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[209.51.188.17]) by mx.google.com with ESMTPS id h18-20020ac85e12000000b003fdeb6b4fd5si10534801qtx.766.2023.07.05.02.02.09 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Wed, 05 Jul 2023 02:02:09 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=aw+Q3lIQ; spf=pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-devel-bounces+patch=linaro.org@nongnu.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qGyO3-00085H-AX; Wed, 05 Jul 2023 05:01:23 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qGyO0-00083O-JB for qemu-devel@nongnu.org; Wed, 05 Jul 2023 05:01:20 -0400 Received: from mail-wm1-x329.google.com ([2a00:1450:4864:20::329]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qGyNx-0000iu-1g for qemu-devel@nongnu.org; Wed, 05 Jul 2023 05:01:19 -0400 Received: by mail-wm1-x329.google.com with SMTP id 5b1f17b1804b1-3fbd33a57dcso45471895e9.0 for ; Wed, 05 Jul 2023 02:01:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1688547674; x=1691139674; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=kAGOvaX+oVgTitIG676Zopi82+678c3iJq+qpHOtacQ=; b=aw+Q3lIQVeuNxgRlqqBkZnSvyOhTK/i5gAzJ07ZYxvg+TmTiLX1wyxjmwFmtt/6Y75 wuUTcgmKpVGk5RfyFRbzafR5qqESqVpXrcGEOah0O1YtKgskd8GogbxHqZtEuUjvfTv4 O8imugCbf70UJ6Ck6SuyDFrrp4EPkriP69gtQuEzzhyF2Ff0MST4ABQLbUA7fSIu7enR N7ZTNMu+/y2sr2HkHqLcQKWZgu3HUNhCJth1M1dlWvrTeI9WIIcJZjgMnVPLfj+tkDiz D5nwxWwGln4PAsmBUBHQQMoLKwZFowYtgy63RtlYxSgyz/cGHYT/j2XZue66Hkg1erCt bc6A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1688547674; x=1691139674; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=kAGOvaX+oVgTitIG676Zopi82+678c3iJq+qpHOtacQ=; b=B8Q0WF4+u/a+qmTo+UmnV6vdrgVjtTAT4w2VfvUvzynF/ZoAmD6QuBnfbIrybttBkt uoh0xUjKzmbnsctK3cYMJxl5oTmtxwQp2dTqSqo4JnCMqsYUPwp5/AvXjOchKWGAe69m 6qZ8BfEUtf7pcgojkQKJEZCaMNszvx7EXSef3z3pq9vIRiDMB8hrP70psbJSZOuwvn8J O+svyjR1bcovai3AcAGaLL88BuBY/UySGeKeAwaw70/n26222VLMdVFWrGl5vvn1vQ9l W1nt+EtOF8vfy9KqtNktMJ3FqCmDaA+oz4ilzwN0mplEH6F6O2BfkSdfTWqhOvwVjhf2 Jc2A== X-Gm-Message-State: AC+VfDwrzVLTKRGEtWyxLDcElQpM9okpil/nLEnFpS5qgQ2dSPCoz2K6 k7GxjE/qC7YqpR9x4L5r6wenNtTKqYWJ6dXMBLs= X-Received: by 2002:a05:600c:2299:b0:3fb:b2a5:aeac with SMTP id 25-20020a05600c229900b003fbb2a5aeacmr13589319wmf.20.1688547674578; Wed, 05 Jul 2023 02:01:14 -0700 (PDT) Received: from localhost.localdomain ([31.32.81.187]) by smtp.gmail.com with ESMTPSA id cw8-20020a056000090800b00311d8c2561bsm30350140wrb.60.2023.07.05.02.01.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Jul 2023 02:01:14 -0700 (PDT) From: Pierrick Bouvier To: qemu-devel@nongnu.org Cc: laurent@vivier.eu, richard.henderson@linaro.org, sir@cmpwn.com, Pierrick Bouvier Subject: [PATCH v2] linux-user/syscall: Implement execve without execveat Date: Wed, 5 Jul 2023 11:00:56 +0200 Message-Id: <20230705090056.610699-1-pierrick.bouvier@linaro.org> X-Mailer: git-send-email 2.40.1 MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::329; envelope-from=pierrick.bouvier@linaro.org; helo=mail-wm1-x329.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: qemu-devel-bounces+patch=linaro.org@nongnu.org Support for execveat syscall was implemented in 55bbe4 and is available since QEMU 8.0.0. It relies on host execveat, which is widely available on most of Linux kernels today. However, this change breaks qemu-user self emulation, if "host" qemu version is less than 8.0.0. Indeed, it does not implement yet execveat. This strange use case happens with most of distribution today having binfmt support. With a concrete failing example: $ qemu-x86_64-7.2 qemu-x86_64-8.0 /bin/bash -c /bin/ls /bin/bash: line 1: /bin/ls: Function not implemented -> not implemented means execve returned ENOSYS qemu-user-static 7.2 and 8.0 can be conveniently grabbed from debian packages qemu-user-static* [1]. One usage of this is running wine-arm64 from linux-x64 (details [2]). This is by updating qemu embedded in docker image that we ran into this issue. The solution to update host qemu is not always possible. Either it's complicated or ask you to recompile it, or simply is not accessible (GitLab CI, GitHub Actions). Thus, it could be worth to implement execve without relying on execveat, which is the goal of this patch. This patch was tested with example presented in this commit message. [1] http://ftp.us.debian.org/debian/pool/main/q/qemu/ [1] https://www.linaro.org/blog/emulate-windows-on-arm/ Signed-off-by: Pierrick Bouvier Reviewed-by: Michael Tokarev --- linux-user/syscall.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 08162cc966..4945ddd7f2 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -659,6 +659,7 @@ safe_syscall4(pid_t, wait4, pid_t, pid, int *, status, int, options, \ #endif safe_syscall5(int, waitid, idtype_t, idtype, id_t, id, siginfo_t *, infop, \ int, options, struct rusage *, rusage) +safe_syscall3(int, execve, const char *, filename, char **, argv, char **, envp) safe_syscall5(int, execveat, int, dirfd, const char *, filename, char **, argv, char **, envp, int, flags) #if defined(TARGET_NR_select) || defined(TARGET_NR__newselect) || \ @@ -8615,9 +8616,9 @@ ssize_t do_guest_readlink(const char *pathname, char *buf, size_t bufsiz) return ret; } -static int do_execveat(CPUArchState *cpu_env, int dirfd, - abi_long pathname, abi_long guest_argp, - abi_long guest_envp, int flags) +static int do_execv(CPUArchState *cpu_env, int dirfd, + abi_long pathname, abi_long guest_argp, + abi_long guest_envp, int flags, bool is_execveat) { int ret; char **argp, **envp; @@ -8696,11 +8697,14 @@ static int do_execveat(CPUArchState *cpu_env, int dirfd, goto execve_efault; } + const char* exe = p; if (is_proc_myself(p, "exe")) { - ret = get_errno(safe_execveat(dirfd, exec_path, argp, envp, flags)); - } else { - ret = get_errno(safe_execveat(dirfd, p, argp, envp, flags)); + exe = exec_path; } + ret = is_execveat ? + safe_execveat(dirfd, exe, argp, envp, flags): + safe_execve(exe, argp, envp); + ret = get_errno(ret); unlock_user(p, pathname, 0); @@ -9251,9 +9255,9 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1, return ret; #endif case TARGET_NR_execveat: - return do_execveat(cpu_env, arg1, arg2, arg3, arg4, arg5); + return do_execv(cpu_env, arg1, arg2, arg3, arg4, arg5, true); case TARGET_NR_execve: - return do_execveat(cpu_env, AT_FDCWD, arg1, arg2, arg3, 0); + return do_execv(cpu_env, AT_FDCWD, arg1, arg2, arg3, 0, false); case TARGET_NR_chdir: if (!(p = lock_user_string(arg1))) return -TARGET_EFAULT;