| /* |
| * 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/binfmts.h> |
| #include <linux/slab.h> |
| #include <linux/ctype.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; |
| |
| /* |
| * 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, struct pt_regs *regs) |
| { |
| Node *fmt; |
| struct file * interp_file = NULL; |
| char iname[BINPRM_BUF_SIZE]; |
| char *iname_addr = iname; |
| int retval; |
| int fd_binary = -1; |
| |
| retval = -ENOEXEC; |
| if (!enabled) |
| goto _ret; |
| |
| retval = -ENOEXEC; |
| if (bprm->recursion_depth > BINPRM_MAX_RECURSION) |
| goto _ret; |
| |
| /* to keep locking time low, we copy the interpreter string */ |
| read_lock(&entries_lock); |
| fmt = check_file(bprm); |
| if (fmt) |
| strlcpy(iname, fmt->interpreter, BINPRM_BUF_SIZE); |
| read_unlock(&entries_lock); |
| if (!fmt) |
| goto _ret; |
| |
| if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) { |
| retval = remove_arg_zero(bprm); |
| if (retval) |
| goto _ret; |
| } |
| |
| if (fmt->flags & MISC_FMT_OPEN_BINARY) { |
| |
| /* if the binary should be opened on behalf of the |
| * interpreter than keep it open and assign descriptor |
| * to it */ |
| fd_binary = get_unused_fd(); |
| if (fd_binary < 0) { |
| retval = fd_binary; |
| goto _ret; |
| } |
| fd_install(fd_binary, bprm->file); |
| |
| /* 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; |
| |
| allow_write_access(bprm->file); |
| bprm->file = NULL; |
| |
| /* mark the bprm that fd should be passed to interp */ |
| bprm->interp_flags |= BINPRM_FLAGS_EXECFD; |
| bprm->interp_data = fd_binary; |
| |
| } else { |
| allow_write_access(bprm->file); |
| fput(bprm->file); |
| bprm->file = NULL; |
| } |
| /* make argv[1] be the path to the binary */ |
| retval = copy_strings_kernel (1, &bprm->interp, bprm); |
| if (retval < 0) |
| goto _error; |
| bprm->argc++; |
| |
| /* add the interp as argv[0] */ |
| retval = copy_strings_kernel (1, &iname_addr, bprm); |
| if (retval < 0) |
| goto _error; |
| bprm->argc ++; |
| |
| bprm->interp = iname; /* for binfmt_script */ |
| |
| interp_file = open_exec (iname); |
| retval = PTR_ERR (interp_file); |
| if (IS_ERR (interp_file)) |
| goto _error; |
| |
| bprm->file = interp_file; |
| if (fmt->flags & MISC_FMT_CREDENTIALS) { |
| /* |
| * No need to call prepare_binprm(), it's already been |
| * done. bprm->buf is stale, update from interp_file. |
| */ |
| memset(bprm->buf, 0, BINPRM_BUF_SIZE); |
| retval = kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); |
| } else |
| retval = prepare_binprm (bprm); |
| |
| if (retval < 0) |
| goto _error; |
| |
| bprm->recursion_depth++; |
| |
| retval = search_binary_handler (bprm, regs); |
| if (retval < 0) |
| goto _error; |
| |
| _ret: |
| return retval; |
| _error: |
| if (fd_binary > 0) |
| sys_close(fd_binary); |
| bprm->interp_flags = 0; |
| 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 int unquote(char *from) |
| { |
| char c = 0, *s = from, *p = from; |
| |
| while ((c = *s++) != '\0') { |
| if (c == '\\' && *s == 'x') { |
| s++; |
| c = toupper(*s++); |
| *p = (c - (isdigit(c) ? '0' : 'A' - 10)) << 4; |
| c = toupper(*s++); |
| *p++ |= c - (isdigit(c) ? '0' : 'A' - 10); |
| continue; |
| } |
| *p++ = c; |
| } |
| return p - from; |
| } |
| |
| 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 > 256)) |
| 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 = unquote(e->magic); |
| if (e->mask && unquote(e->mask) != 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_mode = mode; |
| inode->i_atime = inode->i_mtime = inode->i_ctime = |
| current_fs_time(inode->i_sb); |
| } |
| return inode; |
| } |
| |
| static void bm_clear_inode(struct 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) { |
| dentry->d_inode->i_nlink--; |
| 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->f_path.dentry->d_inode->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->f_path.dentry->d_inode->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.mnt->mnt_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, |
| }; |
| |
| /* /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.mnt->mnt_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, |
| }; |
| |
| /* /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.mnt->mnt_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); |
| default: return res; |
| } |
| return count; |
| } |
| |
| static const struct file_operations bm_status_operations = { |
| .read = bm_status_read, |
| .write = bm_status_write, |
| }; |
| |
| /* Superblock handling */ |
| |
| static const struct super_operations s_ops = { |
| .statfs = simple_statfs, |
| .clear_inode = bm_clear_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, 0x42494e4d, bm_files); |
| if (!err) |
| sb->s_op = &s_ops; |
| return err; |
| } |
| |
| static int bm_get_sb(struct file_system_type *fs_type, |
| int flags, const char *dev_name, void *data, struct vfsmount *mnt) |
| { |
| return get_sb_single(fs_type, flags, data, bm_fill_super, mnt); |
| } |
| |
| 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", |
| .get_sb = bm_get_sb, |
| .kill_sb = kill_litter_super, |
| }; |
| |
| static int __init init_misc_binfmt(void) |
| { |
| int err = register_filesystem(&bm_fs_type); |
| if (!err) { |
| err = insert_binfmt(&misc_format); |
| if (err) |
| unregister_filesystem(&bm_fs_type); |
| } |
| 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"); |