swtpm: Allow file desciptor passing for pid file

Allow the passing of a file descriptor where the PID file will
be written into.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>

man/man8/swtpm.8

@@ -133,7 +133,7 @@
 .\" ========================================================================
 .\"
 .IX Title "swtpm 8"
-.TH swtpm 8 "2018-04-03" "swtpm" ""
+.TH swtpm 8 "2018-04-05" "swtpm" ""
 .\" For nroff, turn off justification.  Always turn off hyphenation; it makes
 .\" way too many mistakes in technical documents.
 .if n .ad l
@@ -333,10 +333,11 @@ has been read.
 This variant of the migration key parameter allows to provide a passphrase in a file.
 A maximum of 32 bytes are read from the file and a key is derived from it using a
 \&\s-1SHA512\s0 hash. Currently only 128 bit keys are supported.
-.IP "\fB\-\-pid file=<pidfile>\fR" 4
-.IX Item "--pid file=<pidfile>"
+.IP "\fB\-\-pid file=<pidfile>|fd=<filedescriptor>\fR" 4
+.IX Item "--pid file=<pidfile>|fd=<filedescriptor>"
 This options allows to set the name of file where the process \s-1ID \s0(pid) of the \s-1TPM\s0
-will be written into.
+will be written into. It is also possible to pass a file descriptor to a file that
+has been opened for writing.
 .IP "\fB\-r|\-\-runas <owner>\fR" 4
 .IX Item "-r|--runas <owner>"
 Switch to the given user. This option can only be used when swtpm is started as root.

man/man8/swtpm.pod

@@ -244,10 +244,11 @@ This variant of the migration key parameter allows to provide a passphrase in a
 A maximum of 32 bytes are read from the file and a key is derived from it using a
 SHA512 hash. Currently only 128 bit keys are supported.
 
-=item B<--pid file=E<lt>pidfileE<gt>>
+=item B<--pid file=E<lt>pidfileE<gt>|fd=E<lt>filedescriptorE<gt>>
 
 This options allows to set the name of file where the process ID (pid) of the TPM
-will be written into.
+will be written into. It is also possible to pass a file descriptor to a file that
+has been opened for writing.
 
 =item B<-r|--runas E<lt>ownerE<gt>>
 

man/man8/swtpm_cuse.8

@@ -133,7 +133,7 @@
 .\" ========================================================================
 .\"
 .IX Title "swtpm_cuse 8"
-.TH swtpm_cuse 8 "2017-11-11" "swtpm" ""
+.TH swtpm_cuse 8 "2018-04-05" "swtpm" ""
 .\" For nroff, turn off justification.  Always turn off hyphenation; it makes
 .\" way too many mistakes in technical documents.
 .if n .ad l
@@ -254,10 +254,11 @@ has been read.
 This variant of the migration key parameter allows to provide a passphrase in a file.
 A maximum of 32 bytes are read from the file and a key is derived from it using a
 \&\s-1SHA512\s0 hash. Currently only 128 bit keys are supported.
-.IP "\fB\-\-pid file=<pidfile>\fR" 4
-.IX Item "--pid file=<pidfile>"
+.IP "\fB\-\-pid file=<pidfile>\fR|fd=<filedescriptor>>" 4
+.IX Item "--pid file=<pidfile>|fd=<filedescriptor>>"
 This options allows to set the name of file where the process \s-1ID \s0(pid) of the \s-1CUSE TPM\s0
-will be written into. The file will be written by the root user.
+will be written into. The file will be written by the root user. It is also possible to
+pass a file descriptor to a file that has been opened for writing.
 .SH "SEE ALSO"
 .IX Header "SEE ALSO"
 \&\fBswtpm_bios\fR, \fBswtpm_ioctl\fR

man/man8/swtpm_cuse.pod

@@ -132,10 +132,11 @@ This variant of the migration key parameter allows to provide a passphrase in a
 A maximum of 32 bytes are read from the file and a key is derived from it using a
 SHA512 hash. Currently only 128 bit keys are supported.
 
-=item B<--pid file=E<lt>pidfileE<gt>>
+=item B<--pid file=E<lt>pidfileE<gt>>|fd=E<lt>filedescriptorE<gt>>
 
 This options allows to set the name of file where the process ID (pid) of the CUSE TPM
-will be written into. The file will be written by the root user.
+will be written into. The file will be written by the root user. It is also possible to
+pass a file descriptor to a file that has been opened for writing.
 
 =back
 

src/swtpm/common.c

@@ -112,6 +112,10 @@ static const OptionDesc pid_opt_desc[] = {
         .name = "file",
         .type = OPT_TYPE_STRING,
     },
+    {
+        .name = "fd",
+        .type = OPT_TYPE_INT,
+    },
     END_OPTION_DESC
 };
 
@@ -418,18 +422,18 @@ handle_migration_key_options(char *options)
  *
  * @options: the 'pid' options to parse
  * @pidfile: Point to pointer for pidfile
+ * @pidfilefd: Pointer to file descriptor for pidfile
  *
  * Returns 0 on success, -1 on failure.
  */
 static int
-parse_pid_options(char *options, char **pidfile)
+parse_pid_options(char *options, char **pidfile, int *pidfilefd)
 {
     OptionValues *ovs = NULL;
     char *error = NULL;
     const char *filename = NULL;
 
     ovs = options_parse(options, pid_opt_desc, &error);
-
     if (!ovs) {
         logprintf(STDERR_FILENO, "Error parsing pid options: %s\n",
                 error);
@@ -437,16 +441,19 @@ parse_pid_options(char *options, char **pidfile)
     }
 
     filename = option_get_string(ovs, "file", NULL);
-    if (!filename) {
+    *pidfilefd = option_get_int(ovs, "fd", -1);
+    if (!filename && *pidfilefd < 0) {
         logprintf(STDERR_FILENO,
-                  "The file parameter is required for the pid option.\n");
+                  "The file or fd parameter is required for the pid option.\n");
         goto error;
     }
 
-    *pidfile = strdup(filename);
-    if (!*pidfile) {
-        logprintf(STDERR_FILENO, "Out of memory.");
-        goto error;
+    if (filename) {
+        *pidfile = strdup(filename);
+        if (!*pidfile) {
+            logprintf(STDERR_FILENO, "Out of memory.");
+            goto error;
+        }
     }
 
     option_values_free(ovs);
@@ -471,15 +478,18 @@ int
 handle_pid_options(char *options)
 {
     char *pidfile = NULL;
+    int pidfilefd = -1;
     int ret = 0;
 
     if (!options)
         return 0;
 
-    if (parse_pid_options(options, &pidfile) < 0)
+    if (parse_pid_options(options, &pidfile, &pidfilefd) < 0)
         return -1;
 
-    if (pidfile_set(pidfile) < 0)
+    if (pidfile && pidfile_set(pidfile) < 0)
+        ret = -1;
+    else if (pidfile_set_fd(pidfilefd) < 0)
         ret = -1;
 
     free(pidfile);

src/swtpm/cuse_tpm.c

@@ -200,7 +200,8 @@ static const char *usage =
 "                       log level 5 and higher will enable libtpms logging;\n"
 "                       all logged output will be prefixed with prefix;\n"
 "                       the log file can be reset (truncate)\n"
-"--pid file=<path>   :  write the process ID into the given file\n"
+"--pid file=<path>|fd=<filedescriptor>\n"
+"                    :  write the process ID into the given file\n"
 "--tpmstate dir=<dir>\n"
 "                    :  set the directory where the TPM's state will be written\n"
 "                       into; the TPM_PATH environment variable can be used\n"

src/swtpm/pidfile.c

@@ -47,6 +47,7 @@
 #include "logging.h"
 
 static char *g_pidfile;
+static int pidfilefd = -1;
 
 int pidfile_set(const char *pidfile)
 {
@@ -59,6 +60,13 @@ int pidfile_set(const char *pidfile)
    return 0;
 }
 
+int pidfile_set_fd(int newpidfilefd)
+{
+    pidfilefd = newpidfilefd;
+
+    return 0;
+}
+
 /*
  * pidfile_write: Write the given pid to the pidfile
  *
@@ -70,10 +78,14 @@ int pidfile_write(pid_t pid)
 {
     FILE *f;
 
-    if (!g_pidfile)
+    if (g_pidfile) {
+        f = fopen(g_pidfile, "w+");
+    } else if (pidfilefd >= 0) {
+        f = fdopen(pidfilefd, "w");
+    } else {
         return 0;
+    }
 
-    f = fopen(g_pidfile, "w+");
     if (!f) {
         logprintf(STDERR_FILENO, "Could not open pidfile %s : %s\n",
                   g_pidfile, strerror(errno));

src/swtpm/pidfile.h

@@ -39,6 +39,7 @@
 #define _SWTPM_PIDFILE_H_
 
 int pidfile_set(const char *pidfile);
+int pidfile_set_fd(int newpidfilefd);
 int pidfile_write(pid_t pid);
 void pidfile_remove(void);
 

src/swtpm/swtpm.c

@@ -141,7 +141,7 @@ static void usage(FILE *file, const char *prgname, const char *iface)
     "--locality [reject-locality-4][,allow-set-locality]\n"
     "                 : reject-locality-4: reject any command in locality 4\n"
     "                   allow-set-locality: accept SetLocality command\n"
-    "--pid file=<path>\n"
+    "--pid file=<path>|fd=<filedescriptor>\n"
     "                 : write the process ID into the given file\n"
     "--tpmstate dir=<dir>\n"
     "                 : set the directory where the TPM's state will be written\n"

src/swtpm/swtpm_chardev.c

@@ -168,7 +168,7 @@ static void usage(FILE *file, const char *prgname, const char *iface)
     "--key pwdfile=<path>[,mode=aes-cbc][,remove=[true|false]]\n"
     "                 : provide a passphrase in a file; the AES key will be\n"
     "                   derived from this passphrase\n"
-    "--pid file=<path>\n"
+    "--pid file=<path>|fd=<filedescriptor>\n"
     "                 : write the process ID into the given file\n"
     "--tpmstate dir=<dir>\n"
     "                 : set the directory where the TPM's state will be written\n"