276 lines
7.1 KiB
C
276 lines
7.1 KiB
C
|
|
/* This file deals with protection in the file system. It contains the code
|
|
* for four system calls that relate to protection.
|
|
*
|
|
* The entry points into this file are
|
|
* do_chmod: perform the CHMOD and FCHMOD system calls
|
|
* do_chown: perform the CHOWN and FCHOWN system calls
|
|
* do_umask: perform the UMASK system call
|
|
* do_access: perform the ACCESS system call
|
|
*
|
|
* Changes for VFS:
|
|
* Jul 2006 (Balazs Gerofi)
|
|
*/
|
|
|
|
#include "fs.h"
|
|
#include <unistd.h>
|
|
#include <minix/callnr.h>
|
|
#include "file.h"
|
|
#include "fproc.h"
|
|
#include "param.h"
|
|
|
|
#include <minix/vfsif.h>
|
|
#include "vnode.h"
|
|
#include "vmnt.h"
|
|
|
|
|
|
|
|
/*===========================================================================*
|
|
* do_chmod *
|
|
*===========================================================================*/
|
|
PUBLIC int do_chmod()
|
|
{
|
|
struct filp *flp;
|
|
struct vnode *vp;
|
|
int r;
|
|
uid_t uid;
|
|
gid_t gid;
|
|
mode_t new_mode;
|
|
|
|
if (call_nr == CHMOD) {
|
|
/* Perform the chmod(name, mode) system call. */
|
|
if (fetch_name(m_in.name, m_in.name_length, M3) != OK) return(err_code);
|
|
|
|
/* Request lookup */
|
|
r = lookup_vp(0 /*flags*/, 0 /*!use_realuid*/, &vp);
|
|
if (r != OK) return r;
|
|
}
|
|
else if (call_nr == FCHMOD) {
|
|
if (!(flp = get_filp(m_in.m3_i1))) return err_code;
|
|
vp= flp->filp_vno;
|
|
dup_vnode(vp);
|
|
}
|
|
else panic(__FILE__, "do_chmod called with strange call_nr", call_nr);
|
|
|
|
uid= fp->fp_effuid;
|
|
gid= fp->fp_effgid;
|
|
|
|
/* Only the owner or the super_user may change the mode of a file.
|
|
* No one may change the mode of a file on a read-only file system.
|
|
*/
|
|
if (vp->v_uid != uid && uid != SU_UID)
|
|
r = EPERM;
|
|
else
|
|
r = read_only(vp);
|
|
|
|
/* If error, return inode. */
|
|
if (r != OK) {
|
|
put_vnode(vp);
|
|
return(r);
|
|
}
|
|
|
|
/* Now make the change. Clear setgid bit if file is not in caller's grp */
|
|
if (uid != SU_UID && vp->v_gid != gid)
|
|
m_in.mode &= ~I_SET_GID_BIT;
|
|
|
|
/* Issue request */
|
|
r = req_chmod(vp->v_fs_e, vp->v_inode_nr, m_in.mode, &new_mode);
|
|
|
|
if (r == OK)
|
|
vp->v_mode = new_mode;
|
|
put_vnode(vp);
|
|
|
|
return OK;
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* do_chown *
|
|
*===========================================================================*/
|
|
PUBLIC int do_chown()
|
|
{
|
|
int inode_nr;
|
|
int fs_e;
|
|
struct filp *flp;
|
|
struct vnode *vp;
|
|
int r;
|
|
uid_t uid;
|
|
gid_t gid;
|
|
mode_t new_mode;
|
|
|
|
if (call_nr == CHOWN) {
|
|
/* Perform the chmod(name, mode) system call. */
|
|
if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
|
|
|
|
/* Request lookup */
|
|
r = lookup_vp(0 /*flags*/, 0 /*!use_realuid*/, &vp);
|
|
if (r != OK) return r;
|
|
}
|
|
else if (call_nr == FCHOWN) {
|
|
if (!(flp = get_filp(m_in.m1_i1))) return err_code;
|
|
vp= flp->filp_vno;
|
|
dup_vnode(vp);
|
|
}
|
|
else panic(__FILE__, "do_chmod called with strange call_nr", call_nr);
|
|
|
|
uid= fp->fp_effuid;
|
|
gid= fp->fp_effgid;
|
|
|
|
r= OK;
|
|
if (uid == SU_UID) {
|
|
/* The super user can do anything. */
|
|
} else {
|
|
/* Regular users can only change groups of their own files. */
|
|
if (vp->v_uid != uid)
|
|
r = EPERM; /* File does not belong to the caller */
|
|
if (vp->v_uid != m_in.owner)
|
|
r = EPERM; /* no giving away */
|
|
if (gid != m_in.group)
|
|
r = EPERM; /* only change to the current gid */
|
|
}
|
|
if (r != OK) {
|
|
put_vnode(vp);
|
|
return r;
|
|
}
|
|
|
|
/* Issue request */
|
|
r = req_chown(vp->v_fs_e, vp->v_inode_nr, m_in.owner, m_in.group, &new_mode);
|
|
|
|
if(r == OK) {
|
|
vp->v_uid = m_in.owner;
|
|
vp->v_gid = m_in.group;
|
|
vp->v_mode = new_mode;
|
|
}
|
|
|
|
put_vnode(vp);
|
|
|
|
return r;
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* do_umask *
|
|
*===========================================================================*/
|
|
PUBLIC int do_umask()
|
|
{
|
|
/* Perform the umask(co_mode) system call. */
|
|
register mode_t r;
|
|
|
|
r = ~fp->fp_umask; /* set 'r' to complement of old mask */
|
|
fp->fp_umask = ~(m_in.co_mode & RWX_MODES);
|
|
return(r); /* return complement of old mask */
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* do_access *
|
|
*===========================================================================*/
|
|
PUBLIC int do_access()
|
|
{
|
|
/* Perform the access(name, mode) system call. */
|
|
int r;
|
|
struct vnode *vp;
|
|
|
|
/* First check to see if the mode is correct. */
|
|
if ( (m_in.mode & ~(R_OK | W_OK | X_OK)) != 0 && m_in.mode != F_OK)
|
|
return(EINVAL);
|
|
|
|
if (fetch_name(m_in.name, m_in.name_length, M3) != OK) return(err_code);
|
|
|
|
/* Request lookup */
|
|
r = lookup_vp(0 /*flags*/, TRUE /*use_realuid*/, &vp);
|
|
if (r != OK) return r;
|
|
|
|
r= forbidden(vp, m_in.mode, 1 /*use_realuid*/);
|
|
put_vnode(vp);
|
|
return r;
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* forbidden *
|
|
*===========================================================================*/
|
|
PUBLIC int forbidden(struct vnode *vp, mode_t access_desired, int use_realuid)
|
|
{
|
|
/* Given a pointer to an inode, 'rip', and the access desired, determine
|
|
* if the access is allowed, and if not why not. The routine looks up the
|
|
* caller's uid in the 'fproc' table. If access is allowed, OK is returned
|
|
* if it is forbidden, EACCES is returned.
|
|
*/
|
|
|
|
register struct super_block *sp;
|
|
register mode_t bits, perm_bits;
|
|
uid_t uid;
|
|
gid_t gid;
|
|
int r, shift, type;
|
|
|
|
if (vp->v_uid == (uid_t)-1 || vp->v_gid == (gid_t)-1)
|
|
{
|
|
printf("forbidden: bad uid/gid in vnode: inode %d on dev 0x%x\n",
|
|
vp->v_inode_nr, vp->v_dev);
|
|
printf("forbidden: last allocated at %s, %d\n", vp->v_file, vp->v_line);
|
|
return EACCES;
|
|
}
|
|
|
|
/* Isolate the relevant rwx bits from the mode. */
|
|
bits = vp->v_mode;
|
|
if (use_realuid)
|
|
{
|
|
uid= fp->fp_realuid;
|
|
gid= fp->fp_realgid;
|
|
}
|
|
else
|
|
{
|
|
uid= fp->fp_effuid;
|
|
gid= fp->fp_effgid;
|
|
}
|
|
if (uid == SU_UID) {
|
|
/* Grant read and write permission. Grant search permission for
|
|
* directories. Grant execute permission (for non-directories) if
|
|
* and only if one of the 'X' bits is set.
|
|
*/
|
|
if ( (bits & I_TYPE) == I_DIRECTORY ||
|
|
bits & ((X_BIT << 6) | (X_BIT << 3) | X_BIT))
|
|
perm_bits = R_BIT | W_BIT | X_BIT;
|
|
else
|
|
perm_bits = R_BIT | W_BIT;
|
|
} else {
|
|
if (uid == vp->v_uid) shift = 6; /* owner */
|
|
else if (gid == vp->v_gid ) shift = 3; /* group */
|
|
else shift = 0; /* other */
|
|
perm_bits = (bits >> shift) & (R_BIT | W_BIT | X_BIT);
|
|
}
|
|
|
|
/* If access desired is not a subset of what is allowed, it is refused. */
|
|
r = OK;
|
|
if ((perm_bits | access_desired) != perm_bits) {
|
|
r = EACCES;
|
|
}
|
|
|
|
/* Check to see if someone is trying to write on a file system that is
|
|
* mounted read-only.
|
|
*/
|
|
if (r == OK)
|
|
if (access_desired & W_BIT)
|
|
r = read_only(vp);
|
|
|
|
return(r);
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* read_only *
|
|
*===========================================================================*/
|
|
PUBLIC int read_only(vp)
|
|
struct vnode *vp; /* ptr to inode whose file sys is to be cked */
|
|
{
|
|
/* Check to see if the file system on which the inode 'ip' resides is mounted
|
|
* read only. If so, return EROFS, else return OK.
|
|
*/
|
|
register struct vmnt *mp;
|
|
|
|
mp = vp->v_vmnt;
|
|
return(mp->m_flags ? EROFS : OK);
|
|
}
|
|
|
|
|