commit 2a2c7049b8b7e6c95f495df2cd9788a47b6e835c Author: Nick Mathewson nickm@torproject.org Date: Wed Oct 30 15:00:53 2019 -0400

Add a CFLG_IMMUTABLE flag to mark a field as unchangeable. --- src/lib/conf/conftypes.h | 5 +++++ src/lib/confmgt/confmgt.c | 45 +++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/src/lib/conf/conftypes.h b/src/lib/conf/conftypes.h index 69a5f79bf..d4e2ea218 100644 --- a/src/lib/conf/conftypes.h +++ b/src/lib/conf/conftypes.h @@ -178,6 +178,11 @@ typedef struct struct_magic_decl_t { * however, setting them appends to their old value. */ #define CFLG_NOREPLACE (1u<<5) +/** + * Flag to indicate that an option or type cannot be changed while Tor is + * running. + **/ +#define CFLG_IMMUTABLE (1u<<6)

/** * A group of flags that should be set on all obsolete options and types. diff --git a/src/lib/confmgt/confmgt.c b/src/lib/confmgt/confmgt.c index 1218a63ae..137bb2137 100644 --- a/src/lib/confmgt/confmgt.c +++ b/src/lib/confmgt/confmgt.c @@ -1154,6 +1154,41 @@ config_init(const config_mgr_t *mgr, void *options) }

/** + * Helper for config_validate_single: see whether any immutable option + * has changed between old_options and new_options. + * + * On success return 0; on failure set *msg_out to a newly allocated + * string explaining what is wrong, and return -1. + */ +static int +config_check_immutable_flags(const config_format_t *fmt, + const void *old_options, + const void *new_options, + char **msg_out) +{ + tor_assert(fmt); + tor_assert(new_options); + if (BUG(! old_options)) + return 0; + + unsigned i; + for (i = 0; fmt->vars[i].member.name; ++i) { + const config_var_t *v = &fmt->vars[i]; + if (! config_var_has_flag(v, CFLG_IMMUTABLE)) + continue; + + if (! struct_var_eq(old_options, new_options, &v->member)) { + tor_asprintf(msg_out, + "While Tor is running, changing %s is not allowed", + v->member.name); + return -1; + } + } + + return 0; +} + +/** * Normalize and validate a single object `options` within a configuration * suite, according to its format. `options` may be modified as appropriate * in order to set ancillary data. If `old_options` is provided, make sure @@ -1189,10 +1224,16 @@ config_validate_single(const config_format_t *fmt, } }

- if (fmt->check_transition_fn && old_options) { - if (fmt->check_transition_fn(old_options, options, msg_out) < 0) { + if (old_options) { + if (config_check_immutable_flags(fmt, old_options, options, msg_out) < 0) { return VSTAT_TRANSITION_ERR; } + + if (fmt->check_transition_fn) { + if (fmt->check_transition_fn(old_options, options, msg_out) < 0) { + return VSTAT_TRANSITION_ERR; + } + } }

if (fmt->post_normalize_fn) {