From owner-freebsd-hackers@freebsd.org Wed May 6 18:32:33 2020 Return-Path: Delivered-To: freebsd-hackers@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 3F3F82DC171 for ; Wed, 6 May 2020 18:32:33 +0000 (UTC) (envelope-from damjan.jov@gmail.com) Received: from mail-il1-x12c.google.com (mail-il1-x12c.google.com [IPv6:2607:f8b0:4864:20::12c]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 49HQDw1tJVz41kj for ; Wed, 6 May 2020 18:32:32 +0000 (UTC) (envelope-from damjan.jov@gmail.com) Received: by mail-il1-x12c.google.com with SMTP id c16so415441ilr.3 for ; Wed, 06 May 2020 11:32:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=PYSG1rmiRdqmjnxNqr2XDXuPAOw7QknT5rHRfZZLjI8=; b=B8ZjsLiXOQiAL9OEj8bSnBVuaM5oJl8WSY3prAR5uczd+L5ZeT+NXpTRptWVbwkC2n gBWtFczVa16/04VMRm2xicb1U2FyiZ7tZs4g2Zv8PEhz5gp9vvOfn7OxhP2ZD4qqvrPH w7U1NvPOknPO3CHyfeZ1FnR1l9NO0OAqIBOJo1v7joq/FqOm45DcTW1ZGI7hE8Qg4ogo 9S0t1QFXBnlBb9ek9c5e9ckY+gOuOhh96RHdbsc+pbVo3lWyuFXWuFMVDN0FGb8fhRhu +bmz46BCWRY7bhMBjNVSKacL19g2fxnf5Pm+dbUvXkvi0kZysOdHmkF822DtCwpMFPPO X1tQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=PYSG1rmiRdqmjnxNqr2XDXuPAOw7QknT5rHRfZZLjI8=; b=juEvx4REf8pVRKpU7AMVl0pZDdbBMfOt0YMIl3K04S2P99UgRv3pp3I9JEROUlvIng MuoaVZ7N/b9bVYH0dIiBVmNT/Jp94a+HUuI215rCQBPo4jMaNzK33eVIEEiy88JyITRm cesu/rGgHA3CqAebvLtHs4ZkupbV4yhkH8TGYCL8GNvC442C3HZQArVuIZqWn4S+lcIC R2alWQDbdlkpgz9CIJsGQc1nN3knKP3Qo0aZcVDUzPeR3gTVh2jiAaCJwGG5IxvR7Epj XUqy5zcnGEsPoBxFCRRkOpTToXUJUu3FwEbUUlH3JJzTsKLuDYgmZgKbUxf4crnAc/rs Tu2Q== X-Gm-Message-State: AGi0PuZ6pSVY7y77Ohv3/AXC4FBjljoZeymRQfWLO31hpQSDqX75Tzqq S5rwsbeMXgDUrnftpXCgAnoqsQHjU0I7kYcyLexjnG87bA9yWg== X-Google-Smtp-Source: APiQypKfxmvl+S/t8eIrrhz6c9Hs89QC/7rxXV/gRGP7CHKDUDxxYNDFPORROo+eI74I4Bul93RIgI5SvcOfq57VsMQ= X-Received: by 2002:a92:af11:: with SMTP id n17mr10901387ili.197.1588789950800; Wed, 06 May 2020 11:32:30 -0700 (PDT) MIME-Version: 1.0 From: Damjan Jovanovic Date: Wed, 6 May 2020 20:32:08 +0200 Message-ID: Subject: Allow procstat to view current working directory? [xfce4-terminal, linprocfs, ...] To: Hackers freeBSD X-Rspamd-Queue-Id: 49HQDw1tJVz41kj X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=B8ZjsLiX; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of damjanjov@gmail.com designates 2607:f8b0:4864:20::12c as permitted sender) smtp.mailfrom=damjanjov@gmail.com X-Spamd-Result: default: False [-2.00 / 15.00]; R_SPF_ALLOW(-0.20)[+ip6:2607:f8b0:4000::/36]; FREEMAIL_FROM(0.00)[gmail.com]; URI_COUNT_ODD(1.00)[3]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[gmail.com:+]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; FROM_EQ_ENVFROM(0.00)[]; IP_SCORE(0.00)[ip: (-8.99), ipnet: 2607:f8b0::/32(-0.33), asn: 15169(-0.43), country: US(-0.05)]; MIME_TRACE(0.00)[0:+,1:+,2:~]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; TAGGED_FROM(0.00)[]; SUBJECT_HAS_QUESTION(0.00)[]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; FROM_HAS_DN(0.00)[]; DWL_DNSWL_NONE(0.00)[gmail.com.dwl.dnswl.org : 127.0.5.0]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; IP_SCORE_FREEMAIL(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; RCVD_IN_DNSWL_NONE(0.00)[c.2.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.4.6.8.4.0.b.8.f.7.0.6.2.list.dnswl.org : 127.0.5.0]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[] Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.30 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 06 May 2020 18:32:33 -0000 Hi Currently "procstat fd [pid]" cannot view anything, even for other processes owned by the user making the call, not even their current working directory (CWD), unless it has PGET_CANDEBUG permission. linprocfs however allows reading the CWD for any process because it doesn't perform that check (sys/compat/linprocfs/linprocfs.c, function linprocfs_doproccwd()). Applications use this, eg. xfce4-terminal relies on /compat/linux/proc//cwd to find the shell's CWD, so that when you open a new tab, it starts in the same CWD as the tab you opened it from ( https://github.com/xfce-mirror/xfce4-terminal/blob/master/terminal/terminal-screen.c#L2343). I would like to patch xfce4-terminal to use libprocstat for that instead of needing linprocfs to be mounted, but since procstat is more restrictive, it will break it. Can we please downgrade PGET_CANDEBUG to at least PGET_CANSEE, so you can view the CWD for processes you own? Maybe other open files still need to be hidden, but the CWD doesn't seem like a major security concern. Linux's own /proc filesystem never hides the CWD (lrwxrwxrwx), and only hides file descriptors for processes you don't own. A patch along the following lines could be a start: diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c index 423968b2e1cc..f487232d2cff 100644 --- a/sys/kern/kern_descrip.c +++ b/sys/kern/kern_descrip.c @@ -3692,7 +3692,7 @@ sysctl_kern_proc_filedesc(SYSCTL_HANDLER_ARGS) sbuf_new_for_sysctl(&sb, NULL, FILEDESC_SBUF_SIZE, req); sbuf_clear_flags(&sb, SBUF_INCLUDENUL); - error = pget((pid_t)name[0], PGET_CANDEBUG | PGET_NOTWEXIT, &p); + error = pget((pid_t)name[0], PGET_CANSEE | PGET_NOTWEXIT, &p); if (error != 0) { sbuf_delete(&sb); return (error); @@ -3768,7 +3768,7 @@ sysctl_kern_proc_ofiledesc(SYSCTL_HANDLER_ARGS) struct proc *p; name = (int *)arg1; - error = pget((pid_t)name[0], PGET_CANDEBUG | PGET_NOTWEXIT, &p); + error = pget((pid_t)name[0], PGET_CANSEE | PGET_NOTWEXIT, &p); if (error != 0) return (error); fdp = fdhold(p); Thank you Damjan