1 files changed, 780 insertions, 0 deletions

diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
new file mode 100644
index 000000000000..8ae0db6cd69c
--- /dev/null
+++ b/fs/binfmt_misc.c
@@ -0,0 +1,780 @@
+/*
+ *  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/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 <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 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;
+        struct files_struct *files = NULL;
+
+        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)
+                strlcpy(iname, fmt->interpreter, BINPRM_BUF_SIZE);
+        read_unlock(&entries_lock);
+        if (!fmt)
+                goto _ret;
+
+        if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
+                remove_arg_zero(bprm);
+        }
+
+        if (fmt->flags & MISC_FMT_OPEN_BINARY) {
+
+                files = current->files;
+                retval = unshare_files();
+                if (retval < 0)
+                        goto _ret;
+                if (files == current->files) {
+                        put_files_struct(files);
+                        files = NULL;
+                }
+                /* 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 _unshare;
+                }
+                fd_install(fd_binary, bprm->file);
+
+                /* if the binary is not readable than enforce mm->dumpable=0
+                   regardless of the interpreter's permissions */
+                if (permission(bprm->file->f_dentry->d_inode, MAY_READ, NULL))
+                        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;
+
+        retval = search_binary_handler (bprm, regs);
+        if (retval < 0)
+                goto _error;
+
+        if (files) {
+                steal_locks(files);
+                put_files_struct(files);
+                files = NULL;
+        }
+_ret:
+        return retval;
+_error:
+        if (fd_binary > 0)
+                sys_close(fd_binary);
+        bprm->interp_flags = 0;
+        bprm->interp_data = 0;
+_unshare:
+        if (files) {
+                put_files_struct(current->files);
+                current->files = files;
+        }
+        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 inline 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 = (Node *) 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_uid = 0;
+                inode->i_gid = 0;
+                inode->i_blksize = PAGE_CACHE_SIZE;
+                inode->i_blocks = 0;
+                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->u.generic_ip);
+}
+
+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_dentry->d_inode->u.generic_ip;
+        loff_t pos = *ppos;
+        ssize_t res;
+        char *page;
+        int len;
+
+        if (!(page = (char*) __get_free_page(GFP_KERNEL)))
+                return -ENOMEM;
+
+        entry_status(e, page);
+        len = strlen(page);
+
+        res = -EINVAL;
+        if (pos < 0)
+                goto out;
+        res = 0;
+        if (pos >= len)
+                goto out;
+        if (len < pos + nbytes)
+                nbytes = len - pos;
+        res = -EFAULT;
+        if (copy_to_user(buf, page + pos, nbytes))
+                goto out;
+        *ppos = pos + nbytes;
+        res = nbytes;
+out:
+        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_dentry->d_inode->u.generic_ip;
+        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_vfsmnt->mnt_sb->s_root);
+                        down(&root->d_inode->i_sem);
+
+                        kill_node(e);
+
+                        up(&root->d_inode->i_sem);
+                        dput(root);
+                        break;
+                default: return res;
+        }
+        return count;
+}
+
+static 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_vfsmnt->mnt_sb;
+        int err = 0;
+
+        e = create_entry(buffer, count);
+
+        if (IS_ERR(e))
+                return PTR_ERR(e);
+
+        root = dget(sb->s_root);
+        down(&root->d_inode->i_sem);
+        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("binfmt_misc", &bm_mnt, &entry_count);
+        if (err) {
+                iput(inode);
+                inode = NULL;
+                goto out2;
+        }
+
+        e->dentry = dget(dentry);
+        inode->u.generic_ip = 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:
+        up(&root->d_inode->i_sem);
+        dput(root);
+
+        if (err) {
+                kfree(e);
+                return -EINVAL;
+        }
+        return count;
+}
+
+static 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" : "disabled";
+        int len = strlen(s);
+        loff_t pos = *ppos;
+
+        if (pos < 0)
+                return -EINVAL;
+        if (pos >= len)
+                return 0;
+        if (len < pos + nbytes)
+                nbytes = len - pos;
+        if (copy_to_user(buf, s + pos, nbytes))
+                return -EFAULT;
+        *ppos = pos + nbytes;
+        return nbytes;
+}
+
+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_vfsmnt->mnt_sb->s_root);
+                        down(&root->d_inode->i_sem);
+
+                        while (!list_empty(&entries))
+                                kill_node(list_entry(entries.next, Node, list));
+
+                        up(&root->d_inode->i_sem);
+                        dput(root);
+                default: return res;
+        }
+        return count;
+}
+
+static struct file_operations bm_status_operations = {
+        .read           = bm_status_read,
+        .write          = bm_status_write,
+};
+
+/* Superblock handling */
+
+static 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[] = {
+                [1] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
+                [2] = {"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 struct super_block *bm_get_sb(struct file_system_type *fs_type,
+        int flags, const char *dev_name, void *data)
+{
+        return get_sb_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",
+        .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 = register_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");