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authorSumit Bose <sbose@redhat.com>2010-02-09 12:39:49 +0100
committerStephen Gallagher <sgallagh@redhat.com>2010-03-11 09:05:50 -0500
commit5a88e963744e5da453e88b5c36499f04712df097 (patch)
tree1afc7d9fab016d91c050558d92f5e5deb6f0eab3 /src/sss_client/common.c
parentce8e76190d96612961ef7e83fda74f1146a5fb12 (diff)
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Add better checks on PAM socket
- check if the public socket belongs to root and has 0666 permissions - use a SCM_CREDENTIALS message if available
Diffstat (limited to 'src/sss_client/common.c')
-rw-r--r--src/sss_client/common.c122
1 files changed, 118 insertions, 4 deletions
diff --git a/src/sss_client/common.c b/src/sss_client/common.c
index 6732c24f..f1c8d185 100644
--- a/src/sss_client/common.c
+++ b/src/sss_client/common.c
@@ -23,6 +23,9 @@
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
+/* for struct ucred */
+#define _GNU_SOURCE
+
#include <nss.h>
#include <security/pam_modules.h>
#include <errno.h>
@@ -36,6 +39,8 @@
#include <string.h>
#include <fcntl.h>
#include <poll.h>
+
+#include "config.h"
#include "sss_cli.h"
/* common functions */
@@ -50,6 +55,104 @@ static void sss_cli_close_socket(void)
}
}
+static int exchange_credentials(void)
+{
+#ifdef HAVE_UCRED
+ int ret;
+ struct msghdr msg;
+ struct cmsghdr *cmsg;
+ struct iovec iov;
+ char dummy='a';
+ char buf[CMSG_SPACE(sizeof(struct ucred))];
+ struct ucred *creds;
+ int enable = 1;
+ struct pollfd pfd;
+
+ ret = setsockopt(sss_cli_sd, SOL_SOCKET, SO_PASSCRED, &enable, sizeof(int));
+ if (ret == -1) {
+ return errno;
+ }
+
+ iov.iov_base = &dummy;
+ iov.iov_len = 1;
+
+ memset(&msg, 0, sizeof(msg));
+
+ msg.msg_name = NULL;
+ msg.msg_namelen = 0;
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+
+ msg.msg_control = buf;
+ msg.msg_controllen = sizeof(buf);
+
+ cmsg = CMSG_FIRSTHDR(&msg);
+ cmsg->cmsg_level = SOL_SOCKET;
+ cmsg->cmsg_type = SCM_CREDENTIALS;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
+
+ creds = (struct ucred *) CMSG_DATA(cmsg);
+
+ creds->uid = geteuid();
+ creds->gid = getegid();
+ creds->pid = getpid();
+
+ msg.msg_controllen = cmsg->cmsg_len;
+
+ pfd.fd = sss_cli_sd;
+ pfd.events = POLLOUT;
+ ret = poll(&pfd, 1, SSS_CLI_SOCKET_TIMEOUT);
+ if (ret != 1 || !(pfd.revents & POLLOUT) ) {
+ return errno;
+ }
+
+ ret = sendmsg(sss_cli_sd, &msg, 0);
+ if (ret == -1) {
+ return errno;
+ }
+
+ memset(&msg, 0, sizeof(msg));
+
+ msg.msg_name = NULL;
+ msg.msg_namelen = 0;
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+
+ msg.msg_control = buf;
+ msg.msg_controllen = sizeof(buf);
+
+ pfd.fd = sss_cli_sd;
+ pfd.events = POLLIN;
+ ret = poll(&pfd, 1, SSS_CLI_SOCKET_TIMEOUT);
+
+ if (ret != 1 || !(pfd.revents & POLLIN) ) {
+ return errno;
+ }
+
+ ret = recvmsg(sss_cli_sd, &msg, 0);
+ if (ret == -1) {
+ return errno;
+ }
+
+ cmsg = CMSG_FIRSTHDR(&msg);
+
+ if (msg.msg_controllen != 0 && cmsg->cmsg_level == SOL_SOCKET &&
+ cmsg->cmsg_type == SCM_CREDENTIALS) {
+ creds = (struct ucred *) CMSG_DATA(cmsg);
+ if (creds->uid != 0 || creds->gid!= 0) {
+ return SSS_STATUS_UNAVAIL;
+ }
+ }
+
+ return SSS_STATUS_SUCCESS;
+
+#else
+
+ return SSS_STATUS_SUCCESS;
+
+#endif
+}
+
/* Requests:
*
* byte 0-3: 32bit unsigned with length (the complete packet length: 0 to X)
@@ -599,9 +702,10 @@ static enum sss_status sss_cli_check_socket(int *errnop, const char *socket_name
sss_cli_sd = mysd;
- if (sss_nss_check_version(socket_name) == NSS_STATUS_SUCCESS) {
- return SSS_STATUS_SUCCESS;
- }
+ if (exchange_credentials() == SSS_STATUS_SUCCESS)
+ if (sss_nss_check_version(socket_name) == NSS_STATUS_SUCCESS) {
+ return SSS_STATUS_SUCCESS;
+ }
sss_cli_close_socket();
*errnop = EFAULT;
@@ -653,12 +757,22 @@ int sss_pam_make_request(enum sss_cli_command cmd,
if (ret != 0) return PAM_SERVICE_ERR;
if ( ! (stat_buf.st_uid == 0 &&
stat_buf.st_gid == 0 &&
- (stat_buf.st_mode&(S_IFSOCK|S_IRUSR|S_IWUSR)) == stat_buf.st_mode)) {
+ S_ISSOCK(stat_buf.st_mode) &&
+ (stat_buf.st_mode & ~S_IFMT) == 0600 )) {
return PAM_SERVICE_ERR;
}
ret = sss_cli_check_socket(errnop, SSS_PAM_PRIV_SOCKET_NAME);
} else {
+ ret = stat(SSS_PAM_SOCKET_NAME, &stat_buf);
+ if (ret != 0) return PAM_SERVICE_ERR;
+ if ( ! (stat_buf.st_uid == 0 &&
+ stat_buf.st_gid == 0 &&
+ S_ISSOCK(stat_buf.st_mode) &&
+ (stat_buf.st_mode & ~S_IFMT) == 0666 )) {
+ return PAM_SERVICE_ERR;
+ }
+
ret = sss_cli_check_socket(errnop, SSS_PAM_SOCKET_NAME);
}
if (ret != NSS_STATUS_SUCCESS) {