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[79.214.176.215]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a86e54852e9sm252483866b.37.2024.08.28.07.43.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Aug 2024 07:43:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1724856187; x=1725460987; darn=nongnu.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=hpVn81vMDt7oTw6ywsivWZmGXqKq2KnSx//V2GcwNPE=; b=mi+UCsGr6kJ89p67MdPSo1R3pIPA8m+58XR7MCNAn9Sfs9WqNPvW79+l4IJV0U0c62 uovHxQsNGayoNQ228lB1e8vwHzD2I9OD3J8SEnlR7IchIpwrga8n7BVKrp5RX/SHnUbi q2KEonuKTadBcGPTRmnCAgDvXV1uvgMR7X78z19BEfO03xpxumPs1rCebG9/eQ6JyWxg 6wTZFwIVqgTk5LhfHM3O13xUeW0JjR1bq7Tb+DdFGp2O9s7iJ5RE5Dvo084O8wkqwK1o ImzHIsPoH7X9X8z9sua8sd6mNL2VeMz1lnjzOZfD1bNqPLRTKWQyJLwbxc9R8YAbNm1q jNtw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724856187; x=1725460987; 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=hpVn81vMDt7oTw6ywsivWZmGXqKq2KnSx//V2GcwNPE=; b=XNVB0q3rZ6fJuUH3aC61jHjJDVtop8pp72c8H5vpJDdM3sgmR+xuk6tjrytLEaPyE1 nnpot7IuhdfcuDmuyn+13T0ov/1Uy/MKf4zsKErqmc1WbVGelRi/oCkErwqq2f/zTT+c RCMBnm0AlFrxw734uQYpy0R2O3oaBJKb9RIOo35+ZLSq9fiERKPSqmlw4zA78cUqd293 4H/pnRf3HI8Nfbu/Ip0n2wBKDr+x7sDG5hPLO/MadWLlm0R4nL1BsvmfmetW5TEY5ewH Ak2dO29LuiC2sHYCQaBIYs7T9jQ9cSWddr2556ARBc3w28WhzfiV3OlUuKQptZUT/+fw 5OPQ== X-Gm-Message-State: AOJu0YxgWgE+W1sUKbKERBAm/ptyqxK3QVvR9W84VcX2gku8xGv9jH3g LwWGE/uSH0LPfrvWcVDirOhf4thJxTzGKfhkupLOyWJ3/AAkP+6VDstw2RY8 X-Google-Smtp-Source: AGHT+IHrAYQHjSYlXUDX+ubTdzqvMQcN7UY1cXgE3SFMxxqqRxL8Mnks8gvnxDnfKCWatyxrJQKjxg== X-Received: by 2002:a17:907:7214:b0:a7a:9f0f:ab26 with SMTP id a640c23a62f3a-a86a52b36b2mr1204181166b.23.1724856185930; Wed, 28 Aug 2024 07:43:05 -0700 (PDT) From: Michael Vogt X-Google-Original-From: Michael Vogt To: qemu-devel@nongnu.org Cc: Laurent Vivier , Michael Vogt Subject: [PATCH] linux-user: add openat2 support in linux-user Date: Wed, 28 Aug 2024 16:42:28 +0200 Message-ID: <20240828144227.32977-2-mvogt@redhat.com> X-Mailer: git-send-email 2.45.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2a00:1450:4864:20::633; envelope-from=michael.vogt@gmail.com; helo=mail-ej1-x633.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, FREEMAIL_FROM=0.001, 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @gmail.com) X-ZM-MESSAGEID: 1724856224980116600 Content-Type: text/plain; charset="utf-8" This commit adds support for the `openat2()` syscall in the `linux-user` userspace emulator. It is implemented by extracting a new helper `maybe_do_fake_open()` out of the exiting `do_guest_openat()` and share that with the new `do_guest_openat2()`. Unfortunatly we cannot just make do_guest_openat2() a superset of do_guest_openat() because the openat2() syscall is stricter with the argument checking and will return an error for invalid flags or mode combinations (which open()/openat() will ignore). Note that in this commit using openat2() for a "faked" file in /proc will ignore the "resolve" flags. This is not great but it seems similar to the exiting behavior when openat() is called with a dirfd to "/proc". Here too the fake file lookup may not catch the special file because "realpath()" is used to determine if the path is in /proc. Alternatively to ignoring we could simply fail with `-TARGET_ENOSYS` (or similar) if `resolve` flags are passed and we found something that looks like a file in /proc that needs faking. Signed-off-by: Michael Vogt Buglink: https://github.com/osbuild/bootc-image-builder/issues/619 --- linux-user/qemu.h | 4 +++ linux-user/syscall.c | 73 ++++++++++++++++++++++++++++++++++++--- linux-user/syscall_defs.h | 7 ++++ meson.build | 1 + 4 files changed, 81 insertions(+), 4 deletions(-) diff --git a/linux-user/qemu.h b/linux-user/qemu.h index 2e90a97175..47b6d7da88 100644 --- a/linux-user/qemu.h +++ b/linux-user/qemu.h @@ -164,6 +164,10 @@ struct TaskState { abi_long do_brk(abi_ulong new_brk); int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *pathname, int flags, mode_t mode, bool safe); +#ifdef HAVE_OPENAT2_H +int do_guest_openat2(CPUArchState *cpu_env, int dirfd, const char *pathnam= e, + struct target_open_how *how, bool safe); +#endif ssize_t do_guest_readlink(const char *pathname, char *buf, size_t bufsiz); =20 /* user access */ diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 9d5415674d..f3a47bbfc0 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -85,6 +85,12 @@ #include #endif =20 +#ifdef HAVE_OPENAT2_H +#include +/* glibc has no header for SYS_openat2 so we need to get it via syscall.h = */ +#include +#endif + #define termios host_termios #define winsize host_winsize #define termio host_termio @@ -653,6 +659,10 @@ safe_syscall3(ssize_t, read, int, fd, void *, buff, si= ze_t, count) safe_syscall3(ssize_t, write, int, fd, const void *, buff, size_t, count) safe_syscall4(int, openat, int, dirfd, const char *, pathname, \ int, flags, mode_t, mode) +#ifdef HAVE_OPENAT2_H +safe_syscall4(int, openat2, int, dirfd, const char *, pathname, \ + const struct open_how *, how, size_t, size); +#endif #if defined(TARGET_NR_wait4) || defined(TARGET_NR_waitpid) safe_syscall4(pid_t, wait4, pid_t, pid, int *, status, int, options, \ struct rusage *, rusage) @@ -8334,8 +8344,9 @@ static int open_net_route(CPUArchState *cpu_env, int = fd) } #endif =20 -int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *fname, - int flags, mode_t mode, bool safe) +static int maybe_do_fake_open(CPUArchState *cpu_env, int dirfd, + const char *fname, int flags, mode_t mode, + bool safe) { g_autofree char *proc_name =3D NULL; const char *pathname; @@ -8418,13 +8429,48 @@ int do_guest_openat(CPUArchState *cpu_env, int dirf= d, const char *fname, return fd; } =20 + return -1; +} + +int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *fname, + int flags, mode_t mode, bool safe) +{ + int fd =3D maybe_do_fake_open(cpu_env, dirfd, fname, flags, mode, safe= ); + if (fd >=3D 0) + return fd; + if (safe) { - return safe_openat(dirfd, path(pathname), flags, mode); + return safe_openat(dirfd, path(fname), flags, mode); } else { - return openat(dirfd, path(pathname), flags, mode); + return openat(dirfd, path(fname), flags, mode); } } =20 +#ifdef HAVE_OPENAT2_H +int do_guest_openat2(CPUArchState *cpu_env, int dirfd, const char *fname, + struct target_open_how *how, bool safe) +{ + /* + * Ideally we would pass "how->resolve" flags into this helper too but + * the lookup for files that need faking is based on "realpath()" so + * neither a dirfd for "proc" nor restrictions via "resolve" flags can + * be honored right now. + */ + int fd =3D maybe_do_fake_open(cpu_env, dirfd, fname, how->flags, how->= mode, + safe); + if (fd >=3D 0) + return fd; + + if (safe) { + return safe_openat2(dirfd, fname, (struct open_how *)how, + sizeof(struct target_open_how)); + } else { + return syscall(SYS_openat2, dirfd, fname, (struct open_hosw *)how, + sizeof(struct target_open_how)); + } +} +#endif + ssize_t do_guest_readlink(const char *pathname, char *buf, size_t bufsiz) { ssize_t ret; @@ -9197,6 +9243,25 @@ static abi_long do_syscall1(CPUArchState *cpu_env, i= nt num, abi_long arg1, fd_trans_unregister(ret); unlock_user(p, arg2, 0); return ret; +#if defined(TARGET_NR_openat2) && defined(HAVE_OPENAT2_H) + case TARGET_NR_openat2: + { + struct target_open_how how, *target_how; + if (!(p =3D lock_user_string(arg2))) + return -TARGET_EFAULT; + if (!(lock_user_struct(VERIFY_READ, target_how, arg3, 1))) + return -TARGET_EFAULT; + how.flags =3D target_to_host_bitmask(target_how->flags, + fcntl_flags_tbl); + how.mode =3D tswap64(target_how->mode); + how.resolve =3D tswap64(target_how->resolve); + ret =3D get_errno(do_guest_openat2(cpu_env, arg1, p, &how, tru= e)); + fd_trans_unregister(ret); + unlock_user_struct(target_how, arg3, 0); + unlock_user(p, arg2, 0); + return ret; + } +#endif #if defined(TARGET_NR_name_to_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) case TARGET_NR_name_to_handle_at: ret =3D do_name_to_handle_at(arg1, arg2, arg3, arg4, arg5); diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h index a00b617cae..2ae694261c 100644 --- a/linux-user/syscall_defs.h +++ b/linux-user/syscall_defs.h @@ -2754,4 +2754,11 @@ struct target_sched_param { abi_int sched_priority; }; =20 +/* from kernel's include/uapi/linux/openat2.h */ +struct target_open_how { + __u64 flags; + __u64 mode; + __u64 resolve; +}; + #endif diff --git a/meson.build b/meson.build index fbda17c987..220ccbcbe6 100644 --- a/meson.build +++ b/meson.build @@ -2465,6 +2465,7 @@ config_host_data.set('CONFIG_LINUX_MAGIC_H', cc.has_h= eader('linux/magic.h')) config_host_data.set('CONFIG_VALGRIND_H', cc.has_header('valgrind/valgrind= .h')) config_host_data.set('HAVE_BTRFS_H', cc.has_header('linux/btrfs.h')) config_host_data.set('HAVE_DRM_H', cc.has_header('libdrm/drm.h')) +config_host_data.set('HAVE_OPENAT2_H', cc.has_header('linux/openat2.h')) config_host_data.set('HAVE_PTY_H', cc.has_header('pty.h')) config_host_data.set('HAVE_SYS_DISK_H', cc.has_header('sys/disk.h')) config_host_data.set('HAVE_SYS_IOCCOM_H', cc.has_header('sys/ioccom.h')) --=20 2.45.2