X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fpam-module.c;h=54a7b451e8b540de180395aee9305e3f9e09035f;hp=08de006f687852580d68aab55d5e54f4541d1525;hb=74fe1fe36e35a26d764f1e3119d5f6d014db573c;hpb=a838e6a17a40df902b50a9ce5b2e944dfc5a7e08

diff --git a/src/pam-module.c b/src/pam-module.c
index 08de006f6..54a7b451e 100644
--- a/src/pam-module.c
+++ b/src/pam-module.c
@@ -1,4 +1,4 @@
-/*-*- Mode: C; c-basic-offset: 8 -*-*/
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
 
 /***
   This file is part of systemd.
@@ -31,20 +31,21 @@
 #include <security/pam_ext.h>
 #include <security/pam_misc.h>
 
-#include <libcgroup.h>
-
 #include "util.h"
 #include "cgroup-util.h"
 #include "macro.h"
 #include "sd-daemon.h"
+#include "strv.h"
 
 static int parse_argv(pam_handle_t *handle,
                       int argc, const char **argv,
                       bool *create_session,
                       bool *kill_session,
-                      bool *kill_user) {
+                      bool *kill_user,
+                      char ***controllers) {
 
         unsigned i;
+        bool controller_set = false;
 
         assert(argc >= 0);
         assert(argc == 0 || argv);
@@ -60,6 +61,7 @@ static int parse_argv(pam_handle_t *handle,
 
                         if (create_session)
                                 *create_session = k;
+
                 } else if (startswith(argv[i], "kill-session=")) {
                         if ((k = parse_boolean(argv[i] + 13)) < 0) {
                                 pam_syslog(handle, LOG_ERR, "Failed to parse kill-session= argument.");
@@ -77,12 +79,43 @@ static int parse_argv(pam_handle_t *handle,
 
                         if (kill_user)
                                 *kill_user = k;
+
+                } else if (startswith(argv[i], "controllers=")) {
+
+                        if (controllers) {
+                                char **l;
+
+                                if (!(l = strv_split(argv[i] + 12, ","))) {
+                                        pam_syslog(handle, LOG_ERR, "Out of memory.");
+                                        return -ENOMEM;
+                                }
+
+                                strv_free(*controllers);
+                                *controllers = l;
+                        }
+
+                        controller_set = true;
+
                 } else {
                         pam_syslog(handle, LOG_ERR, "Unknown parameter '%s'.", argv[i]);
                         return -EINVAL;
                 }
         }
 
+        if (!controller_set && controllers) {
+                char **l;
+
+                if (!(l = strv_new("cpu", NULL))) {
+                        pam_syslog(handle, LOG_ERR, "Out of memory");
+                        return -ENOMEM;
+                }
+
+                *controllers = l;
+        }
+
+        if (controllers)
+                strv_remove(*controllers, "name=systemd");
+
         if (kill_session && *kill_session && kill_user)
                 *kill_user = true;
 
@@ -97,16 +130,30 @@ static int open_file_and_lock(const char *fn) {
         if ((fd = open(fn, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW|O_CREAT, 0600)) < 0)
                 return -errno;
 
+        /* The BSD socket semantics are a lot nicer than those of
+         * POSIX locks. Which is why we use flock() here. BSD locking
+         * does not work across NFS which however is not needed here
+         * as the filesystems in question should be local, and only
+         * locally accessible, and most likely even tmpfs. */
+
         if (flock(fd, LOCK_EX) < 0)
                 return -errno;
 
         return fd;
 }
 
-static uint64_t get_session_id(void) {
+enum {
+        SESSION_ID_AUDIT = 'a',
+        SESSION_ID_COUNTER = 'c',
+        SESSION_ID_RANDOM = 'r'
+};
+
+static uint64_t get_session_id(int *mode) {
         char *s;
         int fd;
 
+        assert(mode);
+
         /* First attempt: let's use the session ID of the audit
          * system, if it is available. */
         if (read_one_line_file("/proc/self/sessionid", &s) >= 0) {
@@ -116,8 +163,10 @@ static uint64_t get_session_id(void) {
                 r = safe_atou32(s, &u);
                 free(s);
 
-                if (r >= 0 && u != (uint32_t) -1)
+                if (r >= 0 && u != (uint32_t) -1 && u > 0) {
+                        *mode = SESSION_ID_AUDIT;
                         return (uint64_t) u;
+                }
         }
 
         /* Second attempt, use our own counter. */
@@ -149,10 +198,14 @@ static uint64_t get_session_id(void) {
 
                 close_nointr_nofail(fd);
 
-                if (r >= 0)
+                if (r >= 0) {
+                        *mode = SESSION_ID_COUNTER;
                         return counter;
+                }
         }
 
+        *mode = SESSION_ID_RANDOM;
+
         /* Last attempt, pick a random value */
         return (uint64_t) random_ull();
 }
@@ -161,53 +214,89 @@ static int get_user_data(
                 const char **ret_username,
                 struct passwd **ret_pw) {
 
-        const char *username;
-        struct passwd *pw;
+        const char *username = NULL;
+        struct passwd *pw = NULL;
         int r;
+        bool have_loginuid = false;
+        char *s;
 
         assert(handle);
         assert(ret_username);
         assert(ret_pw);
 
-        if ((r = pam_get_user(handle, &username, NULL)) != PAM_SUCCESS) {
-                pam_syslog(handle, LOG_ERR, "Failed to get user name.");
-                return r;
+        if (read_one_line_file("/proc/self/loginuid", &s) >= 0) {
+                uint32_t u;
+
+                r = safe_atou32(s, &u);
+                free(s);
+
+                if (r >= 0 && u != (uint32_t) -1 && u > 0) {
+                        have_loginuid = true;
+                        pw = pam_modutil_getpwuid(handle, u);
+                }
         }
 
-        if (!username || !*username) {
-                pam_syslog(handle, LOG_ERR, "User name not valid.");
-                return PAM_AUTH_ERR;
+        if (!have_loginuid) {
+                if ((r = pam_get_user(handle, &username, NULL)) != PAM_SUCCESS) {
+                        pam_syslog(handle, LOG_ERR, "Failed to get user name.");
+                        return r;
+                }
+
+                if (!username || !*username) {
+                        pam_syslog(handle, LOG_ERR, "User name not valid.");
+                        return PAM_AUTH_ERR;
+                }
+
+                pw = pam_modutil_getpwnam(handle, username);
         }
 
-        if (!(pw = pam_modutil_getpwnam(handle, username))) {
+        if (!pw) {
                 pam_syslog(handle, LOG_ERR, "Failed to get user data.");
                 return PAM_USER_UNKNOWN;
         }
 
         *ret_pw = pw;
-        *ret_username = username;
+        *ret_username = username ? username : pw->pw_name;
 
         return PAM_SUCCESS;
 }
 
-static int create_user_group(pam_handle_t *handle, const char *group, struct passwd *pw, bool attach) {
+static int create_user_group(
+                pam_handle_t *handle,
+                const char *controller,
+                const char *group,
+                struct passwd *pw,
+                bool attach,
+                bool remember) {
+
         int r;
 
         assert(handle);
         assert(group);
 
         if (attach)
-                r = cg_create_and_attach("name=systemd", group, 0);
+                r = cg_create_and_attach(controller, group, 0);
         else
-                r = cg_create("name=systemd", group);
+                r = cg_create(controller, group);
 
         if (r < 0) {
                 pam_syslog(handle, LOG_ERR, "Failed to create cgroup: %s", strerror(-r));
                 return PAM_SESSION_ERR;
         }
 
-        if ((r = cg_set_task_access("name=systemd", group, 0755, pw->pw_uid, pw->pw_gid)) < 0 ||
-            (r = cg_set_group_access("name=systemd", group, 0755, pw->pw_uid, pw->pw_gid)) < 0) {
+        if (r > 0 && remember) {
+                /* Remember that it was us who created this group, and
+                 * that hence we need to remove it too. This is a
+                 * protection against removing the cgroup when run
+                 * recursively. */
+                if ((r = pam_set_data(handle, "systemd.created", INT_TO_PTR(1), NULL)) != PAM_SUCCESS) {
+                        pam_syslog(handle, LOG_ERR, "Failed to install created variable.");
+                        return r;
+                }
+        }
+
+        if ((r = cg_set_task_access(controller, group, 0644, pw->pw_uid, pw->pw_gid)) < 0 ||
+            (r = cg_set_group_access(controller, group, 0755, pw->pw_uid, pw->pw_gid)) < 0) {
                 pam_syslog(handle, LOG_ERR, "Failed to change access modes: %s", strerror(-r));
                 return PAM_SESSION_ERR;
         }
@@ -226,23 +315,18 @@ _public_ PAM_EXTERN int pam_sm_open_session(
         char *buf = NULL;
         int lock_fd = -1;
         bool create_session = true;
+        char **controllers = NULL, **c;
 
         assert(handle);
 
-        pam_syslog(handle, LOG_INFO, "pam-systemd initializing");
-
-        if (parse_argv(handle, argc, argv, &create_session, NULL, NULL) < 0)
-                return PAM_SESSION_ERR;
+        /* pam_syslog(handle, LOG_DEBUG, "pam-systemd initializing"); */
 
         /* Make this a NOP on non-systemd systems */
         if (sd_booted() <= 0)
                 return PAM_SUCCESS;
 
-        if ((r = cgroup_init()) != 0) {
-                pam_syslog(handle, LOG_ERR, "libcgroup initialization failed: %s", cgroup_strerror(r));
-                r = PAM_SESSION_ERR;
-                goto finish;
-        }
+        if (parse_argv(handle, argc, argv, &create_session, NULL, NULL, &controllers) < 0)
+                return PAM_SESSION_ERR;
 
         if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS)
                 goto finish;
@@ -283,12 +367,21 @@ _public_ PAM_EXTERN int pam_sm_open_session(
 
                 /* Reuse or create XDG session ID */
                 if (!(id = pam_getenv(handle, "XDG_SESSION_ID"))) {
+                        int mode;
 
-                        if (asprintf(&buf, "%llu", (unsigned long long) get_session_id()) < 0) {
+                        if (asprintf(&buf, "%llux", (unsigned long long) get_session_id(&mode)) < 0) {
                                 r = PAM_BUF_ERR;
                                 goto finish;
                         }
 
+                        /* To avoid id clashes we add the session id
+                         * source to our session ids. Note that the
+                         * session id source might change during
+                         * runtime, because a filesystem became
+                         * writable or the system reconfigured. */
+                        buf[strlen(buf)-1] =
+                                mode != SESSION_ID_AUDIT ? (char) mode : 0;
+
                         if ((r = pam_misc_setenv(handle, "XDG_SESSION_ID", buf, 0)) != PAM_SUCCESS) {
                                 pam_syslog(handle, LOG_ERR, "Failed to set session id.");
                                 goto finish;
@@ -303,16 +396,23 @@ _public_ PAM_EXTERN int pam_sm_open_session(
 
                 r = asprintf(&buf, "/user/%s/%s", username, id);
         } else
-                r = asprintf(&buf, "/user/%s/no-session", username);
+                r = asprintf(&buf, "/user/%s/master", username);
 
         if (r < 0) {
                 r = PAM_BUF_ERR;
                 goto finish;
         }
 
-        if ((r = create_user_group(handle, buf, pw, true)) != PAM_SUCCESS)
+        pam_syslog(handle, LOG_INFO, "Moving new user session for %s into control group %s.", username, buf);
+
+        if ((r = create_user_group(handle, SYSTEMD_CGROUP_CONTROLLER, buf, pw, true, true)) != PAM_SUCCESS)
                 goto finish;
 
+        /* The additional controllers don't really matter, so we
+         * ignore the return value */
+        STRV_FOREACH(c, controllers)
+                create_user_group(handle, *c, buf, pw, true, false);
+
         r = PAM_SUCCESS;
 
 finish:
@@ -321,48 +421,35 @@ finish:
         if (lock_fd >= 0)
                 close_nointr_nofail(lock_fd);
 
+        strv_free(controllers);
+
         return r;
 }
 
 static int session_remains(pam_handle_t *handle, const char *user_path) {
-        struct cgroup_file_info info;
-        int level = 0, r;
-        void *iterator = NULL;
+        int r;
         bool remains = false;
+        DIR *d;
+        char *subgroup;
 
-        zero(info);
-
-        r = cgroup_walk_tree_begin("name=systemd", user_path, 0, &iterator, &info, &level);
-        while (r == 0) {
-
-                if (info.type != CGROUP_FILE_TYPE_DIR)
-                        goto next;
-
-                if (streq(info.path, ""))
-                        goto next;
-
-                if (streq(info.path, "no-session"))
-                        goto next;
+        if ((r = cg_enumerate_subgroups(SYSTEMD_CGROUP_CONTROLLER, user_path, &d)) < 0)
+                return r;
 
-                remains = true;
-                break;
+        while ((r = cg_read_subgroup(d, &subgroup)) > 0) {
 
-        next:
+                remains = !streq(subgroup, "master");
+                free(subgroup);
 
-                r = cgroup_walk_tree_next(0, &iterator, &info, level);
+                if (remains)
+                        break;
         }
 
+        closedir(d);
 
-        if (remains)
-                r = 1;
-        else if (r == 0 || r == ECGEOF)
-                r = 0;
-        else
-                r = cg_translate_error(r, errno);
-
-        assert_se(cgroup_walk_tree_end(&iterator) == 0);
+        if (r < 0)
+                return r;
 
-        return r;
+        return !!remains;
 }
 
 _public_ PAM_EXTERN int pam_sm_close_session(
@@ -377,16 +464,18 @@ _public_ PAM_EXTERN int pam_sm_close_session(
         char *session_path = NULL, *nosession_path = NULL, *user_path = NULL;
         const char *id;
         struct passwd *pw;
+        const void *created = NULL;
+        char **controllers = NULL, **c;
 
         assert(handle);
 
-        if (parse_argv(handle, argc, argv, NULL, &kill_session, &kill_user) < 0)
-                return PAM_SESSION_ERR;
-
         /* Make this a NOP on non-systemd systems */
         if (sd_booted() <= 0)
                 return PAM_SUCCESS;
 
+        if (parse_argv(handle, argc, argv, NULL, &kill_session, &kill_user, &controllers) < 0)
+                return PAM_SESSION_ERR;
+
         if ((r = get_user_data(handle, &username, &pw)) != PAM_SUCCESS)
                 goto finish;
 
@@ -396,46 +485,58 @@ _public_ PAM_EXTERN int pam_sm_close_session(
                 goto finish;
         }
 
+        /* We are probably still in some session/user dir. Move ourselves out of the way as first step */
+        if ((r = cg_attach(SYSTEMD_CGROUP_CONTROLLER, "/user", 0)) < 0)
+                pam_syslog(handle, LOG_ERR, "Failed to move us away: %s", strerror(-r));
+
+        STRV_FOREACH(c, controllers)
+                if ((r = cg_attach(*c, "/user", 0)) < 0)
+                        pam_syslog(handle, LOG_ERR, "Failed to move us away in %s hierarchy: %s", *c, strerror(-r));
+
         if (asprintf(&user_path, "/user/%s", username) < 0) {
                 r = PAM_BUF_ERR;
                 goto finish;
         }
 
-        if ((id = pam_getenv(handle, "XDG_SESSION_ID"))) {
+        pam_get_data(handle, "systemd.created", &created);
+
+        if ((id = pam_getenv(handle, "XDG_SESSION_ID")) && created) {
 
                 if (asprintf(&session_path, "/user/%s/%s", username, id) < 0 ||
-                    asprintf(&nosession_path, "/user/%s/no-session", username) < 0) {
+                    asprintf(&nosession_path, "/user/%s/master", username) < 0) {
                         r = PAM_BUF_ERR;
                         goto finish;
                 }
 
                 if (kill_session)  {
-                        /* Kill processes in session cgroup */
-                        if ((r = cg_kill_recursive_and_wait("name=systemd", session_path)) < 0)
+                        pam_syslog(handle, LOG_INFO, "Killing remaining processes of user session %s of %s.", id, username);
+
+                        /* Kill processes in session cgroup, and delete it */
+                        if ((r = cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, session_path, true)) < 0)
                                 pam_syslog(handle, LOG_ERR, "Failed to kill session cgroup: %s", strerror(-r));
+                } else {
+                        pam_syslog(handle, LOG_INFO, "Moving remaining processes of user session %s of %s into control group %s.", id, username, nosession_path);
 
-                } else  {
-                        /* Migrate processes from session to
-                         * no-session cgroup. First, try to create the
-                         * no-session group in case it doesn't exist
-                         * yet. */
-                        create_user_group(handle, nosession_path, pw, 0);
+                        /* Migrate processes from session to user
+                         * cgroup. First, try to create the user group
+                         * in case it doesn't exist yet. Also, delete
+                         * the session group. */
+                        create_user_group(handle, SYSTEMD_CGROUP_CONTROLLER, nosession_path, pw, false, false);
 
-                        if ((r = cg_migrate_recursive("name=systemd", session_path, nosession_path, false)) < 0)
+                        if ((r = cg_migrate_recursive(SYSTEMD_CGROUP_CONTROLLER, session_path, nosession_path, false, true)) < 0)
                                 pam_syslog(handle, LOG_ERR, "Failed to migrate session cgroup: %s", strerror(-r));
                 }
 
-                /* Delete session cgroup */
-                if (r < 0)
-                        pam_syslog(handle, LOG_INFO, "Couldn't empty session cgroup, not deleting.");
-                else {
-                        if ((r = cg_delete("name=systemd", session_path)) < 0)
-                                pam_syslog(handle, LOG_ERR, "Failed to delete session cgroup: %s", strerror(-r));
+                STRV_FOREACH(c, controllers) {
+                        create_user_group(handle, *c, nosession_path, pw, false, false);
+
+                        if ((r = cg_migrate_recursive(*c, session_path, nosession_path, false, true)) < 0)
+                                pam_syslog(handle, LOG_ERR, "Failed to migrate session cgroup in hierarchy %s: %s", *c, strerror(-r));
                 }
         }
 
         /* GC user tree */
-        cg_trim("name=systemd", user_path, false);
+        cg_trim(SYSTEMD_CGROUP_CONTROLLER, user_path, false);
 
         if ((r = session_remains(handle, user_path)) < 0)
                 pam_syslog(handle, LOG_ERR, "Failed to determine whether a session remains: %s", strerror(-r));
@@ -443,33 +544,37 @@ _public_ PAM_EXTERN int pam_sm_close_session(
         /* Kill user processes not attached to any session */
         if (kill_user && r == 0) {
 
-                /* Kill no-session cgroup */
-                if ((r = cg_kill_recursive_and_wait("name=systemd", user_path)) < 0)
+                /* Kill user cgroup */
+                if ((r = cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, user_path, true)) < 0)
                         pam_syslog(handle, LOG_ERR, "Failed to kill user cgroup: %s", strerror(-r));
         } else {
 
-                if ((r = cg_is_empty_recursive("name=systemd", user_path, true)) < 0)
+                if ((r = cg_is_empty_recursive(SYSTEMD_CGROUP_CONTROLLER, user_path, true)) < 0)
                         pam_syslog(handle, LOG_ERR, "Failed to check user cgroup: %s", strerror(-r));
 
-                /* If we managed to kill somebody, don't cleanup the cgroup. */
-                if (r == 0)
+                /* Remove user cgroup */
+                if (r > 0) {
+                        if ((r = cg_delete(SYSTEMD_CGROUP_CONTROLLER, user_path)) < 0)
+                                pam_syslog(handle, LOG_ERR, "Failed to delete user cgroup: %s", strerror(-r));
+
+                /* If we managed to find somebody, don't cleanup the cgroup. */
+                } else if (r == 0)
                         r = -EBUSY;
         }
 
+        STRV_FOREACH(c, controllers)
+                cg_trim(*c, user_path, true);
+
         if (r >= 0) {
                 const char *runtime_dir;
 
-                /* Remove user cgroup */
-                if ((r = cg_delete("name=systemd", user_path)) < 0)
-                        pam_syslog(handle, LOG_ERR, "Failed to delete user cgroup: %s", strerror(-r));
-
-                /* This will migrate us to the /user cgroup. */
-
                 if ((runtime_dir = pam_getenv(handle, "XDG_RUNTIME_DIR")))
                         if ((r = rm_rf(runtime_dir, false, true)) < 0)
                                 pam_syslog(handle, LOG_ERR, "Failed to remove runtime directory: %s", strerror(-r));
         }
 
+        /* pam_syslog(handle, LOG_DEBUG, "pam-systemd done"); */
+
         r = PAM_SUCCESS;
 
 finish:
@@ -480,5 +585,7 @@ finish:
         free(nosession_path);
         free(user_path);
 
+        strv_free(controllers);
+
         return r;
 }