consolidate BINPRM_FLAGS_ENFORCE_NONDUMP handling

new helper: would_dump(bprm, file).  Checks if we are allowed to
read the file and if we are not - sets ENFORCE_NODUMP.  Exported,
used in places that previously open-coded the same logics.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

5 files changed, 15 insertions, 9 deletions

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 303983fabfd6..dd0fdfc56d38 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -668,8 +668,7 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
                          * mm->dumpable = 0 regardless of the interpreter's
                          * permissions.
                          */
-                        if (file_permission(interpreter, MAY_READ) < 0)
-                                bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
+                        would_dump(bprm, interpreter);
 
                         retval = kernel_read(interpreter, 0, bprm->buf,
                                              BINPRM_BUF_SIZE);
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 2bc5dc644b4c..30745f459faf 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -245,8 +245,7 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm,
                          * mm->dumpable = 0 regardless of the interpreter's
                          * permissions.
                          */
-                        if (file_permission(interpreter, MAY_READ) < 0)
-                                bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
+                        would_dump(bprm, interpreter);
 
                         retval = kernel_read(interpreter, 0, bprm->buf,
                                              BINPRM_BUF_SIZE);
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index 1befe2ec8186..ba1a1ae4a18a 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -149,8 +149,7 @@ static int load_misc_binary(struct linux_binprm *bprm, struct pt_regs *regs)
 
                 /* if the binary is not readable than enforce mm->dumpable=0
                    regardless of the interpreter's permissions */
-                if (file_permission(bprm->file, MAY_READ))
-                        bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
+                would_dump(bprm, bprm->file);
 
                 allow_write_access(bprm->file);
                 bprm->file = NULL;
diff --git a/fs/exec.c b/fs/exec.c
index 6075a1e727ae..f9f12ad299af 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1105,6 +1105,13 @@ out:
 }
 EXPORT_SYMBOL(flush_old_exec);
 
+void would_dump(struct linux_binprm *bprm, struct file *file)
+{
+        if (inode_permission(file->f_path.dentry->d_inode, MAY_READ) < 0)
+                bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
+}
+EXPORT_SYMBOL(would_dump);
+
 void setup_new_exec(struct linux_binprm * bprm)
 {
         int i, ch;
@@ -1144,9 +1151,10 @@ void setup_new_exec(struct linux_binprm * bprm)
         if (bprm->cred->uid != current_euid() ||
             bprm->cred->gid != current_egid()) {
                 current->pdeath_signal = 0;
-        } else if (file_permission(bprm->file, MAY_READ) ||
-                   bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
-                set_dumpable(current->mm, suid_dumpable);
+        } else {
+                would_dump(bprm, bprm->file);
+                if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
+                        set_dumpable(current->mm, suid_dumpable);
         }
 
         /*
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index 8845613fd7e3..fd88a3945aa1 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -111,6 +111,7 @@ extern int __must_check remove_arg_zero(struct linux_binprm *);
 extern int search_binary_handler(struct linux_binprm *, struct pt_regs *);
 extern int flush_old_exec(struct linux_binprm * bprm);
 extern void setup_new_exec(struct linux_binprm * bprm);
+extern void would_dump(struct linux_binprm *, struct file *);
 
 extern int suid_dumpable;
 #define SUID_DUMP_DISABLE       0       /* No setuid dumping */