Merge branch 'akpm' (Andrew's patch-bomb)

[firefly-linux-kernel-4.4.55.git] / fs / exec.c

diff --git a/fs/exec.c b/fs/exec.c
index 721a299295117f92d271f17afd224db1787712a1..18c45cac368fe3ec830c7f0c8433e5cd2db0fc2d 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1175,9 +1175,24 @@ void free_bprm(struct linux_binprm *bprm)
                mutex_unlock(&current->signal->cred_guard_mutex);
                abort_creds(bprm->cred);
        }
+       /* If a binfmt changed the interp, free it. */
+       if (bprm->interp != bprm->filename)
+               kfree(bprm->interp);
        kfree(bprm);
 }
 
+int bprm_change_interp(char *interp, struct linux_binprm *bprm)
+{
+       /* If a binfmt changed the interp, free it first. */
+       if (bprm->interp != bprm->filename)
+               kfree(bprm->interp);
+       bprm->interp = kstrdup(interp, GFP_KERNEL);
+       if (!bprm->interp)
+               return -ENOMEM;
+       return 0;
+}
+EXPORT_SYMBOL(bprm_change_interp);
+
 /*
  * install the new credentials for this executable
  */
@@ -1266,14 +1281,13 @@ int prepare_binprm(struct linux_binprm *bprm)
        bprm->cred->egid = current_egid();
 
        if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) &&
-           !current->no_new_privs) {
+           !current->no_new_privs &&
+           kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) &&
+           kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) {
                /* Set-uid? */
                if (mode & S_ISUID) {
-                       if (!kuid_has_mapping(bprm->cred->user_ns, inode->i_uid))
-                               return -EPERM;
                        bprm->per_clear |= PER_CLEAR_ON_SETID;
                        bprm->cred->euid = inode->i_uid;
-
                }
 
                /* Set-gid? */
@@ -1283,8 +1297,6 @@ int prepare_binprm(struct linux_binprm *bprm)
                 * executable.
                 */
                if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
-                       if (!kgid_has_mapping(bprm->cred->user_ns, inode->i_gid))
-                               return -EPERM;
                        bprm->per_clear |= PER_CLEAR_ON_SETID;
                        bprm->cred->egid = inode->i_gid;
                }
@@ -1356,6 +1368,10 @@ int search_binary_handler(struct linux_binprm *bprm)
        struct linux_binfmt *fmt;
        pid_t old_pid, old_vpid;
 
+       /* This allows 4 levels of binfmt rewrites before failing hard. */
+       if (depth > 5)
+               return -ELOOP;
+
        retval = security_bprm_check(bprm);
        if (retval)
                return retval;
@@ -1380,12 +1396,8 @@ int search_binary_handler(struct linux_binprm *bprm)
                        if (!try_module_get(fmt->module))
                                continue;
                        read_unlock(&binfmt_lock);
+                       bprm->recursion_depth = depth + 1;
                        retval = fn(bprm);
-                       /*
-                        * Restore the depth counter to its starting value
-                        * in this call, so we don't have to rely on every
-                        * load_binary function to restore it on return.
-                        */
                        bprm->recursion_depth = depth;
                        if (retval >= 0) {
                                if (depth == 0) {
@@ -1657,7 +1669,6 @@ int get_dumpable(struct mm_struct *mm)
        return __get_dumpable(mm->flags);
 }
 
-#ifdef __ARCH_WANT_SYS_EXECVE
 SYSCALL_DEFINE3(execve,
                const char __user *, filename,
                const char __user *const __user *, argv,
@@ -1685,23 +1696,3 @@ asmlinkage long compat_sys_execve(const char __user * filename,
        return error;
 }
 #endif
-#endif
-
-#ifdef __ARCH_WANT_KERNEL_EXECVE
-int kernel_execve(const char *filename,
-                 const char *const argv[],
-                 const char *const envp[])
-{
-       int ret = do_execve(filename,
-                       (const char __user *const __user *)argv,
-                       (const char __user *const __user *)envp);
-       if (ret < 0)
-               return ret;
-
-       /*
-        * We were successful.  We won't be returning to our caller, but
-        * instead to user space by manipulating the kernel stack.
-        */
-       ret_from_kernel_execve(current_pt_regs());
-}
-#endif