fcopy part 4

1 files changed, 35 insertions, 32 deletions

diff --git a/src/firejail/fs_home.c b/src/firejail/fs_home.c
index d8cd9ce4d..1612da5d3 100644
--- a/src/firejail/fs_home.c
+++ b/src/firejail/fs_home.c
@@ -212,12 +212,6 @@ void fs_private_homedir(void) {
         
         uid_t u = getuid();
         gid_t g = getgid();
-        struct stat s;
-        if (stat(homedir, &s) == -1) {
-                fprintf(stderr, "Error: cannot find user home directory\n");
-                exit(1);
-        }
-        
 
         // mount bind private_homedir on top of homedir
         if (arg_debug)
@@ -351,11 +345,9 @@ void fs_check_private_dir(void) {
 //***********************************************************************************
 static char *check_dir_or_file(const char *name) {
         assert(name);
-        struct stat s;
 
         // basic checks
         invalid_filename(name);
-
         if (arg_debug)
                 printf("Private home: checking %s\n", name);
 
@@ -372,28 +364,44 @@ static char *check_dir_or_file(const char *name) {
                 fname = tmp;
         }
 
-        // check the file is in user home directory, a full home directory is not allowed
-        char *rname = realpath(fname, NULL);
-        if (!rname ||
-            strncmp(rname, cfg.homedir, strlen(cfg.homedir)) != 0 ||
-            strcmp(rname, cfg.homedir) == 0) {
-                fprintf(stderr, "Error: invalid file %s\n", name);
-                exit(1);
+        // we allow only files in user home directory or symbolic links to files or directories owned by the user
+        struct stat s;
+        if (lstat(fname, &s) == 0 && S_ISLNK(s.st_mode)) {
+                if (stat(fname, &s) == 0) {     
+                        if (s.st_uid != getuid()) {
+                                fprintf(stderr, "Error: symbolic link %s to file or directory not owned by the user\n", fname);
+                                exit(1);
+                        }
+                        return fname;
+                }
+                else {
+                        fprintf(stderr, "Error: invalid file %s\n", name);
+                        exit(1);
+                }
         }
-        
-        // only top files and directories in user home are allowed
-        char *ptr = rname + strlen(cfg.homedir);
-        assert(*ptr != '\0');
-        ptr = strchr(++ptr, '/');
-        if (ptr) {
-                if (*ptr != '\0') {
-                        fprintf(stderr, "Error: only top files and directories in user home are allowed\n");
+        else {
+                // check the file is in user home directory, a full home directory is not allowed
+                char *rname = realpath(fname, NULL);
+                if (!rname ||
+                    strncmp(rname, cfg.homedir, strlen(cfg.homedir)) != 0 ||
+                    strcmp(rname, cfg.homedir) == 0) {
+                        fprintf(stderr, "Error: invalid file %s\n", name);
                         exit(1);
                 }
+                
+                // only top files and directories in user home are allowed
+                char *ptr = rname + strlen(cfg.homedir);
+                assert(*ptr != '\0');
+                ptr = strchr(++ptr, '/');
+                if (ptr) {
+                        if (*ptr != '\0') {
+                                fprintf(stderr, "Error: only top files and directories in user home are allowed\n");
+                                exit(1);
+                        }
+                }
+                free(fname);
+                return rname;
         }
-
-        free(fname);
-        return rname;
 }
 
 static void duplicate(char *name) {
@@ -405,7 +413,7 @@ static void duplicate(char *name) {
         assert(strncmp(fname, cfg.homedir, strlen(cfg.homedir)) == 0);
 
         struct stat s;
-        if (stat(fname, &s) == -1) {
+        if (lstat(fname, &s) == -1) {
                 free(fname);
                 return;
         }
@@ -445,11 +453,6 @@ void fs_private_home_list(void) {
 
         uid_t uid = getuid();
         gid_t gid = getgid();
-        struct stat s;
-        if (stat(homedir, &s) == -1) {
-                fprintf(stderr, "Error: cannot find user home directory\n");
-                exit(1);
-        }
 
         // create /run/firejail/mnt/home directory
         mkdir_attr(RUN_HOME_DIR, 0755, uid, gid);