Upgrade to 4.4.50-rt62

[kvmfornfv.git] / kernel / fs / exec.c

diff --git a/kernel/fs/exec.c b/kernel/fs/exec.c
index 0e7125b..74962ac 100644 (file)
--- a/kernel/fs/exec.c
+++ b/kernel/fs/exec.c
@@ -19,7 +19,7 @@
  * current->executable is only used by the procfs.  This allows a dispatch
  * table to check for several different types  of binary formats.  We keep
  * trying until we recognize the file or we run out of supported binary
- * formats. 
+ * formats.
  */
 
 #include <linux/slab.h>
@@ -56,6 +56,7 @@
 #include <linux/pipe_fs_i.h>
 #include <linux/oom.h>
 #include <linux/compat.h>
+#include <linux/user_namespace.h>
 
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
@@ -98,6 +99,12 @@ static inline void put_binfmt(struct linux_binfmt * fmt)
        module_put(fmt->module);
 }
 
+bool path_noexec(const struct path *path)
+{
+       return (path->mnt->mnt_flags & MNT_NOEXEC) ||
+              (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
+}
+
 #ifdef CONFIG_USELIB
 /*
  * Note that a shared library must be both readable and executable due to
@@ -132,7 +139,7 @@ SYSCALL_DEFINE1(uselib, const char __user *, library)
                goto exit;
 
        error = -EACCES;
-       if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
+       if (path_noexec(&file->f_path))
                goto exit;
 
        fsnotify_open(file);
@@ -777,7 +784,7 @@ static struct file *do_open_execat(int fd, struct filename *name, int flags)
        if (!S_ISREG(file_inode(file)->i_mode))
                goto exit;
 
-       if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
+       if (path_noexec(&file->f_path))
                goto exit;
 
        err = deny_write_access(file);
@@ -1110,6 +1117,13 @@ int flush_old_exec(struct linux_binprm * bprm)
        flush_thread();
        current->personality &= ~bprm->per_clear;
 
+       /*
+        * We have to apply CLOEXEC before we change whether the process is
+        * dumpable (in setup_new_exec) to avoid a race with a process in userspace
+        * trying to access the should-be-closed file descriptors of a process
+        * undergoing exec(2).
+        */
+       do_close_on_exec(current->files);
        return 0;
 
 out:
@@ -1119,8 +1133,22 @@ EXPORT_SYMBOL(flush_old_exec);
 
 void would_dump(struct linux_binprm *bprm, struct file *file)
 {
-       if (inode_permission(file_inode(file), MAY_READ) < 0)
+       struct inode *inode = file_inode(file);
+       if (inode_permission(inode, MAY_READ) < 0) {
+               struct user_namespace *old, *user_ns;
                bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
+
+               /* Ensure mm->user_ns contains the executable */
+               user_ns = old = bprm->mm->user_ns;
+               while ((user_ns != &init_user_ns) &&
+                      !privileged_wrt_inode_uidgid(user_ns, inode))
+                       user_ns = user_ns->parent;
+
+               if (old != user_ns) {
+                       bprm->mm->user_ns = get_user_ns(user_ns);
+                       put_user_ns(old);
+               }
+       }
 }
 EXPORT_SYMBOL(would_dump);
 
@@ -1150,7 +1178,6 @@ void setup_new_exec(struct linux_binprm * bprm)
            !gid_eq(bprm->cred->gid, current_egid())) {
                current->pdeath_signal = 0;
        } else {
-               would_dump(bprm, bprm->file);
                if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
                        set_dumpable(current->mm, suid_dumpable);
        }
@@ -1159,7 +1186,6 @@ void setup_new_exec(struct linux_binprm * bprm)
           group */
        current->self_exec_id++;
        flush_signal_handlers(current, 0);
-       do_close_on_exec(current->files);
 }
 EXPORT_SYMBOL(setup_new_exec);
 
@@ -1250,7 +1276,7 @@ static void check_unsafe_exec(struct linux_binprm *bprm)
        unsigned n_fs;
 
        if (p->ptrace) {
-               if (p->ptrace & PT_PTRACE_CAP)
+               if (ptracer_capable(p, current_user_ns()))
                        bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
                else
                        bprm->unsafe |= LSM_UNSAFE_PTRACE;
@@ -1583,6 +1609,8 @@ static int do_execveat_common(int fd, struct filename *filename,
        if (retval < 0)
                goto out;
 
+       would_dump(bprm, bprm->file);
+
        retval = exec_binprm(bprm);
        if (retval < 0)
                goto out;