From: "Eric W. Biederman" Date: Tue, 2 Dec 2014 13:56:30 -0600 Subject: [PATCH] userns: Unbreak the unprivileged remount tests A security fix in caused the way the unprivileged remount tests were using user namespaces to break. Tweak the way user namespaces are being used so the test works again. Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman" --- .../selftests/mount/unprivileged-remount-test.c | 32 ++++++++++++++++------ 1 file changed, 24 insertions(+), 8 deletions(-) diff --git a/tools/testing/selftests/mount/unprivileged-remount-test.c b/tools/testing/selftests/mount/unprivileged-remount-test.c index 9669d375625a..517785052f1c 100644 --- a/tools/testing/selftests/mount/unprivileged-remount-test.c +++ b/tools/testing/selftests/mount/unprivileged-remount-test.c @@ -53,17 +53,14 @@ static void die(char *fmt, ...) exit(EXIT_FAILURE); } -static void write_file(char *filename, char *fmt, ...) +static void vmaybe_write_file(bool enoent_ok, char *filename, char *fmt, va_list ap) { char buf[4096]; int fd; ssize_t written; int buf_len; - va_list ap; - va_start(ap, fmt); buf_len = vsnprintf(buf, sizeof(buf), fmt, ap); - va_end(ap); if (buf_len < 0) { die("vsnprintf failed: %s\n", strerror(errno)); @@ -74,6 +71,8 @@ static void write_file(char *filename, char *fmt, ...) fd = open(filename, O_WRONLY); if (fd < 0) { + if ((errno == ENOENT) && enoent_ok) + return; die("open of %s failed: %s\n", filename, strerror(errno)); } @@ -92,6 +91,26 @@ static void write_file(char *filename, char *fmt, ...) } } +static void maybe_write_file(char *filename, char *fmt, ...) +{ + va_list ap; + + va_start(ap, fmt); + vmaybe_write_file(true, filename, fmt, ap); + va_end(ap); + +} + +static void write_file(char *filename, char *fmt, ...) +{ + va_list ap; + + va_start(ap, fmt); + vmaybe_write_file(false, filename, fmt, ap); + va_end(ap); + +} + static int read_mnt_flags(const char *path) { int ret; @@ -144,13 +163,10 @@ static void create_and_enter_userns(void) strerror(errno)); } + maybe_write_file("/proc/self/setgroups", "deny"); write_file("/proc/self/uid_map", "0 %d 1", uid); write_file("/proc/self/gid_map", "0 %d 1", gid); - if (setgroups(0, NULL) != 0) { - die("setgroups failed: %s\n", - strerror(errno)); - } if (setgid(0) != 0) { die ("setgid(0) failed %s\n", strerror(errno)); -- 2.1.0