[Libguestfs] [PATCH nbdkit] server: Allow file descriptors to be passed to nbdkit_read_password.
Richard W.M. Jones
rjones at redhat.com
Thu Oct 17 21:38:15 UTC 2019
Allow password parameters such as ‘password=-FD’ where FD is a file
descriptor number inherited by nbdkit from the parent process. This
is another way to allow programs to hand passwords to nbdkit in a very
secure way, for example over a pipe so they never touch the
filesystem.
Previously nbdkit allowed you to use literal passwords on the command
line if they began with a ‘-’ (but were not just that single
character). However that was contrary to the documentation, and this
commit now prevents that.
---
docs/nbdkit-plugin.pod | 4 ++
plugins/curl/nbdkit-curl-plugin.pod | 10 ++++-
plugins/ssh/nbdkit-ssh-plugin.pod | 8 +++-
plugins/vddk/nbdkit-vddk-plugin.pod | 11 +++++-
server/public.c | 58 +++++++++++++++++++++--------
server/test-public.c | 31 +++++++++++++++
6 files changed, 102 insertions(+), 20 deletions(-)
diff --git a/docs/nbdkit-plugin.pod b/docs/nbdkit-plugin.pod
index e34ffd1..0afd5e1 100644
--- a/docs/nbdkit-plugin.pod
+++ b/docs/nbdkit-plugin.pod
@@ -1120,6 +1120,10 @@ or from a file:
nbdkit myplugin password=+/tmp/secret
+or from a file descriptor inherited by nbdkit:
+
+ nbdkit myplugin password=-99
+
(If the password begins with a C<-> or C<+> character then it must be
passed in a file).
diff --git a/plugins/curl/nbdkit-curl-plugin.pod b/plugins/curl/nbdkit-curl-plugin.pod
index 63500a4..827e0bd 100644
--- a/plugins/curl/nbdkit-curl-plugin.pod
+++ b/plugins/curl/nbdkit-curl-plugin.pod
@@ -70,10 +70,16 @@ Ask for the password (interactively) when nbdkit starts up.
=item B<password=+>FILENAME
-Read the password from the named file. This is the most secure method
+Read the password from the named file. This is a secure method
to supply a password, as long as you set the permissions on the file
appropriately.
+=item B<password=->FD
+
+Read the password from file descriptor number C<FD>, inherited from
+the parent process when nbdkit starts up. This is also a secure
+method to supply a password.
+
=item B<protocols=>PROTO,PROTO,...
Limit the protocols that are allowed in the URL. Use this option for
@@ -100,6 +106,8 @@ The default is to allow any protocol.
=item B<proxy-password=+>FILENAME
+=item B<proxy-password=->FD
+
=item B<proxy-user=>USERNAME
Set the proxy username and password.
diff --git a/plugins/ssh/nbdkit-ssh-plugin.pod b/plugins/ssh/nbdkit-ssh-plugin.pod
index 0d0bc2b..687c08c 100644
--- a/plugins/ssh/nbdkit-ssh-plugin.pod
+++ b/plugins/ssh/nbdkit-ssh-plugin.pod
@@ -96,10 +96,16 @@ Ask for the password (interactively) when nbdkit starts up.
=item B<password=+>FILENAME
-Read the password from the named file. This is the most secure method
+Read the password from the named file. This is a secure method
to supply a password, as long as you set the permissions on the file
appropriately.
+=item B<password=->FD
+
+Read the password from file descriptor number C<FD>, inherited from
+the parent process when nbdkit starts up. This is also a secure
+method to supply a password.
+
=item [B<path=>]PATH
Specify the path to the remote file. This can be a relative path in
diff --git a/plugins/vddk/nbdkit-vddk-plugin.pod b/plugins/vddk/nbdkit-vddk-plugin.pod
index bf6f7e7..4ae647c 100644
--- a/plugins/vddk/nbdkit-vddk-plugin.pod
+++ b/plugins/vddk/nbdkit-vddk-plugin.pod
@@ -6,7 +6,8 @@ nbdkit-vddk-plugin - nbdkit VMware VDDK plugin
nbdkit vddk file=FILENAME [config=FILENAME] [libdir=LIBRARY]
[vm=moref=ID] [server=HOSTNAME] [user=USERNAME]
- [password=PASSWORD | password=- | password=+FILENAME]
+ [password=PASSWORD | password=- | password=+FILENAME |
+ password=-FD]
[cookie=COOKIE] [thumbprint=THUMBPRINT]
[port=PORT] [nfchostport=PORT] [single-link=true]
[snapshot=MOREF] [transports=MODE:MODE:...]
@@ -140,10 +141,16 @@ Ask for the password (interactively) when nbdkit starts up.
=item B<password=+>FILENAME
-Read the password from the named file. This is the most secure method
+Read the password from the named file. This is a secure method
to supply a password, as long as you set the permissions on the file
appropriately.
+=item B<password=->FD
+
+Read the password from file descriptor number C<FD>, inherited from
+the parent process when nbdkit starts up. This is also a secure
+method to supply a password.
+
=item B<port=>PORT
The port on the VCenter/ESXi host. Defaults to 443.
diff --git a/server/public.c b/server/public.c
index 9a3aa31..418945f 100644
--- a/server/public.c
+++ b/server/public.c
@@ -405,6 +405,8 @@ nbdkit_parse_bool (const char *str)
}
/* Read a password from configuration value. */
+static int read_password_from_fd (const char *what, int fd, char **password);
+
int
nbdkit_read_password (const char *value, char **password)
{
@@ -412,7 +414,6 @@ nbdkit_read_password (const char *value, char **password)
struct termios orig, temp;
ssize_t r;
size_t n;
- FILE *fp;
*password = NULL;
@@ -448,6 +449,16 @@ nbdkit_read_password (const char *value, char **password)
(*password)[r-1] = '\0';
}
+ /* Read from numbered file descriptor. */
+ else if (value[0] == '-') {
+ int fd;
+
+ if (nbdkit_parse_int ("password file descriptor", &value[1], &fd) == -1)
+ return -1;
+ if (read_password_from_fd (&value[1], fd, password) == -1)
+ return -1;
+ }
+
/* Read password from a file. */
else if (value[0] == '+') {
int fd;
@@ -457,22 +468,8 @@ nbdkit_read_password (const char *value, char **password)
nbdkit_error ("open %s: %m", &value[1]);
return -1;
}
- fp = fdopen (fd, "r");
- if (fp == NULL) {
- nbdkit_error ("fdopen %s: %m", &value[1]);
- close (fd);
+ if (read_password_from_fd (&value[1], fd, password) == -1)
return -1;
- }
- r = getline (password, &n, fp);
- err = errno;
- fclose (fp);
- if (r == -1) {
- errno = err;
- nbdkit_error ("could not read password from file %s: %m", &value[1]);
- return -1;
- }
- if (*password && r > 0 && (*password)[r-1] == '\n')
- (*password)[r-1] = '\0';
}
/* Parameter is the password. */
@@ -487,6 +484,35 @@ nbdkit_read_password (const char *value, char **password)
return 0;
}
+static int
+read_password_from_fd (const char *what, int fd, char **password)
+{
+ FILE *fp;
+ size_t n;
+ ssize_t r;
+ int err;
+
+ fp = fdopen (fd, "r");
+ if (fp == NULL) {
+ nbdkit_error ("fdopen %s: %m", what);
+ close (fd);
+ return -1;
+ }
+ r = getline (password, &n, fp);
+ err = errno;
+ fclose (fp);
+ if (r == -1) {
+ errno = err;
+ nbdkit_error ("could not read password from %s: %m", what);
+ return -1;
+ }
+
+ if (*password && r > 0 && (*password)[r-1] == '\n')
+ (*password)[r-1] = '\0';
+
+ return 0;
+}
+
int
nbdkit_nanosleep (unsigned sec, unsigned nsec)
{
diff --git a/server/test-public.c b/server/test-public.c
index ea10189..4a7eb17 100644
--- a/server/test-public.c
+++ b/server/test-public.c
@@ -335,6 +335,8 @@ test_nbdkit_read_password (void)
{
bool pass = true;
char template[] = "+/tmp/nbdkit_testpw_XXXXXX";
+ char template2[] = "/tmp/nbdkit_testpw2_XXXXXX";
+ char fdbuf[16];
char *pw = template;
int fd;
@@ -391,6 +393,35 @@ test_nbdkit_read_password (void)
unlink (&template[1]);
}
+ /* Test reading password from file descriptor. */
+ fd = mkstemp (template2);
+ if (fd < 0) {
+ perror ("mkstemp");
+ pass = false;
+ }
+ else if (write (fd, "abc\n", 4) != 4) {
+ fprintf (stderr, "Failed to write to file %s\n", template2);
+ pass = false;
+ }
+ else {
+ snprintf (fdbuf, sizeof fdbuf, "-%d", fd);
+ lseek (fd, 0, 0);
+ if (nbdkit_read_password (fdbuf, &pw) == -1) {
+ fprintf (stderr, "Failed to read password from fd %s\n", fdbuf);
+ pass = false;
+ }
+ else if (strcmp (pw, "abc") != 0) {
+ fprintf (stderr, "Wrong file password, expected 'abc' got '%s'\n", pw);
+ pass = false;
+ }
+ free (pw);
+ }
+
+ if (fd >= 0) {
+ /* Don't close fd, it is closed by nbdkit_read_password. */
+ unlink (template2);
+ }
+
if (error_flagged) {
fprintf (stderr, "Wrong error message handling\n");
pass = false;
--
2.23.0
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