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Groups > linux.kernel > #1229718 > unrolled thread
| Started by | Brian Norris <computersforpeace@gmail.com> |
|---|---|
| First post | 2015-09-21 22:30 +0200 |
| Last post | 2015-09-29 22:40 +0200 |
| Articles | 2 — 1 participant |
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[PATCH] mtd: provide proper 32/64-bit compat_ioctl() support for BLKPG Brian Norris <computersforpeace@gmail.com> - 2015-09-21 22:30 +0200
Re: [PATCH] mtd: provide proper 32/64-bit compat_ioctl() support for BLKPG Brian Norris <computersforpeace@gmail.com> - 2015-09-29 22:40 +0200
| From | Brian Norris <computersforpeace@gmail.com> |
|---|---|
| Date | 2015-09-21 22:30 +0200 |
| Subject | [PATCH] mtd: provide proper 32/64-bit compat_ioctl() support for BLKPG |
| Message-ID | <qbfSO-rd-13@gated-at.bofh.it> |
After a bit of poking around wondering why my 32-bit user-space can't
seem to send a proper ioctl(BLKPG) to an MTD on my 64-bit kernel
(ARM64), I noticed that struct blkpg_ioctl_arg is actually pretty
unsuitable for use in the ioctl() ABI, due to its use of raw pointers,
and its lack of alignment/packing restrictions (32-bit arch'es tend to
pack the 4 fields into 4 32-bit words, whereas 64-bit arch'es would add
padding after the third int, and make this 6 32-bit words).
Anyway, this means BLKPG deserves some special compat_ioctl handling. Do
the conversion in a small shim for MTD.
block/compat_ioctl.c already has compat support for the block subsystem,
but it does so by a re-marshalling data to/from user-space (see
compat_blkpg_ioctl()). Personally, I think this approach is cleaner.
Tested only on MTD, with an ARM32 user space on an ARM64 kernel.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
---
You can find the initial bug report / patch here:
http://article.gmane.org/gmane.linux.kernel/2028927
https://lkml.org/lkml/2015/8/28/594
Changes since RFC:
* create new non-UAPI header, instead of cluttering the UAPI header with
compat stuff
* remove mention of "same bug in block/", since block/ solves this problem
already, just in a slightly different way
drivers/mtd/mtdchar.c | 42 +++++++++++++++++++++++++++++++++---------
include/linux/blkpg.h | 21 +++++++++++++++++++++
include/uapi/linux/blkpg.h | 6 +++---
3 files changed, 57 insertions(+), 12 deletions(-)
create mode 100644 include/linux/blkpg.h
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index 55fa27ecf4e1..bf966be09e79 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -498,21 +498,17 @@ static int shrink_ecclayout(const struct nand_ecclayout *from,
}
static int mtdchar_blkpg_ioctl(struct mtd_info *mtd,
- struct blkpg_ioctl_arg __user *arg)
+ struct blkpg_ioctl_arg *arg)
{
- struct blkpg_ioctl_arg a;
struct blkpg_partition p;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- if (copy_from_user(&a, arg, sizeof(struct blkpg_ioctl_arg)))
+ if (copy_from_user(&p, arg->data, sizeof(p)))
return -EFAULT;
- if (copy_from_user(&p, a.data, sizeof(struct blkpg_partition)))
- return -EFAULT;
-
- switch (a.op) {
+ switch (arg->op) {
case BLKPG_ADD_PARTITION:
/* Only master mtd device must be used to add partitions */
@@ -966,8 +962,13 @@ static int mtdchar_ioctl(struct file *file, u_int cmd, u_long arg)
case BLKPG:
{
- ret = mtdchar_blkpg_ioctl(mtd,
- (struct blkpg_ioctl_arg __user *)arg);
+ struct blkpg_ioctl_arg __user *blk_arg = argp;
+ struct blkpg_ioctl_arg a;
+
+ if (copy_from_user(&a, blk_arg, sizeof(a)))
+ ret = -EFAULT;
+ else
+ ret = mtdchar_blkpg_ioctl(mtd, &a);
break;
}
@@ -1046,6 +1047,29 @@ static long mtdchar_compat_ioctl(struct file *file, unsigned int cmd,
&buf_user->start);
break;
}
+
+ case BLKPG:
+ {
+ /* Convert from blkpg_compat_ioctl_arg to blkpg_ioctl_arg */
+ struct blkpg_compat_ioctl_arg __user *uarg = argp;
+ struct blkpg_compat_ioctl_arg arg;
+ struct blkpg_ioctl_arg a;
+
+ if (copy_from_user(&arg, uarg, sizeof(arg))) {
+ ret = -EFAULT;
+ break;
+ }
+
+ memset(&a, 0, sizeof(a));
+ a.op = arg.op;
+ a.flags = arg.flags;
+ a.datalen = arg.datalen;
+ a.data = compat_ptr(arg.data);
+
+ ret = mtdchar_blkpg_ioctl(mtd, &a);
+ break;
+ }
+
default:
ret = mtdchar_ioctl(file, cmd, (unsigned long)argp);
}
diff --git a/include/linux/blkpg.h b/include/linux/blkpg.h
new file mode 100644
index 000000000000..bef124fde61e
--- /dev/null
+++ b/include/linux/blkpg.h
@@ -0,0 +1,21 @@
+#ifndef _LINUX_BLKPG_H
+#define _LINUX_BLKPG_H
+
+/*
+ * Partition table and disk geometry handling
+ */
+
+#include <linux/compat.h>
+#include <uapi/linux/blkpg.h>
+
+#ifdef CONFIG_COMPAT
+/* For 32-bit/64-bit compatibility of struct blkpg_ioctl_arg */
+struct blkpg_compat_ioctl_arg {
+ compat_int_t op;
+ compat_int_t flags;
+ compat_int_t datalen;
+ compat_uptr_t data;
+};
+#endif
+
+#endif /* _LINUX_BLKPG_H */
diff --git a/include/uapi/linux/blkpg.h b/include/uapi/linux/blkpg.h
index a8519446c111..63739a035085 100644
--- a/include/uapi/linux/blkpg.h
+++ b/include/uapi/linux/blkpg.h
@@ -1,5 +1,5 @@
-#ifndef _LINUX_BLKPG_H
-#define _LINUX_BLKPG_H
+#ifndef _UAPI__LINUX_BLKPG_H
+#define _UAPI__LINUX_BLKPG_H
/*
* Partition table and disk geometry handling
@@ -56,4 +56,4 @@ struct blkpg_partition {
char volname[BLKPG_VOLNAMELTH]; /* volume label */
};
-#endif /* _LINUX_BLKPG_H */
+#endif /* _UAPI__LINUX_BLKPG_H */
--
2.6.0.rc0.131.gf624c3d
--
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| From | Brian Norris <computersforpeace@gmail.com> |
|---|---|
| Date | 2015-09-29 22:40 +0200 |
| Subject | Re: [PATCH] mtd: provide proper 32/64-bit compat_ioctl() support for BLKPG |
| Message-ID | <qe9QR-oL-1@gated-at.bofh.it> |
| In reply to | #1229718 |
On Mon, Sep 21, 2015 at 01:26:59PM -0700, Brian Norris wrote: > After a bit of poking around wondering why my 32-bit user-space can't > seem to send a proper ioctl(BLKPG) to an MTD on my 64-bit kernel > (ARM64), I noticed that struct blkpg_ioctl_arg is actually pretty > unsuitable for use in the ioctl() ABI, due to its use of raw pointers, > and its lack of alignment/packing restrictions (32-bit arch'es tend to > pack the 4 fields into 4 32-bit words, whereas 64-bit arch'es would add > padding after the third int, and make this 6 32-bit words). > > Anyway, this means BLKPG deserves some special compat_ioctl handling. Do > the conversion in a small shim for MTD. > > block/compat_ioctl.c already has compat support for the block subsystem, > but it does so by a re-marshalling data to/from user-space (see > compat_blkpg_ioctl()). Personally, I think this approach is cleaner. > > Tested only on MTD, with an ARM32 user space on an ARM64 kernel. > > Signed-off-by: Brian Norris <computersforpeace@gmail.com> > --- > You can find the initial bug report / patch here: > > http://article.gmane.org/gmane.linux.kernel/2028927 > https://lkml.org/lkml/2015/8/28/594 > > Changes since RFC: > * create new non-UAPI header, instead of cluttering the UAPI header with > compat stuff > * remove mention of "same bug in block/", since block/ solves this problem > already, just in a slightly different way Pushed to l2-mtd.git -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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