Messages in this thread | | | Date | Tue, 8 Oct 2019 21:34:51 +0100 | From | Al Viro <> | Subject | Re: [PATCH] Convert filldir[64]() from __put_user() to unsafe_put_user() |
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On Tue, Oct 08, 2019 at 08:58:58PM +0100, Al Viro wrote:
> The difference is, they have separate "for read" and "for write" primitives > and they want the range in their user_access_end() analogue. Separating > the read and write isn't a problem for callers (we want them close to > the actual memory accesses). Passing the range to user_access_end() just > might be tolerable, unless it makes you throw up...
NOTE: I'm *NOT* suggesting to bring back the VERIFY_READ/VERIFY_WRITE argument to access_ok(). We'd gotten rid of it, and for a very good reason (and decades overdue).
The main difference between access_ok() and user_access_begin() is that the latter is right next to actual memory access, with user_access_end() on the other side, also very close. And most of those guys would be concentrated in a few functions, where we bloody well know which direction we are copying.
Even if we try and map ppc allow_..._to_user() on user_access_begin(), access_ok() remains as it is (and I hope we'll get rid of the majority of its caller in process).
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