diff options
| -rw-r--r-- | conf.c | 81 | ||||
| -rw-r--r-- | util.c | 50 | ||||
| -rw-r--r-- | util.h | 1 |
3 files changed, 73 insertions, 59 deletions
@@ -1022,6 +1022,70 @@ static int conf_runas(const char *opt, unsigned int *uid, unsigned int *gid) } /** + * conf_ugid() - Determine UID and GID to run as + * @runas: --runas option, may be NULL + * @uid: User ID, set on success + * @gid: Group ID, set on success + * + * Return: 0 on success, negative error code on failure + */ +static int conf_ugid(const char *runas, uid_t *uid, gid_t *gid) +{ + const char root_uid_map[] = " 0 0 4294967295"; + struct passwd *pw; + char buf[BUFSIZ]; + int ret; + int fd; + + /* If user has specified --runas, that takes precedence... */ + if (runas) { + ret = conf_runas(runas, uid, gid); + if (ret) + err("Invalid --runas option: %s", runas); + return ret; + } + + /* ...otherwise default to current user and group... */ + *uid = geteuid(); + *gid = getegid(); + + /* ...as long as it's not root... */ + if (*uid) + return 0; + + /* ...or at least not root in the init namespace... */ + if ((fd = open("/proc/self/uid_map", O_RDONLY | O_CLOEXEC)) < 0) + return 0; + + if (read(fd, buf, BUFSIZ) != sizeof(root_uid_map) || + strncmp(buf, root_uid_map, sizeof(root_uid_map) - 1)) { + close(fd); + return 0; + } + + close(fd); + + /* ...otherwise use nobody:nobody */ + warn("Don't run as root. Changing to nobody..."); +#ifndef GLIBC_NO_STATIC_NSS + pw = getpwnam("nobody"); + if (!pw) { + perror("getpwnam"); + exit(EXIT_FAILURE); + } + + *uid = pw->pw_uid; + *gid = pw->pw_gid; +#else + (void)pw; + + /* Common value for 'nobody', not really specified */ + *uid = *gid = 65534; +#endif + return 0; +} + +/** * conf() - Process command-line arguments and set configuration * @c: Execution context * @argc: Argument count @@ -1085,9 +1149,10 @@ void conf(struct ctx *c, int argc, char **argv) struct fqdn *dnss = c->dns_search; uint32_t *dns4 = c->ip4.dns; int name, ret, mask, b, i; + const char *runas = NULL; unsigned int ifi = 0; - uid_t uid = 0; - gid_t gid = 0; + uid_t uid; + gid_t gid; if (c->mode == MODE_PASTA) c->no_dhcp_dns = c->no_dhcp_dns_search = 1; @@ -1210,15 +1275,12 @@ void conf(struct ctx *c, int argc, char **argv) c->trace = c->debug = c->foreground = 1; break; case 12: - if (uid || gid) { + if (runas) { err("Multiple --runas options given"); usage(argv[0]); } - if (conf_runas(optarg, &uid, &gid)) { - err("Invalid --runas option: %s", optarg); - usage(argv[0]); - } + runas = optarg; break; case 'd': if (c->debug) { @@ -1499,7 +1561,10 @@ void conf(struct ctx *c, int argc, char **argv) } } while (name != -1); - check_root(&uid, &gid); + ret = conf_ugid(runas, &uid, &gid); + if (ret) + usage(argv[0]); + drop_root(uid, gid); if (c->mode == MODE_PASTA) { @@ -483,56 +483,6 @@ void drop_caps(void) } /** - * check_root() - Check if root in init ns, exit if we can't drop to user - */ -void check_root(uid_t *uid, gid_t *gid) -{ - const char root_uid_map[] = " 0 0 4294967295"; - struct passwd *pw; - char buf[BUFSIZ]; - int fd; - - if (!*uid) - *uid = geteuid(); - - if (!*gid) - *gid = getegid(); - - if (*uid) - return; - - if ((fd = open("/proc/self/uid_map", O_RDONLY | O_CLOEXEC)) < 0) - return; - - if (read(fd, buf, BUFSIZ) != sizeof(root_uid_map) || - strncmp(buf, root_uid_map, sizeof(root_uid_map) - 1)) { - close(fd); - return; - } - - close(fd); - - if (!*uid) { - fprintf(stderr, "Don't run as root. Changing to nobody...\n"); -#ifndef GLIBC_NO_STATIC_NSS - pw = getpwnam("nobody"); - if (!pw) { - perror("getpwnam"); - exit(EXIT_FAILURE); - } - - *uid = pw->pw_uid; - *gid = pw->pw_gid; -#else - (void)pw; - - /* Common value for 'nobody', not really specified */ - *uid = *gid = 65534; -#endif - } -} - -/** * drop_root() - Switch to given UID and GID * @uid: User ID to switch to * @gid: Group ID to switch to @@ -234,7 +234,6 @@ char *line_read(char *buf, size_t len, int fd); void procfs_scan_listen(struct ctx *c, uint8_t proto, int ip_version, int ns, uint8_t *map, uint8_t *exclude); void drop_caps(void); -void check_root(uid_t *uid, gid_t *gid); void drop_root(uid_t uid, gid_t gid); int ns_enter(const struct ctx *c); void write_pidfile(int fd, pid_t pid); |