From 8199e6f7402ca2232de6f57b918d2b1fb9c224cb Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Fri, 9 May 2025 15:32:39 +0200 Subject: selftests/filesystems: create setup_userns() helper Add helper to utils.c and use it in statmount userns tests. Reviewed-by: John Hubbard Signed-off-by: Amir Goldstein Link: https://lore.kernel.org/20250509133240.529330-8-amir73il@gmail.com Reviewed-by: Christian Brauner Signed-off-by: Christian Brauner --- tools/testing/selftests/filesystems/utils.c | 66 +++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) (limited to 'tools/testing/selftests/filesystems/utils.c') diff --git a/tools/testing/selftests/filesystems/utils.c b/tools/testing/selftests/filesystems/utils.c index 5a114af822af..c43a69dffd83 100644 --- a/tools/testing/selftests/filesystems/utils.c +++ b/tools/testing/selftests/filesystems/utils.c @@ -18,6 +18,7 @@ #include #include #include +#include #include "../kselftest.h" #include "wrappers.h" @@ -449,6 +450,71 @@ out_close: return fret; } +static int write_file(const char *path, const char *val) +{ + int fd = open(path, O_WRONLY); + size_t len = strlen(val); + int ret; + + if (fd == -1) { + ksft_print_msg("opening %s for write: %s\n", path, strerror(errno)); + return -1; + } + + ret = write(fd, val, len); + if (ret == -1) { + ksft_print_msg("writing to %s: %s\n", path, strerror(errno)); + return -1; + } + if (ret != len) { + ksft_print_msg("short write to %s\n", path); + return -1; + } + + ret = close(fd); + if (ret == -1) { + ksft_print_msg("closing %s\n", path); + return -1; + } + + return 0; +} + +int setup_userns(void) +{ + int ret; + char buf[32]; + uid_t uid = getuid(); + gid_t gid = getgid(); + + ret = unshare(CLONE_NEWNS|CLONE_NEWUSER|CLONE_NEWPID); + if (ret) { + ksft_exit_fail_msg("unsharing mountns and userns: %s\n", + strerror(errno)); + return ret; + } + + sprintf(buf, "0 %d 1", uid); + ret = write_file("/proc/self/uid_map", buf); + if (ret) + return ret; + ret = write_file("/proc/self/setgroups", "deny"); + if (ret) + return ret; + sprintf(buf, "0 %d 1", gid); + ret = write_file("/proc/self/gid_map", buf); + if (ret) + return ret; + + ret = mount("", "/", NULL, MS_REC|MS_PRIVATE, NULL); + if (ret) { + ksft_print_msg("making mount tree private: %s\n", strerror(errno)); + return ret; + } + + return 0; +} + /* caps_down - lower all effective caps */ int caps_down(void) { -- cgit v1.2.3