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xattr-util: try new *xattrat() family syscalls first

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Added in https://github.com/torvalds/linux/commit/6140be90ec70c39fa844741ca3cc807dd0866394

However, when O_PATH fds are encountered we'd have to go by
/proc/self/fd/ still, since the kernel people are reluctant
to make the new syscalls work with them
(https://lore.kernel.org/linux-fsdevel/20250206-steril-raumplanung-733224062432@brauner/)
Hence getxattrat() and listxattrat() are not employed.

While at it, remove the discrepancy between path being NULL
and empty - I don't grok the "security issue" claimed earlier,
but nowadays even the kernel treats the two as identical:
https://github.com/torvalds/linux/commit/e896474fe4851ffc4dd860c92daa906783090346
This commit is contained in:
Mike Yuan
2025-02-09 14:51:04 +01:00
parent baca3581ea
commit b8df25dcfe
5 changed files with 323 additions and 225 deletions
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src/test/test-xattr-util.c
+19 -12
View File
@@ -82,7 +82,7 @@ TEST(getcrtime) {
static void verify_xattr(int dfd, const char *expected) {
_cleanup_free_ char *value = NULL;
assert_se(getxattr_at_malloc(dfd, "test", "user.foo", 0, &value) == (int) strlen(expected));
ASSERT_OK_EQ(getxattr_at_malloc(dfd, "test", "user.foo", 0, &value), (int) strlen(expected));
ASSERT_STREQ(value, expected);
}
@@ -98,31 +98,38 @@ TEST(xsetxattr) {
assert_se(touch(x) >= 0);
/* by full path */
r = xsetxattr(AT_FDCWD, x, "user.foo", "fullpath", SIZE_MAX, 0);
r = xsetxattr(AT_FDCWD, x, 0, "user.foo", "fullpath");
if (ERRNO_IS_NEG_NOT_SUPPORTED(r))
return (void) log_tests_skipped_errno(r, "no xattrs supported on /var/tmp");
assert_se(r >= 0);
ASSERT_OK(r);
verify_xattr(dfd, "fullpath");
/* by dirfd */
assert_se(xsetxattr(dfd, "test", "user.foo", "dirfd", SIZE_MAX, 0) >= 0);
ASSERT_ERROR(xsetxattr_full(dfd, "test", 0, "user.foo", "dirfd", SIZE_MAX, XATTR_CREATE), EEXIST);
verify_xattr(dfd, "fullpath");
ASSERT_OK(xsetxattr_full(dfd, "test", 0, "user.foo", "dirfd", SIZE_MAX, XATTR_REPLACE));
verify_xattr(dfd, "dirfd");
/* by fd (O_PATH) */
fd = openat(dfd, "test", O_PATH|O_CLOEXEC);
assert_se(fd >= 0);
assert_se(xsetxattr(fd, NULL, "user.foo", "fd_opath", SIZE_MAX, 0) >= 0);
ASSERT_OK_ERRNO(fd = openat(dfd, "test", O_PATH|O_CLOEXEC));
ASSERT_OK(xremovexattr(fd, "", 0, "user.foo"));
ASSERT_OK(xsetxattr_full(fd, NULL, AT_EMPTY_PATH, "user.foo", "fd_opath", SIZE_MAX, XATTR_CREATE));
verify_xattr(dfd, "fd_opath");
assert_se(xsetxattr(fd, "", "user.foo", "fd_opath", SIZE_MAX, 0) == -EINVAL);
assert_se(xsetxattr(fd, "", "user.foo", "fd_opath_empty", SIZE_MAX, AT_EMPTY_PATH) >= 0);
ASSERT_OK(xsetxattr(fd, "", 0, "user.foo", "fd_opath_empty"));
verify_xattr(dfd, "fd_opath_empty");
fd = safe_close(fd);
fd = openat(dfd, "test", O_RDONLY|O_CLOEXEC);
assert_se(xsetxattr(fd, NULL, "user.foo", "fd_regular", SIZE_MAX, 0) >= 0);
ASSERT_OK(xsetxattr_full(fd, NULL, 0, "user.foo", "fd_regular", SIZE_MAX, XATTR_REPLACE));
verify_xattr(dfd, "fd_regular");
assert_se(xsetxattr(fd, "", "user.foo", "fd_regular_empty", SIZE_MAX, 0) == -EINVAL);
assert_se(xsetxattr(fd, "", "user.foo", "fd_regular_empty", SIZE_MAX, AT_EMPTY_PATH) >= 0);
ASSERT_OK(xsetxattr(fd, "", 0, "user.foo", "fd_regular_empty"));
verify_xattr(dfd, "fd_regular_empty");
}