From a5c091e3026eb41d3a4daef3db95b47a3445aa11 Mon Sep 17 00:00:00 2001 From: Tobias Blass Date: Wed, 13 Jun 2018 00:39:24 +0200 Subject: [PATCH 1/3] Perform (partial) server initialization before dropping privileges. Some operations during backend creation (e.g. becoming DRM master) require CAP_SYS_ADMIN privileges. At this point, sway has dropped them already, though. This patch splits the privileged part of server_init into its own function and calls it before dropping its privileges. This fixes the bug with minimal security implications. --- include/sway/server.h | 2 ++ sway/main.c | 5 +++++ sway/server.c | 11 ++++++++--- 3 files changed, 15 insertions(+), 3 deletions(-) diff --git a/include/sway/server.h b/include/sway/server.h index 65d96e7a..963d4dc1 100644 --- a/include/sway/server.h +++ b/include/sway/server.h @@ -47,6 +47,8 @@ struct sway_server { struct sway_server server; +/* Prepares an unprivileged server_init by performing all privileged operations in advance */ +bool server_privileged_prepare(struct sway_server *server); bool server_init(struct sway_server *server); void server_fini(struct sway_server *server); void server_run(struct sway_server *server); diff --git a/sway/main.c b/sway/main.c index a7e808ad..a325dc3a 100644 --- a/sway/main.c +++ b/sway/main.c @@ -359,6 +359,11 @@ int main(int argc, char **argv) { executable_sanity_check(); bool suid = false; + + if (!server_privileged_prepare(&server)) { + return 1; + } + #ifdef __linux__ if (getuid() != geteuid() || getgid() != getegid()) { // Retain capabilities after setuid() diff --git a/sway/server.c b/sway/server.c index 824b1d8e..4745ab6e 100644 --- a/sway/server.c +++ b/sway/server.c @@ -25,9 +25,8 @@ #include "sway/tree/layout.h" -bool server_init(struct sway_server *server) { - wlr_log(L_DEBUG, "Initializing Wayland server"); - +bool server_privileged_prepare(struct sway_server *server) { + wlr_log(L_DEBUG, "Preparing Wayland server initialization"); server->wl_display = wl_display_create(); server->wl_event_loop = wl_display_get_event_loop(server->wl_display); server->backend = wlr_backend_autocreate(server->wl_display, NULL); @@ -36,6 +35,12 @@ bool server_init(struct sway_server *server) { wlr_log(L_ERROR, "Unable to create backend"); return false; } + return true; +} + +bool server_init(struct sway_server *server) { + wlr_log(L_DEBUG, "Initializing Wayland server"); + struct wlr_renderer *renderer = wlr_backend_get_renderer(server->backend); assert(renderer); From aa9f058e3e8c49be88cadbf506d0c089795968b3 Mon Sep 17 00:00:00 2001 From: Rostislav Pehlivanov Date: Fri, 22 Jun 2018 13:44:16 +0100 Subject: [PATCH 2/3] Init the dmabuf exporting protocol in wlroots Allows desktop capture via the dmabuf-capture wlroots example client. --- sway/server.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/sway/server.c b/sway/server.c index 824b1d8e..8af0bc5b 100644 --- a/sway/server.c +++ b/sway/server.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -97,6 +98,7 @@ bool server_init(struct sway_server *server) { deco_manager, WLR_SERVER_DECORATION_MANAGER_MODE_SERVER); wlr_linux_dmabuf_create(server->wl_display, renderer); + wlr_export_dmabuf_manager_v1_create(server->wl_display); server->socket = wl_display_add_socket_auto(server->wl_display); if (!server->socket) { From ad085c13325d17a242a813879b8574ba3dd43cc7 Mon Sep 17 00:00:00 2001 From: ael-code Date: Fri, 22 Jun 2018 15:41:44 +0200 Subject: [PATCH 3/3] bugfix: avoid access after free if src is NULL due to a previous error we cannot use it in the command result string. Moreover if `src` points to `p.we_wordv[0]` we cannot use it after `wordfree(&p)` in the command result string. Bonus feature: If there was an error accessing the file, the string rapresentation of the error is now included in the command result string. --- sway/commands/output/background.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/sway/commands/output/background.c b/sway/commands/output/background.c index 0c5c164f..82bccf68 100644 --- a/sway/commands/output/background.c +++ b/sway/commands/output/background.c @@ -3,6 +3,7 @@ #include #include #include +#include #include "sway/commands.h" #include "sway/config.h" #include "log.h" @@ -71,21 +72,27 @@ struct cmd_results *output_cmd_background(int argc, char **argv) { if (conf) { char *conf_path = dirname(conf); src = malloc(strlen(conf_path) + strlen(src) + 2); - if (src) { - sprintf(src, "%s/%s", conf_path, p.we_wordv[0]); - } else { + if (!src) { + free(conf); + wordfree(&p); wlr_log(L_ERROR, - "Unable to allocate background source"); + "Unable to allocate resource: Not enough memory"); + return cmd_results_new(CMD_FAILURE, "output", + "Unable to allocate resources"); } + sprintf(src, "%s/%s", conf_path, p.we_wordv[0]); free(conf); } else { wlr_log(L_ERROR, "Unable to allocate background source"); } } - if (!src || access(src, F_OK) == -1) { + + if (access(src, F_OK) == -1) { + struct cmd_results *cmd_res = cmd_results_new(CMD_FAILURE, "output", + "Unable to access background file '%s': %s", src, strerror(errno)); + free(src); wordfree(&p); - return cmd_results_new(CMD_INVALID, "output", - "Background file unreadable (%s).", src); + return cmd_res; } output->background = strdup(src);