67 lines
2.0 KiB
Diff
67 lines
2.0 KiB
Diff
From d486bca7e7912c6a4b547a3c607db0d0d3124bbf Mon Sep 17 00:00:00 2001
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From: Michal Sekletar <msekleta@redhat.com>
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Date: Mon, 23 Oct 2023 13:38:35 +0200
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Subject: [PATCH] core: extract host name using avahi_unescape_label()
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Previously we could create invalid escape sequence when we split the
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string on dot. For example, from valid host name "foo\\.bar" we have
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created invalid name "foo\\" and tried to set that as the host name
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which crashed the daemon.
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Fixes #453
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CVE-2023-38471
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---
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avahi-core/server.c | 27 +++++++++++++++++++++------
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1 file changed, 21 insertions(+), 6 deletions(-)
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--- a/avahi-core/server.c
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+++ b/avahi-core/server.c
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@@ -1295,7 +1295,11 @@ static void update_fqdn(AvahiServer *s)
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}
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int avahi_server_set_host_name(AvahiServer *s, const char *host_name) {
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- char *hn = NULL;
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+ char label_escaped[AVAHI_LABEL_MAX*4+1];
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+ char label[AVAHI_LABEL_MAX];
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+ char *hn = NULL, *h;
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+ size_t len;
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+
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assert(s);
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AVAHI_CHECK_VALIDITY(s, !host_name || avahi_is_valid_host_name(host_name), AVAHI_ERR_INVALID_HOST_NAME);
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@@ -1305,17 +1309,28 @@ int avahi_server_set_host_name(AvahiServ
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else
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hn = avahi_normalize_name_strdup(host_name);
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- hn[strcspn(hn, ".")] = 0;
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+ h = hn;
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+ if (!avahi_unescape_label((const char **)&hn, label, sizeof(label))) {
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+ avahi_free(h);
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+ return AVAHI_ERR_INVALID_HOST_NAME;
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+ }
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+
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+ avahi_free(h);
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- if (avahi_domain_equal(s->host_name, hn) && s->state != AVAHI_SERVER_COLLISION) {
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- avahi_free(hn);
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+ h = label_escaped;
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+ len = sizeof(label_escaped);
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+ if (!avahi_escape_label(label, strlen(label), &h, &len))
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+ return AVAHI_ERR_INVALID_HOST_NAME;
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+
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+ if (avahi_domain_equal(s->host_name, label_escaped) && s->state != AVAHI_SERVER_COLLISION)
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return avahi_server_set_errno(s, AVAHI_ERR_NO_CHANGE);
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- }
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withdraw_host_rrs(s);
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avahi_free(s->host_name);
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- s->host_name = hn;
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+ s->host_name = avahi_strdup(label_escaped);
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+ if (!s->host_name)
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+ return AVAHI_ERR_NO_MEMORY;
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update_fqdn(s);
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