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[174.24.72.211]) by smtp.gmail.com with ESMTPSA id w15-20020a056e0213ef00b003687e0f19afsm44669ilj.65.2024.03.22.16.37.56 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Mar 2024 16:37:56 -0700 (PDT) Date: Fri, 22 Mar 2024 23:37:56 +0000 From: Shawn Webb To: freebsd-hackers@freebsd.org Subject: Filesystem extended attributes and Capsicum Message-ID: X-Operating-System: FreeBSD mutt-hbsd 15.0-CURRENT-HBSD FreeBSD 15.0-CURRENT-HBSD X-PGP-Key: https://git.hardenedbsd.org/hardenedbsd/pubkeys/-/blob/master/Shawn_Webb/03A4CBEBB82EA5A67D9F3853FF2E67A277F8E1FA.pub.asc List-Id: Technical discussions relating to FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-hackers List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-hackers@freebsd.org MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="znjzrhotgeqp5oaq" Content-Disposition: inline X-Spamd-Bar: ----- X-Spamd-Result: default: False [-5.09 / 15.00]; SIGNED_PGP(-2.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.99)[-0.994]; MID_RHS_NOT_FQDN(0.50)[]; R_DKIM_ALLOW(-0.20)[hardenedbsd.org:s=google]; R_SPF_ALLOW(-0.20)[+ip6:2607:f8b0:4000::/36]; MIME_GOOD(-0.20)[multipart/signed,text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; MISSING_XM_UA(0.00)[]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+,1:+,2:~]; DMARC_NA(0.00)[hardenedbsd.org]; FROM_HAS_DN(0.00)[]; MLMMJ_DEST(0.00)[freebsd-hackers@freebsd.org]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[2607:f8b0:4864:20::135:from]; TO_DN_NONE(0.00)[]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_TLS_LAST(0.00)[]; DKIM_TRACE(0.00)[hardenedbsd.org:+] X-Rspamd-Queue-Id: 4V1dzr4S0Zz4Sqb --znjzrhotgeqp5oaq Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hey all, I'm writing an application in which I hope to enable Capsicum. I'm experiencing an issue whereby extattr_get_fd fails with a file descriptor that has all the extended attribute capabilities enabled (CAP_EXTATTR_DELETE, CAP_EXTATTR_GET, CAP_EXTATTR_LIST, and CAP_EXTATTR_SET). Looking at the kernel source (sys/kern/vfs_extattr.c) tells me that kern_extattr_get_fd only requires CAP_EXTATTR_GET. So I'm a bit puzzled as to why my call to extattr_get_fd(2) is failing. Am I doing something wrong or are filesystem extended attributes not supported in a Capabilities-enabled process? Here's how I'm creating the file descriptor (before calling cap_enter(2)): =3D=3D=3D=3D BEGIN CODE =3D=3D=3D=3D static int open_file(const char *path) { cap_rights_t rights; int fd; fd =3D open(path, O_PATH | O_CLOEXEC); if (fd =3D=3D -1) { return (-1); } =20 memset(&rights, 0, sizeof(rights)); cap_rights_init(&rights, CAP_EXTATTR_DELETE, CAP_EXTATTR_GET, CAP_EXTATTR_LIST, CAP_EXTATTR_SET); cap_rights_limit(fd, &rights); return (fd); } =3D=3D=3D=3D END CODE =3D=3D=3D=3D Eventually, after calling cap_enter(2), the following code is called: =3D=3D=3D=3D BEGIN CODE =3D=3D=3D=3D #define ATTRNAME_ENABLED "hbsd.pax.aslr" sz =3D extattr_get_fd(fd, ctx->hc_namespace, ATTRNAME_ENABLED, NULL= , 0); if (sz <=3D 0) {=20 if (errno =3D=3D ENOATTR) { /* * This is okay, it just means that nothing has been= set. * No error condition here. */ return (RES_SUCCESS); } return (RES_FAIL); } =3D=3D=3D=3D END CODE =3D=3D=3D=3D For reference, the program's code is here: https://git.hardenedbsd.org/shawn.webb/hbsdctrl/-/tree/main?ref_type=3Dheads The library code, which is what's responsible for calling the filesystem extended attribute related syscalls is here: https://git.hardenedbsd.org/hardenedbsd/HardenedBSD/-/tree/hardened/current= /hbsdcontrol-v2/lib/libhbsdcontrol?ref_type=3Dheads =46rom the rights(4) manual page, I'm instructed all I need are to apply those capabilities to that file descriptor: =3D=3D=3D=3D BEGIN PASTE =3D=3D=3D=3D CAP_EXTATTR_DELETE Permit extattr_delete_fd(2). CAP_EXTATTR_GET Permit extattr_get_fd(2). CAP_EXTATTR_LIST Permit extattr_list_fd(2). CAP_EXTATTR_SET Permit extattr_set_fd(2). =3D=3D=3D=3D END PASTE =3D=3D=3D=3D So I'm a bit unsure if I'm doing something wrong. Thanks, --=20 Shawn Webb Cofounder / Security Engineer HardenedBSD Tor-ified Signal: +1 303-901-1600 / shawn_webb_opsec.50 https://git.hardenedbsd.org/hardenedbsd/pubkeys/-/raw/master/Shawn_Webb/03A= 4CBEBB82EA5A67D9F3853FF2E67A277F8E1FA.pub.asc --znjzrhotgeqp5oaq Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEA6TL67gupaZ9nzhT/y5nonf44foFAmX+FkwACgkQ/y5nonf4 4fprhxAAoDCJ/T6dut1kQvt63wy48bjeDjrtrIziKs0F03nQKzQHEi2BHl97Syc+ LyqsxEGaxQtMRV8I4mGCqXk+uazKxLiz43H8GM1ln2kpI6xVGWqENdTVhQJdYyBn 8cpTw7hxJSsrY31Qio4Mjs4WQKdyYdHCwXAaTMloIo/uNT9HJ6ZXn4HZIgxUq/5k cKB9AbURFWqR9czMNriHnRxOIuV58cd0OO2LEssprwS6NOYp3U5td1cgml8CKbWM Nx2oRnwMYwOigDTmLHSfilUV2crqwfB+/jcICPO7cPZ9GIP4xRNulNQ6pmqTsW8k AiBzMtLKxbSn/HfXCGa6eWURDuDMrM3JzfxTbD+J9Fo6CYW58mIDQsKmxDi42n/M FQJDPLOX66MlXhM3ewxxKgtAU1lYFxfsOe8pi4BrMJVwiea9HJHLKrDqvvV8+TyI RCelE7aPT4ipYcs7D08FfT8PB4arLhImcDUE7Nfk8zbiymHMfoqPzomr0U5KE9Mc mi+u7pl1UiESSUsTDY68Wxu5xDlkK9lr4RctI90kuyoKs5SYHXf10rAicYxXDw2X LZKUYUSlAg6HHNQCxtcUkLcd8Hnfw3GkrWRjwjZ/uYzJMAq0zaNyy26XsdCcFq0G pmOpjxe19B5OS0wBsuB2DIT3CP8vmEin948x0OAR/FMInpUS71w= =2waD -----END PGP SIGNATURE----- --znjzrhotgeqp5oaq--