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Thu, 03 Aug 2023 22:48:04 +0200 From: Helge Deller To: qemu-devel@nongnu.org Cc: Peter Maydell , =?utf-8?q?Daniel_P_=2E_Berrang?= =?utf-8?q?=C3=A9?= , qemu-arm@nongnu.org, Richard Henderson , Laurent Vivier , Helge Deller Subject: [PATCH v3 1/3] linux-user: Fix openat() emulation to correctly detect accesses to /proc Date: Thu, 3 Aug 2023 22:48:01 +0200 Message-ID: <20230803204803.639733-2-deller@gmx.de> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230803204803.639733-1-deller@gmx.de> References: <20230803204803.639733-1-deller@gmx.de> MIME-Version: 1.0 X-Provags-ID: V03:K1:FWY0+UEU+U6Ysrxr9GvdMR9C0hGXfG7CzpCGA3MsfxX9XVIBQ4B Yk2LkXdZXd/NUNJEw/XMZ+3V7AFITZB0+/Zfe+KaasTZbeOuqCQBrylzGlY/U1IqnRB5Yrh FQfz5m9gVBjxHPmkZvagu++ZGlH4hgnyzz3dpgOCO+JxYpPvMqvUd3GiFHWZHJtWd7/E11R dh768SfjRZMYNVMK6kNaQ== UI-OutboundReport: notjunk:1;M01:P0:UU1Tlh3NTCg=;X5hFlEhISiimliao1YqqmdYEM3J +cSrVgXc6jAl/6gU0ofMT6zSNRzQo22mRCJIXTA+C2VlSMEyoKqEFUONrsi3KR6B/tUpcguPl 1DNjGSuT8ssLy6SGAAymW80Roy8oEKK5OA5Hq7hyz7fBYnNEoUsWhIE2qjr+Q0l3hh6QQc9uQ AjFzWhjRZj+79p/lfT7AuB+Lq4Dqs6oeeHEREzb1cI+o4GzEdIN5H1KfLhMdSygoeB+31Nxh0 KDaHOvugHxYdEIThrECjkIJheSKdsGEODLur4P5iChYHQKkElVCaVhmvBMR53PiWqSAO55aJ6 /OW+BOJAKApyzWPQNh+OPV3IuqL3mWRXxXuIP/oRtrJsLwWxY9WoXSACTMWDziStGLkxmBJRy lxnfmKICIIqZa/2jC28E/TS6vaSbioF/e3+5k0LQ3lG2gmLzZBP4n8muGawGdLyoieX2H20yh OErwWWr2QrgUSerAM8K8E0wOHEWIbTswyqGZ3G3tMFnI7ft2Tg8qJbkZDYhGNLUbkZ9V51SKu Ny2+/1yBTcLIk2tFZbxMEfoqTRGLxBnU8ot0RcBd/cEPGLZgIEnFThoclhhZgnusMSVknAqoj 73xMTkMPt8UADs8F+Zakg9oljOeG83xaECnvg+vf4sxc6A4PE/R1Xm0V6RWPqmjhw8BkypwXH 0Yx5d+30uwLI3JOx6QJZwEsL+9VrBSIn5fyAGfSmE1qpRHhMXBbSRmwo9/BvRE8309dgEY8kR LXkvQXk0ZLIjgBefhT9joa601SVMkV2rCFC7vM8rNwsWGwOH/bvQwNC5wpgmv0bOgtBptGBcv uD7XOZ+8m+U9TT1kfO9ROJ35ABRGk/2LFwA+wwh+L7ZA1kIkyVZXpWuEusu/+p1sa1KMPZhUg LQvFxU8omKsdm8T19QlZb9HSDiiEUSWnYwLZ6HytOKIZqCInYcfmU9XkBG10zqOrgBxLIX6/9 D4mJHg== Received-SPF: pass client-ip=212.227.17.21; envelope-from=deller@gmx.de; helo=mout.gmx.net X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org In qemu we catch accesses to files like /proc/cpuinfo or /proc/net/route and return to the guest contents which would be visible on a real system (instead what the host would show). This patch fixes a bug, where for example the accesses cat /proc////cpuinfo or cd /proc && cat cpuinfo will not be recognized by qemu and where qemu will wrongly show the contents of the host's /proc/cpuinfo file. Signed-off-by: Helge Deller --- v3: - use g_autofree on returned value from realpath v2: - use g_autofree instead of pathname on stack Daniel P. Berrangé requested to not put buffers on stack. Using g_autofree keeps code much cleaner than using extended semantics of realpath(), unless I can use g_autofree on malloced area from realpath(). --- linux-user/syscall.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) -- 2.41.0 diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 95727a816a..1ec7d27e37 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -8539,9 +8539,12 @@ static int open_hardware(CPUArchState *cpu_env, int fd) } #endif -int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *pathname, + +int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *fname, int flags, mode_t mode, bool safe) { + g_autofree char *proc_name = NULL; + const char *pathname; struct fake_open { const char *filename; int (*fill)(CPUArchState *cpu_env, int fd); @@ -8567,6 +8570,14 @@ int do_guest_openat(CPUArchState *cpu_env, int dirfd, const char *pathname, { NULL, NULL, NULL } }; + /* if this is a file from /proc/ filesystem, expand full name */ + proc_name = realpath(fname, NULL); + if (proc_name && strncmp(proc_name, "/proc/", 6) == 0) { + pathname = proc_name; + } else { + pathname = fname; + } + if (is_proc_myself(pathname, "exe")) { if (safe) { return safe_openat(dirfd, exec_path, flags, mode);