added whitelist support for /etc

2 files changed, 56 insertions, 1 deletions

diff --git a/src/firejail/firejail.h b/src/firejail/firejail.h
index d853daa44..387fc441c 100644
--- a/src/firejail/firejail.h
+++ b/src/firejail/firejail.h
@@ -81,6 +81,7 @@
 #define RUN_WHITELIST_DEV_DIR   "/run/firejail/mnt/orig-dev"
 #define RUN_WHITELIST_OPT_DIR   "/run/firejail/mnt/orig-opt"
 #define RUN_WHITELIST_SRV_DIR   "/run/firejail/mnt/orig-srv"
+#define RUN_WHITELIST_ETC_DIR   "/run/firejail/mnt/orig-etc"
 
 #define RUN_XAUTHORITY_FILE     "/run/firejail/mnt/.Xauthority"
 #define RUN_XAUTHORITY_SEC_FILE "/run/firejail/mnt/sec.Xauthority"
@@ -197,7 +198,8 @@ typedef struct profile_entry_t {
         unsigned var_dir:1;     // whitelist in /var directory
         unsigned dev_dir:1;     // whitelist in /dev directory
         unsigned opt_dir:1;     // whitelist in /opt directory
-        unsigned srv_dir:1;     // whitelist in /srv directory
+        unsigned srv_dir:1;     // whitelist in /srv directory
+        unsigned etc_dir:1;     // whitelist in /etc directory
 }ProfileEntry;
 
 typedef struct config_t {
diff --git a/src/firejail/fs_whitelist.c b/src/firejail/fs_whitelist.c
index bfc773374..0ae5a7155 100644
--- a/src/firejail/fs_whitelist.c
+++ b/src/firejail/fs_whitelist.c
@@ -257,6 +257,15 @@ static void whitelist_path(ProfileEntry *entry) {
                 if (asprintf(&wfile, "%s/%s", RUN_WHITELIST_SRV_DIR, fname) == -1)
                         errExit("asprintf");
         }
+        else if (entry->etc_dir) {
+                fname = path + 4; // strlen("/etc")
+                if (*fname == '\0')
+                        goto errexit;
+
+                if (asprintf(&wfile, "%s/%s", RUN_WHITELIST_ETC_DIR, fname) == -1)
+                        errExit("asprintf");
+        }
+
         // check if the file exists
         struct stat s;
         if (wfile && stat(wfile, &s) == 0) {
@@ -325,6 +334,7 @@ void fs_whitelist(void) {
         int dev_dir = 0;                // /dev directory flag
         int opt_dir = 0;                // /opt directory flag
         int srv_dir = 0;                // /srv directory flag
+        int etc_dir = 0;                // /etc directory flag
 
         size_t nowhitelist_c = 0;
         size_t nowhitelist_m = 32;
@@ -414,6 +424,8 @@ void fs_whitelist(void) {
                                         opt_dir = 1;
                                 else if (strncmp(new_name, "/srv/", 5) == 0)
                                         srv_dir = 1;
+                                else if (strncmp(new_name, "/etc/", 5) == 0)
+                                        etc_dir = 1;
                         }
 
                         entry->data = EMPTY_STRING;
@@ -533,6 +545,19 @@ void fs_whitelist(void) {
                                 goto errexit;
                         }
                 }
+                else if (strncmp(new_name, "/etc/", 5) == 0) {
+                        entry->etc_dir = 1;
+                        etc_dir = 1;
+                        // special handling for some of the symlinks
+                        if (strcmp(new_name, "/etc/localtime") == 0);
+                        else if (strcmp(new_name, "/etc/mtab") == 0);
+                        else if (strcmp(new_name, "/etc/os-release") == 0);
+                        // both path and absolute path are under /etc
+                        else {
+                                if (strncmp(fname, "/etc/", 5) != 0)
+                                        goto errexit;
+                        }
+                }
                 else {
                         goto errexit;
                 }
@@ -718,6 +743,27 @@ void fs_whitelist(void) {
                         srv_dir = 0;
         }
 
+        // /etc mountpoint
+        if (etc_dir) {
+                // check if /etc directory exists
+                struct stat s;
+                if (stat("/etc", &s) == 0) {
+                        // keep a copy of real /etc directory in RUN_WHITELIST_ETC_DIR
+                        mkdir_attr(RUN_WHITELIST_ETC_DIR, 0755, 0, 0);
+                        if (mount("/etc", RUN_WHITELIST_ETC_DIR, NULL, MS_BIND|MS_REC, NULL) < 0)
+                                errExit("mount bind");
+
+                        // mount tmpfs on /srv
+                        if (arg_debug || arg_debug_whitelists)
+                                printf("Mounting tmpfs on /etc directory\n");
+                        if (mount("tmpfs", "/etc", "tmpfs", MS_NOSUID | MS_STRICTATIME | MS_REC,  "mode=755,gid=0") < 0)
+                                errExit("mounting tmpfs on /etc");
+                        fs_logger("tmpfs /etc");
+                }
+                else
+                        etc_dir = 0;
+        }
+
 
         // go through profile rules again, and interpret whitelist commands
         entry = cfg.profile;
@@ -817,6 +863,13 @@ void fs_whitelist(void) {
                 fs_logger2("tmpfs", RUN_WHITELIST_SRV_DIR);
         }
 
+        // mask the real /etc directory, currently mounted on RUN_WHITELIST_ETC_DIR
+        if (etc_dir) {
+                if (mount("tmpfs", RUN_WHITELIST_ETC_DIR, "tmpfs", MS_NOSUID | MS_STRICTATIME | MS_REC,  "mode=755,gid=0") < 0)
+                        errExit("mount tmpfs");
+                fs_logger2("tmpfs", RUN_WHITELIST_ETC_DIR);
+        }
+
         if (new_name)
                 free(new_name);