treewide: Dodge dynamic memory allocation in strerror() from glibc > 2.402024_12_11.09478d5

With glibc commit 25a5eb4010df ("string: strerror, strsignal cannot
use buffer after dlmopen (bug 32026)"), strerror() now needs, at least
on x86, the getrandom() and brk() system calls, in order to fill in
the locale-translated error message. But getrandom() and brk() are not
allowed by our seccomp profiles.

This became visible on Fedora Rawhide with the "podman login and
logout" Podman tests, defined at test/e2e/login_logout_test.go in the
Podman source tree, where pasta would terminate upon printing error
descriptions (at least the ones related to the SO_ERROR queue for
spliced connections).

Avoid dynamic memory allocation by calling strerrordesc_np() instead,
which is a GNU function returning a static, untranslated version of
the error description. If it's not available, keep calling strerror(),
which at that point should be simple enough as to be usable (at least,
that's currently the case for musl).

Reported-by: Paul Holzinger <pholzing@redhat.com>
Link: https://github.com/containers/podman/issues/24804
Analysed-by: Paul Holzinger <pholzing@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Tested-by: Paul Holzinger <pholzing@redhat.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/util.c b/util.c
index 55cae3f..11973c4 100644
--- a/util.c
+++ b/util.c
@@ -90,7 +90,7 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
 
 	ret = -errno;
 	if (fd < 0) {
-		warn("L4 socket: %s", strerror(-ret));
+		warn("L4 socket: %s", strerror_(-ret));
 		return ret;
 	}
 
@@ -162,7 +162,7 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
 
 	if (type == EPOLL_TYPE_TCP_LISTEN && listen(fd, 128) < 0) {
 		ret = -errno;
-		warn("TCP socket listen: %s", strerror(-ret));
+		warn("TCP socket listen: %s", strerror_(-ret));
 		close(fd);
 		return ret;
 	}
@@ -171,7 +171,7 @@ int sock_l4_sa(const struct ctx *c, enum epoll_type type,
 	ev.data.u64 = ref.u64;
 	if (epoll_ctl(c->epollfd, EPOLL_CTL_ADD, fd, &ev) == -1) {
 		ret = -errno;
-		warn("L4 epoll_ctl: %s", strerror(-ret));
+		warn("L4 epoll_ctl: %s", strerror_(-ret));
 		return ret;
 	}