Many distros do not call into pam_keyinit to set up the session keyring properly at login time. When cifscreds add is used in such a session, the kernel will spawn a new session keyring in which to install the credentials. That keyring will then go away once the cifscreds process exits. Check for this situation by looking to see if the session and user-session keyrings are the same. Throw a warning if so, and add some verbiage to the cifscreds manpage that explains the issue. Also, if the session keyring can't be queried for any reason, then cause the program to error out. Cc: David Howells <dhowells@xxxxxxxxxx> Reported-by: Milan Knížek <knizek.confy@xxxxxxxxx> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxx> --- cifscreds.1 | 9 ++++++++- cifscreds.c | 34 ++++++++++++++++++++++++++++++++++ cifscreds.pod | 8 ++++++++ 3 files changed, 50 insertions(+), 1 deletion(-) diff --git a/cifscreds.1 b/cifscreds.1 index 44a02a2..83afae6 100644 --- a/cifscreds.1 +++ b/cifscreds.1 @@ -124,7 +124,7 @@ .\" ======================================================================== .\" .IX Title "CIFSCREDS 1" -.TH CIFSCREDS 1 "2012-01-24" "" "" +.TH CIFSCREDS 1 "2012-07-17" "" "" .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l @@ -186,6 +186,13 @@ different username. The cifscreds utility requires a kernel built with support for the \&\fBlogin\fR key type. That key type was added in v3.3 in mainline Linux kernels. +.PP +Since \fBcifscreds\fR adds keys to the session keyring, it is highly +recommended that one use \fBpam_keyinit\fR to ensure that a session keyring +is established at login time. +.SH "SEE ALSO" +.IX Header "SEE ALSO" +\&\fIpam_keyinit\fR\|(8) .SH "AUTHORS" .IX Header "AUTHORS" The cifscreds program was originally developed by Igor Druzhinin diff --git a/cifscreds.c b/cifscreds.c index efc76e6..bb35c02 100644 --- a/cifscreds.c +++ b/cifscreds.c @@ -28,6 +28,7 @@ #include <ctype.h> #include <keyutils.h> #include <getopt.h> +#include <errno.h> #include "mount.h" #include "resolve_host.h" #include "util.h" @@ -465,6 +466,36 @@ static int cifscreds_update(struct cmdarg *arg) return EXIT_SUCCESS; } +static int +check_session_keyring(void) +{ + key_serial_t ses_key, uses_key; + + ses_key = keyctl_get_keyring_ID(KEY_SPEC_SESSION_KEYRING, 0); + if (ses_key == -1) { + if (errno == ENOKEY) + fprintf(stderr, "Error: you have no session keyring. " + "Consider using pam_keyinit to " + "install one.\n"); + else + fprintf(stderr, "Error: unable to query session " + "keyring: %s\n", strerror(errno)); + return (int)ses_key; + } + + /* A problem querying the user-session keyring isn't fatal. */ + uses_key = keyctl_get_keyring_ID(KEY_SPEC_USER_SESSION_KEYRING, 0); + if (uses_key == -1) + return 0; + + if (ses_key == uses_key) + fprintf(stderr, "Warning: you have no persistent session " + "keyring. cifscreds keys will not persist " + "after this process exits. See " + "pam_keyinit(8).\n"); + return 0; +} + int main(int argc, char **argv) { struct command *cmd, *best; @@ -535,5 +566,8 @@ int main(int argc, char **argv) if (arg.user == NULL) arg.user = getusername(getuid()); + if (check_session_keyring()) + return EXIT_FAILURE; + return best->action(&arg); } diff --git a/cifscreds.pod b/cifscreds.pod index 17e453f..c3bafb5 100644 --- a/cifscreds.pod +++ b/cifscreds.pod @@ -79,6 +79,14 @@ The cifscreds utility requires a kernel built with support for the B<login> key type. That key type was added in v3.3 in mainline Linux kernels. +Since B<cifscreds> adds keys to the session keyring, it is highly +recommended that one use B<pam_keyinit> to ensure that a session keyring +is established at login time. + +=head1 SEE ALSO + +pam_keyinit(8) + =head1 AUTHORS The cifscreds program was originally developed by Igor Druzhinin -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html