On Tue, 2017-10-17 at 09:33 -0700, Daniel Cashman wrote:
> From: Dan Cashman <[email protected]>
>
> The file_contexts labeling backend, specified in label_file.c,
> currently assumes
> that only one path will be specified as an option to
> selabel_open(). The split
> of platform and non-platform policy on device, however, will
> necessitate the
> loading of two disparate policy files. Rather than combining the
> files and then
> calling the existing API on a newly-formed file, just add the ability
> to specify
> multiple files to use. Order of opt specification to selabel_open
> matters.
>
> This corresponds to AOSP commit
> 50400d38203e4db08314168e60c281cc61a717a8, which
> lead to a fork with upstream, which we'd like to correct.
>
> Signed-off-by: Dan Cashman <[email protected]>
> ---
> libselinux/src/label.c | 21 +++++---
> libselinux/src/label_db.c | 13 ++++-
> libselinux/src/label_file.c | 104 +++++++++++++++++++++++++++++-
> ----------
> libselinux/src/label_internal.h | 5 +-
> libselinux/src/label_media.c | 10 +++-
> libselinux/src/label_x.c | 10 +++-
> 6 files changed, 124 insertions(+), 39 deletions(-)
>
> diff --git a/libselinux/src/label.c b/libselinux/src/label.c
> index 48f4d2d6..0dfa054c 100644
> --- a/libselinux/src/label.c
> +++ b/libselinux/src/label.c
> @@ -143,7 +143,11 @@ static int selabel_fini(struct selabel_handle
> *rec,
> struct selabel_lookup_rec *lr,
> int translating)
> {
> - if (compat_validate(rec, lr, rec->spec_file, 0))
> + char *path = NULL;
> +
> + if (rec->spec_files)
> + path = rec->spec_files[0];
> + if (compat_validate(rec, lr, path, 0))
> return -1;
>
> if (translating && !lr->ctx_trans &&
> @@ -226,11 +230,9 @@ struct selabel_handle *selabel_open(unsigned int
> backend,
> rec->digest = selabel_is_digest_set(opts, nopts, rec-
> >digest);
>
> if ((*initfuncs[backend])(rec, opts, nopts)) {
> - free(rec->spec_file);
> - free(rec);
> + selabel_close(rec);
> rec = NULL;
> }
> -
> out:
> return rec;
> }
> @@ -337,10 +339,17 @@ int selabel_digest(struct selabel_handle *rec,
>
> void selabel_close(struct selabel_handle *rec)
> {
> + size_t i;
> +
> + if (rec->spec_files) {
> + for (i = 0; i < rec->spec_files_len; i++)
> + free(rec->spec_files[i]);
> + free(rec->spec_files);
> + }
> if (rec->digest)
> selabel_digest_fini(rec->digest);
> - rec->func_close(rec);
> - free(rec->spec_file);
> + if (rec->func_close)
> + rec->func_close(rec);
> free(rec);
> }
>
> diff --git a/libselinux/src/label_db.c b/libselinux/src/label_db.c
> index c46d0a1d..9a35abea 100644
> --- a/libselinux/src/label_db.c
> +++ b/libselinux/src/label_db.c
> @@ -290,7 +290,18 @@ db_init(const struct selinux_opt *opts, unsigned
> nopts,
> errno = EINVAL;
> return NULL;
> }
> - rec->spec_file = strdup(path);
> + rec->spec_files_len = 1;
> + rec->spec_files = calloc(rec->spec_files_len, sizeof(rec-
> >spec_files[0]));
> + if (!rec->spec_files) {
> + free(catalog);
> + return NULL;
> + }
> + rec->spec_files[0] = strdup(path);
> + if (!rec->spec_files[0]) {
> + free(catalog);
> + free(rec->spec_files);
> + return NULL;
> + }
>
> /*
> * Parse for each lines
> diff --git a/libselinux/src/label_file.c
> b/libselinux/src/label_file.c
> index 560d8c3d..b3b36bc2 100644
> --- a/libselinux/src/label_file.c
> +++ b/libselinux/src/label_file.c
> @@ -709,28 +709,61 @@ static int init(struct selabel_handle *rec,
> const struct selinux_opt *opts,
> unsigned n)
> {
> struct saved_data *data = (struct saved_data *)rec->data;
> - const char *path = NULL;
> + size_t num_paths = 0;
> + char **path = NULL;
> const char *prefix = NULL;
> - int status = -1, baseonly = 0;
> + int status = -1;
> + size_t i;
> + bool baseonly = false;
> + bool path_provided;
>
> /* Process arguments */
> - while (n--)
> - switch(opts[n].type) {
> + i = n;
> + while (i--)
> + switch(opts[i].type) {
> case SELABEL_OPT_PATH:
> - path = opts[n].value;
> + num_paths++;
> break;
> case SELABEL_OPT_SUBSET:
> - prefix = opts[n].value;
> + prefix = opts[i].value;
> break;
> case SELABEL_OPT_BASEONLY:
> - baseonly = !!opts[n].value;
> + baseonly = !!opts[i].value;
> break;
> }
>
> + if (!num_paths) {
> + num_paths = 1;
> + path_provided = false;
> + } else {
> + path_provided = true;
> + }
> +
> + path = calloc(num_paths, sizeof(*path));
> + if (path == NULL) {
> + goto finish;
> + }
> + rec->spec_files = path;
> + rec->spec_files_len = num_paths;
> +
> + if (path_provided) {
> + for (i = 0; i < n; i++) {
> + switch(opts[i].type) {
> + case SELABEL_OPT_PATH:
> + *path = strdup(opts[i].value);
Perhaps surprisingly, opts[i].value can be NULL here and some callers
rely on that. After applying your patch, coreutils, selabel_lookup,
and other userspace programs all seg fault as a result. The use case
is programs where the selinux_opt structure is declared with a
SELABEL_OPT_PATH entry whose value is subsequently filled in, and left
NULL if they want to use the default path for file_contexts.
Internally, libselinux also does this from the
matchpathcon_init_prefix() function.
In any event, you need to handle this case.
> + if (*path == NULL)
> + goto finish;
> + path++;
> + break;
> + default:
> + break;
> + }
> + }
> + }
> #if !defined(BUILD_HOST) && !defined(ANDROID)
> char subs_file[PATH_MAX + 1];
> /* Process local and distribution substitution files */
> - if (!path) {
> + if (!path_provided) {
> status = selabel_subs_init(
> selinux_file_context_subs_dist_path(),
> rec->digest, &data->dist_subs);
> @@ -740,43 +773,52 @@ static int init(struct selabel_handle *rec,
> const struct selinux_opt *opts,
> rec->digest, &data->subs);
> if (status)
> goto finish;
> - path = selinux_file_context_path();
> + rec->spec_files[0] =
> strdup(selinux_file_context_path());
> + if (rec->spec_files[0] == NULL)
> + goto finish;
> } else {
> - snprintf(subs_file, sizeof(subs_file),
> "%s.subs_dist", path);
> - status = selabel_subs_init(subs_file, rec->digest,
> + for (i = 0; i < num_paths; i++) {
> + snprintf(subs_file, sizeof(subs_file),
> "%s.subs_dist", rec->spec_files[i]);
> + status = selabel_subs_init(subs_file, rec-
> >digest,
> &data->dist_subs);
> - if (status)
> - goto finish;
> - snprintf(subs_file, sizeof(subs_file), "%s.subs",
> path);
> - status = selabel_subs_init(subs_file, rec->digest,
> + if (status)
> + goto finish;
> + snprintf(subs_file, sizeof(subs_file),
> "%s.subs", rec->spec_files[i]);
> + status = selabel_subs_init(subs_file, rec-
> >digest,
> &data->subs);
> - if (status)
> - goto finish;
> + if (status)
> + goto finish;
> + }
> + }
> +#else
> + if (!path_provided) {
> + selinux_log(SELINUX_ERROR, "No path given to file
> labeling backend\n");
> + goto finish;
> }
> -
> #endif
> - rec->spec_file = strdup(path);
>
> /*
> - * The do detailed validation of the input and fill the spec
> array
> + * Do detailed validation of the input and fill the spec
> array
> */
> - status = process_file(path, NULL, rec, prefix, rec->digest);
> - if (status)
> - goto finish;
> -
> - if (rec->validating) {
> - status = nodups_specs(data, path);
> + for (i = 0; i < num_paths; i++) {
> + status = process_file(rec->spec_files[i], NULL, rec,
> prefix, rec->digest);
> if (status)
> goto finish;
> +
> + if (rec->validating) {
> + status = nodups_specs(data, rec-
> >spec_files[i]);
> + if (status)
> + goto finish;
> + }
> }
>
> if (!baseonly) {
> - status = process_file(path, "homedirs", rec, prefix,
> + status = process_file(rec->spec_files[0],
> "homedirs", rec, prefix,
> rec-
> >digest);
> if (status && errno != ENOENT)
> goto finish;
>
> - status = process_file(path, "local", rec, prefix,
> + status = process_file(rec->spec_files[0], "local",
> rec, prefix,
> rec-
> >digest);
> if (status && errno != ENOENT)
> goto finish;
> @@ -804,6 +846,12 @@ static void closef(struct selabel_handle *rec)
> struct stem *stem;
> unsigned int i;
>
> + if (!data)
> + return;
> +
> + /* make sure successive ->func_close() calls are harmless */
> + rec->data = NULL;
> +
> selabel_subs_fini(data->subs);
> selabel_subs_fini(data->dist_subs);
>
> diff --git a/libselinux/src/label_internal.h
> b/libselinux/src/label_internal.h
> index c55efb75..43b63513 100644
> --- a/libselinux/src/label_internal.h
> +++ b/libselinux/src/label_internal.h
> @@ -98,10 +98,11 @@ struct selabel_handle {
> void *data;
>
> /*
> - * The main spec file used. Note for file contexts the local
> and/or
> + * The main spec file(s) used. Note for file contexts the
> local and/or
> * homedirs could also have been used to resolve a context.
> */
> - char *spec_file;
> + size_t spec_files_len;
> + char **spec_files;
>
> /* ptr to SHA1 hash information if SELABEL_OPT_DIGEST set */
> struct selabel_digest *digest;
> diff --git a/libselinux/src/label_media.c
> b/libselinux/src/label_media.c
> index d202e5d5..34260cbb 100644
> --- a/libselinux/src/label_media.c
> +++ b/libselinux/src/label_media.c
> @@ -100,7 +100,15 @@ static int init(struct selabel_handle *rec,
> const struct selinux_opt *opts,
> errno = EINVAL;
> return -1;
> }
> - rec->spec_file = strdup(path);
> + rec->spec_files_len = 1;
> + rec->spec_files = calloc(rec->spec_files_len, sizeof(rec-
> >spec_files[0]));
> + if (!rec->spec_files)
> + return -1;
> + rec->spec_files[0] = strdup(path);
> + if (!rec->spec_files[0]) {
> + free(rec->spec_files);
> + return -1;
> + }
>
> /*
> * Perform two passes over the specification file.
> diff --git a/libselinux/src/label_x.c b/libselinux/src/label_x.c
> index 96745299..fafe034a 100644
> --- a/libselinux/src/label_x.c
> +++ b/libselinux/src/label_x.c
> @@ -127,7 +127,15 @@ static int init(struct selabel_handle *rec,
> const struct selinux_opt *opts,
> errno = EINVAL;
> return -1;
> }
> - rec->spec_file = strdup(path);
> + rec->spec_files_len = 1;
> + rec->spec_files = calloc(rec->spec_files_len, sizeof(rec-
> >spec_files[0]));
> + if (!rec->spec_files)
> + return -1;
> + rec->spec_files[0] = strdup(path);
> + if (!rec->spec_files[0]) {
> + free(rec->spec_files);
> + return -1;
> + }
>
> /*
> * Perform two passes over the specification file.
