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Mon, 29 Apr 2024 12:49:05 -0700 (PDT) Received: from www.outflux.net ([198.0.35.241]) by smtp.gmail.com with ESMTPSA id s1-20020a170902ea0100b001e3d2314f3csm20739290plg.141.2024.04.29.12.49.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Apr 2024 12:49:04 -0700 (PDT) Date: Mon, 29 Apr 2024 12:49:04 -0700 From: Kees Cook To: Allen Pais Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, ebiederm@xmission.com, mcgrof@kernel.org, j.granados@samsung.com Subject: Re: [RFC PATCH] fs/coredump: Enable dynamic configuration of max file note size Message-ID: <202404291245.18281A6D@keescook> References: <20240429172128.4246-1-apais@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240429172128.4246-1-apais@linux.microsoft.com> X-Stat-Signature: 519s7sj3wd4dgpdsuknbro7awf14kd4y X-Rspamd-Queue-Id: 7A82E40010 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1714420146-392738 X-HE-Meta: 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 wcVYGO/K BOFXrkPTb+CSNg7H92JUInOjdsPSzjNjIQ23LIS5/sA7dt+ZyhWPCGFCxtkH/MsQwJ1+rBWVAZXsqeLumFvgi7x6iRoRu7s9gv8X6KA5ha1wCgOsrMCH86eSS8/0gXS7ngi0dX2lVHtZWJDUTYKalh3KNYD/RKA3BuJ7oL1onvtLt5mrktDRZ2kjofhXSiKsiCirCsHUNycxI2fqpr/Nkttbl3Eh+IoWWM6UvJGsQFUjL/wdEWEaMZHdtzFfol1GWQpnIm6xGnQNYI9aGMVmZ5zpIRE+3VsH2rsOPKkLfZh4BCUiek0ecaI2DQYPBZNFLQkok0jHB6K+zYgwzGjpFZRHWxS5q635wegvW X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, 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 Mon, Apr 29, 2024 at 05:21:28PM +0000, Allen Pais wrote: > Introduce the capability to dynamically configure the maximum file > note size for ELF core dumps via sysctl. This enhancement removes > the previous static limit of 4MB, allowing system administrators to > adjust the size based on system-specific requirements or constraints. Under what conditions is this actually needed? > [...] > diff --git a/kernel/sysctl.c b/kernel/sysctl.c > index 81cc974913bb..80cdc37f2fa2 100644 > --- a/kernel/sysctl.c > +++ b/kernel/sysctl.c > @@ -63,6 +63,7 @@ > #include > #include > #include > +#include > > #include "../lib/kstrtox.h" > > @@ -1623,6 +1624,13 @@ static struct ctl_table kern_table[] = { > .mode = 0644, > .proc_handler = proc_dointvec, > }, > + { > + .procname = "max_file_note_size", > + .data = &max_file_note_size, > + .maxlen = sizeof(unsigned int), > + .mode = 0644, > + .proc_handler = proc_dointvec, > + }, Please don't add new sysctls to kernel/sysctl.c. Put this in fs/coredump.c instead, and name it "core_file_note_size_max". (A "max" suffix is more common than prefixes, and I'd like it clarified that it relates to the coredumper with the "core" prefix that match the other coredump sysctls. -Kees -- Kees Cook