[Xen-devel] [PATCH] xenconsole: add option to avoid escape sequences in log

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

Add --replace-escape, -e option to xenconsoled, which replaces ESC with
'.' in console output written to log file. This makes it slightly safer
to do tail -f on a console output of untrusted guest.
The pty output is unaffected by this option.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
---
Is there any more documentation to be updated? I didn't found
xenconsoled man page or such.
---
 tools/console/daemon/io.c   | 18 ++++++++++++++++++
 tools/console/daemon/main.c |  9 +++++++--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/tools/console/daemon/io.c b/tools/console/daemon/io.c
index e22009aa39..c8280e0b7c 100644
--- a/tools/console/daemon/io.c
+++ b/tools/console/daemon/io.c
@@ -68,6 +68,7 @@ extern int log_time_hv;
 extern int log_time_guest;
 extern char *log_dir;
 extern int discard_overflowed_data;
+extern int replace_escape;
 
 static int log_time_hv_needts = 1;
 static int log_time_guest_needts = 1;
@@ -227,8 +228,25 @@ static inline int console_iter_int_arg3(struct domain *d,
        return ret;
 }
 
+static void do_replace_escape(const char *buf, char *dest, int len) {
+       int i;
+
+       memcpy(dest, buf, len);
+       for (i = 0; i < len; i++) {
+               if (dest[i] == '\033')
+                       dest[i] = '.';
+       }
+}
+
 static int write_all(int fd, const char* buf, size_t len)
 {
+       char buf_replaced[len];
+
+       if (replace_escape) {
+               do_replace_escape(buf, buf_replaced, len);
+               buf = buf_replaced;
+       }
+
        while (len) {
                ssize_t ret = write(fd, buf, len);
                if (ret == -1 && errno == EINTR)
diff --git a/tools/console/daemon/main.c b/tools/console/daemon/main.c
index 806d2fd611..b716e38c27 100644
--- a/tools/console/daemon/main.c
+++ b/tools/console/daemon/main.c
@@ -40,6 +40,7 @@ int log_time_hv = 0;
 int log_time_guest = 0;
 char *log_dir = NULL;
 int discard_overflowed_data = 1;
+int replace_escape = 0;
 
 static void handle_hup(int sig)
 {
@@ -48,7 +49,7 @@ static void handle_hup(int sig)
 
 static void usage(char *name)
 {
-       printf("Usage: %s [-h] [-V] [-v] [-i] [--log=none|guest|hv|all] 
[--log-dir=DIR] [--pid-file=PATH] [-t, --timestamp=none|guest|hv|all] [-o, 
--overflow-data=discard|keep]\n", name);
+       printf("Usage: %s [-h] [-V] [-v] [-i] [--log=none|guest|hv|all] 
[--log-dir=DIR] [--pid-file=PATH] [-t, --timestamp=none|guest|hv|all] [-o, 
--overflow-data=discard|keep] [-e, --replace-escape]\n", name);
 }
 
 static void version(char *name)
@@ -93,7 +94,7 @@ static void increase_fd_limit(void)
 
 int main(int argc, char **argv)
 {
-       const char *sopts = "hVvit:o:";
+       const char *sopts = "hVvit:o:e";
        struct option lopts[] = {
                { "help", 0, 0, 'h' },
                { "version", 0, 0, 'V' },
@@ -104,6 +105,7 @@ int main(int argc, char **argv)
                { "pid-file", 1, 0, 'p' },
                { "timestamp", 1, 0, 't' },
                { "overflow-data", 1, 0, 'o'},
+               { "replace-escape", 0, 0, 'e'},
                { 0 },
        };
        bool is_interactive = false;
@@ -168,6 +170,9 @@ int main(int argc, char **argv)
                                discard_overflowed_data = 1;
                        }
                        break;
+               case 'e':
+                       replace_escape = 1;
+                       break;
                case '?':
                        fprintf(stderr,
                                "Try `%s --help' for more information\n",
-- 
2.17.1


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