a9d0ffbd0d
The next commit will make mode_t 32-bits, ino_t 64-bits, nlink_t 32-bits, and off_t 64-bits. However, in the protocol there is no room for that. When analyzing the usage of these data types we can see that of mode_t we currently use 15 bits and that future flags (if copied from NetBSD) are only of importance to VFS and not to the actual file system on disk. Therefore we can get away with keeping the protocol version of mode_t (pmode_t) 16 bits. At this point it is unlikely that MINIX will support file systems that can hold more than 2^32 files. Keeping the protocol version of ino_t (pino_t) 32-bits and exposing it as 64-bits to the rest of the system is fine. uid_t and gid_t are already 32-bits, but in behind the scenes they're 16-bits. This is sufficient since we don't support uid/gids larger than 2^16-1. off_t will become 64-bits, but the protocol had room reserved for that since it was revised years ago. So to make the difference clear between what the protocol supports and what is exposed to the system, we define protocol version of these data types. Change-Id: Ifb883aafb222142e69d6dcc3049a47170b78b3ee
159 lines
4.3 KiB
C
159 lines
4.3 KiB
C
/* Created (MFS based):
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* February 2010 (Evgeniy Ivanov)
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*/
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#include "fs.h"
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#include "inode.h"
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#include "super.h"
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#include <minix/vfsif.h>
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static int in_group(gid_t grp);
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/*===========================================================================*
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* fs_chmod *
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*===========================================================================*/
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int fs_chmod()
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{
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/* Perform the chmod(name, mode) system call. */
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register struct inode *rip;
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pmode_t mode;
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mode = (pmode_t) fs_m_in.REQ_MODE;
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/* Temporarily open the file. */
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if( (rip = get_inode(fs_dev, (pino_t) fs_m_in.REQ_INODE_NR)) == NULL)
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return(EINVAL);
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/* Now make the change. Clear setgid bit if file is not in caller's grp */
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rip->i_mode = (rip->i_mode & ~ALL_MODES) | (mode & ALL_MODES);
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rip->i_update |= CTIME;
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rip->i_dirt = IN_DIRTY;
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/* Return full new mode to caller. */
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fs_m_out.RES_MODE = rip->i_mode;
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put_inode(rip);
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return(OK);
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}
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/*===========================================================================*
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* fs_chown *
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*===========================================================================*/
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int fs_chown()
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{
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register struct inode *rip;
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register int r;
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/* Temporarily open the file. */
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if( (rip = get_inode(fs_dev, (pino_t) fs_m_in.REQ_INODE_NR)) == NULL)
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return(EINVAL);
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/* Not permitted to change the owner of a file on a read-only file sys. */
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r = read_only(rip);
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if (r == OK) {
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rip->i_uid = fs_m_in.REQ_UID;
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rip->i_gid = fs_m_in.REQ_GID;
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rip->i_mode &= ~(I_SET_UID_BIT | I_SET_GID_BIT);
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rip->i_update |= CTIME;
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rip->i_dirt = IN_DIRTY;
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}
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/* Update caller on current mode, as it may have changed. */
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fs_m_out.RES_MODE = rip->i_mode;
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put_inode(rip);
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return(r);
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}
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/*===========================================================================*
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* forbidden *
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*===========================================================================*/
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int forbidden(register struct inode *rip, pmode_t access_desired)
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{
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/* Given a pointer to an inode, 'rip', and the access desired, determine
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* if the access is allowed, and if not why not. The routine looks up the
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* caller's uid in the 'fproc' table. If access is allowed, OK is returned
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* if it is forbidden, EACCES is returned.
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*/
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register struct inode *old_rip = rip;
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register pmode_t bits, perm_bits;
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int r, shift;
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/* Isolate the relevant rwx bits from the mode. */
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bits = rip->i_mode;
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if (caller_uid == SU_UID) {
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/* Grant read and write permission. Grant search permission for
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* directories. Grant execute permission (for non-directories) if
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* and only if one of the 'X' bits is set.
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*/
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if ( (bits & I_TYPE) == I_DIRECTORY ||
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bits & ((X_BIT << 6) | (X_BIT << 3) | X_BIT))
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perm_bits = R_BIT | W_BIT | X_BIT;
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else
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perm_bits = R_BIT | W_BIT;
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} else {
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if (caller_uid == rip->i_uid) shift = 6; /* owner */
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else if (caller_gid == rip->i_gid) shift = 3; /* group */
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else if (in_group(rip->i_gid) == OK) shift = 3; /* other groups */
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else shift = 0; /* other */
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perm_bits = (bits >> shift) & (R_BIT | W_BIT | X_BIT);
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}
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/* If access desired is not a subset of what is allowed, it is refused. */
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r = OK;
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if ((perm_bits | access_desired) != perm_bits) r = EACCES;
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/* Check to see if someone is trying to write on a file system that is
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* mounted read-only.
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*/
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if (r == OK) {
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if (access_desired & W_BIT) {
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r = read_only(rip);
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}
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}
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if (rip != old_rip) put_inode(rip);
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return(r);
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}
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/*===========================================================================*
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* in_group *
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*===========================================================================*/
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static int in_group(gid_t grp)
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{
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int i;
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if (credentials.vu_ngroups > NGROUPS_MAX)
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return(EINVAL);
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for (i = 0; i < credentials.vu_ngroups; i++)
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if (credentials.vu_sgroups[i] == grp)
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return(OK);
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return(EINVAL);
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}
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/*===========================================================================*
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* read_only *
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*===========================================================================*/
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int read_only(ip)
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struct inode *ip; /* ptr to inode whose file sys is to be cked */
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{
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/* Check to see if the file system on which the inode 'ip' resides is mounted
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* read only. If so, return EROFS, else return OK.
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*/
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register struct super_block *sp;
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sp = ip->i_sp;
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return(sp->s_rd_only ? EROFS : OK);
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}
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