add more EUID improvements

8 files changed, 65 insertions, 59 deletions

diff --git a/src/fcopy/main.c b/src/fcopy/main.c
index 31810de9a..f279af89f 100644
--- a/src/fcopy/main.c
+++ b/src/fcopy/main.c
@@ -88,7 +88,8 @@ static void selinux_relabel_path(const char *path, const char *inside_path) {
                 if (arg_debug)
                         printf("Relabeling %s as %s (%s)\n", path, inside_path, fcon);
 
-                setfilecon_raw(procfs_path, fcon);
+                if (setfilecon_raw(procfs_path, fcon) != 0 && arg_debug)
+                        printf("Cannot relabel %s: %s\n", path, strerror(errno));
         }
         freecon(fcon);
  close:
diff --git a/src/firejail/fs.c b/src/firejail/fs.c
index dd4c2139d..6d01b5e5d 100644
--- a/src/firejail/fs.c
+++ b/src/firejail/fs.c
@@ -200,8 +200,6 @@ static void disable_file(OPERATION op, const char *filename) {
                 }
 
                 fs_tmpfs(fname, uid);
-                EUID_USER(); // fs_tmpfs returns with EUID 0
-
                 selinux_relabel_path(fname, fname);
         }
         else
@@ -282,6 +280,8 @@ static void globbing(OPERATION op, const char *pattern, const char *noblacklist[
 
 // blacklist files or directories by mounting empty files on top of them
 void fs_blacklist(void) {
+        EUID_ASSERT();
+
         ProfileEntry *entry = cfg.profile;
         if (!entry)
                 return;
@@ -293,7 +293,6 @@ void fs_blacklist(void) {
         if (noblacklist == NULL)
                 errExit("failed allocating memory for noblacklist entries");
 
-        EUID_USER();
         while (entry) {
                 OPERATION op = OPERATION_MAX;
                 char *ptr;
@@ -469,8 +468,6 @@ void fs_blacklist(void) {
         for (i = 0; i < noblacklist_c; i++)
                 free(noblacklist[i]);
         free(noblacklist);
-
-        EUID_ROOT();
 }
 
 //***********************************************
@@ -479,7 +476,7 @@ void fs_blacklist(void) {
 
 // mount a writable tmpfs on directory; requires a resolved path
 void fs_tmpfs(const char *dir, unsigned check_owner) {
-        EUID_USER();
+        EUID_ASSERT();
         assert(dir);
         if (arg_debug)
                 printf("Mounting tmpfs on %s, check owner: %s\n", dir, (check_owner)? "yes": "no");
@@ -504,12 +501,13 @@ void fs_tmpfs(const char *dir, unsigned check_owner) {
                 errExit("fstatvfs");
         unsigned long flags = buf.f_flag & ~(MS_RDONLY|MS_BIND|MS_REMOUNT);
         // mount via the symbolic link in /proc/self/fd
-        EUID_ROOT();
         char *proc;
         if (asprintf(&proc, "/proc/self/fd/%d", fd) == -1)
                 errExit("asprintf");
+        EUID_ROOT();
         if (mount("tmpfs", proc, "tmpfs", flags|MS_NOSUID|MS_NODEV, options) < 0)
                 errExit("mounting tmpfs");
+        EUID_USER();
         // check the last mount operation
         MountData *mdata = get_last_mount();
         if (strcmp(mdata->fstype, "tmpfs") != 0 || strcmp(mdata->dir, dir) != 0)
diff --git a/src/firejail/fs_dev.c b/src/firejail/fs_dev.c
index 8cc3ecc62..a43b18344 100644
--- a/src/firejail/fs_dev.c
+++ b/src/firejail/fs_dev.c
@@ -330,8 +330,10 @@ void fs_dev_disable_sound(void) {
         }
 
         // disable all jack sockets in /dev/shm
+        EUID_USER();
         glob_t globbuf;
         int globerr = glob("/dev/shm/jack*", GLOB_NOSORT, NULL, &globbuf);
+        EUID_ROOT();
         if (globerr)
                 return;
 
diff --git a/src/firejail/fs_home.c b/src/firejail/fs_home.c
index 0ed476063..590337da1 100644
--- a/src/firejail/fs_home.c
+++ b/src/firejail/fs_home.c
@@ -395,14 +395,16 @@ void fs_private(void) {
                         }
                         if (chown(homedir, u, g) < 0)
                                 errExit("chown");
-
                         fs_logger2("mkdir", homedir);
                         fs_logger2("tmpfs", homedir);
                 }
-                else
+                else {
                         // mask user home directory
                         // the directory should be owned by the current user
+                        EUID_USER();
                         fs_tmpfs(homedir, 1);
+                        EUID_ROOT();
+                }
 
                 selinux_relabel_path(homedir, homedir);
         }
@@ -564,12 +566,13 @@ void fs_private_home_list(void) {
         int xflag = store_xauthority();
         int aflag = store_asoundrc();
 
-        // create /run/firejail/mnt/home directory
         EUID_ROOT();
+        // create /run/firejail/mnt/home directory
         mkdir_attr(RUN_HOME_DIR, 0755, uid, gid);
         selinux_relabel_path(RUN_HOME_DIR, homedir);
 
-        fs_logger_print();      // save the current log
+        // save the current log
+        fs_logger_print();
         EUID_USER();
 
         // copy the list of files in the new home directory
diff --git a/src/firejail/fs_whitelist.c b/src/firejail/fs_whitelist.c
index 943f275de..7afebed1f 100644
--- a/src/firejail/fs_whitelist.c
+++ b/src/firejail/fs_whitelist.c
@@ -105,6 +105,7 @@ static int whitelist_mkpath(const char* path, mode_t mode) {
 }
 
 static void whitelist_file(int dirfd, const char *relpath, const char *path) {
+        EUID_ASSERT();
         assert(relpath && path);
 
         // open mount source, using a file descriptor that refers to the
@@ -130,12 +131,9 @@ static void whitelist_file(int dirfd, const char *relpath, const char *path) {
         }
 
         // create mount target as root, except if inside home or run/user/$UID directory
-        int userprivs = 0;
-        if ((strncmp(path, cfg.homedir, homedir_len) == 0 && path[homedir_len] == '/') ||
-            (strncmp(path, runuser, runuser_len) == 0 && path[runuser_len] == '/')) {
-                EUID_USER();
-                userprivs = 1;
-        }
+        if ((strncmp(path, cfg.homedir, homedir_len) != 0 || path[homedir_len] != '/') &&
+            (strncmp(path, runuser, runuser_len) != 0 || path[runuser_len] != '/'))
+                EUID_ROOT();
 
         // create path of the mount target
         int fd2 = whitelist_mkpath(path, 0755);
@@ -146,8 +144,7 @@ static void whitelist_file(int dirfd, const char *relpath, const char *path) {
                 if (arg_debug || arg_debug_whitelists)
                         printf("Debug %d: skip whitelist %s\n", __LINE__, path);
                 close(fd);
-                if (userprivs)
-                        EUID_ROOT();
+                EUID_USER();
                 return;
         }
 
@@ -166,8 +163,7 @@ static void whitelist_file(int dirfd, const char *relpath, const char *path) {
                         }
                         close(fd);
                         close(fd2);
-                        if (userprivs)
-                                EUID_ROOT();
+                        EUID_USER();
                         return;
                 }
                 fd3 = openat(fd2, file, O_PATH|O_DIRECTORY|O_NOFOLLOW|O_CLOEXEC);
@@ -184,19 +180,17 @@ static void whitelist_file(int dirfd, const char *relpath, const char *path) {
                 }
                 close(fd);
                 close(fd2);
-                if (userprivs)
-                        EUID_ROOT();
+                EUID_USER();
                 return;
         }
-
         close(fd2);
-        if (userprivs)
-                EUID_ROOT();
 
         if (arg_debug || arg_debug_whitelists)
                 printf("Whitelisting %s\n", path);
+        EUID_ROOT();
         if (bind_mount_by_fd(fd, fd3))
                 errExit("mount bind");
+        EUID_USER();
         // check the last mount operation
         MountData *mptr = get_last_mount(); // will do exit(1) if the mount cannot be found
 #ifdef TEST_MOUNTINFO
@@ -219,22 +213,19 @@ static void whitelist_file(int dirfd, const char *relpath, const char *path) {
 }
 
 static void whitelist_symlink(const char *link, const char *target) {
+        EUID_ASSERT();
         assert(link && target);
 
         // create files as root, except if inside home or run/user/$UID directory
-        int userprivs = 0;
-        if ((strncmp(link, cfg.homedir, homedir_len) == 0 && link[homedir_len] == '/') ||
-            (strncmp(link, runuser, runuser_len) == 0 && link[runuser_len] == '/')) {
-                EUID_USER();
-                userprivs = 1;
-        }
+        if ((strncmp(link, cfg.homedir, homedir_len) != 0 || link[homedir_len] != '/') &&
+            (strncmp(link, runuser, runuser_len) != 0 || link[runuser_len] != '/'))
+                EUID_ROOT();
 
         int fd = whitelist_mkpath(link, 0755);
         if (fd == -1) {
                 if (arg_debug || arg_debug_whitelists)
                         printf("Debug %d: cannot create symbolic link %s\n", __LINE__, link);
-                if (userprivs)
-                        EUID_ROOT();
+                EUID_USER();
                 return;
         }
 
@@ -252,8 +243,7 @@ static void whitelist_symlink(const char *link, const char *target) {
                 printf("Created symbolic link %s -> %s\n", link, target);
 
         close(fd);
-        if (userprivs)
-                EUID_ROOT();
+        EUID_USER();
 }
 
 static void globbing(const char *pattern) {
@@ -330,10 +320,11 @@ static void tmpfs_topdirs(const TopDir *topdirs) {
                 // init tmpfs
                 if (strcmp(topdirs[i].path, "/run") == 0) {
                         // restore /run/firejail directory
-                        if (mkdir(RUN_FIREJAIL_DIR, 0755) == -1)
-                                errExit("mkdir");
+                        EUID_ROOT();
+                        mkdir_attr(RUN_FIREJAIL_DIR, 0755, 0, 0);
                         if (bind_mount_fd_to_path(fd, RUN_FIREJAIL_DIR))
                                 errExit("mount bind");
+                        EUID_USER();
                         close(fd);
                         fs_logger2("whitelist", RUN_FIREJAIL_DIR);
 
@@ -351,12 +342,14 @@ static void tmpfs_topdirs(const TopDir *topdirs) {
                                         errExit("asprintf");
                                 if (strcmp(env, pamtmpdir) == 0) {
                                         // create empty user-owned /tmp/user/$UID directory
+                                        EUID_ROOT();
                                         mkdir_attr("/tmp/user", 0711, 0, 0);
                                         selinux_relabel_path("/tmp/user", "/tmp/user");
                                         fs_logger("mkdir /tmp/user");
                                         mkdir_attr(pamtmpdir, 0700, getuid(), 0);
                                         selinux_relabel_path(pamtmpdir, pamtmpdir);
                                         fs_logger2("mkdir", pamtmpdir);
+                                        EUID_USER();
                                 }
                                 free(pamtmpdir);
                         }
@@ -374,11 +367,8 @@ static void tmpfs_topdirs(const TopDir *topdirs) {
         }
 
         // user home directory
-        if (tmpfs_home) {
-                EUID_USER();
+        if (tmpfs_home)
                 fs_private(); // checks owner if outside /home
-                EUID_ROOT();
-        }
 
         // /run/user/$UID directory
         if (tmpfs_runuser) {
@@ -402,6 +392,7 @@ static int reject_topdir(const char *dir) {
 // keep track of whitelist top level directories by adding them to an array
 // open each directory
 static TopDir *add_topdir(const char *dir, TopDir *topdirs, const char *path) {
+        EUID_ASSERT();
         assert(dir && path);
 
         // /proc and /sys are not allowed
@@ -516,6 +507,8 @@ static char *extract_topdir(const char *path) {
 }
 
 void fs_whitelist(void) {
+        EUID_ASSERT();
+
         ProfileEntry *entry = cfg.profile;
         if (!entry)
                 return;
@@ -536,7 +529,6 @@ void fs_whitelist(void) {
                 errExit("calloc");
 
         // verify whitelist files, extract symbolic links, etc.
-        EUID_USER();
         while (entry) {
                 int nowhitelist_flag = 0;
 
@@ -630,7 +622,7 @@ void fs_whitelist(void) {
                 if (!fname) {
                         if (arg_debug || arg_debug_whitelists) {
                                 printf("Removed path: %s\n", entry->data);
-                                printf("\texpanded: %s\n", new_name);
+                                printf("\tnew_name: %s\n", new_name);
                                 printf("\trealpath: (null)\n");
                                 printf("\t%s\n", strerror(errno));
                         }
@@ -712,7 +704,6 @@ void fs_whitelist(void) {
         free(nowhitelist);
 
         // mount tmpfs on all top level directories
-        EUID_ROOT();
         tmpfs_topdirs(topdirs);
 
         // go through profile rules again, and interpret whitelist commands
diff --git a/src/firejail/sandbox.c b/src/firejail/sandbox.c
index 995827fb7..83e50aee2 100644
--- a/src/firejail/sandbox.c
+++ b/src/firejail/sandbox.c
@@ -1004,10 +1004,12 @@ int sandbox(void* sandbox_arg) {
         // apply the profile file
         //****************************
         // apply all whitelist commands ...
+        EUID_USER();
         fs_whitelist();
 
         // ... followed by blacklist commands
         fs_blacklist(); // mkdir and mkfile are processed all over again
+        EUID_ROOT();
 
         //****************************
         // nosound/no3d/notv/novideo and fix for pulseaudio 7.0
diff --git a/src/firejail/selinux.c b/src/firejail/selinux.c
index 6969e7a3d..fa59882ed 100644
--- a/src/firejail/selinux.c
+++ b/src/firejail/selinux.c
@@ -21,6 +21,7 @@
 #include "firejail.h"
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <errno.h>
 
 #include <fcntl.h>
 #ifndef O_PATH
@@ -57,7 +58,17 @@ void selinux_relabel_path(const char *path, const char *inside_path)
 
         /* Open the file as O_PATH, to pin it while we determine and adjust the label
          * Defeat symlink races by not allowing symbolic links */
+        int called_as_root = 0;
+        if (geteuid() == 0)
+                called_as_root = 1;
+        if (called_as_root)
+                EUID_USER();
+
         fd = safer_openat(-1, path, O_NOFOLLOW|O_CLOEXEC|O_PATH);
+
+        if (called_as_root)
+                EUID_ROOT();
+
         if (fd < 0)
                 return;
         if (fstat(fd, &st) < 0)
@@ -68,8 +79,16 @@ void selinux_relabel_path(const char *path, const char *inside_path)
                 if (arg_debug)
                         printf("Relabeling %s as %s (%s)\n", path, inside_path, fcon);
 
-                setfilecon_raw(procfs_path, fcon);
+                if (!called_as_root)
+                        EUID_ROOT();
+
+                if (setfilecon_raw(procfs_path, fcon) != 0 && arg_debug)
+                        printf("Cannot relabel %s: %s\n", path, strerror(errno));
+
+                if (!called_as_root)
+                        EUID_USER();
         }
+
         freecon(fcon);
  close:
         close(fd);
diff --git a/src/firejail/util.c b/src/firejail/util.c
index 094a68c60..f0df45eb2 100644
--- a/src/firejail/util.c
+++ b/src/firejail/util.c
@@ -459,31 +459,21 @@ int is_dir(const char *fname) {
         if (*fname == '\0')
                 return 0;
 
-        int called_as_root = 0;
-        if (geteuid() == 0)
-                called_as_root = 1;
-
-        if (called_as_root)
-                EUID_USER();
-
         // if fname doesn't end in '/', add one
         int rv;
         struct stat s;
         if (fname[strlen(fname) - 1] == '/')
-                rv = stat(fname, &s);
+                rv = stat_as_user(fname, &s);
         else {
                 char *tmp;
                 if (asprintf(&tmp, "%s/", fname) == -1) {
                         fprintf(stderr, "Error: cannot allocate memory, %s:%d\n", __FILE__, __LINE__);
                         errExit("asprintf");
                 }
-                rv = stat(tmp, &s);
+                rv = stat_as_user(tmp, &s);
                 free(tmp);
         }
 
-        if (called_as_root)
-                EUID_ROOT();
-
         if (rv == -1)
                 return 0;