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charset=us-ascii Content-Disposition: inline In-Reply-To: <202308251535.551E797B1@keescook> X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: E05D11C0018 X-Stat-Signature: hmxay379r5kb1cwtn519ruzpe4z9kg57 X-Rspam-User: X-HE-Tag: 1693141746-718214 X-HE-Meta: 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 mTT+ufem 1uSplW1TDTnbKkfy1tO8w9qEMPOK4ZPjAVzEUA3zo/qgBSLAhRfdBgsta5pY+WVuf8smmaBhpsNkgAcoQ4asIiZNlL8yoYH1PoEnL/LsudGYZlj/YqlB59HJMtLUo2DzLRaGx37HUg2eX3a8EbQ5tji+rRW6iZ8KMyoED6HvAd+GBPu7xzS/tUnoa6klDxrW+VBH+6F5IzJEwx0Dh1LuQ9s3LczCp/nwvOOjOKxPjDmE29CuD0wV0Rt+QLhVQnJOdnmc0YShuTHtfrqrsq29RlBBem7k9WZOhsD1JtQO8ukvCd1soSwZNExrRXPkOlOJZIFA00w7g6xF27rczwJsSNB3kZpjeBtSDNtx/nd4IIIAa7D1zm2iLOAIdeBmYoY4BxEEfK62UlEpURO2lzXiD4RVTjRvrmdIpE3ZL2zln9ATPLw45JWeVXZshiQatA07wyv0yYxIyfcymZOW4YgxA26Ncaw== 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: On Fri, Aug 25, 2023 at 03:38:36PM -0700, Kees Cook wrote: > On Tue, Jul 04, 2023 at 05:36:28PM +0200, Florent Revest wrote: > > static inline int prctl_set_mdwe(unsigned long bits, unsigned long arg3, > > unsigned long arg4, unsigned long arg5) > > { > > + unsigned long current_bits; > > + > > if (arg3 || arg4 || arg5) > > return -EINVAL; > > > > - if (bits & ~(PR_MDWE_REFUSE_EXEC_GAIN)) > > + if (bits & ~(PR_MDWE_REFUSE_EXEC_GAIN | PR_MDWE_NO_INHERIT)) > > + return -EINVAL; > > + > > + /* NO_INHERIT only makes sense with REFUSE_EXEC_GAIN */ > > + if (bits & PR_MDWE_NO_INHERIT && !(bits & PR_MDWE_REFUSE_EXEC_GAIN)) > > return -EINVAL; > > > > + current_bits = get_current_mdwe(); > > + if (current_bits && current_bits != bits) > > + return -EPERM; /* Cannot unset the flags */ > > I was pondering why PR_MDWE_NO_INHERIT can't be unset, but I guess it > doesn't matter. Anything forked with have it off, and any process > wanting to launch stuff before locking down can just skip running the > prctl() until later. I had a similar doubt initially but then realised that the no-inherit mode won't be inherited and concluded it's ok. -- Catalin