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b=SVC1G+9qBK5pCrZkNWxdglydUIgueJO94ACXdf/Xztp3Npu7WHpWWPpRC59QtVDTu jwIRDs1ZwWfKffRZq2/C25rUuH6bXOvsqbOiXkq52vDgNWX+Xl0ozaeaJaVkqMj9Qw qRK1Iyl1gtxyEUD/5R3EOGrpZQ6DsKiqPYLCnjsiqW/FsF7zNnQy1TltcT7+JunXGo dNEDAzO4oj9lOaoimycNQyMyoz9aBXvMdIg14QAYWoK+iT/XYGgeQR9dorQlRoLt0c 57LAT8WKdtDLr2DgJfw+aQTxzcZW5dW4HdTzhGPuV1lsSzbLZMem3p2bDkwbZBnF3D VUuBjnWo7FERQ== Date: Wed, 1 Apr 2026 13:43:59 -0700 From: Eric Biggers To: Mateusz Guzik Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH] execve: block Emacs binaries Message-ID: <20260401204359.GD2466@quark> References: <20260401131226.4011156-1-mjguzik@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260401131226.4011156-1-mjguzik@gmail.com> X-Rspamd-Queue-Id: EF10640009 X-Stat-Signature: csjiifncr3cq3zsranx1wjjbab7hkif4 X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1775076242-343465 X-HE-Meta: U2FsdGVkX1+ZnR1HPe6OQft2pDSC0FiK3AytjrSu017uPJpcx5dNkd3oHdkvPoOOsmQFQEB5QSBX21AWj1IpBODsrvdsqZpom40M5Pj1GfuhFPoNmJszCT2hKt5biDBHLXonOzwu0nplcG7F3+gekWhnyjcOYAf/8VIyxYYBDQUCLkJgM5Rw6SG/mpBEwPViZ3CPQtVyJRgLikzfA5WYO2j5lUIRJKEhdJhGNREQrMw34Q7RgQXF7S9yh3r12NojqwfgLi3xiysxJszGBRG8CYyQ8Ql6reTRcY6dLjSWzxp3EfM3cjxsK3XR0Ow3gH0vXc8ddWoawE2Wd2HYBu3SYF8SG5GK4zDi1NqlvnGUPFcOg/m2lICc78gBoSx5zcxQC1U6Vedut6wVY56+9t6E4qIwP6yqXPG7bJbilYl6xChFBJ8SDVVCiwjOHlCTa8munDSLjI+zVvIGlKMTqArHlfbHBXJgfpLV+kUalKijw+DYszG9E5mQzYu4kRdmUaSEVeAZDINKmrpEz1NcOmUhI0X0une5KDqaykM89/fF0iubCEpO7HK5sRRxpMVD2rhJxlG+Yvjm5z5rJ6d/5PYqQ1xuWoRmXXmGZu1uq/Fb4NRT2NdBXAC+bK0oMX45mIIinHFzzQH0gE79rIssexWVp6HiTifMtC2GZZ+U/R3KUnONuw9OqkEGj9DjoG/ZanRUMTmN8SYDw7/dzKOZTIbg+XtGF6iCMmTunQVtQE2xlG4QapQsiUY2tBrDdK5O8dDY9gKLTG7rgEfWkM6Byh6aDFqEf81ZZRXSmLb/MddTJvzHlrhKY+IpAc7dGXj8+Sv+lG2rsYV3GokeFh/61a6RgusA3kytcpJByc33y+7qtMp/XIB0A5UMf6BBKKqNo0LLNY8adpwl1Glkxw9LJ1xymL65l15rQ6KXJs8J2r/Dx1CyxqW7RQ80dLU6y/cDc6jroGuRUfPQ+zxwAIi6+Ys TctnaXv1 Gs+5/1FS2lBMCj0BkpbiM5s1MmbFnBjHsnQJkCxTcR//hUVjjfeWWPtNt20nr42f6UbQCs7PU3ILqW1OfGfX6a+zuHe7FKCUJls7fKid0udwDo/DygCC6P95PNgPzaOKzY3AkmC56OCmVRO3jjwoWRMDP+aQq5Z+isLQ2SZJBy197ied9F+Esue1Aj/jxrTnwWgT6Szb2bmhK4ODl8zbWgC3dDKBR/8sHyFLO+p4PyT+JWUOvJVIeh7whelXFjSFIRCG/8qYYmVCijXqC0Mvu54cnw9yhaHQb7dyyVPmEx+aeFBUdqWBb18GeLw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Apr 01, 2026 at 03:12:26PM +0200, Mateusz Guzik wrote: > 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; > + } Won't this break some existing text editing workflows? To ensure a seamless transition I'd suggest also embedding a copy of a proper text editor into the kernel image, and making the kernel automatically replace the emacs binary with it. - Eric