diff options
| -rw-r--r-- | isolation.c | 67 | ||||
| -rw-r--r-- | isolation.h | 3 | ||||
| -rw-r--r-- | passt.c | 3 | ||||
| -rw-r--r-- | util.c | 49 | ||||
| -rw-r--r-- | util.h | 1 |
5 files changed, 63 insertions, 60 deletions
diff --git a/isolation.c b/isolation.c index c868e66..ea85fdb 100644 --- a/isolation.c +++ b/isolation.c @@ -24,13 +24,18 @@ * done anything we need to do with those resources, so we have * multiple stages of self-isolation. In order these are: * - * 1. isolate_initial() + * 1a. isolate_initial() * ==================== * * Executed immediately after startup, drops capabilities we don't * need at any point during execution (or which we gain back when we - * need by joining other namespaces), and closes any leaked file we - * might have inherited from the parent process. + * need by joining other namespaces). + * + * 1b. isolate_fds() + * ================ + * + * Executed immediately after isolate_initial(). Closes any leaked + * files we might have inherited from the parent process. * * 2. isolate_user() * ================= @@ -58,6 +63,7 @@ #include <errno.h> #include <fcntl.h> +#include <getopt.h> #include <grp.h> #include <inttypes.h> #include <limits.h> @@ -88,6 +94,7 @@ #include "passt.h" #include "log.h" #include "isolation.h" +#include "conf.h" #define CAP_VERSION _LINUX_CAPABILITY_VERSION_3 #define CAP_WORDS _LINUX_CAPABILITY_U32S_3 @@ -193,16 +200,13 @@ static int move_root(void) /** * isolate_initial() - Early, mostly config independent self isolation - * @argc: Argument count - * @argv: Command line options: only --fd (if present) is relevant here * * Should: * - drop unneeded capabilities - * - close all open files except for standard streams and the one from --fd * Mustn't: * - remove filesystem access (we need to access files during setup) */ -void isolate_initial(int argc, char **argv) +void isolate_initial(void) { uint64_t keep; @@ -243,8 +247,55 @@ void isolate_initial(int argc, char **argv) keep |= BIT(CAP_SETFCAP) | BIT(CAP_SYS_PTRACE); drop_caps_ep_except(keep); +} + + +/* + * isolate_fds() - Close leaked files, but not --fd, stdin, stdout, stderr + * @argc: Argument count + * @argv: Command line options, as we need to skip any file given via --fd + * + * Should: + * - close all open files except for standard streams and the one from --fd + */ +void isolate_fds(int argc, char **argv) +{ + const struct option optfd[] = { { "fd", required_argument, NULL, 'F' }, + { 0 }, }; + long fd = -1; + int name, rc; + + do { + name = getopt_long(argc, argv, "-:F:", optfd, NULL); + + if (name == 'F') + fd = conf_tap_fd(optarg); + } while (name != -1); + + if (fd == -1) { + rc = close_range(STDERR_FILENO + 1, ~0U, CLOSE_RANGE_UNSHARE); + } else if (fd == STDERR_FILENO + 1) { /* Still a single range */ + rc = close_range(STDERR_FILENO + 2, ~0U, CLOSE_RANGE_UNSHARE); + } else { + rc = close_range(STDERR_FILENO + 1, fd - 1, + CLOSE_RANGE_UNSHARE); + if (!rc) + rc = close_range(fd + 1, ~0U, CLOSE_RANGE_UNSHARE); + } - close_open_files(argc, argv); + if (rc) { + if (errno == ENOSYS || errno == EINVAL) { + /* This probably means close_range() or the + * CLOSE_RANGE_UNSHARE flag is not supported by the + * kernel. Not much we can do here except carry on and + * hope for the best. + */ + warn( +"Can't use close_range() to ensure no files leaked by parent"); + } else { + die_perror("Failed to close files leaked by parent"); + } + } } /** diff --git a/isolation.h b/isolation.h index 66b6968..e1b1bc5 100644 --- a/isolation.h +++ b/isolation.h @@ -10,7 +10,8 @@ #include <stdbool.h> #include <unistd.h> -void isolate_initial(int argc, char **argv); +void isolate_initial(void); +void isolate_fds(int argc, char **argv); void isolate_user(const struct ctx *c, uid_t uid, gid_t gid, bool use_userns, const char *userns); int isolate_prefork(const struct ctx *c); @@ -344,7 +344,8 @@ int main(int argc, char **argv) arch_avx2_exec(argv); - isolate_initial(argc, argv); + isolate_initial(); + isolate_fds(argc, argv); sigemptyset(&sa.sa_mask); sa.sa_flags = 0; @@ -26,7 +26,6 @@ #include <stdbool.h> #include <linux/errqueue.h> #include <linux/in6.h> -#include <getopt.h> #include "linux_dep.h" #include "util.h" @@ -38,7 +37,6 @@ #include "epoll_ctl.h" #include "pasta.h" #include "serialise.h" -#include "conf.h" #ifdef HAS_GETRANDOM #include <sys/random.h> #endif @@ -925,53 +923,6 @@ const char *str_ee_origin(const struct sock_extended_err *ee) } /** - * close_open_files() - Close leaked files, but not --fd, stdin, stdout, stderr - * @argc: Argument count - * @argv: Command line options, as we need to skip any file given via --fd - */ -void close_open_files(int argc, char **argv) -{ - const struct option optfd[] = { { "fd", required_argument, NULL, 'F' }, - { 0 }, - }; - long fd = -1; - int name, rc; - - do { - name = getopt_long(argc, argv, "-:F:", optfd, NULL); - - if (name == 'F') - fd = conf_tap_fd(optarg); - } while (name != -1); - - if (fd == -1) { - rc = close_range(STDERR_FILENO + 1, ~0U, CLOSE_RANGE_UNSHARE); - } else if (fd == STDERR_FILENO + 1) { /* Still a single range */ - rc = close_range(STDERR_FILENO + 2, ~0U, CLOSE_RANGE_UNSHARE); - } else { - rc = close_range(STDERR_FILENO + 1, fd - 1, - CLOSE_RANGE_UNSHARE); - if (!rc) - rc = close_range(fd + 1, ~0U, CLOSE_RANGE_UNSHARE); - } - - if (rc) { - if (errno == ENOSYS || errno == EINVAL) { - /* This probably means close_range() or the - * CLOSE_RANGE_UNSHARE flag is not supported by the - * kernel. Not much we can do here except carry on and - * hope for the best. - */ - warn( -"Can't use close_range() to ensure no files leaked by parent"); - } else { - die_perror("Failed to close files leaked by parent"); - } - } - -} - -/** * snprintf_check() - snprintf() wrapper, checking for truncation and errors * @str: Output buffer * @size: Maximum size to write to @str @@ -168,7 +168,6 @@ intmax_t read_file_integer(const char *path, intmax_t fallback); int write_remainder(int fd, const struct iovec *iov, size_t iovcnt, size_t skip, size_t length); int read_remainder(int fd, const struct iovec *iov, size_t cnt, size_t skip); -void close_open_files(int argc, char **argv); bool snprintf_check(char *str, size_t size, const char *format, ...); long clamped_scale(long x, long y, long lo, long hi, long f); |