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Resent-From: ulfvonbelow Original-Sender: "Debbugs-submit" Resent-CC: guix-patches@gnu.org Resent-Date: Fri, 11 Aug 2023 09:07:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 65221 X-GNU-PR-Package: guix-patches X-GNU-PR-Keywords: patch To: 65221@debbugs.gnu.org Received: via spool by 65221-submit@debbugs.gnu.org id=B65221.169174479122779 (code B ref 65221); Fri, 11 Aug 2023 09:07:02 +0000 Received: (at 65221) by debbugs.gnu.org; 11 Aug 2023 09:06:31 +0000 Received: from localhost ([127.0.0.1]:44894 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1qUO6J-0005vK-3a for submit@debbugs.gnu.org; Fri, 11 Aug 2023 05:06:31 -0400 Received: from tilde.club ([142.44.150.184]:33084 ident=postfix) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1qUO6G-0005vC-Ll for 65221@debbugs.gnu.org; Fri, 11 Aug 2023 05:06:29 -0400 Received: by tilde.club (Postfix, from userid 5378) id 68AEC224F468B; Fri, 11 Aug 2023 09:06:28 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 tilde.club 68AEC224F468B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=tilde.club; s=mail; t=1691744788; bh=zT+RsBzrdwyHo9JkTvV911XbenRJjrkflyhLBtnqsII=; h=From:To:Subject:Date:In-Reply-To:References:From; b=UkXPcBtjRYG/oW0cImwMh3XsOKQeRLKp4PtyxHFIP+kVZE/ZWU8N5Pz1dMk3o1/8l cuQAmxsHOWy0ZN4WSqtuGgDrQaSGNPN2Xn3oOHZq1uy3rg3p1/xdqZ8sot+nzlyLwe uiaJlxhXj5u9y6m7UevqV5LRrsV/FebvQd9nkb3A= From: ulfvonbelow Date: Fri, 11 Aug 2023 04:06:15 -0500 Message-Id: <20230811090615.3707-2-striness@tilde.club> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230811090615.3707-1-striness@tilde.club> References: <20230811090615.3707-1-striness@tilde.club> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: guix-patches@gnu.org List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-patches-bounces+larch=yhetil.org@gnu.org Sender: guix-patches-bounces+larch=yhetil.org@gnu.org X-Migadu-Flow: FLOW_IN X-Migadu-Country: US X-Migadu-Queue-Id: 8DA7E4979B X-Migadu-Scanner: mx0.migadu.com X-Migadu-Spam-Score: -3.58 X-Spam-Score: -3.58 X-TUID: Y017jiQIsrRk There are currently some corner cases in how EXTRA-PORTS works due to it not managing FDs 0, 1, and 2. Specifically, if one were to include a port in EXTRA-PORTS with FD 0, 1, or 2, it would *not* be preserved, and would instead represent the file that EXEC-COMMAND assigned to that file descriptor. To avoid this, it's necessary to call PRESERVE-PORTS *before* redirecting the input, but this could clobber LOG-PORT or INPUT-PORT, so it would become necessary to include LOG-PORT and INPUT-PORT in the call to PRESERVE-PORTS, then do the redirection using the new FD assignment, then close them. This complication can be avoided if we simply let PRESERVE-PORTS itself do the redirection. This also solves other edge cases, like if LOG-PORT has fileno 0 or 1 (previously passing a LOG-PORT of (current-output-port) would cause an error, as the underlying file descriptor would be closed before dup2 was called to copy it), or if INPUT-PORT has fileno 0. To solve this, we modify PRESERVE-PORTS to allow both file descriptors and ports, and to start the range it copies into at 0 instead of 3. We then modify EXEC-COMMAND to explicitly pass the desired standard I/O FDs / ports at the front of the list it passes to PRESERVE-PORTS. * modules/shepherd/service.scm (preserve-ports): Allow elements of EXTRA-PORTS to be either ports or file descriptors. Start the range of FDs being duplicated into at 0 instead of 3. (exec-command): use PRESERVE-PORTS for redirecting FDs 0, 1, and 2. --- modules/shepherd/service.scm | 74 +++++++++++++++++------------------- 1 file changed, 35 insertions(+), 39 deletions(-) diff --git a/modules/shepherd/service.scm b/modules/shepherd/service.scm index ffbd03c..5f735fe 100644 --- a/modules/shepherd/service.scm +++ b/modules/shepherd/service.scm @@ -1435,10 +1435,10 @@ FILE." supplementary-groups))) (define (preserve-ports extra-ports) - "Duplicate the FDs (fd1 fd2 ... fdN) corresponding to the N ports in -EXTRA-PORTS into the FD range (3 4 ... 3+N). This will work regardless of the + "Duplicate the FDs (fd0 fd1 ... fdN) corresponding to the N+1 ports or FDs in +EXTRA-PORTS into the FD range (0 1 ... N). This will work regardless of the numeric values of fd1 ... fdN. Any open file descriptors not in EXTRA-PORTS -and numbered 3 or higher WILL be closed or marked FD_CLOEXEC." +WILL be closed or marked FD_CLOEXEC." ;; We employ the following strategy: copy FDs as high as possible, in ;; descending order of FD, so as to avoid clobbering, then copy the high FDs ;; to low FDs, in the order specified in EXTRA-PORTS. If more than half of @@ -1449,8 +1449,9 @@ and numbered 3 or higher WILL be closed or marked FD_CLOEXEC." (let* ((max-fds-count (max-file-descriptors)) (highest-fd (- max-fds-count 1)) (extra-fds-count (length extra-ports)) - (preserved-fds-count (+ 3 extra-fds-count)) - (extra-fds (map fileno extra-ports)) + (extra-fds (map (lambda (x) + (if (port? x) (fileno x) x)) + extra-ports)) (index+fd (map cons (iota extra-fds-count) extra-fds)) @@ -1470,15 +1471,15 @@ and numbered 3 or higher WILL be closed or marked FD_CLOEXEC." (for-each (match-lambda ((by-fileno-index original-index . original-fd) (dup2 (- highest-fd by-fileno-index) - (+ 3 original-index)))) + original-index))) index2+fd) (for-each (lambda (fd) (catch-system-error (let ((flags (fcntl fd F_GETFD))) (when (zero? (logand flags FD_CLOEXEC)) (fcntl fd F_SETFD (logior FD_CLOEXEC flags)))))) - (iota (- max-fds-count preserved-fds-count) - preserved-fds-count)))) + (iota (- max-fds-count extra-fds-count) + extra-fds-count)))) (define* (exec-command command #:key @@ -1525,39 +1526,34 @@ false." (chdir directory) (environ environment-variables) - ;; Redirect stdin. - (catch-system-error (close-fdes 0)) - ;; Make sure file descriptor zero is used, so we don't end up reusing - ;; it for something unrelated, which can confuse some packages. - (dup2 (if input-port - (fileno input-port) - (open-fdes "/dev/null" O_RDONLY)) - 0) - - (when (or log-port log-file) - (catch #t - (lambda () - ;; Redirect stdout and stderr to use LOG-FILE. - (catch-system-error (close-fdes 1)) - (catch-system-error (close-fdes 2)) - (dup2 (if log-file - (open-fdes log-file (logior O_CREAT O_WRONLY O_APPEND) - #o640) - (fileno log-port)) - 1) - (dup2 1 2)) - - (lambda (key . args) - (when log-file - (format (current-error-port) - "failed to open log-file ~s:~%" log-file)) - (print-exception (current-error-port) #f key args) - (primitive-exit 1)))) - - ;; Close all the file descriptors except stdout, stderr, and EXTRA-PORTS. + ;; Close all the file descriptors except stdin, stdout, stderr, and + ;; EXTRA-PORTS. ;; Make EXTRA-PORTS available starting from file descriptor 3. ;; This clears their FD_CLOEXEC flag. - (preserve-ports extra-ports) + (let* ( ;; Make sure file descriptor zero is used, so we don't end up reusing + ;; it for something unrelated, which can confuse some packages. + (stdin (or input-port (open-fdes "/dev/null" O_RDONLY))) + (stdout (catch #t + (lambda () + (or log-port + (and log-file + (open-fdes log-file + (logior O_CREAT O_WRONLY O_APPEND) + #o640)) + 1)) + (lambda (key . args) + (when log-file + (format (current-error-port) + "failed to open log-file ~s:~%" log-file)) + (print-exception (current-error-port) #f key args) + (primitive-exit 1)))) + (stderr (if (or log-port log-file) + stdout + 2))) + (preserve-ports (cons* stdin + stdout + stderr + extra-ports))) ;; setgid must be done *before* setuid, otherwise the user will ;; likely no longer have permissions to setgid. -- 2.40.1