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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>#include <linux/module.h>#include <linux/hex.h>#include <linux/init.h>#include <linux/sched/mm.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/fs_context.h>#include <linux/syscalls.h>#include <linux/fs.h>#include <linux/uaccess.h>
#include "internal.h"
#ifdef DEBUG# define USE_DEBUG 1#else# define USE_DEBUG 0#endif
enum { VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */};
enum {Enabled, Magic};#define MISC_FMT_PRESERVE_ARGV0 (1UL << 31)#define MISC_FMT_OPEN_BINARY (1UL << 30)#define MISC_FMT_CREDENTIALS (1UL << 29)#define MISC_FMT_OPEN_FILE (1UL << 28)
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 */ const char *interpreter; /* filename of interpreter */ char *name; struct dentry *dentry; struct file *interp_file; refcount_t users; /* sync removal with load_misc_binary() */} Node;
static struct file_system_type bm_fs_type;
/* * 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
/** * search_binfmt_handler - search for a binary handler for @bprm * @misc: handle to binfmt_misc instance * @bprm: binary for which we are looking for a handler * * Search for a binary type handler for @bprm in the list of registered binary * type handlers. * * Return: binary type list entry on success, NULL on failure */static Node *search_binfmt_handler(struct binfmt_misc *misc, struct linux_binprm *bprm){ char *p = strrchr(bprm->interp, '.'); Node *e;
/* Walk all the registered handlers. */ list_for_each_entry(e, &misc->entries, list) { char *s; int j;
/* Make sure this one is currently enabled. */ if (!test_bit(Enabled, &e->flags)) continue;
/* Do matching based on extension if applicable. */ if (!test_bit(Magic, &e->flags)) { if (p && !strcmp(e->magic, p + 1)) return e; continue; }
/* Do matching based on magic & mask. */ 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;}
/** * get_binfmt_handler - try to find a binary type handler * @misc: handle to binfmt_misc instance * @bprm: binary for which we are looking for a handler * * Try to find a binfmt handler for the binary type. If one is found take a * reference to protect against removal via bm_{entry,status}_write(). * * Return: binary type list entry on success, NULL on failure */static Node *get_binfmt_handler(struct binfmt_misc *misc, struct linux_binprm *bprm){ Node *e;
read_lock(&misc->entries_lock); e = search_binfmt_handler(misc, bprm); if (e) refcount_inc(&e->users); read_unlock(&misc->entries_lock); return e;}
/** * put_binfmt_handler - put binary handler node * @e: node to put * * Free node syncing with load_misc_binary() and defer final free to * load_misc_binary() in case it is using the binary type handler we were * requested to remove. */static void put_binfmt_handler(Node *e){ if (refcount_dec_and_test(&e->users)) { if (e->flags & MISC_FMT_OPEN_FILE) filp_close(e->interp_file, NULL); kfree(e); }}
/** * load_binfmt_misc - load the binfmt_misc of the caller's user namespace * * To be called in load_misc_binary() to load the relevant struct binfmt_misc. * If a user namespace doesn't have its own binfmt_misc mount it can make use * of its ancestor's binfmt_misc handlers. This mimicks the behavior of * pre-namespaced binfmt_misc where all registered binfmt_misc handlers where * available to all user and user namespaces on the system. * * Return: the binfmt_misc instance of the caller's user namespace */static struct binfmt_misc *load_binfmt_misc(void){ const struct user_namespace *user_ns; struct binfmt_misc *misc;
user_ns = current_user_ns(); while (user_ns) { /* Pairs with smp_store_release() in bm_fill_super(). */ misc = smp_load_acquire(&user_ns->binfmt_misc); if (misc) return misc;
user_ns = user_ns->parent; }
return &init_binfmt_misc;}
/* * the loader itself */static int load_misc_binary(struct linux_binprm *bprm){ Node *fmt; struct file *interp_file = NULL; int retval = -ENOEXEC; struct binfmt_misc *misc;
misc = load_binfmt_misc(); if (!misc->enabled) return retval;
fmt = get_binfmt_handler(misc, bprm); if (!fmt) return retval;
/* Need to be able to load the file after exec */ retval = -ENOENT; if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE) goto ret;
if (fmt->flags & MISC_FMT_PRESERVE_ARGV0) { bprm->interp_flags |= BINPRM_FLAGS_PRESERVE_ARGV0; } else { retval = remove_arg_zero(bprm); if (retval) goto ret; }
/* make argv[1] be the path to the binary */ retval = copy_string_kernel(bprm->interp, bprm); if (retval < 0) goto ret; bprm->argc++;
/* add the interp as argv[0] */ retval = copy_string_kernel(fmt->interpreter, bprm); if (retval < 0) goto ret; bprm->argc++;
/* Update interp in case binfmt_script needs it. */ retval = bprm_change_interp(fmt->interpreter, bprm); if (retval < 0) goto ret;
if (fmt->flags & MISC_FMT_OPEN_FILE) { interp_file = file_clone_open(fmt->interp_file); if (!IS_ERR(interp_file)) deny_write_access(interp_file); } else { interp_file = open_exec(fmt->interpreter); } retval = PTR_ERR(interp_file); if (IS_ERR(interp_file)) goto ret;
bprm->interpreter = interp_file; if (fmt->flags & MISC_FMT_OPEN_BINARY) bprm->have_execfd = 1; if (fmt->flags & MISC_FMT_CREDENTIALS) bprm->execfd_creds = 1;
retval = 0;ret:
/* * If we actually put the node here all concurrent calls to * load_misc_binary() will have finished. We also know * that for the refcount to be zero someone must have concurently * removed the binary type handler from the list and it's our job to * free it. */ put_binfmt_handler(fmt);
return retval;}
/* 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; } } s[-1] ='\0'; 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': pr_debug("register: flag: P (preserve argv0)\n"); p++; e->flags |= MISC_FMT_PRESERVE_ARGV0; break; case 'O': pr_debug("register: flag: O (open binary)\n"); p++; e->flags |= MISC_FMT_OPEN_BINARY; break; case 'C': pr_debug("register: flag: C (preserve creds)\n"); p++; /* this flags also implies the open-binary flag */ 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; } }
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;
pr_debug("register: received %zu bytes\n", count);
/* 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_KERNEL_ACCOUNT); 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 */
pr_debug("register: delim: %#x {%c}\n", del, del);
/* Pad the buffer with the delim to simplify parsing below. */ memset(buf + count, del, 8);
/* Parse the 'name' field. */ 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;
pr_debug("register: name: {%s}\n", e->name);
/* Parse the 'type' field. */ switch (*p++) { case 'E': pr_debug("register: type: E (extension)\n"); e->flags = 1 << Enabled; break; case 'M': pr_debug("register: type: M (magic)\n"); e->flags = (1 << Enabled) | (1 << Magic); break; default: goto einval; } if (*p++ != del) goto einval;
if (test_bit(Magic, &e->flags)) { /* Handle the 'M' (magic) format. */ char *s;
/* Parse the 'offset' field. */ s = strchr(p, del); if (!s) goto einval; *s = '\0'; if (p != s) { int r = kstrtoint(p, 10, &e->offset); if (r != 0 || e->offset < 0) goto einval; } p = s; if (*p++) goto einval; pr_debug("register: offset: %#x\n", e->offset);
/* Parse the 'magic' field. */ e->magic = p; p = scanarg(p, del); if (!p) goto einval; if (!e->magic[0]) goto einval; if (USE_DEBUG) print_hex_dump_bytes( KBUILD_MODNAME ": register: magic[raw]: ", DUMP_PREFIX_NONE, e->magic, p - e->magic);
/* Parse the 'mask' field. */ e->mask = p; p = scanarg(p, del); if (!p) goto einval; if (!e->mask[0]) { e->mask = NULL; pr_debug("register: mask[raw]: none\n"); } else if (USE_DEBUG) print_hex_dump_bytes( KBUILD_MODNAME ": register: mask[raw]: ", DUMP_PREFIX_NONE, e->mask, p - e->mask);
/* * Decode the magic & mask fields. * Note: while we might have accepted embedded NUL bytes from * above, the unescape helpers here will stop at the first one * it encounters. */ 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 > BINPRM_BUF_SIZE || BINPRM_BUF_SIZE - e->size < e->offset) goto einval; pr_debug("register: magic/mask length: %i\n", e->size); if (USE_DEBUG) { print_hex_dump_bytes( KBUILD_MODNAME ": register: magic[decoded]: ", DUMP_PREFIX_NONE, e->magic, e->size);
if (e->mask) { int i; char *masked = kmalloc(e->size, GFP_KERNEL_ACCOUNT);
print_hex_dump_bytes( KBUILD_MODNAME ": register: mask[decoded]: ", DUMP_PREFIX_NONE, e->mask, e->size);
if (masked) { for (i = 0; i < e->size; ++i) masked[i] = e->magic[i] & e->mask[i]; print_hex_dump_bytes( KBUILD_MODNAME ": register: magic[masked]: ", DUMP_PREFIX_NONE, masked, e->size);
kfree(masked); } } } } else { /* Handle the 'E' (extension) format. */
/* Skip the 'offset' field. */ p = strchr(p, del); if (!p) goto einval; *p++ = '\0';
/* Parse the 'magic' field. */ e->magic = p; p = strchr(p, del); if (!p) goto einval; *p++ = '\0'; if (!e->magic[0] || strchr(e->magic, '/')) goto einval; pr_debug("register: extension: {%s}\n", e->magic);
/* Skip the 'mask' field. */ p = strchr(p, del); if (!p) goto einval; *p++ = '\0'; }
/* Parse the 'interpreter' field. */ e->interpreter = p; p = strchr(p, del); if (!p) goto einval; *p++ = '\0'; if (!e->interpreter[0]) goto einval; pr_debug("register: interpreter: {%s}\n", e->interpreter);
/* Parse the 'flags' field. */ 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 > 3) return -EINVAL; if (copy_from_user(s, buffer, count)) return -EFAULT; if (!count) return 0; 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 = page; const char *status = "disabled";
if (test_bit(Enabled, &e->flags)) status = "enabled";
if (!VERBOSE_STATUS) { sprintf(page, "%s\n", status); return; }
dp += sprintf(dp, "%s\ninterpreter %s\n", status, e->interpreter);
/* print the special flags */ dp += sprintf(dp, "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'; if (e->flags & MISC_FMT_OPEN_FILE) *dp++ = 'F'; *dp++ = '\n';
if (!test_bit(Magic, &e->flags)) { sprintf(dp, "extension .%s\n", e->magic); } else { dp += sprintf(dp, "offset %i\nmagic ", e->offset); dp = bin2hex(dp, e->magic, e->size); if (e->mask) { dp += sprintf(dp, "\nmask "); dp = bin2hex(dp, e->mask, e->size); } *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; simple_inode_init_ts(inode); } return inode;}
/** * i_binfmt_misc - retrieve struct binfmt_misc from a binfmt_misc inode * @inode: inode of the relevant binfmt_misc instance * * This helper retrieves struct binfmt_misc from a binfmt_misc inode. This can * be done without any memory barriers because we are guaranteed that * user_ns->binfmt_misc is fully initialized. It was fully initialized when the * binfmt_misc mount was first created. * * Return: struct binfmt_misc of the relevant binfmt_misc instance */static struct binfmt_misc *i_binfmt_misc(struct inode *inode){ return inode->i_sb->s_user_ns->binfmt_misc;}
/** * bm_evict_inode - cleanup data associated with @inode * @inode: inode to which the data is attached * * Cleanup the binary type handler data associated with @inode if a binary type * entry is removed or the filesystem is unmounted and the super block is * shutdown. * * If the ->evict call was not caused by a super block shutdown but by a write * to remove the entry or all entries via bm_{entry,status}_write() the entry * will have already been removed from the list. We keep the list_empty() check * to make that explicit.*/static void bm_evict_inode(struct inode *inode){ Node *e = inode->i_private;
clear_inode(inode);
if (e) { struct binfmt_misc *misc;
misc = i_binfmt_misc(inode); write_lock(&misc->entries_lock); if (!list_empty(&e->list)) list_del_init(&e->list); write_unlock(&misc->entries_lock); put_binfmt_handler(e); }}
/** * remove_binfmt_handler - remove a binary type handler * @misc: handle to binfmt_misc instance * @e: binary type handler to remove * * Remove a binary type handler from the list of binary type handlers and * remove its associated dentry. This is called from * binfmt_{entry,status}_write(). In the future, we might want to think about * adding a proper ->unlink() method to binfmt_misc instead of forcing caller's * to use writes to files in order to delete binary type handlers. But it has * worked for so long that it's not a pressing issue. */static void remove_binfmt_handler(struct binfmt_misc *misc, Node *e){ write_lock(&misc->entries_lock); list_del_init(&e->list); write_unlock(&misc->entries_lock); locked_recursive_removal(e->dentry, NULL);}
/* /<entry> */
static ssize_tbm_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;
page = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!page) return -ENOMEM;
entry_status(e, page);
res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page));
kfree(page); return res;}
static ssize_t bm_entry_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos){ struct inode *inode = file_inode(file); Node *e = inode->i_private; int res = parse_command(buffer, count);
switch (res) { case 1: /* Disable this handler. */ clear_bit(Enabled, &e->flags); break; case 2: /* Enable this handler. */ set_bit(Enabled, &e->flags); break; case 3: /* Delete this handler. */ inode = d_inode(inode->i_sb->s_root); inode_lock_nested(inode, I_MUTEX_PARENT);
/* * In order to add new element or remove elements from the list * via bm_{entry,register,status}_write() inode_lock() on the * root inode must be held. * The lock is exclusive ensuring that the list can't be * modified. Only load_misc_binary() can access but does so * read-only. So we only need to take the write lock when we * actually remove the entry from the list. */ if (!list_empty(&e->list)) remove_binfmt_handler(i_binfmt_misc(inode), e);
inode_unlock(inode); 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 */
/* add to filesystem */static int add_entry(Node *e, struct super_block *sb){ struct dentry *dentry = simple_start_creating(sb->s_root, e->name); struct inode *inode; struct binfmt_misc *misc;
if (IS_ERR(dentry)) return PTR_ERR(dentry);
inode = bm_get_inode(sb, S_IFREG | 0644); if (unlikely(!inode)) { simple_done_creating(dentry); return -ENOMEM; }
refcount_set(&e->users, 1); e->dentry = dentry; inode->i_private = e; inode->i_fop = &bm_entry_operations;
d_make_persistent(dentry, inode); misc = i_binfmt_misc(inode); write_lock(&misc->entries_lock); list_add(&e->list, &misc->entries); write_unlock(&misc->entries_lock); simple_done_creating(dentry); return 0;}
static ssize_t bm_register_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos){ Node *e; struct super_block *sb = file_inode(file)->i_sb; int err = 0; struct file *f = NULL;
e = create_entry(buffer, count);
if (IS_ERR(e)) return PTR_ERR(e);
if (e->flags & MISC_FMT_OPEN_FILE) { /* * Now that we support unprivileged binfmt_misc mounts make * sure we use the credentials that the register @file was * opened with to also open the interpreter. Before that this * didn't matter much as only a privileged process could open * the register file. */ scoped_with_creds(file->f_cred) f = open_exec(e->interpreter); if (IS_ERR(f)) { pr_notice("register: failed to install interpreter file %s\n", e->interpreter); kfree(e); return PTR_ERR(f); } e->interp_file = f; }
err = add_entry(e, sb); if (err) { if (f) { exe_file_allow_write_access(f); filp_close(f, NULL); } kfree(e); return err; } return count;}
static const struct file_operations bm_register_operations = { .write = bm_register_write, .llseek = noop_llseek,};
/* /status */
static ssize_tbm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos){ struct binfmt_misc *misc; char *s;
misc = i_binfmt_misc(file_inode(file)); s = misc->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){ struct binfmt_misc *misc; int res = parse_command(buffer, count); Node *e, *next; struct inode *inode;
misc = i_binfmt_misc(file_inode(file)); switch (res) { case 1: /* Disable all handlers. */ misc->enabled = false; break; case 2: /* Enable all handlers. */ misc->enabled = true; break; case 3: /* Delete all handlers. */ inode = d_inode(file_inode(file)->i_sb->s_root); inode_lock_nested(inode, I_MUTEX_PARENT);
/* * In order to add new element or remove elements from the list * via bm_{entry,register,status}_write() inode_lock() on the * root inode must be held. * The lock is exclusive ensuring that the list can't be * modified. Only load_misc_binary() can access but does so * read-only. So we only need to take the write lock when we * actually remove the entry from the list. */ list_for_each_entry_safe(e, next, &misc->entries, list) remove_binfmt_handler(misc, e);
inode_unlock(inode); 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 void bm_put_super(struct super_block *sb){ struct user_namespace *user_ns = sb->s_fs_info;
sb->s_fs_info = NULL; put_user_ns(user_ns);}
static const struct super_operations s_ops = { .statfs = simple_statfs, .evict_inode = bm_evict_inode, .put_super = bm_put_super,};
static int bm_fill_super(struct super_block *sb, struct fs_context *fc){ int err; struct user_namespace *user_ns = sb->s_user_ns; struct binfmt_misc *misc; static const struct tree_descr bm_files[] = { [2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO}, [3] = {"register", &bm_register_operations, S_IWUSR}, /* last one */ {""} };
if (WARN_ON(user_ns != current_user_ns())) return -EINVAL;
/* * Lazily allocate a new binfmt_misc instance for this namespace, i.e. * do it here during the first mount of binfmt_misc. We don't need to * waste memory for every user namespace allocation. It's likely much * more common to not mount a separate binfmt_misc instance than it is * to mount one. * * While multiple superblocks can exist they are keyed by userns in * s_fs_info for binfmt_misc. Hence, the vfs guarantees that * bm_fill_super() is called exactly once whenever a binfmt_misc * superblock for a userns is created. This in turn lets us conclude * that when a binfmt_misc superblock is created for the first time for * a userns there's no one racing us. Therefore we don't need any * barriers when we dereference binfmt_misc. */ misc = user_ns->binfmt_misc; if (!misc) { /* * If it turns out that most user namespaces actually want to * register their own binary type handler and therefore all * create their own separate binfmt_misc mounts we should * consider turning this into a kmem cache. */ misc = kzalloc_obj(struct binfmt_misc); if (!misc) return -ENOMEM;
INIT_LIST_HEAD(&misc->entries); rwlock_init(&misc->entries_lock);
/* Pairs with smp_load_acquire() in load_binfmt_misc(). */ smp_store_release(&user_ns->binfmt_misc, misc); }
/* * When the binfmt_misc superblock for this userns is shutdown * ->enabled might have been set to false and we don't reinitialize * ->enabled again in put_super() as someone might already be mounting * binfmt_misc again. It also would be pointless since by the time * ->put_super() is called we know that the binary type list for this * bintfmt_misc mount is empty making load_misc_binary() return * -ENOEXEC independent of whether ->enabled is true. Instead, if * someone mounts binfmt_misc for the first time or again we simply * reset ->enabled to true. */ misc->enabled = true;
err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files); if (!err) sb->s_op = &s_ops; return err;}
static void bm_free(struct fs_context *fc){ if (fc->s_fs_info) put_user_ns(fc->s_fs_info);}
static int bm_get_tree(struct fs_context *fc){ return get_tree_keyed(fc, bm_fill_super, get_user_ns(fc->user_ns));}
static const struct fs_context_operations bm_context_ops = { .free = bm_free, .get_tree = bm_get_tree,};
static int bm_init_fs_context(struct fs_context *fc){ fc->ops = &bm_context_ops; return 0;}
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", .init_fs_context = bm_init_fs_context, .fs_flags = FS_USERNS_MOUNT, .kill_sb = kill_anon_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_DESCRIPTION("Kernel support for miscellaneous binaries");MODULE_LICENSE("GPL");