chroot: unify path name handling

1 files changed, 16 insertions, 12 deletions

diff --git a/src/firejail/chroot.c b/src/firejail/chroot.c
index 7411a2b48..a18c181ab 100644
--- a/src/firejail/chroot.c
+++ b/src/firejail/chroot.c
@@ -61,28 +61,32 @@ errout:
 }
 
 // copy /etc/resolv.conf or /etc/machine-id in chroot directory
-static void update_file(int parentfd, const char *fname) {
-        assert(fname);
-        assert(fname[0] == '/');
+static void update_file(int parentfd, const char *relpath) {
+        assert(relpath && relpath[0] && relpath[0] != '/');
 
-        int in = open(fname, O_RDONLY|O_CLOEXEC);
+        char *abspath;
+        if (asprintf(&abspath, "/%s", relpath) == -1)
+                errExit("asprintf");
+        int in = open(abspath, O_RDONLY|O_CLOEXEC);
+        free(abspath);
         if (in == -1)
                 goto errout;
+
         struct stat src;
         if (fstat(in, &src) == -1)
                 errExit("fstat");
         // try to detect if file has been bind mounted into the chroot
         struct stat dst;
-        if (fstatat(parentfd, fname+1, &dst, 0) == 0) {
+        if (fstatat(parentfd, relpath, &dst, 0) == 0) {
                 if (src.st_dev == dst.st_dev && src.st_ino == dst.st_ino) {
                         close(in);
                         return;
                 }
         }
         if (arg_debug)
-                printf("Updating %s in chroot\n", fname);
-        unlinkat(parentfd, fname+1, 0);
-        int out = openat(parentfd, fname+1, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, S_IRUSR | S_IWRITE | S_IRGRP | S_IROTH);
+                printf("Updating chroot /%s\n", relpath);
+        unlinkat(parentfd, relpath, 0);
+        int out = openat(parentfd, relpath, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, S_IRUSR | S_IWRITE | S_IRGRP | S_IROTH);
         if (out == -1) {
                 close(in);
                 goto errout;
@@ -94,12 +98,12 @@ static void update_file(int parentfd, const char *fname) {
         return;
 
 errout:
-        fwarning("%s not initialized\n", fname);
+        fwarning("chroot /%s not initialized\n", relpath);
 }
 
 // exit if error
 static void check_subdir(int parentfd, const char *subdir, int check_writable) {
-        assert(subdir);
+        assert(subdir && subdir[0] && subdir[0] != '/');
         struct stat s;
         if (fstatat(parentfd, subdir, &s, AT_SYMLINK_NOFOLLOW) != 0) {
                 fprintf(stderr, "Error: cannot find /%s in chroot directory\n", subdir);
@@ -223,7 +227,7 @@ void fs_chroot(const char *rootdir) {
                 close(dst);
 
                 // update /etc/machine-id in chroot
-                update_file(parentfd, "/etc/machine-id");
+                update_file(parentfd, "etc/machine-id");
         }
 
         // create /run/firejail directory in chroot
@@ -262,7 +266,7 @@ void fs_chroot(const char *rootdir) {
         close(fd);
 
         // update chroot resolv.conf
-        update_file(parentfd, "/etc/resolv.conf");
+        update_file(parentfd, "etc/resolv.conf");
 
 #ifdef HAVE_GCOV
         __gcov_flush();