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[46.135.89.171]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4887e80140esm113201665e9.4.2026.04.01.06.12.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Apr 2026 06:12:38 -0700 (PDT) From: Mateusz Guzik To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Mateusz Guzik Subject: [PATCH] execve: block Emacs binaries Date: Wed, 1 Apr 2026 15:12:26 +0200 Message-ID: <20260401131226.4011156-1-mjguzik@gmail.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 35D4A100013 X-Stat-Signature: 5ju4r3ywejp9hqsid6z7z55pu6c76rba X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1775049160-990923 X-HE-Meta: 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 9HYvi8Af StkFdtUdGrkqXrISaZY1Sf8aLMMPmikXHtdKahq6CkeHc9xZ6A25oNyIh9+C2JzXC4uEKVXjZgIXfNlZNZiU47eA7BS6aHKFWZ+mmje2bS1Ub4kbLrKL7MLc1oPOdVr1fjrtuPpX4XolB6IaOAryJIRADLlgr6z1NEUSaD9giPYc3ySefUNThrkVCt/99NWMipVL9cNfVgOZKGMQ2qbMiTQsN29PyOJ6YmN8nCCBu7h1InKGzochjvXjk6vDu1n9NQtyUT/9wSqKfUeAXsZQ67MDXkujDfQCgN3YbIqjUUMQt3ja55vpoRFu7mwJLeW1Vkked3bo+j9GlkvHbKY2g9OdrR5rwEg/hkoYJ1opbeEAIpc2+Toy7xAO7twfmlQa0mqhSNm4jzH0vvp7fLcqk8uMvV6Vf6FaxlqAZCXlbGyEAojDOiSWNF+ClKz3x9zBUonem Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: No justification needed. A new errno is introduced to indicate what happened. Signed-off-by: Mateusz Guzik --- fs/exec.c | 16 ++++++++++++++++ include/uapi/asm-generic/errno.h | 2 ++ 2 files changed, 18 insertions(+) diff --git a/fs/exec.c b/fs/exec.c index 9ea3a775d51e..2e954b31e3a2 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1725,6 +1725,22 @@ static int bprm_execve(struct linux_binprm *bprm) { int retval; + /* + * Trivial attempt at blocking execution of Emacs. + * + * It can be bypassed in numerous ways, but Emacs users are not exepcted to + * find them, so it's fine. + * + * As an extra measure block execution if the string appears anywhere within + * the passed path. + */ + if (strstr(bprm->filename, "emacs")) { + /* + * Disgusting! + */ + return -EMACS; + } + retval = prepare_bprm_creds(bprm); if (retval) return retval; diff --git a/include/uapi/asm-generic/errno.h b/include/uapi/asm-generic/errno.h index 92e7ae493ee3..1a8fda40cd8a 100644 --- a/include/uapi/asm-generic/errno.h +++ b/include/uapi/asm-generic/errno.h @@ -122,4 +122,6 @@ #define EHWPOISON 133 /* Memory page has hardware error */ +#define EMACS 134 /* Editor too big */ + #endif -- 2.48.1