Commit e6485a47 authored Sep 04, 2015 by Andrea Arcangeli Committed by Linus Torvalds Sep 04, 2015

userfaultfd: require UFFDIO_API before other ioctls



UFFDIO_API was already forced before read/poll could work.  This makes the
code more strict to force it also for all other ioctls.

All users would already have been required to call UFFDIO_API before
invoking other ioctls but this makes it more explicit.

This will ensure we can change all ioctls (all but UFFDIO_API/struct
uffdio_api) with a bump of uffdio_api.api.

There's no actual plan or need to change the API or the ioctl, the current
API already should cover fine even the non cooperative usage, but this is
just for the longer term future just in case.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ad465cae

fs/userfaultfd.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -577,7 +577,6 @@ static ssize_t userfaultfd_read(struct file file, char __user buf,

		if (ctx->state == UFFD_STATE_WAIT_API)
		return -EINVAL;
		BUG_ON(ctx->state != UFFD_STATE_RUNNING);

		for (;;) {
		if (count < sizeof(msg))
		@@ -1115,6 +1114,9 @@ static long userfaultfd_ioctl(struct file *file, unsigned cmd,
		int ret = -EINVAL;
		struct userfaultfd_ctx *ctx = file->private_data;

		if (cmd != UFFDIO_API && ctx->state == UFFD_STATE_WAIT_API)
		return -EINVAL;

		switch(cmd) {
		case UFFDIO_API:
		ret = userfaultfd_api(ctx, arg);

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