diff --git a/fs/exec.c b/fs/exec.c index 061e0f9fb4ef..128964d1e9d6 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1101,6 +1101,17 @@ void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec) perf_event_comm(tsk, exec); } +/* + * The file the process presents as: its exe link and comm. A transparent + * dispatch presents as the binary, which is bprm->executable. + */ +static struct file *bprm_identity_file(const struct linux_binprm *bprm) +{ + if (bprm->interp_flags & BINPRM_FLAGS_TRANSPARENT_INTERP) + return bprm->executable; + return bprm->file; +} + /* * Calling this is the point of no return. None of the failures will be * seen by userspace since either the process is already taking a fatal @@ -1151,7 +1162,7 @@ int begin_new_exec(struct linux_binprm * bprm) * not visible until then. Doing it here also ensures * we don't race against replace_mm_exe_file(). */ - retval = set_mm_exe_file(bprm->mm, bprm->file); + retval = set_mm_exe_file(bprm->mm, bprm_identity_file(bprm)); if (retval) goto out; @@ -1241,6 +1252,8 @@ int begin_new_exec(struct linux_binprm * bprm) * Let's fix it up to be something reasonable. */ if (bprm->comm_from_dentry) { + struct file *comm_file = bprm_identity_file(bprm); + /* * Hold RCU lock to keep the name from being freed behind our back. * Use acquire semantics to make sure the terminating NUL from @@ -1250,7 +1263,7 @@ int begin_new_exec(struct linux_binprm * bprm) * detecting a concurrent rename and just want a terminated name. */ rcu_read_lock(); - __set_task_comm(me, smp_load_acquire(&bprm->file->f_path.dentry->d_name.name), + __set_task_comm(me, smp_load_acquire(&comm_file->f_path.dentry->d_name.name), true); rcu_read_unlock(); } else { @@ -1291,10 +1304,17 @@ int begin_new_exec(struct linux_binprm * bprm) /* Pass the opened binary to the interpreter. */ if (bprm->have_execfd) { - retval = FD_ADD(0, bprm->executable); - if (retval < 0) - goto out_unlock; + struct file *executable = bprm->executable; + + /* mm->exe_file carries its own write denial now so drop it. */ + exe_file_allow_write_access(executable); bprm->executable = NULL; + retval = FD_ADD(0, executable); + if (retval < 0) { + /* The reference was not consumed. */ + fput(executable); + goto out_unlock; + } bprm->execfd = retval; } return 0; @@ -1413,8 +1433,7 @@ static void free_bprm(struct linux_binprm *bprm) if (bprm->old_mm) exec_mm_put_old(bprm->old_mm); do_close_execat(bprm->file); - if (bprm->executable) - fput(bprm->executable); + do_close_execat(bprm->executable); /* If a binfmt changed the interp, free it. */ if (bprm->interp != bprm->filename) kfree(bprm->interp); @@ -1740,8 +1759,7 @@ static int exec_binprm(struct linux_binprm *bprm) do_close_execat(exec); return -ENOEXEC; } - /* Only the reference is kept, for AT_EXECFD. */ - exe_file_allow_write_access(exec); + /* Kept for AT_EXECFD; the write denial rides along until hand-over. */ bprm->executable = exec; } else { do_close_execat(exec);