The branch main has been updated by kevans: URL: https://cgit.FreeBSD.org/src/commit/?id=276d9b88a9e6fd6fd90e57c36444756ad297d2ab
commit 276d9b88a9e6fd6fd90e57c36444756ad297d2ab Author: Jan Bramkamp <[email protected]> AuthorDate: 2026-05-06 23:28:53 +0000 Commit: Kyle Evans <[email protected]> CommitDate: 2026-05-06 23:28:53 +0000 jail: avoid leaking jail config fds to exec.* hooks The jail(8) command must not leave parsed configuration files open since the file descriptors will be leaked to child processes including the untrusted exec.start or exec.stop hooks. While fopen() doesn't provide direct access to O_CLOEXEC, it does provide access to FD_CLOEXEC via "e" in the mode string which provides the desired defense in depth against leaking file descriptors into exec.* hooks since those always execve() into a shell. Jail configuration is potentially sensitive and some hooks execute from within the jail context, leaving some opening for the jail to exfiltrate information about the host environment. (Commit message wordsmithed by kevans) PR: 295052 Reviewed by: kevans MFC after: 3 days --- usr.sbin/jail/config.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/usr.sbin/jail/config.c b/usr.sbin/jail/config.c index 1bad04ccde68..f1e2da215790 100644 --- a/usr.sbin/jail/config.c +++ b/usr.sbin/jail/config.c @@ -321,6 +321,7 @@ static void parse_config(const char *cfname, int is_stdin) { struct cflex cflex = {.cfname = cfname, .error = 0}; + FILE *yfp = NULL; void *scanner; yylex_init_extra(&cflex, &scanner); @@ -328,7 +329,7 @@ parse_config(const char *cfname, int is_stdin) cflex.cfname = "STDIN"; yyset_in(stdin, scanner); } else { - FILE *yfp = fopen(cfname, "r"); + yfp = fopen(cfname, "re"); if (!yfp) err(1, "%s", cfname); yyset_in(yfp, scanner); @@ -336,6 +337,8 @@ parse_config(const char *cfname, int is_stdin) if (yyparse(scanner) || cflex.error) exit(1); yylex_destroy(scanner); + if (yfp != NULL) + fclose(yfp); } /*
