mirror of
https://github.com/linuxkit/linuxkit.git
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133 lines
3.5 KiB
Diff
133 lines
3.5 KiB
Diff
From af8784a4b7d89b3514a8fb1e483dd2e9c4f8697e Mon Sep 17 00:00:00 2001
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From: James Bottomley <James.Bottomley@HansenPartnership.com>
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Date: Wed, 17 Feb 2016 16:51:16 -0800
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Subject: [PATCH 44/44] binfmt_misc: add persistent opened binary handler for
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containers
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This patch adds a new flag 'F' to the binfmt handlers. If you pass in
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'F' the binary that runs the emulation will be opened immediately and
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in future, will be cloned from the open file.
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The net effect is that the handler survives both changeroots and mount
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namespace changes, making it easy to work with foreign architecture
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containers without contaminating the container image with the
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emulator.
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Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
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Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
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---
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fs/binfmt_misc.c | 41 +++++++++++++++++++++++++++++++++++++++--
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1 file changed, 39 insertions(+), 2 deletions(-)
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diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
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index 78f005f37847..4beb3d9e0001 100644
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--- a/fs/binfmt_misc.c
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+++ b/fs/binfmt_misc.c
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@@ -26,6 +26,8 @@
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#include <linux/fs.h>
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#include <linux/uaccess.h>
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+#include "internal.h"
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+
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#ifdef DEBUG
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# define USE_DEBUG 1
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#else
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@@ -43,6 +45,7 @@ enum {Enabled, Magic};
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#define MISC_FMT_PRESERVE_ARGV0 (1 << 31)
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#define MISC_FMT_OPEN_BINARY (1 << 30)
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#define MISC_FMT_CREDENTIALS (1 << 29)
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+#define MISC_FMT_OPEN_FILE (1 << 28)
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typedef struct {
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struct list_head list;
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@@ -54,6 +57,7 @@ typedef struct {
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char *interpreter; /* filename of interpreter */
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char *name;
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struct dentry *dentry;
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+ struct file *interp_file;
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} Node;
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static DEFINE_RWLOCK(entries_lock);
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@@ -201,7 +205,13 @@ static int load_misc_binary(struct linux_binprm *bprm)
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if (retval < 0)
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goto error;
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- interp_file = open_exec(iname);
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+ if (fmt->flags & MISC_FMT_OPEN_FILE && fmt->interp_file) {
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+ interp_file = filp_clone_open(fmt->interp_file);
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+ if (!IS_ERR(interp_file))
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+ deny_write_access(interp_file);
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+ } else {
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+ interp_file = open_exec(iname);
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+ }
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retval = PTR_ERR(interp_file);
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if (IS_ERR(interp_file))
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goto error;
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@@ -285,6 +295,11 @@ static char *check_special_flags(char *sfs, Node *e)
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e->flags |= (MISC_FMT_CREDENTIALS |
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MISC_FMT_OPEN_BINARY);
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break;
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+ case 'F':
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+ pr_debug("register: flag: F: open interpreter file now\n");
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+ p++;
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+ e->flags |= MISC_FMT_OPEN_FILE;
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+ break;
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default:
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cont = 0;
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}
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@@ -543,6 +558,8 @@ static void entry_status(Node *e, char *page)
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*dp++ = 'O';
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if (e->flags & MISC_FMT_CREDENTIALS)
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*dp++ = 'C';
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+ if (e->flags & MISC_FMT_OPEN_FILE)
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+ *dp++ = 'F';
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*dp++ = '\n';
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if (!test_bit(Magic, &e->flags)) {
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@@ -590,6 +607,11 @@ static void kill_node(Node *e)
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}
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write_unlock(&entries_lock);
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+ if ((e->flags & MISC_FMT_OPEN_FILE) && e->interp_file) {
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+ filp_close(e->interp_file, NULL);
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+ e->interp_file = NULL;
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+ }
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+
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if (dentry) {
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drop_nlink(d_inode(dentry));
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d_drop(dentry);
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@@ -698,6 +720,21 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer,
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goto out2;
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}
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+ if (e->flags & MISC_FMT_OPEN_FILE) {
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+ struct file *f;
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+
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+ f = open_exec(e->interpreter);
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+ if (IS_ERR(f)) {
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+ err = PTR_ERR(f);
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+ pr_notice("register: failed to install interpreter file %s\n", e->interpreter);
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+ simple_release_fs(&bm_mnt, &entry_count);
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+ iput(inode);
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+ inode = NULL;
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+ goto out2;
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+ }
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+ e->interp_file = f;
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+ }
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+
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e->dentry = dget(dentry);
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inode->i_private = e;
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inode->i_fop = &bm_entry_operations;
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@@ -716,7 +753,7 @@ out:
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if (err) {
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kfree(e);
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- return -EINVAL;
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+ return err;
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}
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return count;
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}
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--
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2.13.0
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