From 81e4b9cf365df4cde30157a85cc9f3d673946118 Mon Sep 17 00:00:00 2001 From: Aleksa Sarai Date: Fri, 8 Aug 2025 03:55:06 +1000 Subject: selftests/mount_setattr: add smoke tests for open_tree_attr(2) bug There appear to be no other open_tree_attr(2) tests at the moment, but as a minimal solution just add some additional checks in the existing MOUNT_ATTR_IDMAP tests to make sure that open_tree_attr(2) cannot be used to bypass the tested restrictions that apply to mount_setattr(2). Signed-off-by: Aleksa Sarai Link: https://lore.kernel.org/20250808-open_tree_attr-bugfix-idmap-v1-2-0ec7bc05646c@cyphar.com Signed-off-by: Christian Brauner --- .../selftests/mount_setattr/mount_setattr_test.c | 77 ++++++++++++++++++---- 1 file changed, 64 insertions(+), 13 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/mount_setattr/mount_setattr_test.c b/tools/testing/selftests/mount_setattr/mount_setattr_test.c index b1e4618399be..a688871a98eb 100644 --- a/tools/testing/selftests/mount_setattr/mount_setattr_test.c +++ b/tools/testing/selftests/mount_setattr/mount_setattr_test.c @@ -107,6 +107,26 @@ #endif #endif +#ifndef __NR_open_tree_attr + #if defined __alpha__ + #define __NR_open_tree_attr 577 + #elif defined _MIPS_SIM + #if _MIPS_SIM == _MIPS_SIM_ABI32 /* o32 */ + #define __NR_open_tree_attr (467 + 4000) + #endif + #if _MIPS_SIM == _MIPS_SIM_NABI32 /* n32 */ + #define __NR_open_tree_attr (467 + 6000) + #endif + #if _MIPS_SIM == _MIPS_SIM_ABI64 /* n64 */ + #define __NR_open_tree_attr (467 + 5000) + #endif + #elif defined __ia64__ + #define __NR_open_tree_attr (467 + 1024) + #else + #define __NR_open_tree_attr 467 + #endif +#endif + #ifndef MOUNT_ATTR_IDMAP #define MOUNT_ATTR_IDMAP 0x00100000 #endif @@ -121,6 +141,12 @@ static inline int sys_mount_setattr(int dfd, const char *path, unsigned int flag return syscall(__NR_mount_setattr, dfd, path, flags, attr, size); } +static inline int sys_open_tree_attr(int dfd, const char *path, unsigned int flags, + struct mount_attr *attr, size_t size) +{ + return syscall(__NR_open_tree_attr, dfd, path, flags, attr, size); +} + static ssize_t write_nointr(int fd, const void *buf, size_t count) { ssize_t ret; @@ -1222,6 +1248,12 @@ TEST_F(mount_setattr_idmapped, attached_mount_inside_current_mount_namespace) attr.userns_fd = get_userns_fd(0, 10000, 10000); ASSERT_GE(attr.userns_fd, 0); ASSERT_NE(sys_mount_setattr(open_tree_fd, "", AT_EMPTY_PATH, &attr, sizeof(attr)), 0); + /* + * Make sure that open_tree_attr() without OPEN_TREE_CLONE is not a way + * to bypass this mount_setattr() restriction. + */ + ASSERT_LT(sys_open_tree_attr(open_tree_fd, "", AT_EMPTY_PATH, &attr, sizeof(attr)), 0); + ASSERT_EQ(close(attr.userns_fd), 0); ASSERT_EQ(close(open_tree_fd), 0); } @@ -1255,6 +1287,12 @@ TEST_F(mount_setattr_idmapped, attached_mount_outside_current_mount_namespace) ASSERT_GE(attr.userns_fd, 0); ASSERT_NE(sys_mount_setattr(open_tree_fd, "", AT_EMPTY_PATH, &attr, sizeof(attr)), 0); + /* + * Make sure that open_tree_attr() without OPEN_TREE_CLONE is not a way + * to bypass this mount_setattr() restriction. + */ + ASSERT_LT(sys_open_tree_attr(open_tree_fd, "", AT_EMPTY_PATH, &attr, sizeof(attr)), 0); + ASSERT_EQ(close(attr.userns_fd), 0); ASSERT_EQ(close(open_tree_fd), 0); } @@ -1321,6 +1359,19 @@ TEST_F(mount_setattr_idmapped, detached_mount_outside_current_mount_namespace) ASSERT_EQ(close(open_tree_fd), 0); } +static bool expected_uid_gid(int dfd, const char *path, int flags, + uid_t expected_uid, gid_t expected_gid) +{ + int ret; + struct stat st; + + ret = fstatat(dfd, path, &st, flags); + if (ret < 0) + return false; + + return st.st_uid == expected_uid && st.st_gid == expected_gid; +} + /** * Validate that currently changing the idmapping of an idmapped mount fails. */ @@ -1331,6 +1382,8 @@ TEST_F(mount_setattr_idmapped, change_idmapping) .attr_set = MOUNT_ATTR_IDMAP, }; + ASSERT_TRUE(expected_uid_gid(-EBADF, "/mnt/D", 0, 0, 0)); + if (!mount_setattr_supported()) SKIP(return, "mount_setattr syscall not supported"); @@ -1348,27 +1401,25 @@ TEST_F(mount_setattr_idmapped, change_idmapping) AT_EMPTY_PATH, &attr, sizeof(attr)), 0); ASSERT_EQ(close(attr.userns_fd), 0); + EXPECT_FALSE(expected_uid_gid(open_tree_fd, ".", 0, 0, 0)); + EXPECT_TRUE(expected_uid_gid(open_tree_fd, ".", 0, 10000, 10000)); + /* Change idmapping on a detached mount that is already idmapped. */ attr.userns_fd = get_userns_fd(0, 20000, 10000); ASSERT_GE(attr.userns_fd, 0); ASSERT_NE(sys_mount_setattr(open_tree_fd, "", AT_EMPTY_PATH, &attr, sizeof(attr)), 0); + /* + * Make sure that open_tree_attr() without OPEN_TREE_CLONE is not a way + * to bypass this mount_setattr() restriction. + */ + EXPECT_LT(sys_open_tree_attr(open_tree_fd, "", AT_EMPTY_PATH, &attr, sizeof(attr)), 0); + EXPECT_FALSE(expected_uid_gid(open_tree_fd, ".", 0, 20000, 20000)); + EXPECT_TRUE(expected_uid_gid(open_tree_fd, ".", 0, 10000, 10000)); + ASSERT_EQ(close(attr.userns_fd), 0); ASSERT_EQ(close(open_tree_fd), 0); } -static bool expected_uid_gid(int dfd, const char *path, int flags, - uid_t expected_uid, gid_t expected_gid) -{ - int ret; - struct stat st; - - ret = fstatat(dfd, path, &st, flags); - if (ret < 0) - return false; - - return st.st_uid == expected_uid && st.st_gid == expected_gid; -} - TEST_F(mount_setattr_idmapped, idmap_mount_tree_invalid) { int open_tree_fd = -EBADF; -- cgit v1.2.3 From 2319f9d0aa644eb9666c7be903078f50ecc2eb5b Mon Sep 17 00:00:00 2001 From: Nam Cao Date: Mon, 11 Aug 2025 09:49:57 +0200 Subject: selftests/coredump: Remove the read() that fails the test Resolve a conflict between commit 6a68d28066b6 ("selftests/coredump: Fix "socket_detect_userspace_client" test failure") and commit 994dc26302ed ("selftests/coredump: fix build") The first commit adds a read() to wait for write() from another thread to finish. But the second commit removes the write(). Now that the two commits are in the same tree, the read() now gets EOF and the test fails. Remove this read() so that the test passes. Signed-off-by: Nam Cao Link: https://lore.kernel.org/20250811074957.4079616-1-namcao@linutronix.de Signed-off-by: Christian Brauner --- tools/testing/selftests/coredump/stackdump_test.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'tools/testing') diff --git a/tools/testing/selftests/coredump/stackdump_test.c b/tools/testing/selftests/coredump/stackdump_test.c index 5a5a7a5f7e1d..a4ac80bb1003 100644 --- a/tools/testing/selftests/coredump/stackdump_test.c +++ b/tools/testing/selftests/coredump/stackdump_test.c @@ -446,9 +446,6 @@ TEST_F(coredump, socket_detect_userspace_client) if (info.coredump_mask & PIDFD_COREDUMPED) goto out; - if (read(fd_coredump, &c, 1) < 1) - goto out; - exit_code = EXIT_SUCCESS; out: if (fd_peer_pidfd >= 0) -- cgit v1.2.3