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Tue, 01 Aug 2023 21:10:37 +0200 From: Helge Deller To: qemu-devel@nongnu.org Cc: Peter Maydell , Richard Henderson , Laurent Vivier , =?utf-8?q?Daniel_P_=2E_Berrang=C3=A9?= , qemu-arm@nongnu.org, Helge Deller Subject: [PATCH 1/2] linux-user: Fix openat() emulation to correctly detect accesses to /proc Date: Tue, 1 Aug 2023 21:10:34 +0200 Message-ID: <20230801191035.374120-2-deller@gmx.de> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230801191035.374120-1-deller@gmx.de> References: <20230801191035.374120-1-deller@gmx.de> MIME-Version: 1.0 X-Provags-ID: V03:K1:t2Qxvy/8uIfWsppEqM5abCnaRoULrkykz2ZZeXCLGXfQJOOPBAP J27DaF0PPCWxDac6ygd3ozCHVLG5VyovwcyXD5SOyPxkXT9/KQedMBvsIr3666V1ljzzSP+ UK4plnoZgiQGmOvv6amqPweeqYQBGnHxUpxLFd+/G9P3mu72AAM7Rt31tLwuFj0Ppq/FelH /aFyBLFlbACObr4uJw3/w== UI-OutboundReport: notjunk:1;M01:P0:zBl5iumgsRU=;vRj4BaMYLi2Ah55QRXZv1dNAIYC MeDzHyAVn0i/6xLMETkxIbIPAKMEezsex/L9BnYGl9ALQvn6lxl968TFm0dHu3iyj0ZRsohk/ Gk4VJr2D9+pRfPNAwj5IulZ2OJmm4pxVlr1EweSdF1DtPOdSfWfiK1vDprkt6bwMxFtV8qvel UFqHLU7keLrhW4tTFncKvb8q0DNqIbrzESDyUUM6xbP/xVYRuWZsaIoAkUxb+4V6g0N6bFeeP azonhVqN9oF0HUliOprdxvTGRRtl8D/9qVhmWTzpBwLwo501VYcsKiBvzgAUphsXJE6KMbDhx TMjvbmRUEDPpgt8/p1f2khIVLdZLyxI6HKzlQV3hWqiPQsJRRkuMWdM+Kp3G1sB4emj9JEyZK cUqTVpxuVycwhFv7/6XsnuyCgYjXxXL31ly5fyBTSqzxQX2iP7HQwGvqhBEpelbRyPoOBx+23 eGFmC7M59id9B8TkIH+yLVYvhpk3TUMZGLSyl6r1dVpfBfWLhCjVCc77h+dLpQr6u4bHujCGb anZm6J8uoZjNY9EFg6mmoYdeTjqvBhLqS9dpaNB3nLnNC6rjBdnRdCqG5FBO1HIEe6y5K97U3 2cxptu6zO6HLqrMUEbfeIhzC556AtdcbrPMz5Grj62LBCa/tOzCallnHRFXh1cDAVSr0dc8da if0chTETwORqRN2NB+1zb1Wgn85oxXYgE8E/xQsy6Qc46Ny5iLMeip78xqcDkPazcgfvQKW/q OVsDjozgab5gNbYqFJ9LNaCuGJ4CcQV6bJCEoZzHPaklNlL0GvujeDVikTgGZcbD+szZKQMi0 PpovMEoA8yIJnrNq6YTQMpo78rfrvmzVoM2qJFr8zGwLUfTfKW1vE4DR/lNtr220BbT8nQWSi mi2DW3SNioPDXhGXcvSsM3gBcRnysZSd/VeIISyeEnAcg//bSbAHCJkBrRdO8kPElt/z4rTQF HedYIIlznfIkZqeuAMZeETt6x5k= Received-SPF: pass client-ip=212.227.17.22; 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_H4=0.001, RCVD_IN_MSPIKE_WL=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 --- 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 | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) -- 2.41.0 diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 95727a816a..a089463969 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 = g_new(char, PATH_MAX); + const char *pathname; struct fake_open { const char *filename; int (*fill)(CPUArchState *cpu_env, int fd); @@ -8567,6 +8570,13 @@ 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 */ + if (realpath(fname, 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);