repo: skip dead symlinks and symlinks pointing inside the repo

libpkg/pkg_repo_create.c

 /*-
- * Copyright (c) 2011-2019 Baptiste Daroussin <bapt@FreeBSD.org>
+ * Copyright (c) 2011-2021 Baptiste Daroussin <bapt@FreeBSD.org>
  * Copyright (c) 2011-2012 Julien Laffaye <jlaffaye@FreeBSD.org>
  * Copyright (c) 2011-2012 Marin Atanasov Nikolov <dnaeon@gmail.com>
  * Copyright (c) 2012-2013 Matthew Seaman <matthew@FreeBSD.org>
@@ -218,7 +218,14 @@ pkg_create_repo_read_fts(struct pkg_fts_item **items, FTS *fts,
 	char *ext;
 	int linklen = 0;
 	char tmp_name[MAXPATHLEN] = { 0 };
+	char repo_path[MAXPATHLEN];
+	size_t repo_path_len;
 
+	if (realpath(repopath, repo_path) == NULL) {
+		pkg_emit_errno("invalid repo path", repopath);
+		return (EPKG_FATAL);
+	}
+	repo_path_len = strlen(repo_path);
 	errno = 0;
 
 	while ((fts_ent = fts_read(fts)) != NULL) {
@@ -246,6 +253,14 @@ pkg_create_repo_read_fts(struct pkg_fts_item **items, FTS *fts,
 		}
 		/* Follow symlinks. */
 		if (fts_ent->fts_info == FTS_SL) {
+			/*
+			 * Skip symlinks pointing inside the repo
+			 * and dead symlinks
+			 */
+			if (realpath(fts_ent->fts_path, tmp_name) == NULL)
+				continue;
+			if (strncmp(repo_path, tmp_name, repo_path_len) == 0)
+				continue;
 			/* Skip symlinks to hashed packages */
 			if (meta->hash) {
 				linklen = readlink(fts_ent->fts_path,

tests/frontend/repo.sh

@@ -6,7 +6,8 @@ tests_init \
 	repo_v1 \
 	repo_v2 \
 	repo_multiversion \
-	repo_multiformat
+	repo_multiformat \
+	repo_symlinks
 
 repo_v1_body() {
 	touch plop
@@ -181,3 +182,34 @@ EOF
 	atf_check -o match:"Installing plop-1\.1" \
 		pkg -C ./pkg.conf install -y plop
 }
+
+repo_symlinks_body() {
+	atf_check -s exit:0 sh ${RESOURCEDIR}/test_subr.sh new_pkg test test 1.0 "${TMPDIR}"
+	atf_check pkg create --format txz -M test.ucl
+	mkdir repo
+	ln -sf ../test-1.0.txz ./repo/meh-1.0.txz
+	atf_check -o ignore pkg repo repo
+	cat > pkg.conf << EOF
+PKG_DBDIR=${TMPDIR}
+REPOS_DIR=[]
+repositories: {
+	local: { url : file://${TMPDIR}/repo }
+}
+EOF
+
+	atf_check -o ignore \
+		pkg -C ./pkg.conf update
+	atf_check -o inline:"test\n" \
+		pkg -C ./pkg.conf rquery -a "%n"
+
+	rm -rf repo
+	mkdir repo
+	cp test-1.0.txz repo/
+	ln -fs test-1.0.txz ./repo/meh-1.0.txz
+
+	atf_check -o ignore pkg repo repo
+	atf_check -o ignore \
+		pkg -C ./pkg.conf update -f
+	atf_check -o inline:"test\n" \
+		pkg -C ./pkg.conf rquery -a "%n"
+}