &iov32[i].iov_base) ||
-		    get_user(len, &iov32[i].iov_len) ||
-		    put_user(compat_ptr(base), &iov[i].iov_base) ||
-		    put_user(len, &iov[i].iov_len))
-			return -EFAULT;
-	}
-
-	if (put_user(iov, &sgio->dxferp))
-		return -EFAULT;
-	return 0;
-}
-
-static int sg_ioctl_trans(struct file *file, unsigned int cmd,
-			sg_io_hdr32_t __user *sgio32)
-{
-	sg_io_hdr_t __user *sgio;
-	u16 iovec_count;
-	u32 data;
-	void __user *dxferp;
-	int err;
-	int interface_id;
-
-	if (get_user(interface_id, &sgio32->interface_id))
-		return -EFAULT;
-	if (interface_id != 'S')
-		return do_ioctl(file, cmd, (unsigned long)sgio32);
-
-	if (get_user(iovec_count, &sgio32->iovec_count))
-		return -EFAULT;
-
-	{
-		void __user *top = compat_alloc_user_space(0);
-		void __user *new = compat_alloc_user_space(sizeof(sg_io_hdr_t) +
-				       (iovec_count * sizeof(sg_iovec_t)));
-		if (new > top)
-			return -EINVAL;
-
-		sgio = new;
-	}
-
-	/* Ok, now construct.  */
-	if (copy_in_user(&sgio->interface_id, &sgio32->interface_id,
-			 (2 * sizeof(int)) +
-			 (2 * sizeof(unsigned char)) +
-			 (1 * sizeof(unsigned short)) +
-			 (1 * sizeof(unsigned int))))
-		return -EFAULT;
-
-	if (get_user(data, &sgio32->dxferp))
-		return -EFAULT;
-	dxferp = compat_ptr(data);
-	if (iovec_count) {
-		if (sg_build_iovec(sgio, dxferp, iovec_count))
-			return -EFAULT;
-	} else {
-		if (put_user(dxferp, &sgio->dxferp))
-			return -EFAULT;
-	}
-
-	{
-		unsigned char __user *cmdp;
-		unsigned char __user *sbp;
-
-		if (get_user(data, &sgio32->cmdp))
-			return -EFAULT;
-		cmdp = compat_ptr(data);
-
-		if (get_user(data, &sgio32->sbp))
-			return -EFAULT;
-		sbp = compat_ptr(data);
-
-		if (put_user(cmdp, &sgio->cmdp) ||
-		    put_user(sbp, &sgio->sbp))
-			return -EFAULT;
-	}
-
-	if (copy_in_user(&sgio->timeout, &sgio32->timeout,
-			 3 * sizeof(int)))
-		return -EFAULT;
-
-	if (get_user(data, &sgio32->usr_ptr))
-		return -EFAULT;
-	if (put_user(compat_ptr(data), &sgio->usr_ptr))
-		return -EFAULT;
-
-	err = do_ioctl(file, cmd, (unsigned long) sgio);
-
-	if (err >= 0) {
-		void __user *datap;
-
-		if (copy_in_user(&sgio32->pack_id, &sgio->pack_id,
-				 sizeof(int)) ||
-		    get_user(datap, &sgio->usr_ptr) ||
-		    put_user((u32)(unsigned long)datap,
-			     &sgio32->usr_ptr) ||
-		    copy_in_user(&sgio32->status, &sgio->status,
-				 (4 * sizeof(unsigned char)) +
-				 (2 * sizeof(unsigned short)) +
-				 (3 * sizeof(int))))
-			err = -EFAULT;
-	}
-
-	return err;
-}
-
 struct compat_sg_req_info { /* used by SG_GET_REQUEST_TABLE ioctl() */
 	char req_state;
 	char orphan;
@@ -358,6 +213,7 @@ COMPATIBLE_IOCTL(SCSI_IOCTL_GET_PCI)
 #endif
 #ifdef CONFIG_BLOCK
 /* SG stuff */
+COMPATIBLE_IOCTL(SG_IO)
 COMPATIBLE_IOCTL(SG_SET_TIMEOUT)
 COMPATIBLE_IOCTL(SG_GET_TIMEOUT)
 COMPATIBLE_IOCTL(SG_EMULATED_HOST)
@@ -435,8 +291,6 @@ static long do_ioctl_trans(unsigned int cmd,
 	case PPPIOCSACTIVE32:
 		return ppp_sock_fprog_ioctl_trans(file, cmd, argp);
 #ifdef CONFIG_BLOCK
-	case SG_IO:
-		return sg_ioctl_trans(file, cmd, argp);
 	case SG_GET_REQUEST_TABLE:
 		return sg_grt_trans(file, cmd, argp);
 #endif