bbaecc0882
The current code places a 256 byte limit on the registration format.
This ends up being fairly limited when you try to do matching against a
binary format like ELF:
- the magic & mask formats cannot have any embedded NUL chars
(string_unescape_inplace halts at the first NUL)
- each escape sequence quadruples the size: \x00 is needed for NUL
- trying to match bytes at the start of the file as well as further
on leads to a lot of \x00 sequences in the mask
- magic & mask have to be the same length (when decoded)
- still need bytes for the other fields
- impossible!
Let's look at a concrete (and common) example: using QEMU to run MIPS
ELFs. The name field uses 11 bytes "qemu-mipsel". The interp uses 20
bytes "/usr/bin/qemu-mipsel". The type & flags takes up 4 bytes. We
need 7 bytes for the delimiter (usually ":"). We can skip offset. So
already we're down to 107 bytes to use with the magic/mask instead of
the real limit of 128 (BINPRM_BUF_SIZE). If people use shell code to
register (which they do the majority of the time), they're down to ~26
possible bytes since the escape sequence must be \x##.
The ELF format looks like (both 32 & 64 bit):
e_ident: 16 bytes
e_type: 2 bytes
e_machine: 2 bytes
Those 20 bytes are enough for most architectures because they have so few
formats in the first place, thus they can be uniquely identified. That
also means for shell users, since 20 is smaller than 26, they can sanely
register a handler.
But for some targets (like MIPS), we need to poke further. The ELF fields
continue on:
e_entry: 4 or 8 bytes
e_phoff: 4 or 8 bytes
e_shoff: 4 or 8 bytes
e_flags: 4 bytes
We only care about e_flags here as that includes the bits to identify
whether the ELF is O32/N32/N64. But now we have to consume another 16
bytes (for 32 bit ELFs) or 28 bytes (for 64 bit ELFs) just to match the
flags. If every byte is escaped, we send 288 more bytes to the kernel
((20 {e_ident,e_type,e_machine} + 12 {e_entry,e_phoff,e_shoff} + 4
{e_flags}) * 2 {mask,magic} * 4 {escape}) and we've clearly blown our
budget.
Even if we try to be clever and do the decoding ourselves (rather than
relying on the kernel to process \x##), we still can't hit the mark --
string_unescape_inplace treats mask & magic as C strings so NUL cannot
be embedded. That leaves us with having to pass \x00 for the 12/24
entry/phoff/shoff bytes (as those will be completely random addresses),
and that is a minimum requirement of 48/96 bytes for the mask alone.
Add up the rest and we blow through it (this is for 64 bit ELFs):
magic: 20 {e_ident,e_type,e_machine} + 24 {e_entry,e_phoff,e_shoff} +
4 {e_flags} = 48 # ^^ See note below.
mask: 20 {e_ident,e_type,e_machine} + 96 {e_entry,e_phoff,e_shoff} +
4 {e_flags} = 120
Remember above we had 107 left over, and now we're at 168. This is of
course the *best* case scenario -- you'll also want to have NUL bytes
in the magic & mask too to match literal zeros.
Note: the reason we can use 24 in the magic is that we can work off of the
fact that for bytes the mask would clobber, we can stuff any value into
magic that we want. So when mask is \x00, we don't need the magic to also
be \x00, it can be an unescaped raw byte like '!'. This lets us handle
more formats (barely) under the current 256 limit, but that's a pretty
tall hoop to force people to jump through.
With all that said, let's bump the limit from 256 bytes to 1920. This way
we support escaping every byte of the mask & magic field (which is 1024
bytes by themselves -- 128 * 4 * 2), and we leave plenty of room for other
fields. Like long paths to the interpreter (when you have source in your
/really/long/homedir/qemu/foo). Since the current code stuffs more than
one structure into the same buffer, we leave a bit of space to easily
round up to 2k. 1920 is just as arbitrary as 256 ;).
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
742 lines
15 KiB
C
742 lines
15 KiB
C
/*
|
|
* binfmt_misc.c
|
|
*
|
|
* Copyright (C) 1997 Richard Günther
|
|
*
|
|
* binfmt_misc detects binaries via a magic or filename extension and invokes
|
|
* a specified wrapper. This should obsolete binfmt_java, binfmt_em86 and
|
|
* binfmt_mz.
|
|
*
|
|
* 1997-04-25 first version
|
|
* [...]
|
|
* 1997-05-19 cleanup
|
|
* 1997-06-26 hpa: pass the real filename rather than argv[0]
|
|
* 1997-06-30 minor cleanup
|
|
* 1997-08-09 removed extension stripping, locking cleanup
|
|
* 2001-02-28 AV: rewritten into something that resembles C. Original didn't.
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/init.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/magic.h>
|
|
#include <linux/binfmts.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/ctype.h>
|
|
#include <linux/string_helpers.h>
|
|
#include <linux/file.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/namei.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/syscalls.h>
|
|
#include <linux/fs.h>
|
|
|
|
#include <asm/uaccess.h>
|
|
|
|
enum {
|
|
VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
|
|
};
|
|
|
|
static LIST_HEAD(entries);
|
|
static int enabled = 1;
|
|
|
|
enum {Enabled, Magic};
|
|
#define MISC_FMT_PRESERVE_ARGV0 (1<<31)
|
|
#define MISC_FMT_OPEN_BINARY (1<<30)
|
|
#define MISC_FMT_CREDENTIALS (1<<29)
|
|
|
|
typedef struct {
|
|
struct list_head list;
|
|
unsigned long flags; /* type, status, etc. */
|
|
int offset; /* offset of magic */
|
|
int size; /* size of magic/mask */
|
|
char *magic; /* magic or filename extension */
|
|
char *mask; /* mask, NULL for exact match */
|
|
char *interpreter; /* filename of interpreter */
|
|
char *name;
|
|
struct dentry *dentry;
|
|
} Node;
|
|
|
|
static DEFINE_RWLOCK(entries_lock);
|
|
static struct file_system_type bm_fs_type;
|
|
static struct vfsmount *bm_mnt;
|
|
static int entry_count;
|
|
|
|
/*
|
|
* Max length of the register string. Determined by:
|
|
* - 7 delimiters
|
|
* - name: ~50 bytes
|
|
* - type: 1 byte
|
|
* - offset: 3 bytes (has to be smaller than BINPRM_BUF_SIZE)
|
|
* - magic: 128 bytes (512 in escaped form)
|
|
* - mask: 128 bytes (512 in escaped form)
|
|
* - interp: ~50 bytes
|
|
* - flags: 5 bytes
|
|
* Round that up a bit, and then back off to hold the internal data
|
|
* (like struct Node).
|
|
*/
|
|
#define MAX_REGISTER_LENGTH 1920
|
|
|
|
/*
|
|
* Check if we support the binfmt
|
|
* if we do, return the node, else NULL
|
|
* locking is done in load_misc_binary
|
|
*/
|
|
static Node *check_file(struct linux_binprm *bprm)
|
|
{
|
|
char *p = strrchr(bprm->interp, '.');
|
|
struct list_head *l;
|
|
|
|
list_for_each(l, &entries) {
|
|
Node *e = list_entry(l, Node, list);
|
|
char *s;
|
|
int j;
|
|
|
|
if (!test_bit(Enabled, &e->flags))
|
|
continue;
|
|
|
|
if (!test_bit(Magic, &e->flags)) {
|
|
if (p && !strcmp(e->magic, p + 1))
|
|
return e;
|
|
continue;
|
|
}
|
|
|
|
s = bprm->buf + e->offset;
|
|
if (e->mask) {
|
|
for (j = 0; j < e->size; j++)
|
|
if ((*s++ ^ e->magic[j]) & e->mask[j])
|
|
break;
|
|
} else {
|
|
for (j = 0; j < e->size; j++)
|
|
if ((*s++ ^ e->magic[j]))
|
|
break;
|
|
}
|
|
if (j == e->size)
|
|
return e;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* the loader itself
|
|
*/
|
|
static int load_misc_binary(struct linux_binprm *bprm)
|
|
{
|
|
Node *fmt;
|
|
struct file * interp_file = NULL;
|
|
char iname[BINPRM_BUF_SIZE];
|
|
const char *iname_addr = iname;
|
|
int retval;
|
|
int fd_binary = -1;
|
|
|
|
retval = -ENOEXEC;
|
|
if (!enabled)
|
|
goto _ret;
|
|
|
|
/* to keep locking time low, we copy the interpreter string */
|
|
read_lock(&entries_lock);
|
|
fmt = check_file(bprm);
|
|
if (fmt)
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|
strlcpy(iname, fmt->interpreter, BINPRM_BUF_SIZE);
|
|
read_unlock(&entries_lock);
|
|
if (!fmt)
|
|
goto _ret;
|
|
|
|
if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
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|
retval = remove_arg_zero(bprm);
|
|
if (retval)
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|
goto _ret;
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|
}
|
|
|
|
if (fmt->flags & MISC_FMT_OPEN_BINARY) {
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|
|
|
/* if the binary should be opened on behalf of the
|
|
* interpreter than keep it open and assign descriptor
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|
* to it */
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|
fd_binary = get_unused_fd();
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|
if (fd_binary < 0) {
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|
retval = fd_binary;
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|
goto _ret;
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|
}
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|
fd_install(fd_binary, bprm->file);
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|
|
|
/* if the binary is not readable than enforce mm->dumpable=0
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|
regardless of the interpreter's permissions */
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would_dump(bprm, bprm->file);
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|
|
|
allow_write_access(bprm->file);
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bprm->file = NULL;
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|
|
|
/* mark the bprm that fd should be passed to interp */
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bprm->interp_flags |= BINPRM_FLAGS_EXECFD;
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|
bprm->interp_data = fd_binary;
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|
|
|
} else {
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|
allow_write_access(bprm->file);
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|
fput(bprm->file);
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|
bprm->file = NULL;
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|
}
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|
/* make argv[1] be the path to the binary */
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|
retval = copy_strings_kernel (1, &bprm->interp, bprm);
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|
if (retval < 0)
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|
goto _error;
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|
bprm->argc++;
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|
|
|
/* add the interp as argv[0] */
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|
retval = copy_strings_kernel (1, &iname_addr, bprm);
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|
if (retval < 0)
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|
goto _error;
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|
bprm->argc ++;
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|
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|
/* Update interp in case binfmt_script needs it. */
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|
retval = bprm_change_interp(iname, bprm);
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|
if (retval < 0)
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|
goto _error;
|
|
|
|
interp_file = open_exec (iname);
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|
retval = PTR_ERR (interp_file);
|
|
if (IS_ERR (interp_file))
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|
goto _error;
|
|
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|
bprm->file = interp_file;
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|
if (fmt->flags & MISC_FMT_CREDENTIALS) {
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|
/*
|
|
* No need to call prepare_binprm(), it's already been
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|
* done. bprm->buf is stale, update from interp_file.
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|
*/
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|
memset(bprm->buf, 0, BINPRM_BUF_SIZE);
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|
retval = kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
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|
} else
|
|
retval = prepare_binprm (bprm);
|
|
|
|
if (retval < 0)
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|
goto _error;
|
|
|
|
retval = search_binary_handler(bprm);
|
|
if (retval < 0)
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|
goto _error;
|
|
|
|
_ret:
|
|
return retval;
|
|
_error:
|
|
if (fd_binary > 0)
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|
sys_close(fd_binary);
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|
bprm->interp_flags = 0;
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|
bprm->interp_data = 0;
|
|
goto _ret;
|
|
}
|
|
|
|
/* Command parsers */
|
|
|
|
/*
|
|
* parses and copies one argument enclosed in del from *sp to *dp,
|
|
* recognising the \x special.
|
|
* returns pointer to the copied argument or NULL in case of an
|
|
* error (and sets err) or null argument length.
|
|
*/
|
|
static char *scanarg(char *s, char del)
|
|
{
|
|
char c;
|
|
|
|
while ((c = *s++) != del) {
|
|
if (c == '\\' && *s == 'x') {
|
|
s++;
|
|
if (!isxdigit(*s++))
|
|
return NULL;
|
|
if (!isxdigit(*s++))
|
|
return NULL;
|
|
}
|
|
}
|
|
return s;
|
|
}
|
|
|
|
static char * check_special_flags (char * sfs, Node * e)
|
|
{
|
|
char * p = sfs;
|
|
int cont = 1;
|
|
|
|
/* special flags */
|
|
while (cont) {
|
|
switch (*p) {
|
|
case 'P':
|
|
p++;
|
|
e->flags |= MISC_FMT_PRESERVE_ARGV0;
|
|
break;
|
|
case 'O':
|
|
p++;
|
|
e->flags |= MISC_FMT_OPEN_BINARY;
|
|
break;
|
|
case 'C':
|
|
p++;
|
|
/* this flags also implies the
|
|
open-binary flag */
|
|
e->flags |= (MISC_FMT_CREDENTIALS |
|
|
MISC_FMT_OPEN_BINARY);
|
|
break;
|
|
default:
|
|
cont = 0;
|
|
}
|
|
}
|
|
|
|
return p;
|
|
}
|
|
/*
|
|
* This registers a new binary format, it recognises the syntax
|
|
* ':name:type:offset:magic:mask:interpreter:flags'
|
|
* where the ':' is the IFS, that can be chosen with the first char
|
|
*/
|
|
static Node *create_entry(const char __user *buffer, size_t count)
|
|
{
|
|
Node *e;
|
|
int memsize, err;
|
|
char *buf, *p;
|
|
char del;
|
|
|
|
/* some sanity checks */
|
|
err = -EINVAL;
|
|
if ((count < 11) || (count > MAX_REGISTER_LENGTH))
|
|
goto out;
|
|
|
|
err = -ENOMEM;
|
|
memsize = sizeof(Node) + count + 8;
|
|
e = kmalloc(memsize, GFP_USER);
|
|
if (!e)
|
|
goto out;
|
|
|
|
p = buf = (char *)e + sizeof(Node);
|
|
|
|
memset(e, 0, sizeof(Node));
|
|
if (copy_from_user(buf, buffer, count))
|
|
goto Efault;
|
|
|
|
del = *p++; /* delimeter */
|
|
|
|
memset(buf+count, del, 8);
|
|
|
|
e->name = p;
|
|
p = strchr(p, del);
|
|
if (!p)
|
|
goto Einval;
|
|
*p++ = '\0';
|
|
if (!e->name[0] ||
|
|
!strcmp(e->name, ".") ||
|
|
!strcmp(e->name, "..") ||
|
|
strchr(e->name, '/'))
|
|
goto Einval;
|
|
switch (*p++) {
|
|
case 'E': e->flags = 1<<Enabled; break;
|
|
case 'M': e->flags = (1<<Enabled) | (1<<Magic); break;
|
|
default: goto Einval;
|
|
}
|
|
if (*p++ != del)
|
|
goto Einval;
|
|
if (test_bit(Magic, &e->flags)) {
|
|
char *s = strchr(p, del);
|
|
if (!s)
|
|
goto Einval;
|
|
*s++ = '\0';
|
|
e->offset = simple_strtoul(p, &p, 10);
|
|
if (*p++)
|
|
goto Einval;
|
|
e->magic = p;
|
|
p = scanarg(p, del);
|
|
if (!p)
|
|
goto Einval;
|
|
p[-1] = '\0';
|
|
if (!e->magic[0])
|
|
goto Einval;
|
|
e->mask = p;
|
|
p = scanarg(p, del);
|
|
if (!p)
|
|
goto Einval;
|
|
p[-1] = '\0';
|
|
if (!e->mask[0])
|
|
e->mask = NULL;
|
|
e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX);
|
|
if (e->mask &&
|
|
string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size)
|
|
goto Einval;
|
|
if (e->size + e->offset > BINPRM_BUF_SIZE)
|
|
goto Einval;
|
|
} else {
|
|
p = strchr(p, del);
|
|
if (!p)
|
|
goto Einval;
|
|
*p++ = '\0';
|
|
e->magic = p;
|
|
p = strchr(p, del);
|
|
if (!p)
|
|
goto Einval;
|
|
*p++ = '\0';
|
|
if (!e->magic[0] || strchr(e->magic, '/'))
|
|
goto Einval;
|
|
p = strchr(p, del);
|
|
if (!p)
|
|
goto Einval;
|
|
*p++ = '\0';
|
|
}
|
|
e->interpreter = p;
|
|
p = strchr(p, del);
|
|
if (!p)
|
|
goto Einval;
|
|
*p++ = '\0';
|
|
if (!e->interpreter[0])
|
|
goto Einval;
|
|
|
|
|
|
p = check_special_flags (p, e);
|
|
|
|
if (*p == '\n')
|
|
p++;
|
|
if (p != buf + count)
|
|
goto Einval;
|
|
return e;
|
|
|
|
out:
|
|
return ERR_PTR(err);
|
|
|
|
Efault:
|
|
kfree(e);
|
|
return ERR_PTR(-EFAULT);
|
|
Einval:
|
|
kfree(e);
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
|
|
/*
|
|
* Set status of entry/binfmt_misc:
|
|
* '1' enables, '0' disables and '-1' clears entry/binfmt_misc
|
|
*/
|
|
static int parse_command(const char __user *buffer, size_t count)
|
|
{
|
|
char s[4];
|
|
|
|
if (!count)
|
|
return 0;
|
|
if (count > 3)
|
|
return -EINVAL;
|
|
if (copy_from_user(s, buffer, count))
|
|
return -EFAULT;
|
|
if (s[count-1] == '\n')
|
|
count--;
|
|
if (count == 1 && s[0] == '0')
|
|
return 1;
|
|
if (count == 1 && s[0] == '1')
|
|
return 2;
|
|
if (count == 2 && s[0] == '-' && s[1] == '1')
|
|
return 3;
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* generic stuff */
|
|
|
|
static void entry_status(Node *e, char *page)
|
|
{
|
|
char *dp;
|
|
char *status = "disabled";
|
|
const char * flags = "flags: ";
|
|
|
|
if (test_bit(Enabled, &e->flags))
|
|
status = "enabled";
|
|
|
|
if (!VERBOSE_STATUS) {
|
|
sprintf(page, "%s\n", status);
|
|
return;
|
|
}
|
|
|
|
sprintf(page, "%s\ninterpreter %s\n", status, e->interpreter);
|
|
dp = page + strlen(page);
|
|
|
|
/* print the special flags */
|
|
sprintf (dp, "%s", flags);
|
|
dp += strlen (flags);
|
|
if (e->flags & MISC_FMT_PRESERVE_ARGV0) {
|
|
*dp ++ = 'P';
|
|
}
|
|
if (e->flags & MISC_FMT_OPEN_BINARY) {
|
|
*dp ++ = 'O';
|
|
}
|
|
if (e->flags & MISC_FMT_CREDENTIALS) {
|
|
*dp ++ = 'C';
|
|
}
|
|
*dp ++ = '\n';
|
|
|
|
|
|
if (!test_bit(Magic, &e->flags)) {
|
|
sprintf(dp, "extension .%s\n", e->magic);
|
|
} else {
|
|
int i;
|
|
|
|
sprintf(dp, "offset %i\nmagic ", e->offset);
|
|
dp = page + strlen(page);
|
|
for (i = 0; i < e->size; i++) {
|
|
sprintf(dp, "%02x", 0xff & (int) (e->magic[i]));
|
|
dp += 2;
|
|
}
|
|
if (e->mask) {
|
|
sprintf(dp, "\nmask ");
|
|
dp += 6;
|
|
for (i = 0; i < e->size; i++) {
|
|
sprintf(dp, "%02x", 0xff & (int) (e->mask[i]));
|
|
dp += 2;
|
|
}
|
|
}
|
|
*dp++ = '\n';
|
|
*dp = '\0';
|
|
}
|
|
}
|
|
|
|
static struct inode *bm_get_inode(struct super_block *sb, int mode)
|
|
{
|
|
struct inode * inode = new_inode(sb);
|
|
|
|
if (inode) {
|
|
inode->i_ino = get_next_ino();
|
|
inode->i_mode = mode;
|
|
inode->i_atime = inode->i_mtime = inode->i_ctime =
|
|
current_fs_time(inode->i_sb);
|
|
}
|
|
return inode;
|
|
}
|
|
|
|
static void bm_evict_inode(struct inode *inode)
|
|
{
|
|
clear_inode(inode);
|
|
kfree(inode->i_private);
|
|
}
|
|
|
|
static void kill_node(Node *e)
|
|
{
|
|
struct dentry *dentry;
|
|
|
|
write_lock(&entries_lock);
|
|
dentry = e->dentry;
|
|
if (dentry) {
|
|
list_del_init(&e->list);
|
|
e->dentry = NULL;
|
|
}
|
|
write_unlock(&entries_lock);
|
|
|
|
if (dentry) {
|
|
drop_nlink(dentry->d_inode);
|
|
d_drop(dentry);
|
|
dput(dentry);
|
|
simple_release_fs(&bm_mnt, &entry_count);
|
|
}
|
|
}
|
|
|
|
/* /<entry> */
|
|
|
|
static ssize_t
|
|
bm_entry_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos)
|
|
{
|
|
Node *e = file_inode(file)->i_private;
|
|
ssize_t res;
|
|
char *page;
|
|
|
|
if (!(page = (char*) __get_free_page(GFP_KERNEL)))
|
|
return -ENOMEM;
|
|
|
|
entry_status(e, page);
|
|
|
|
res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page));
|
|
|
|
free_page((unsigned long) page);
|
|
return res;
|
|
}
|
|
|
|
static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
struct dentry *root;
|
|
Node *e = file_inode(file)->i_private;
|
|
int res = parse_command(buffer, count);
|
|
|
|
switch (res) {
|
|
case 1: clear_bit(Enabled, &e->flags);
|
|
break;
|
|
case 2: set_bit(Enabled, &e->flags);
|
|
break;
|
|
case 3: root = dget(file->f_path.dentry->d_sb->s_root);
|
|
mutex_lock(&root->d_inode->i_mutex);
|
|
|
|
kill_node(e);
|
|
|
|
mutex_unlock(&root->d_inode->i_mutex);
|
|
dput(root);
|
|
break;
|
|
default: return res;
|
|
}
|
|
return count;
|
|
}
|
|
|
|
static const struct file_operations bm_entry_operations = {
|
|
.read = bm_entry_read,
|
|
.write = bm_entry_write,
|
|
.llseek = default_llseek,
|
|
};
|
|
|
|
/* /register */
|
|
|
|
static ssize_t bm_register_write(struct file *file, const char __user *buffer,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
Node *e;
|
|
struct inode *inode;
|
|
struct dentry *root, *dentry;
|
|
struct super_block *sb = file->f_path.dentry->d_sb;
|
|
int err = 0;
|
|
|
|
e = create_entry(buffer, count);
|
|
|
|
if (IS_ERR(e))
|
|
return PTR_ERR(e);
|
|
|
|
root = dget(sb->s_root);
|
|
mutex_lock(&root->d_inode->i_mutex);
|
|
dentry = lookup_one_len(e->name, root, strlen(e->name));
|
|
err = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry))
|
|
goto out;
|
|
|
|
err = -EEXIST;
|
|
if (dentry->d_inode)
|
|
goto out2;
|
|
|
|
inode = bm_get_inode(sb, S_IFREG | 0644);
|
|
|
|
err = -ENOMEM;
|
|
if (!inode)
|
|
goto out2;
|
|
|
|
err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
|
|
if (err) {
|
|
iput(inode);
|
|
inode = NULL;
|
|
goto out2;
|
|
}
|
|
|
|
e->dentry = dget(dentry);
|
|
inode->i_private = e;
|
|
inode->i_fop = &bm_entry_operations;
|
|
|
|
d_instantiate(dentry, inode);
|
|
write_lock(&entries_lock);
|
|
list_add(&e->list, &entries);
|
|
write_unlock(&entries_lock);
|
|
|
|
err = 0;
|
|
out2:
|
|
dput(dentry);
|
|
out:
|
|
mutex_unlock(&root->d_inode->i_mutex);
|
|
dput(root);
|
|
|
|
if (err) {
|
|
kfree(e);
|
|
return -EINVAL;
|
|
}
|
|
return count;
|
|
}
|
|
|
|
static const struct file_operations bm_register_operations = {
|
|
.write = bm_register_write,
|
|
.llseek = noop_llseek,
|
|
};
|
|
|
|
/* /status */
|
|
|
|
static ssize_t
|
|
bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
|
|
{
|
|
char *s = enabled ? "enabled\n" : "disabled\n";
|
|
|
|
return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s));
|
|
}
|
|
|
|
static ssize_t bm_status_write(struct file * file, const char __user * buffer,
|
|
size_t count, loff_t *ppos)
|
|
{
|
|
int res = parse_command(buffer, count);
|
|
struct dentry *root;
|
|
|
|
switch (res) {
|
|
case 1: enabled = 0; break;
|
|
case 2: enabled = 1; break;
|
|
case 3: root = dget(file->f_path.dentry->d_sb->s_root);
|
|
mutex_lock(&root->d_inode->i_mutex);
|
|
|
|
while (!list_empty(&entries))
|
|
kill_node(list_entry(entries.next, Node, list));
|
|
|
|
mutex_unlock(&root->d_inode->i_mutex);
|
|
dput(root);
|
|
break;
|
|
default: return res;
|
|
}
|
|
return count;
|
|
}
|
|
|
|
static const struct file_operations bm_status_operations = {
|
|
.read = bm_status_read,
|
|
.write = bm_status_write,
|
|
.llseek = default_llseek,
|
|
};
|
|
|
|
/* Superblock handling */
|
|
|
|
static const struct super_operations s_ops = {
|
|
.statfs = simple_statfs,
|
|
.evict_inode = bm_evict_inode,
|
|
};
|
|
|
|
static int bm_fill_super(struct super_block * sb, void * data, int silent)
|
|
{
|
|
static struct tree_descr bm_files[] = {
|
|
[2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
|
|
[3] = {"register", &bm_register_operations, S_IWUSR},
|
|
/* last one */ {""}
|
|
};
|
|
int err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files);
|
|
if (!err)
|
|
sb->s_op = &s_ops;
|
|
return err;
|
|
}
|
|
|
|
static struct dentry *bm_mount(struct file_system_type *fs_type,
|
|
int flags, const char *dev_name, void *data)
|
|
{
|
|
return mount_single(fs_type, flags, data, bm_fill_super);
|
|
}
|
|
|
|
static struct linux_binfmt misc_format = {
|
|
.module = THIS_MODULE,
|
|
.load_binary = load_misc_binary,
|
|
};
|
|
|
|
static struct file_system_type bm_fs_type = {
|
|
.owner = THIS_MODULE,
|
|
.name = "binfmt_misc",
|
|
.mount = bm_mount,
|
|
.kill_sb = kill_litter_super,
|
|
};
|
|
MODULE_ALIAS_FS("binfmt_misc");
|
|
|
|
static int __init init_misc_binfmt(void)
|
|
{
|
|
int err = register_filesystem(&bm_fs_type);
|
|
if (!err)
|
|
insert_binfmt(&misc_format);
|
|
return err;
|
|
}
|
|
|
|
static void __exit exit_misc_binfmt(void)
|
|
{
|
|
unregister_binfmt(&misc_format);
|
|
unregister_filesystem(&bm_fs_type);
|
|
}
|
|
|
|
core_initcall(init_misc_binfmt);
|
|
module_exit(exit_misc_binfmt);
|
|
MODULE_LICENSE("GPL");
|