Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 * /proc/sys support

 */

#include <linux/sysctl.h>

#include <linux/proc_fs.h>

#include <linux/security.h>

#include "internal.h"

static struct dentry_operations proc_sys_dentry_operations;

static const struct file_operations proc_sys_file_operations;

static struct inode_operations proc_sys_inode_operations;

static void proc_sys_refresh_inode(struct inode *inode, struct ctl_table *table)

{

        /* Refresh the cached information bits in the inode */

        if (table) {

                inode->i_uid = 0;

                inode->i_gid = 0;

                inode->i_mode = table->mode;

                if (table->proc_handler) {

                        inode->i_mode |= S_IFREG;

                        inode->i_nlink = 1;

                } else {

                        inode->i_mode |= S_IFDIR;

                        inode->i_nlink = 0;      /* It is too hard to figure out */

                }

        }

}

static struct inode *proc_sys_make_inode(struct inode *dir, struct ctl_table *table)

{

        struct inode *inode;

        struct proc_inode *dir_ei, *ei;

        int depth;

        inode = new_inode(dir->i_sb);

        if (!inode)

                goto out;

        /* A directory is always one deeper than it's parent */

        dir_ei = PROC_I(dir);

        depth = dir_ei->fd + 1;

        ei = PROC_I(inode);

        ei->fd = depth;

        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;

        inode->i_op = &proc_sys_inode_operations;

        inode->i_fop = &proc_sys_file_operations;

        inode->i_flags |= S_PRIVATE; /* tell selinux to ignore this inode */

        proc_sys_refresh_inode(inode, table);

out:

        return inode;

}

static struct dentry *proc_sys_ancestor(struct dentry *dentry, int depth)

{

        for (;;) {

                struct proc_inode *ei;

                ei = PROC_I(dentry->d_inode);

                if (ei->fd == depth)

                        break; /* found */

                dentry = dentry->d_parent;

        }

        return dentry;

}

static struct ctl_table *proc_sys_lookup_table_one(struct ctl_table *table,

                                                        struct qstr *name)

{

        int len;

        for ( ; table->ctl_name || table->procname; table++) {

                if (!table->procname)

                        continue;

                len = strlen(table->procname);

                if (len != name->len)

                        continue;

                if (memcmp(table->procname, name->name, len) != 0)

                        continue;

                /* I have a match */

                return table;

        }

        return NULL;

}

static struct ctl_table *proc_sys_lookup_table(struct dentry *dentry,

                                                struct ctl_table *table)

{

        struct dentry *ancestor;

        struct proc_inode *ei;

        int depth, i;

        ei = PROC_I(dentry->d_inode);

        depth = ei->fd;

        if (depth == 0)

                return table;

        for (i = 1; table && (i <= depth); i++) {

                ancestor = proc_sys_ancestor(dentry, i);

                table = proc_sys_lookup_table_one(table, &ancestor->d_name);

                if (table)

                        table = table->child;

        }

        return table;

}

static struct ctl_table *proc_sys_lookup_entry(struct dentry *dparent,

                                                struct qstr *name,

                                                struct ctl_table *table)

{

        table = proc_sys_lookup_table(dparent, table);

        if (table)

                table = proc_sys_lookup_table_one(table, name);

        return table;

}

static struct ctl_table *do_proc_sys_lookup(struct dentry *parent,

                                                struct qstr *name,

                                                struct ctl_table_header **ptr)

{

        struct ctl_table_header *head;

        struct ctl_table *table = NULL;

        for (head = sysctl_head_next(NULL); head;

                        head = sysctl_head_next(head)) {

                table = proc_sys_lookup_entry(parent, name, head->ctl_table);

                if (table)

                        break;

        }

        *ptr = head;

        return table;

}

static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,

                                        struct nameidata *nd)

{

        struct ctl_table_header *head;

        struct inode *inode;

        struct dentry *err;

        struct ctl_table *table;

        err = ERR_PTR(-ENOENT);

        table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);

        if (!table)

                goto out;

        err = ERR_PTR(-ENOMEM);

        inode = proc_sys_make_inode(dir, table);

        if (!inode)

                goto out;

        err = NULL;

        dentry->d_op = &proc_sys_dentry_operations;

        d_add(dentry, inode);

out:

        sysctl_head_finish(head);

        return err;

}

static ssize_t proc_sys_read(struct file *filp, char __user *buf,

                                size_t count, loff_t *ppos)

{

        struct dentry *dentry = filp->f_dentry;

        struct ctl_table_header *head;

        struct ctl_table *table;

        ssize_t error;

        size_t res;

        table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);

        /* Has the sysctl entry disappeared on us? */

        error = -ENOENT;

        if (!table)

                goto out;

        /* Has the sysctl entry been replaced by a directory? */

        error = -EISDIR;

        if (!table->proc_handler)

                goto out;

        /*

         * At this point we know that the sysctl was not unregistered

         * and won't be until we finish.

         */

        error = -EPERM;

        if (sysctl_perm(table, MAY_READ))

                goto out;

        /* careful: calling conventions are nasty here */

        res = count;

        error = table->proc_handler(table, 0, filp, buf, &res, ppos);

        if (!error)

                error = res;

out:

        sysctl_head_finish(head);

        return error;

}

static ssize_t proc_sys_write(struct file *filp, const char __user *buf,

                                size_t count, loff_t *ppos)

{

        struct dentry *dentry = filp->f_dentry;

        struct ctl_table_header *head;

        struct ctl_table *table;

        ssize_t error;

        size_t res;

        table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);

        /* Has the sysctl entry disappeared on us? */

        error = -ENOENT;

        if (!table)

                goto out;

        /* Has the sysctl entry been replaced by a directory? */

        error = -EISDIR;

        if (!table->proc_handler)

                goto out;

        /*

         * At this point we know that the sysctl was not unregistered

         * and won't be until we finish.

         */

        error = -EPERM;

        if (sysctl_perm(table, MAY_WRITE))

                goto out;

        /* careful: calling conventions are nasty here */

        res = count;

        error = table->proc_handler(table, 1, filp, (char __user *)buf,

                                    &res, ppos);

        if (!error)

                error = res;

out:

        sysctl_head_finish(head);

        return error;

}

static int proc_sys_fill_cache(struct file *filp, void *dirent,

                                filldir_t filldir, struct ctl_table *table)

{

        struct ctl_table_header *head;

        struct ctl_table *child_table = NULL;

        struct dentry *child, *dir = filp->f_path.dentry;

        struct inode *inode;

        struct qstr qname;

        ino_t ino = 0;

        unsigned type = DT_UNKNOWN;

        int ret;

        qname.name = table->procname;

        qname.len  = strlen(table->procname);

        qname.hash = full_name_hash(qname.name, qname.len);

        /* Suppress duplicates.

         * Only fill a directory entry if it is the value that

         * an ordinary lookup of that name returns.  Hide all

         * others.

         *

         * If we ever cache this translation in the dcache

         * I should do a dcache lookup first.  But for now

         * it is just simpler not to.

         */

        ret = 0;

        child_table = do_proc_sys_lookup(dir, &qname, &head);

        sysctl_head_finish(head);

        if (child_table != table)

                return 0;

        child = d_lookup(dir, &qname);

        if (!child) {

                struct dentry *new;

                new = d_alloc(dir, &qname);

                if (new) {

                        inode = proc_sys_make_inode(dir->d_inode, table);

                        if (!inode)

                                child = ERR_PTR(-ENOMEM);

                        else {

                                new->d_op = &proc_sys_dentry_operations;

                                d_add(new, inode);

                        }

                        if (child)

                                dput(new);

                        else

                                child = new;

                }

        }

        if (!child || IS_ERR(child) || !child->d_inode)

                goto end_instantiate;

        inode = child->d_inode;

        if (inode) {

                ino  = inode->i_ino;

                type = inode->i_mode >> 12;

        }

        dput(child);

end_instantiate:

        if (!ino)

                ino= find_inode_number(dir, &qname);

        if (!ino)

                ino = 1;

        return filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);

}

static int proc_sys_readdir(struct file *filp, void *dirent, filldir_t filldir)

{

        struct dentry *dentry = filp->f_dentry;

        struct inode *inode = dentry->d_inode;

        struct ctl_table_header *head = NULL;

        struct ctl_table *table;

        unsigned long pos;

        int ret;

        ret = -ENOTDIR;

        if (!S_ISDIR(inode->i_mode))

                goto out;

        ret = 0;

        /* Avoid a switch here: arm builds fail with missing __cmpdi2 */

        if (filp->f_pos == 0) {

                if (filldir(dirent, ".", 1, filp->f_pos,

                                inode->i_ino, DT_DIR) < 0)

                        goto out;

                filp->f_pos++;

        }

        if (filp->f_pos == 1) {

                if (filldir(dirent, "..", 2, filp->f_pos,

                                parent_ino(dentry), DT_DIR) < 0)

                        goto out;

                filp->f_pos++;

        }

        pos = 2;

        /* - Find each instance of the directory

         * - Read all entries in each instance

         * - Before returning an entry to user space lookup the entry

         *   by name and if I find a different entry don't return

         *   this one because it means it is a buried dup.

         * For sysctl this should only happen for directory entries.

         */

        for (head = sysctl_head_next(NULL); head; head = sysctl_head_next(head)) {

                table = proc_sys_lookup_table(dentry, head->ctl_table);

                if (!table)

                        continue;

                for (; table->ctl_name || table->procname; table++, pos++) {

                        /* Can't do anything without a proc name */

                        if (!table->procname)

                                continue;

                        if (pos < filp->f_pos)

                                continue;

                        if (proc_sys_fill_cache(filp, dirent, filldir, table) < 0)

                                goto out;

                        filp->f_pos = pos + 1;

                }

        }

        ret = 1;

out:

        sysctl_head_finish(head);

        return ret;

}

static int proc_sys_permission(struct inode *inode, int mask, struct nameidata *nd)

{

        /*

         * sysctl entries that are not writeable,

         * are _NOT_ writeable, capabilities or not.

         */

        struct ctl_table_header *head;

        struct ctl_table *table;

        struct dentry *dentry;

        int mode;

        int depth;

        int error;

        head = NULL;

        depth = PROC_I(inode)->fd;

        /* First check the cached permissions, in case we don't have

         * enough information to lookup the sysctl table entry.

         */

        error = -EACCES;

        mode = inode->i_mode;

        if (current->euid == 0)

                mode >>= 6;

        else if (in_group_p(0))

                mode >>= 3;

        if ((mode & mask & (MAY_READ|MAY_WRITE|MAY_EXEC)) == mask)

                error = 0;

        /* If we can't get a sysctl table entry the permission

         * checks on the cached mode will have to be enough.

         */

        if (!nd || !depth)

                goto out;

        dentry = nd->dentry;

        table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);

        /* If the entry does not exist deny permission */

        error = -EACCES;

        if (!table)

                goto out;

        /* Use the permissions on the sysctl table entry */

        error = sysctl_perm(table, mask);

out:

        sysctl_head_finish(head);

        return error;

}

static int proc_sys_setattr(struct dentry *dentry, struct iattr *attr)

{

        struct inode *inode = dentry->d_inode;

        int error;

        if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))

                return -EPERM;

        error = inode_change_ok(inode, attr);

        if (!error)

                error = inode_setattr(inode, attr);

        return error;

}

/* I'm lazy and don't distinguish between files and directories,

 * until access time.

 */

static const struct file_operations proc_sys_file_operations = {

        .read           = proc_sys_read,

        .write          = proc_sys_write,

        .readdir        = proc_sys_readdir,

};

static struct inode_operations proc_sys_inode_operations = {

        .lookup         = proc_sys_lookup,

        .permission     = proc_sys_permission,

        .setattr        = proc_sys_setattr,

};

static int proc_sys_revalidate(struct dentry *dentry, struct nameidata *nd)

{

        struct ctl_table_header *head;

        struct ctl_table *table;

        table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);

        proc_sys_refresh_inode(dentry->d_inode, table);

        sysctl_head_finish(head);

        return !!table;

}

static struct dentry_operations proc_sys_dentry_operations = {

        .d_revalidate   = proc_sys_revalidate,

};

static struct proc_dir_entry *proc_sys_root;

int proc_sys_init(void)

{

        proc_sys_root = proc_mkdir("sys", NULL);

        proc_sys_root->proc_iops = &proc_sys_inode_operations;

        proc_sys_root->proc_fops = &proc_sys_file_operations;

        proc_sys_root->nlink = 0;

        return 0;

}