Re: [PATCH] Fix blktrace setup 32-bit ioctl on 64-bit kernels

[Jens Axboe <jens.axboe@oracle.com>]

Hi Arnd,

Updated patch below. I kept the code in compat_ioctl.c, to me it seems
like the cleanest approach. I need the BLKTRACESETUP32 define both in
compat_ioctl.c and blktrace.c if I move it, and I need to hard-core the
struct size or define it in both places. And guard the code in
blktrace.c with an ifdef for CONFIG_COMPAT. Not pretty, imho.

I haven't tested this one yet, but at least it compiles and the sizing
seems right. The u16 padding was an artifact of the
__attribute__((packed)) so that could be removed.

diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index 5a5b711..54162e5 100644
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -2052,6 +2052,44 @@ static int raw_ioctl(unsigned fd, unsigned cmd, unsigned long arg)
         }
         return ret;
 }
+
+struct blk_user_trace_setup32 {
+	char name[32];
+	u16 act_mask;
+	u32 buf_size;
+	u32 buf_nr;
+	compat_u64 start_lba;
+	compat_u64 end_lba;
+	u32 pid;
+};
+
+#define BLKTRACESETUP32 _IOWR(0x12,115,struct blk_user_trace_setup32)
+
+static int blktrace32_setup(int fd, unsigned cmd, unsigned long arg)
+{
+	struct blk_user_trace_setup __user *buts = compat_alloc_user_space(sizeof(*buts));
+	struct blk_user_trace_setup32 __user *buts32 = compat_ptr(arg);
+	int err;
+
+	if (copy_in_user(&buts->name, &buts32->name, 32) ||
+	    get_user(buts->act_mask, &buts32->act_mask) ||
+	    get_user(buts->buf_size, &buts32->buf_size) ||
+	    get_user(buts->buf_nr, &buts32->buf_nr) ||
+	    get_user(buts->start_lba, &buts32->start_lba) ||
+	    get_user(buts->end_lba, &buts32->end_lba) ||
+	    get_user(buts->pid, &buts32->pid))
+		return -EFAULT;
+
+	err = sys_ioctl(fd, cmd, (unsigned long) buts);
+	if (err)
+		return err;
+
+	if (copy_to_user(&buts32->name, &buts->name, 32))
+		return -EFAULT;
+
+	return err;
+}
+
 #endif /* CONFIG_BLOCK */
 
 struct serial_struct32 {
@@ -2555,7 +2593,7 @@ COMPATIBLE_IOCTL(BLKSECTSET)
 COMPATIBLE_IOCTL(BLKSSZGET)
 COMPATIBLE_IOCTL(BLKTRACESTART)
 COMPATIBLE_IOCTL(BLKTRACESTOP)
-COMPATIBLE_IOCTL(BLKTRACESETUP)
+HANDLE_IOCTL(BLKTRACESETUP32, blktrace32_setup)
 COMPATIBLE_IOCTL(BLKTRACETEARDOWN)
 ULONG_IOCTL(BLKRASET)
 ULONG_IOCTL(BLKFRASET)

-- 
Jens Axboe