Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-10 14:11:52 +00:00
Code Issues Packages Projects Releases Wiki Activity

binfmt_misc: add persistent opened binary handler for containers

Browse Source 
This patch adds a new flag 'F' to the binfmt handlers.  If you pass in
'F' the binary that runs the emulation will be opened immediately and
in future, will be cloned from the open file.

The net effect is that the handler survives both changeroots and mount
namespace changes, making it easy to work with foreign architecture
containers without contaminating the container image with the
emulator.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
This commit is contained in:
James Bottomley 2016-02-17 16:51:16 -08:00
parent 9a08c352d0
commit 948b701a60
1 changed files with 39 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
fs/binfmt_misc.c
View File

@ -26,6 +26,8 @@
#include <linux/fs.h>
#include <linux/uaccess.h>
#include "internal.h"
#ifdef DEBUG
# define USE_DEBUG 1
#else
@ -43,6 +45,7 @@ enum {Enabled, Magic};
#define MISC_FMT_PRESERVE_ARGV0 (1 << 31)
#define MISC_FMT_OPEN_BINARY (1 << 30)
#define MISC_FMT_CREDENTIALS (1 << 29)
#define MISC_FMT_OPEN_FILE (1 << 28)
typedef struct {
struct list_head list;
@ -54,6 +57,7 @@ typedef struct {
char *interpreter; /* filename of interpreter */
char *name;
struct dentry *dentry;
struct file *interp_file;
} Node;
static DEFINE_RWLOCK(entries_lock);
@ -201,7 +205,13 @@ static int load_misc_binary(struct linux_binprm *bprm)
if (retval < 0)
goto error;
if (fmt->flags & MISC_FMT_OPEN_FILE && fmt->interp_file) {
interp_file = filp_clone_open(fmt->interp_file);
if (!IS_ERR(interp_file))
deny_write_access(interp_file);
} else {
interp_file = open_exec(iname);
}
retval = PTR_ERR(interp_file);
if (IS_ERR(interp_file))
goto error;
@ -285,6 +295,11 @@ static char *check_special_flags(char *sfs, Node *e)
e->flags |= (MISC_FMT_CREDENTIALS |
MISC_FMT_OPEN_BINARY);
break;
case 'F':
pr_debug("register: flag: F: open interpreter file now\n");
p++;
e->flags |= MISC_FMT_OPEN_FILE;
break;
default:
cont = 0;
}
@ -543,6 +558,8 @@ static void entry_status(Node *e, char *page)
*dp++ = 'O';
if (e->flags & MISC_FMT_CREDENTIALS)
*dp++ = 'C';
if (e->flags & MISC_FMT_OPEN_FILE)
*dp++ = 'F';
*dp++ = '\n';
if (!test_bit(Magic, &e->flags)) {
@ -590,6 +607,11 @@ static void kill_node(Node *e)
}
write_unlock(&entries_lock);
if ((e->flags & MISC_FMT_OPEN_FILE) && e->interp_file) {
filp_close(e->interp_file, NULL);
e->interp_file = NULL;
}
if (dentry) {
drop_nlink(d_inode(dentry));
d_drop(dentry);
@ -698,6 +720,21 @@ static ssize_t bm_register_write(struct file *file, const char __user *buffer,
goto out2;
}
if (e->flags & MISC_FMT_OPEN_FILE) {
struct file *f;
f = open_exec(e->interpreter);
if (IS_ERR(f)) {
err = PTR_ERR(f);
pr_notice("register: failed to install interpreter file %s\n", e->interpreter);
simple_release_fs(&bm_mnt, &entry_count);
iput(inode);
inode = NULL;
goto out2;
}
e->interp_file = f;
}
e->dentry = dget(dentry);
inode->i_private = e;
inode->i_fop = &bm_entry_operations;
@ -716,7 +753,7 @@ out:
if (err) {
kfree(e);
return -EINVAL;
return err;
}
return count;
}