1 files changed, 21 insertions, 2 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 3a4b35a14c0d..48871917d363 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -58,6 +58,9 @@
 
 int core_uses_pid;
 char core_pattern[65] = "core";
+int suid_dumpable = 0;
+
+EXPORT_SYMBOL(suid_dumpable);
 /* The maximal length of core_pattern is also specified in sysctl.c */
 
 static struct linux_binfmt *formats;
@@ -864,6 +867,9 @@ int flush_old_exec(struct linux_binprm * bprm)
 
         if (current->euid == current->uid && current->egid == current->gid)
                 current->mm->dumpable = 1;
+        else
+                current->mm->dumpable = suid_dumpable;
+
         name = bprm->filename;
 
         /* Copies the binary name from after last slash */
@@ -884,7 +890,7 @@ int flush_old_exec(struct linux_binprm * bprm)
             permission(bprm->file->f_dentry->d_inode,MAY_READ, NULL) ||
             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
                 suid_keys(current);
-                current->mm->dumpable = 0;
+                current->mm->dumpable = suid_dumpable;
         }
 
         /* An exec changes our domain. We are no longer part of the thread
@@ -1432,6 +1438,8 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
         struct inode * inode;
         struct file * file;
         int retval = 0;
+        int fsuid = current->fsuid;
+        int flag = 0;
 
         binfmt = current->binfmt;
         if (!binfmt || !binfmt->core_dump)
@@ -1441,6 +1449,16 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
                 up_write(&mm->mmap_sem);
                 goto fail;
         }
+
+        /*
+         *      We cannot trust fsuid as being the "true" uid of the
+         *      process nor do we know its entire history. We only know it
+         *      was tainted so we dump it as root in mode 2.
+         */
+        if (mm->dumpable == 2) {        /* Setuid core dump mode */
+                flag = O_EXCL;          /* Stop rewrite attacks */
+                current->fsuid = 0;     /* Dump root private */
+        }
         mm->dumpable = 0;
         init_completion(&mm->core_done);
         spin_lock_irq(&current->sighand->siglock);
@@ -1466,7 +1484,7 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
         lock_kernel();
         format_corename(corename, core_pattern, signr);
         unlock_kernel();
-        file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE, 0600);
+        file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600);
         if (IS_ERR(file))
                 goto fail_unlock;
         inode = file->f_dentry->d_inode;
@@ -1491,6 +1509,7 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs)
 close_fail:
         filp_close(file, NULL);
 fail_unlock:
+        current->fsuid = fsuid;
         complete_all(&mm->core_done);
 fail:
         return retval;