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fileio: port read_file_full() to use connect_unix_path()

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This way we can connect correctly to any AF_UNIX socket in the file
system, and even save some code. Yay!

This also adds some test code for this, that ensures read_file_full()
works correctly for AF_UNIX sockets that violate the 108 char limit.

Supporting sockets like this kinda matters I think, for the simple
reason that apps want to build socket paths via XDG_RUNTIME_DIR and
suchlike, and we should be able to connect to them, even via
non-normalized paths.
This commit is contained in:
Lennart Poettering 2022-05-10 16:18:35 +02:00 committed by Yu Watanabe
parent 2679aee440
commit 28ae8da972
2 changed files with 14 additions and 24 deletions
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27
src/basic/fileio.c
View file

@ -763,8 +763,7 @@ int read_full_file_full(
r = xfopenat(dir_fd, filename, "re", 0, &f);
if (r < 0) {
_cleanup_close_ int dfd = -1, sk = -1;
union sockaddr_union sa;
_cleanup_close_ int sk = -1;
/* ENXIO is what Linux returns if we open a node that is an AF_UNIX socket */
if (r != -ENXIO)
@ -778,22 +777,6 @@ int read_full_file_full(
if (offset != UINT64_MAX)
return -ENXIO;
if (dir_fd == AT_FDCWD)
r = sockaddr_un_set_path(&sa.un, filename);
else {
/* If we shall operate relative to some directory, then let's use O_PATH first to
* open the socket inode, and then connect to it via /proc/self/fd/. We have to do
* this since there's not connectat() that takes a directory fd as first arg. */
dfd = openat(dir_fd, filename, O_PATH|O_CLOEXEC);
if (dfd < 0)
return -errno;
r = sockaddr_un_set_path(&sa.un, FORMAT_PROC_FD_PATH(dfd));
}
if (r < 0)
return r;
sk = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
if (sk < 0)
return -errno;
@ -812,9 +795,11 @@ int read_full_file_full(
return -errno;
}
if (connect(sk, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0)
return errno == ENOTSOCK ? -ENXIO : -errno; /* propagate original error if this is
* not a socket after all */
r = connect_unix_path(sk, dir_fd, filename);
if (IN_SET(r, -ENOTSOCK, -EINVAL)) /* propagate original error if this is not a socket after all */
return -ENXIO;
if (r < 0)
return r;
if (shutdown(sk, SHUT_WR) < 0)
return -errno;

11
src/test/test-fileio.c
View file

@ -881,7 +881,7 @@ TEST(read_full_file_socket) {
_cleanup_close_ int listener = -1;
_cleanup_free_ char *data = NULL, *clientname = NULL;
union sockaddr_union sa;
const char *j;
const char *j, *jj;
size_t size;
pid_t pid;
int r;
@ -897,6 +897,11 @@ TEST(read_full_file_socket) {
assert_se(bind(listener, &sa.sa, SOCKADDR_UN_LEN(sa.un)) >= 0);
assert_se(listen(listener, 1) >= 0);
/* Make sure the socket doesn't fit into a struct sockaddr_un, but we can still access it */
jj = strjoina(z, "/a_very_long_patha_very_long_patha_very_long_patha_very_long_patha_very_long_patha_very_long_patha_very_long_patha_very_long_path");
assert_se(strlen(jj) > sizeof_field(struct sockaddr_un, sun_path));
assert_se(rename(j, jj) >= 0);
/* Bind the *client* socket to some randomized name, to verify that this works correctly. */
assert_se(asprintf(&clientname, "@%" PRIx64 "/test-bindname", random_u64()) >= 0);
@ -924,8 +929,8 @@ TEST(read_full_file_socket) {
_exit(EXIT_SUCCESS);
}
assert_se(read_full_file_full(AT_FDCWD, j, UINT64_MAX, SIZE_MAX, 0, NULL, &data, &size) == -ENXIO);
assert_se(read_full_file_full(AT_FDCWD, j, UINT64_MAX, SIZE_MAX, READ_FULL_FILE_CONNECT_SOCKET, clientname, &data, &size) >= 0);
assert_se(read_full_file_full(AT_FDCWD, jj, UINT64_MAX, SIZE_MAX, 0, NULL, &data, &size) == -ENXIO);
assert_se(read_full_file_full(AT_FDCWD, jj, UINT64_MAX, SIZE_MAX, READ_FULL_FILE_CONNECT_SOCKET, clientname, &data, &size) >= 0);
assert_se(size == strlen(TEST_STR));
assert_se(streq(data, TEST_STR));