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Subject[PATCH V2] nvme: Add compat_ioctl handler for NVME_IOCTL_SUBMIT_IO
Date
Currently 32 bit application gets ENOTTY when it calls
compat_ioctl with NVME_IOCTL_SUBMIT_IO in 64 bit kernel.

The cause is that the results of sizeof(struct nvme_user_io),
which is used to define NVME_IOCTL_SUBMIT_IO,
are not same between 32 bit compiler and 64 bit compiler.

* 32 bit: the result of sizeof nvme_user_io is 44.
* 64 bit: the result of sizeof nvme_user_io is 48.

64 bit compiler seems to add 32 bit padding for multiple of 8 bytes.

This patch adds a compat_ioctl handler.
The handler replaces NVME_IOCTL_SUBMIT_IO32 with NVME_IOCTL_SUBMIT_IO
in case 32 bit application calls compat_ioctl for submit in 64 bit kernel.
Then, it calls nvme_ioctl as usual.

Signed-off-by: Masahiro Yamada (KIOXIA) <masahiro31.yamada@kioxia.com>
---
v2:
- Add a comment explaining what is going on in nvme_compat_ioctl()
- Put nvme_compat_ioctl() under CONFIG_COMPAT and add #else branch
- Move struct nvme_user_io32 #ifdef CONFIG_COMPAT block in core.c
- Fix packed pragma warning by checkpatch.pl
WARNING: __packed is preferred over __attribute__((packed))

drivers/nvme/host/core.c | 45 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 641c07347e8d..8c6998920b2a 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1584,6 +1584,47 @@ static int nvme_ioctl(struct block_device *bdev, fmode_t mode,
return ret;
}

+#ifdef CONFIG_COMPAT
+struct nvme_user_io32 {
+ __u8 opcode;
+ __u8 flags;
+ __u16 control;
+ __u16 nblocks;
+ __u16 rsvd;
+ __u64 metadata;
+ __u64 addr;
+ __u64 slba;
+ __u32 dsmgmt;
+ __u32 reftag;
+ __u16 apptag;
+ __u16 appmask;
+} __attribute__((__packed__));
+
+#define NVME_IOCTL_SUBMIT_IO32 _IOW('N', 0x42, struct nvme_user_io32)
+
+static int nvme_compat_ioctl(struct block_device *bdev, fmode_t mode,
+ unsigned int cmd, unsigned long arg)
+{
+ /*
+ * Corresponds to the difference of NVME_IOCTL_SUBMIT_IO
+ * between 32 bit programs and 64 bit kernel.
+ * The cause is that the results of sizeof(struct nvme_user_io),
+ * which is used to define NVME_IOCTL_SUBMIT_IO,
+ * are not same between 32 bit compiler and 64 bit compiler.
+ * NVME_IOCTL_SUBMIT_IO32 is for 64 bit kernel handling
+ * NVME_IOCTL_SUBMIT_IO issued from 32 bit programs.
+ * Other IOCTL numbers are same between 32 bit and 64 bit.
+ * So there is nothing to do regarding to other IOCTL numbers.
+ */
+ if (cmd == NVME_IOCTL_SUBMIT_IO32)
+ return nvme_ioctl(bdev, mode, NVME_IOCTL_SUBMIT_IO, arg);
+
+ return nvme_ioctl(bdev, mode, cmd, arg);
+}
+#else
+#define nvme_compat_ioctl NULL
+#endif /* CONFIG_COMPAT */
+
static int nvme_open(struct block_device *bdev, fmode_t mode)
{
struct nvme_ns *ns = bdev->bd_disk->private_data;
@@ -2027,7 +2068,7 @@ EXPORT_SYMBOL_GPL(nvme_sec_submit);
static const struct block_device_operations nvme_fops = {
.owner = THIS_MODULE,
.ioctl = nvme_ioctl,
- .compat_ioctl = nvme_ioctl,
+ .compat_ioctl = nvme_compat_ioctl,
.open = nvme_open,
.release = nvme_release,
.getgeo = nvme_getgeo,
@@ -2055,7 +2096,7 @@ const struct block_device_operations nvme_ns_head_ops = {
.open = nvme_ns_head_open,
.release = nvme_ns_head_release,
.ioctl = nvme_ioctl,
- .compat_ioctl = nvme_ioctl,
+ .compat_ioctl = nvme_compat_ioctl,
.getgeo = nvme_getgeo,
.pr_ops = &nvme_pr_ops,
};
--
2.20.1


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