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Thu, 25 Jan 2024 07:27:10 -0500 (EST) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.11.0-alpha0-119-ga8b98d1bd8-fm-20240108.001-ga8b98d1b MIME-Version: 1.0 Message-Id: <070574cb-8d7f-4fe7-9826-cec6110168ff@app.fastmail.com> In-Reply-To: <20240124-alice-mm-v1-2-d1abcec83c44@google.com> References: <20240124-alice-mm-v1-0-d1abcec83c44@google.com> <20240124-alice-mm-v1-2-d1abcec83c44@google.com> Date: Thu, 25 Jan 2024 13:26:50 +0100 From: "Arnd Bergmann" To: "Alice Ryhl" , "Miguel Ojeda" , "Alex Gaynor" , "Wedson Almeida Filho" , "Boqun Feng" , "Gary Guo" , =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Kees Cook" , "Alexander Viro" , "Andrew Morton" Cc: "Greg Kroah-Hartman" , =?UTF-8?Q?Arve_Hj=C3=B8nnev=C3=A5g?= , "Todd Kjos" , "Martijn Coenen" , "Joel Fernandes" , "Carlos Llamas" , "Suren Baghdasaryan" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, "Christian Brauner" Subject: Re: [PATCH 2/3] rust: add typed accessors for userspace pointers Content-Type: text/plain X-Rspamd-Queue-Id: 7147A40010 X-Rspam-User: X-Stat-Signature: 81ak1o1o8t5ijr53pxs1n84hxk9t4tjb X-Rspamd-Server: rspam03 X-HE-Tag: 1706185632-164293 X-HE-Meta: U2FsdGVkX19gzrgyvwKKqm1fBpipaeNsPB9dIZ68u5zgta2jCJGER9XgkgDiomTu88NNBqLWi+TNAY0uJfg7Ub2faBFYVxcE8t7oUfXuQUT8hhgVVZZ29cOtGRINZdTt4e/9d6qfFwIgRLYFheWjTCT7cz7qlKxNUktkEYilW3/xxjHtSQ0mbp6Q+h797h88RKPXadCKYzhoXwuOXNOXvf/M6bm3TJxRiYa5jdYqqK3QXL9wjI2CCuVXJomDaPIoDG6oW00aL+p0tI0gFtwQtNXdgGikTrTBi2ktJyWd55MLRHs+Uj723u/65XSJCXZtBL4Q2ZAmXxzoX06ocL73d9iFeSdWSqpUANqwGG0hPhsV6nadwta9STxbC5VLYaNsApAK7NQ3xA185u85wJ0fuG1KQW+uIlUgQKxQAtju2Eq4rb29e5F7mC5TpFw7J0Qkp3Fey+sfq7KfhUGgGb2z14fywW3XFCoucmhC5MTTZul9Pu/z9NSwCg4Cogqh6UuJ5plcKyv+RQsSdI1q1TUBA8Q5021wqAzNxj7OfJIYOLJILyv6GsI20skecp1Sh2F4eHUH10i35qSk6fZAMlZsbgXPQt9yt+86E4kMVRaHII3y/R4ihfABuhBq62zV8vstAbh6O//BeL8NGp5RjVwo2Zpf0joyD21a3Wa5krvAB0B9Pk6a9XK++DOk353OuEpie4olk9Mq7p3SXZUZSm/mdsyTjrJuyXSHkDgVGRJXVZYtc2i36Aab+FFEBIh6KJQgeGCQ4rclGwcHkBD69VMF//quLHuo6oyYfSTR5s/tB5zjDE76ZD1nTGrH6jbVZfbNoYgB+7duLNPp3A70XSG0fwbEGojpmMqS5eTJEk8NlhLKrrNlNoQVCQ20TczLYgoWqvKA2ExCmo0n+v4nqOUfi0dKvVy/0nM0dFYx1Wx8+FsK28DZqyqIC7mNqV90cBQ+3+IdF98opxDriZcuoTt B1veNxx4 8WtJBLX2ZUVYuppGyY5S1r3PO3TW1vMkKYWzGZy7B+0v8wF76sVmz07O29X5RnCqDJk814RGd0HZWXO8tzpDTwY7S7C/bmsdDRH2XtuI0TLJEpJh+L2eiHeKqay8g4gZG84CDmcvjApAOqM4CcXih4XlMEVOdwV2CWrRepJGNkyBONy6lLiZQ1wHHF/lmvr/doG9snVMyQ3i3Hnl7sgNlWioWvHrLpJ3JF/hwuRNOgpXFPjs= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jan 24, 2024, at 12:20, Alice Ryhl wrote: > +unsigned long > rust_helper_copy_from_user_unsafe_skip_check_object_size(void *to, > const void __user *from, unsigned long n) > +{ > + unsigned long res; > + > + might_fault(); > + instrument_copy_from_user_before(to, from, n); > + if (should_fail_usercopy()) > + return n; > + res = raw_copy_from_user(to, from, n); > + instrument_copy_from_user_after(to, from, n, res); > + return res; > +} > +EXPORT_SYMBOL_GPL(rust_helper_copy_from_user_unsafe_skip_check_object_size); > + > +unsigned long > rust_helper_copy_to_user_unsafe_skip_check_object_size(void __user *to, > const void *from, unsigned long n) > +{ > + might_fault(); > + if (should_fail_usercopy()) > + return n; > + instrument_copy_to_user(to, from, n); > + return raw_copy_to_user(to, from, n); > +} > +EXPORT_SYMBOL_GPL(rust_helper_copy_to_user_unsafe_skip_check_object_size); These functions are almost identical to the ones in lib/usercopy.c for !defined(INLINE_COPY_TO_USER). That version has an extra memset() after a partial copy_from_user(), and you probably want to have the same thing here for consistency. I think ideally we should only have one out-of-line copy of these two functions and have that one shared between rust and architectures that want the C version out of line as well. Arnd