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Thu, 25 Apr 2024 13:57:58 -0700 (PDT) Received: from www.outflux.net ([198.0.35.241]) by smtp.gmail.com with ESMTPSA id ix19-20020a170902f81300b001e895c9ec6asm13735852plb.152.2024.04.25.13.57.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Apr 2024 13:57:58 -0700 (PDT) Date: Thu, 25 Apr 2024 13:57:57 -0700 From: Kees Cook To: Kent Overstreet Cc: Suren Baghdasaryan , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] alloc_tag: Tighten file permissions on /proc/allocinfo Message-ID: <202404251356.F694909C63@keescook> References: <20240425200844.work.184-kees@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 91DC9180008 X-Rspam-User: X-Stat-Signature: rbt98uaudf3n38s7qczp3e7gwhft6bpw X-HE-Tag: 1714078679-267796 X-HE-Meta: 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 dYRacdoF 1rr2kaF+fMM9Y1zt7pAgVl//WakdX0dJq4QJhgty7xw6jCbREWA0wsgCteKTG08irMjz4MnQJBv2ex7YT+5tEAXKrbpFH0b8femGn8x21onljcvzJKzyfSrG/D+Lz6AAa8yP7PimvPTtZr02lD1eIx8raSSl+shx2UNpOLhqD4dVnqTDNNOUvzCIQ88Hd8OiChIzxHdDhO20QGJBIGnlFLIIIykSgkf0yhiCMpL96wch9COkLEENWKLrDbLiNQTxf0/KrUq3J78VmxXvhdl+9ejArM+QaQZn9HxZJYsD0VhBU1cEua5gnmt4CVqoIkYK/Fru2iD7uqyM8YdO70uvCFKytNrv5TRJwohlJq6Cu50qzNiWYfFTrNVWvxcrjt/IxIKaRrcrWHSgl3AboT9i88xjyMw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.001979, 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 Thu, Apr 25, 2024 at 04:45:51PM -0400, Kent Overstreet wrote: > On Thu, Apr 25, 2024 at 01:08:50PM -0700, Kees Cook wrote: > > The /proc/allocinfo file exposes a tremendous about of information about > > kernel build details, memory allocations (obviously), and potentially > > even image layout (due to ordering). As this is intended to be consumed > > by system owners (like /proc/slabinfo), use the same file permissions as > > there: 0400. > > The side effect of locking down more and more reporting interfaces is > that programs that consume those interfaces now have to run as root. I'm fine if you want to tie it to some existing capability, but it shouldn't be world-readable. Also, plenty of diagnostic tools already either run as root or open whatever files they need to before dropping privs. -- Kees Cook