From 687d0825a4636b1841dc0c01fbcbf3160dddab74 Mon Sep 17 00:00:00 2001 From: Michal Vyskocil Date: Wed, 29 Jun 2011 14:22:46 +0200 Subject: [PATCH] nspawn: spawn shell under specified --user Add -u/--user option, which changes the effective and real user and group id to the new value. The user must exists in the chroot, otherwise it will fail. Both username and user id are accepted. The user home is created as well. It also setup HOME, USER, LOGNAME and SHELL variables . --- man/systemd-nspawn.xml | 13 ++++++++ src/nspawn.c | 70 ++++++++++++++++++++++++++++++++++++++---- 2 files changed, 77 insertions(+), 6 deletions(-) diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml index e1b33f72c..03c39fc3d 100644 --- a/man/systemd-nspawn.xml +++ b/man/systemd-nspawn.xml @@ -139,6 +139,19 @@ used. + + + + + Run the command + under specified user, create home + directory and cd into it. As rest + of systemd-nspawn, this is not + the security feature and limits + against accidental changes only. + + + diff --git a/src/nspawn.c b/src/nspawn.c index 1ade6e25e..bead9eea2 100644 --- a/src/nspawn.c +++ b/src/nspawn.c @@ -36,6 +36,7 @@ #include #include #include +#include #include "log.h" #include "util.h" @@ -45,13 +46,15 @@ #include "strv.h" static char *arg_directory = NULL; +static char *arg_user = NULL; static int help(void) { printf("%s [OPTIONS...] [PATH] [ARGUMENTS...]\n\n" "Spawn a minimal namespace container for debugging, testing and building.\n\n" " -h --help Show this help\n" - " -D --directory=NAME Root directory for the container\n", + " -D --directory=NAME Root directory for the container\n" + " -u --user=USER Run the command under specified user or uid\n", program_invocation_short_name); return 0; @@ -62,6 +65,7 @@ static int parse_argv(int argc, char *argv[]) { static const struct option options[] = { { "help", no_argument, NULL, 'h' }, { "directory", required_argument, NULL, 'D' }, + { "user", optional_argument, NULL, 'u' }, { NULL, 0, NULL, 0 } }; @@ -70,7 +74,7 @@ static int parse_argv(int argc, char *argv[]) { assert(argc >= 0); assert(argv); - while ((c = getopt_long(argc, argv, "+hD:", options, NULL)) >= 0) { + while ((c = getopt_long(argc, argv, "+hD:u:", options, NULL)) >= 0) { switch (c) { @@ -87,6 +91,15 @@ static int parse_argv(int argc, char *argv[]) { break; + case 'u': + free(arg_user); + if (!(arg_user = strdup(optarg))) { + log_error("Failed to duplicate user name."); + return -ENOMEM; + } + + break; + case '?': return -EINVAL; @@ -693,14 +706,19 @@ int main(int argc, char *argv[]) { /* child */ const char *hn; + const char *home = NULL; + uid_t uid = (uid_t) -1; + gid_t gid = (gid_t) -1; const char *envp[] = { - "HOME=/root", "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin", - NULL, + NULL, /* TERM */ + NULL, /* HOME */ + NULL, /* USER */ + NULL, /* LOGNAME */ NULL }; - envp[2] = strv_find_prefix(environ, "TERM="); + envp[1] = strv_find_prefix(environ, "TERM="); close_nointr_nofail(master); @@ -757,13 +775,53 @@ int main(int argc, char *argv[]) { if (drop_capabilities() < 0) goto child_fail; + if (arg_user) { + + if (get_user_creds((const char**)&arg_user, &uid, &gid, &home) < 0) { + log_error("get_user_creds() failed: %m"); + goto child_fail; + } + + if (mkdir_parents(home, 0775) < 0) { + log_error("mkdir_parents() failed: %m"); + goto child_fail; + } + + if (safe_mkdir(home, 0775, uid, gid) < 0) { + log_error("safe_mkdir() failed: %m"); + goto child_fail; + } + + if (initgroups((const char*)arg_user, gid) < 0) { + log_error("initgroups() failed: %m"); + goto child_fail; + } + + if (setregid(gid, gid) < 0) { + log_error("setregid() failed: %m"); + goto child_fail; + } + + if (setreuid(uid, uid) < 0) { + log_error("setreuid() failed: %m"); + goto child_fail; + } + } + + if ((asprintf((char**)(envp + 2), "HOME=%s", home? home: "/root") < 0) || + (asprintf((char**)(envp + 3), "USER=%s", arg_user? arg_user : "root") < 0) || + (asprintf((char**)(envp + 4), "LOGNAME=%s", arg_user? arg_user : "root") < 0)) { + log_error("environment setup failed: %m"); + goto child_fail; + } + if ((hn = file_name_from_path(arg_directory))) sethostname(hn, strlen(hn)); if (argc > optind) execvpe(argv[optind], argv + optind, (char**) envp); else { - chdir("/root"); + chdir(home? home : "/root"); execle("/bin/bash", "-bash", NULL, (char**) envp); } -- 2.30.2