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/*

 * sysctl.c: General linux system control interface

 *

 * Begun 24 March 1995, Stephen Tweedie

 * Added /proc support, Dec 1995

 * Added bdflush entry and intvec min/max checking, 2/23/96, Tom Dyas.

 * Added hooks for /proc/sys/net (minor, minor patch), 96/4/1, Mike Shaver.

 * Added kernel/java-{interpreter,appletviewer}, 96/5/10, Mike Shaver.

 */

/*

 * uClinux revisions for NO_MM

 * Copyright (C) 1998  Kenneth Albanowski <kjahds@kjahds.com>,

 *                     The Silver Hammer Group, Ltd.

 */

#include <linux/config.h>

#include <linux/sched.h>

#include <linux/mm.h>

#include <linux/sysctl.h>

#include <linux/swapctl.h>

#include <linux/proc_fs.h>

#include <linux/malloc.h>

#include <linux/stat.h>

#include <linux/ctype.h>

#include <asm/bitops.h>

#include <asm/segment.h>

#include <linux/utsname.h>

#include <linux/swapctl.h>

/* External variables not in a header file. */

extern int panic_timeout;

#ifdef CONFIG_ROOT_NFS

#include <linux/nfs_fs.h>

#endif

static ctl_table root_table[];

static struct ctl_table_header root_table_header =

        {root_table, DNODE_SINGLE(&root_table_header)};

static int parse_table(int *, int, void *, size_t *, void *, size_t,

                       ctl_table *, void **);

static ctl_table kern_table[];

static ctl_table vm_table[];

extern ctl_table net_table[];

/* /proc declarations: */

#ifdef CONFIG_PROC_FS

static int proc_readsys(struct inode * inode, struct file * file,

                        char * buf, int count);

static int proc_writesys(struct inode * inode, struct file * file,

                         const char * buf, int count);

static int proc_sys_permission(struct inode *, int);

struct file_operations proc_sys_file_operations =

{

        NULL,           /* lseek   */

        proc_readsys,   /* read    */

        proc_writesys,  /* write   */

        NULL,           /* readdir */

        NULL,           /* select  */

        NULL,           /* ioctl   */

        NULL,           /* mmap    */

        NULL,           /* no special open code    */

        NULL,           /* no special release code */

        NULL            /* can't fsync */

};

struct inode_operations proc_sys_inode_operations =

{

        &proc_sys_file_operations,

        NULL,           /* create */

        NULL,           /* lookup */

        NULL,           /* link */

        NULL,           /* unlink */

        NULL,           /* symlink */

        NULL,           /* mkdir */

        NULL,           /* rmdir */

        NULL,           /* mknod */

        NULL,           /* rename */

        NULL,           /* readlink */

        NULL,           /* follow_link */

        NULL,           /* readpage */

        NULL,           /* writepage */

        NULL,           /* bmap */

        NULL,           /* truncate */

        proc_sys_permission

};

extern struct proc_dir_entry proc_sys_root;

static void register_proc_table(ctl_table *, struct proc_dir_entry *);

static void unregister_proc_table(ctl_table *, struct proc_dir_entry *);

#endif

extern int bdf_prm[], bdflush_min[], bdflush_max[];

static int do_securelevel_strategy (ctl_table *, int *, int, void *, size_t *,

                                    void *, size_t, void **);

extern char binfmt_java_interpreter[], binfmt_java_appletviewer[];

/* The default sysctl tables: */

static ctl_table root_table[] = {

        {CTL_KERN, "kernel", NULL, 0, 0555, kern_table},

        {CTL_VM, "vm", NULL, 0, 0555, vm_table},

        {CTL_NET, "net", NULL, 0, 0555, net_table},

        {0}

};

static ctl_table kern_table[] = {

        {KERN_OSTYPE, "ostype", system_utsname.sysname, 64,

         0444, NULL, &proc_dostring, &sysctl_string},

        {KERN_OSRELEASE, "osrelease", system_utsname.release, 64,

         0444, NULL, &proc_dostring, &sysctl_string},

        {KERN_VERSION, "version", system_utsname.version, 64,

         0444, NULL, &proc_dostring, &sysctl_string},

        {KERN_NODENAME, "hostname", system_utsname.nodename, 64,

         0644, NULL, &proc_dostring, &sysctl_string},

        {KERN_DOMAINNAME, "domainname", system_utsname.domainname, 64,

         0644, NULL, &proc_dostring, &sysctl_string},

        {KERN_NRINODE, "inode-nr", &nr_inodes, 2*sizeof(int),

         0444, NULL, &proc_dointvec},

        {KERN_MAXINODE, "inode-max", &max_inodes, sizeof(int),

         0644, NULL, &proc_dointvec},

        {KERN_NRFILE, "file-nr", &nr_files, sizeof(int),

         0444, NULL, &proc_dointvec},

        {KERN_MAXFILE, "file-max", &max_files, sizeof(int),

         0644, NULL, &proc_dointvec},

        {KERN_SECURELVL, "securelevel", &securelevel, sizeof(int),

         0444, NULL, &proc_dointvec, (ctl_handler *)&do_securelevel_strategy},

        {KERN_PANIC, "panic", &panic_timeout, sizeof(int),

         0644, NULL, &proc_dointvec},

#ifdef CONFIG_BLK_DEV_INITRD

        {KERN_REALROOTDEV, "real-root-dev", &real_root_dev, sizeof(int),

         0644, NULL, &proc_dointvec},

#endif

#ifdef CONFIG_ROOT_NFS

        {KERN_NFSRNAME, "nfs-root-name", nfs_root_name, NFS_ROOT_NAME_LEN,

         0644, NULL, &proc_dostring, &sysctl_string },

        {KERN_NFSRADDRS, "nfs-root-addrs", nfs_root_addrs, NFS_ROOT_ADDRS_LEN,

         0644, NULL, &proc_dostring, &sysctl_string },

#endif

#ifdef CONFIG_BINFMT_JAVA

        {KERN_JAVA_INTERPRETER, "java-interpreter", binfmt_java_interpreter,

         64, 0644, NULL, &proc_dostring, &sysctl_string },

        {KERN_JAVA_APPLETVIEWER, "java-appletviewer", binfmt_java_appletviewer,

         64, 0644, NULL, &proc_dostring, &sysctl_string },

#endif

        {0}

};

static ctl_table vm_table[] = {

#ifndef NO_MM

        {VM_SWAPCTL, "swapctl",

         &swap_control, sizeof(swap_control_t), 0600, NULL, &proc_dointvec},

        {VM_KSWAPD, "kswapd",

         &kswapd_ctl, sizeof(kswapd_ctl), 0600, NULL, &proc_dointvec},

        {VM_FREEPG, "freepages",

         &min_free_pages, 3*sizeof(int), 0600, NULL, &proc_dointvec},

        {VM_BDFLUSH, "bdflush", &bdf_prm, 9*sizeof(int), 0600, NULL,

         &proc_dointvec_minmax, &sysctl_intvec, NULL,

         &bdflush_min, &bdflush_max},

#endif /* !NO_MM */

        {0}

};

void sysctl_init(void)

{

#ifdef CONFIG_PROC_FS

        register_proc_table(root_table, &proc_sys_root);

#endif

}

int do_sysctl (int *name, int nlen,

               void *oldval, size_t *oldlenp,

               void *newval, size_t newlen)

{

        int error;

        struct ctl_table_header *tmp;

        void *context;

        if (nlen <= 0 || nlen >= CTL_MAXNAME)

                return -ENOTDIR;

        error = verify_area(VERIFY_READ,name,nlen*sizeof(int));

        if (error) return error;

        if (oldval) {

                if (!oldlenp)

                        return -EFAULT;

                error = verify_area(VERIFY_WRITE,oldlenp,sizeof(size_t));

                if (error) return error;

                error = verify_area(VERIFY_WRITE,oldval,get_user(oldlenp));

                if (error) return error;

        }

        if (newval) {

                error = verify_area(VERIFY_READ,newval,newlen);

                if (error) return error;

        }

        tmp = &root_table_header;

        do {

                context = 0;

                error = parse_table(name, nlen, oldval, oldlenp,

                                    newval, newlen, tmp->ctl_table, &context);

                if (context)

                        kfree(context);

                if (error != -ENOTDIR)

                        return error;

                tmp = tmp->DLIST_NEXT(ctl_entry);

        } while (tmp != &root_table_header);

        return -ENOTDIR;

}

extern asmlinkage int sys_sysctl(struct __sysctl_args *args)

{

        struct __sysctl_args tmp;

        int error;

        error = verify_area(VERIFY_READ, args, sizeof(*args));

        if (error)

                return error;

        memcpy_fromfs(&tmp, args, sizeof(tmp));

        return do_sysctl(tmp.name, tmp.nlen, tmp.oldval, tmp.oldlenp,

                         tmp.newval, tmp.newlen);

}

/* Like in_group_p, but testing against egid, not fsgid */

static int in_egroup_p(gid_t grp)

{

        int     i;

        if (grp == current->egid)

                return 1;

        for (i = 0; i < NGROUPS; i++) {

                if (current->groups[i] == NOGROUP)

                        break;

                if (current->groups[i] == grp)

                        return 1;

        }

        return 0;

}

/* ctl_perm does NOT grant the superuser all rights automatically, because

   some sysctl variables are readonly even to root. */

static int test_perm(int mode, int op)

{

        if (!current->euid)

                mode >>= 6;

        else if (in_egroup_p(0))

                mode >>= 3;

        if ((mode & op & 0007) == op)

                return 0;

        return -EACCES;

}

static inline int ctl_perm(ctl_table *table, int op)

{

        return test_perm(table->mode, op);

}

static int parse_table(int *name, int nlen,

                       void *oldval, size_t *oldlenp,

                       void *newval, size_t newlen,

                       ctl_table *table, void **context)

{

        int error;

repeat:

        if (!nlen)

                return -ENOTDIR;

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

                if (get_user(name) == table->ctl_name ||

                    table->ctl_name == CTL_ANY) {

                        if (table->child) {

                                if (ctl_perm(table, 001))

                                        return -EPERM;

                                if (table->strategy) {

                                        error = table->strategy(

                                                table, name, nlen,

                                                oldval, oldlenp,

                                                newval, newlen, context);

                                if (error)

                                        return error;

                                }

                                name++;

                                nlen--;

                                table = table->child;

                                goto repeat;

                        }

                        error = do_sysctl_strategy(table, name, nlen,

                                                   oldval, oldlenp,

                                                   newval, newlen, context);

                        return error;

                }

        };

        return -ENOTDIR;

}

/* Perform the actual read/write of a sysctl table entry. */

int do_sysctl_strategy (ctl_table *table,

                        int *name, int nlen,

                        void *oldval, size_t *oldlenp,

                        void *newval, size_t newlen, void **context)

{

        int op = 0, rc, len;

        if (oldval)

                op |= 004;

        if (newval)

                op |= 002;

        if (ctl_perm(table, op))

                if( table->data != &securelevel || current->euid)

                        return -EPERM;

        if (table->strategy) {

                rc = table->strategy(table, name, nlen, oldval, oldlenp,

                                     newval, newlen, context);

                if (rc < 0)

                        return rc;

                if (rc > 0)

                        return 0;

        }

        /* If there is no strategy routine, or if the strategy returns

         * zero, proceed with automatic r/w */

        if (table->data && table->maxlen) {

                if (oldval && oldlenp && get_user(oldlenp)) {

                        len = get_user(oldlenp);

                        if (len > table->maxlen)

                                len = table->maxlen;

                        memcpy_tofs(oldval, table->data, len);

                        put_user(len, oldlenp);

                }

                if (newval && newlen) {

                        len = newlen;

                        if (len > table->maxlen)

                                len = table->maxlen;

                        memcpy_fromfs(table->data, newval, len);

                }

        }

        return 0;

}

/*

 * This function only checks permission for changing the security level

 * If the tests are successful, the actual change is done by

 * do_sysctl_strategy

 */

static int do_securelevel_strategy (ctl_table *table,

                                    int *name, int nlen,

                                    void *oldval, size_t *oldlenp,

                                    void *newval, size_t newlen, void **context)

{

        int level;

        if (newval && newlen) {

                if (newlen != sizeof (int))

                        return -EINVAL;

                memcpy_fromfs (&level, newval, newlen);

                if (level < securelevel && current->pid != 1)

                        return -EPERM;

        }

        return 0;

}

struct ctl_table_header *register_sysctl_table(ctl_table * table,

                                               int insert_at_head)

{

        struct ctl_table_header *tmp;

        tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);

        if (!tmp)

                return 0;

        *tmp = ((struct ctl_table_header) {table, DNODE_NULL});

        if (insert_at_head)

                DLIST_INSERT_AFTER(&root_table_header, tmp, ctl_entry);

        else

                DLIST_INSERT_BEFORE(&root_table_header, tmp, ctl_entry);

#ifdef CONFIG_PROC_FS

        register_proc_table(table, &proc_sys_root);

#endif

        return tmp;

}

void unregister_sysctl_table(struct ctl_table_header * header)

{

        DLIST_DELETE(header, ctl_entry);

#ifdef CONFIG_PROC_FS

        unregister_proc_table(header->ctl_table, &proc_sys_root);

#endif

        kfree(header);

}

/*

 * /proc/sys support

 */

#ifdef CONFIG_PROC_FS

/* Scan the sysctl entries in table and add them all into /proc */

static void register_proc_table(ctl_table * table, struct proc_dir_entry *root)

{

        struct proc_dir_entry *de, *tmp;

        int exists;

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

                exists = 0;

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

                if (!table->procname)

                        continue;

                /* Maybe we can't do anything with it... */

                if (!table->proc_handler &&

                    !table->child)

                        continue;

                de = kmalloc(sizeof(*de), GFP_KERNEL);

                if (!de) continue;

                de->namelen = strlen(table->procname);

                de->name = table->procname;

                de->mode = table->mode;

                de->nlink = 1;

                de->uid = 0;

                de->gid = 0;

                de->size = 0;

                de->get_info = 0;        /* For internal use if we want it */

                de->fill_inode = 0;      /* To override struct inode fields */

                de->next = de->subdir = 0;

                de->data = (void *) table;

                /* Is it a file? */

                if (table->proc_handler) {

                        de->ops = &proc_sys_inode_operations;

                        de->mode |= S_IFREG;

                }

                /* Otherwise it's a subdir */

                else  {

                        /* First check to see if it already exists */

                        for (tmp = root->subdir; tmp; tmp = tmp->next) {

                                if (tmp->namelen == de->namelen &&

                                    !memcmp(tmp->name,de->name,de->namelen)) {

                                        exists = 1;

                                        kfree (de);

                                        de = tmp;

                                }

                        }

                        if (!exists) {

                                de->ops = &proc_dir_inode_operations;

                                de->nlink++;

                                de->mode |= S_IFDIR;

                        }

                }

                table->de = de;

                if (!exists)

                        proc_register_dynamic(root, de);

                if (de->mode & S_IFDIR )

                        register_proc_table(table->child, de);

        }

}

static void unregister_proc_table(ctl_table * table, struct proc_dir_entry *root)

{

        struct proc_dir_entry *de;

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

                if (!(de = table->de))

                        continue;

                if (de->mode & S_IFDIR) {

                        if (!table->child) {

                                printk (KERN_ALERT "Help - malformed sysctl tree on free\n");

                                continue;

                        }

                        unregister_proc_table(table->child, de);

                }

                /* Don't unregister proc directories which still have

                   entries... */

                if (!((de->mode & S_IFDIR) && de->subdir)) {

                        proc_unregister(root, de->low_ino);

                        table->de = NULL;

                        kfree(de);

                }

        }

}

static int do_rw_proc(int write, struct inode * inode, struct file * file,

                      char * buf, int count)

{

        int error, op;

        struct proc_dir_entry *de;

        struct ctl_table *table;

        size_t res;

        error = verify_area(write ? VERIFY_READ : VERIFY_WRITE, buf, count);

        if (error)

                return error;

        de = (struct proc_dir_entry*) inode->u.generic_ip;

        if (!de || !de->data)

                return -ENOTDIR;

        table = (struct ctl_table *) de->data;

        if (!table || !table->proc_handler)

                return -ENOTDIR;

        op = (write ? 002 : 004);

        if (ctl_perm(table, op))

                return -EPERM;

        res = count;

        error = (*table->proc_handler) (table, write, file, buf, &res);

        if (error)

                return error;

        return res;

}

static int proc_readsys(struct inode * inode, struct file * file,

                        char * buf, int count)

{

        return do_rw_proc(0, inode, file, buf, count);

}

static int proc_writesys(struct inode * inode, struct file * file,

                         const char * buf, int count)

{

        return do_rw_proc(1, inode, file, (char *) buf, count);

}

static int proc_sys_permission(struct inode *inode, int op)

{

        return test_perm(inode->i_mode, op);

}

int proc_dostring(ctl_table *table, int write, struct file *filp,

                  void *buffer, size_t *lenp)

{

        int len;

        char *p, c;

        if (!table->data || !table->maxlen || !*lenp ||

            (filp->f_pos && !write)) {

                *lenp = 0;

                return 0;

        }

        if (write) {

                len = 0;

                p = buffer;

                while (len < *lenp &&

                       (c = get_user(p++)) != 0 && c != '\n')

                        len++;

                if (len >= table->maxlen)

                        len = table->maxlen-1;

                memcpy_fromfs(table->data, buffer, len);

                ((char *) table->data)[len] = 0;

                filp->f_pos += *lenp;

        } else {

                len = strlen(table->data);

                if (len > table->maxlen)

                        len = table->maxlen;

                if (len > *lenp)

                        len = *lenp;

                if (len)

                        memcpy_tofs(buffer, table->data, len);

                if (len < *lenp) {

                        put_user('\n', ((char *) buffer) + len);

                        len++;

                }

                *lenp = len;

                filp->f_pos += len;

        }

        return 0;

}

int proc_dointvec(ctl_table *table, int write, struct file *filp,

                  void *buffer, size_t *lenp)

{

        int *i, vleft, first=1, len, left, neg, val;

        #define TMPBUFLEN 20

        char buf[TMPBUFLEN], *p;

        if (!table->data || !table->maxlen || !*lenp ||

            (filp->f_pos && !write)) {

                *lenp = 0;

                return 0;

        }

        i = (int *) table->data;

        vleft = table->maxlen / sizeof(int);

        left = *lenp;

        for (; left && vleft--; i++, first=0) {

                if (write) {

                        while (left && isspace(get_user((char *) buffer)))

                                left--, ((char *) buffer)++;

                        if (!left)

                                break;

                        neg = 0;

                        len = left;

                        if (len > TMPBUFLEN-1)

                                len = TMPBUFLEN-1;

                        memcpy_fromfs(buf, buffer, len);

                        buf[len] = 0;

                        p = buf;

                        if (*p == '-' && left > 1) {

                                neg = 1;

                                left--, p++;

                        }

                        if (*p < '0' || *p > '9')

                                break;

                        val = simple_strtoul(p, &p, 0);

                        len = p-buf;

                        if ((len < left) && *p && !isspace(*p))