e6c98c3c55
Last_dir didn't consider paths that end in a symlink and hence didn't actually return the last_dir when provided with one. For example, /var/log is a symlink to /usr/log. Issuing `>/var/log' would trigger an assert in AVFS, because /var/ is not the actual last directory; /usr/ is. Last_dir now verifies the final component is not a symlink. If it is, it follows the symlink and restarts finding of the last the directory.
458 lines
13 KiB
C
458 lines
13 KiB
C
/* This file handles the LINK and UNLINK system calls. It also deals with
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* deallocating the storage used by a file when the last UNLINK is done to a
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* file and the blocks must be returned to the free block pool.
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*
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* The entry points into this file are
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* do_link: perform the LINK system call
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* do_unlink: perform the UNLINK and RMDIR system calls
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* do_rename: perform the RENAME system call
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* do_truncate: perform the TRUNCATE system call
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* do_ftruncate: perform the FTRUNCATE system call
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* do_rdlink: perform the RDLNK system call
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*/
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#include "fs.h"
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#include <sys/stat.h>
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#include <string.h>
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#include <minix/com.h>
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#include <minix/callnr.h>
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#include <minix/vfsif.h>
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#include <dirent.h>
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#include <assert.h>
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#include "file.h"
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#include "fproc.h"
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#include "path.h"
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#include "vnode.h"
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#include "param.h"
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/*===========================================================================*
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* do_link *
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*===========================================================================*/
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PUBLIC int do_link()
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{
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/* Perform the link(name1, name2) system call. */
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int r = OK;
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struct vnode *vp = NULL, *dirp = NULL;
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struct vmnt *vmp1 = NULL, *vmp2 = NULL;
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char fullpath[PATH_MAX];
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struct lookup resolve;
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lookup_init(&resolve, fullpath, PATH_NOFLAGS, &vmp1, &vp);
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resolve.l_vmnt_lock = VMNT_WRITE;
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resolve.l_vnode_lock = VNODE_READ;
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/* See if 'name1' (file to be linked to) exists. */
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if (fetch_name(m_in.name1, m_in.name1_length, M1, fullpath) != OK)
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return(err_code);
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if ((vp = eat_path(&resolve, fp)) == NULL) return(err_code);
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/* Does the final directory of 'name2' exist? */
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lookup_init(&resolve, fullpath, PATH_NOFLAGS, &vmp2, &dirp);
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resolve.l_vmnt_lock = VMNT_READ;
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resolve.l_vnode_lock = VNODE_READ;
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if (fetch_name(m_in.name2, m_in.name2_length, M1, fullpath) != OK)
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r = err_code;
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else if ((dirp = last_dir(&resolve, fp)) == NULL)
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r = err_code;
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if (r != OK) {
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unlock_vnode(vp);
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unlock_vmnt(vmp1);
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put_vnode(vp);
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return(r);
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}
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/* Check for links across devices. */
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if (vp->v_fs_e != dirp->v_fs_e)
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r = EXDEV;
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else
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r = forbidden(dirp, W_BIT | X_BIT);
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if (r == OK)
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r = req_link(vp->v_fs_e, dirp->v_inode_nr, fullpath,
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vp->v_inode_nr);
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unlock_vnode(vp);
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unlock_vnode(dirp);
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if (vmp2 != NULL) unlock_vmnt(vmp2);
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unlock_vmnt(vmp1);
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put_vnode(vp);
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put_vnode(dirp);
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return(r);
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}
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/*===========================================================================*
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* do_unlink *
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*===========================================================================*/
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PUBLIC int do_unlink()
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{
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/* Perform the unlink(name) or rmdir(name) system call. The code for these two
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* is almost the same. They differ only in some condition testing. Unlink()
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* may be used by the superuser to do dangerous things; rmdir() may not.
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*/
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struct vnode *dirp, *vp;
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struct vmnt *vmp, *vmp2;
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int r;
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char fullpath[PATH_MAX];
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struct lookup resolve;
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lookup_init(&resolve, fullpath, PATH_RET_SYMLINK, &vmp, &dirp);
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resolve.l_vmnt_lock = VMNT_WRITE;
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resolve.l_vnode_lock = VNODE_READ;
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/* Get the last directory in the path. */
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if (fetch_name(m_in.name, m_in.name_length, M3, fullpath) != OK)
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return(err_code);
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if ((dirp = last_dir(&resolve, fp)) == NULL) return(err_code);
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assert(vmp != NULL);
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/* Make sure that the object is a directory */
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if ((dirp->v_mode & I_TYPE) != I_DIRECTORY) {
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unlock_vnode(dirp);
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unlock_vmnt(vmp);
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put_vnode(dirp);
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return(ENOTDIR);
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}
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/* The caller must have both search and execute permission */
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if ((r = forbidden(dirp, X_BIT | W_BIT)) != OK) {
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unlock_vnode(dirp);
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unlock_vmnt(vmp);
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put_vnode(dirp);
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return(r);
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}
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/* Also, if the sticky bit is set, only the owner of the file or a privileged
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user is allowed to unlink */
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if ((dirp->v_mode & S_ISVTX) == S_ISVTX) {
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/* Look up inode of file to unlink to retrieve owner */
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resolve.l_flags = PATH_RET_SYMLINK;
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resolve.l_vmp = &vmp2; /* Shouldn't actually get locked */
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resolve.l_vmnt_lock = VMNT_READ;
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resolve.l_vnode = &vp;
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resolve.l_vnode_lock = VNODE_READ;
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vp = advance(dirp, &resolve, fp);
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assert(vmp2 == NULL);
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if (vp != NULL) {
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if (vp->v_uid != fp->fp_effuid && fp->fp_effuid != SU_UID)
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r = EPERM;
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unlock_vnode(vp);
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put_vnode(vp);
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} else
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r = err_code;
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if (r != OK) {
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unlock_vnode(dirp);
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unlock_vmnt(vmp);
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put_vnode(dirp);
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return(r);
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}
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}
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assert(vmp != NULL);
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tll_upgrade(&vmp->m_lock);
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if (call_nr == UNLINK)
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r = req_unlink(dirp->v_fs_e, dirp->v_inode_nr, fullpath);
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else
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r = req_rmdir(dirp->v_fs_e, dirp->v_inode_nr, fullpath);
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unlock_vnode(dirp);
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unlock_vmnt(vmp);
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put_vnode(dirp);
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return(r);
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}
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/*===========================================================================*
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* do_rename *
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*===========================================================================*/
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PUBLIC int do_rename()
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{
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/* Perform the rename(name1, name2) system call. */
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int r = OK, r1;
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struct vnode *old_dirp, *new_dirp = NULL, *vp;
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struct vmnt *oldvmp, *newvmp, *vmp2;
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char old_name[PATH_MAX];
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char fullpath[PATH_MAX];
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struct lookup resolve;
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lookup_init(&resolve, fullpath, PATH_NOFLAGS, &oldvmp, &old_dirp);
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/* Do not yet request exclusive lock on vmnt to prevent deadlocks later on */
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resolve.l_vmnt_lock = VMNT_WRITE;
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resolve.l_vnode_lock = VNODE_READ;
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/* See if 'name1' (existing file) exists. Get dir and file inodes. */
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if (fetch_name(m_in.name1, m_in.name1_length, M1, fullpath) != OK)
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return(err_code);
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if ((old_dirp = last_dir(&resolve, fp)) == NULL)
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return(err_code);
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/* If the sticky bit is set, only the owner of the file or a privileged
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user is allowed to rename */
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if ((old_dirp->v_mode & S_ISVTX) == S_ISVTX) {
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/* Look up inode of file to unlink to retrieve owner */
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resolve.l_flags = PATH_RET_SYMLINK;
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resolve.l_vmp = &vmp2; /* Shouldn't actually get locked */
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resolve.l_vmnt_lock = VMNT_READ;
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resolve.l_vnode = &vp;
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resolve.l_vnode_lock = VNODE_READ;
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resolve.l_flags = PATH_RET_SYMLINK;
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vp = advance(old_dirp, &resolve, fp);
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assert(vmp2 == NULL);
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if (vp != NULL) {
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if(vp->v_uid != fp->fp_effuid && fp->fp_effuid != SU_UID)
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r = EPERM;
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unlock_vnode(vp);
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put_vnode(vp);
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} else
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r = err_code;
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if (r != OK) {
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unlock_vnode(old_dirp);
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unlock_vmnt(oldvmp);
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put_vnode(old_dirp);
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return(r);
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}
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}
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/* Save the last component of the old name */
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if(strlen(fullpath) >= sizeof(old_name)) {
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unlock_vnode(old_dirp);
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unlock_vmnt(oldvmp);
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put_vnode(old_dirp);
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return(ENAMETOOLONG);
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}
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strcpy(old_name, fullpath);
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/* See if 'name2' (new name) exists. Get dir inode */
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lookup_init(&resolve, fullpath, PATH_NOFLAGS, &newvmp, &new_dirp);
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resolve.l_vmnt_lock = VMNT_READ;
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resolve.l_vnode_lock = VNODE_READ;
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if (fetch_name(m_in.name2, m_in.name2_length, M1, fullpath) != OK)
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r = err_code;
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else if ((new_dirp = last_dir(&resolve, fp)) == NULL)
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r = err_code;
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if (r != OK) {
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unlock_vnode(old_dirp);
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unlock_vmnt(oldvmp);
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put_vnode(old_dirp);
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return(r);
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}
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/* Both parent directories must be on the same device. */
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if (old_dirp->v_fs_e != new_dirp->v_fs_e) r = EXDEV;
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/* Parent dirs must be writable, searchable and on a writable device */
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if ((r1 = forbidden(old_dirp, W_BIT|X_BIT)) != OK ||
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(r1 = forbidden(new_dirp, W_BIT|X_BIT)) != OK) r = r1;
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if (r == OK) {
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tll_upgrade(&oldvmp->m_lock); /* Upgrade to exclusive access */
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r = req_rename(old_dirp->v_fs_e, old_dirp->v_inode_nr, old_name,
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new_dirp->v_inode_nr, fullpath);
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}
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unlock_vnode(old_dirp);
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unlock_vnode(new_dirp);
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unlock_vmnt(oldvmp);
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if (newvmp) unlock_vmnt(newvmp);
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put_vnode(old_dirp);
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put_vnode(new_dirp);
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return(r);
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}
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/*===========================================================================*
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* do_truncate *
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*===========================================================================*/
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PUBLIC int do_truncate()
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{
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/* truncate_vnode() does the actual work of do_truncate() and do_ftruncate().
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* do_truncate() and do_ftruncate() have to get hold of the inode, either
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* by name or fd, do checks on it, and call truncate_inode() to do the
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* work.
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*/
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struct vnode *vp;
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struct vmnt *vmp;
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int r;
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char fullpath[PATH_MAX];
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struct lookup resolve;
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lookup_init(&resolve, fullpath, PATH_NOFLAGS, &vmp, &vp);
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resolve.l_vmnt_lock = VMNT_EXCL;
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resolve.l_vnode_lock = VNODE_WRITE;
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if ((off_t) m_in.flength < 0) return(EINVAL);
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/* Temporarily open file */
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if (fetch_name(m_in.m2_p1, m_in.m2_i1, M1, fullpath) != OK) return(err_code);
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if ((vp = eat_path(&resolve, fp)) == NULL) return(err_code);
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/* Ask FS to truncate the file */
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if ((r = forbidden(vp, W_BIT)) == OK)
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r = truncate_vnode(vp, m_in.flength);
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unlock_vnode(vp);
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unlock_vmnt(vmp);
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put_vnode(vp);
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return(r);
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}
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/*===========================================================================*
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* do_ftruncate *
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*===========================================================================*/
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PUBLIC int do_ftruncate()
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{
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/* As with do_truncate(), truncate_vnode() does the actual work. */
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struct filp *rfilp;
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int r;
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if ((off_t) m_in.flength < 0) return(EINVAL);
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/* File is already opened; get a vnode pointer from filp */
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if ((rfilp = get_filp(m_in.m2_i1, VNODE_WRITE)) == NULL) return(err_code);
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if (!(rfilp->filp_mode & W_BIT))
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r = EBADF;
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else
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r = truncate_vnode(rfilp->filp_vno, m_in.flength);
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unlock_filp(rfilp);
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return(r);
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}
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/*===========================================================================*
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* truncate_vnode *
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*===========================================================================*/
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PUBLIC int truncate_vnode(vp, newsize)
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struct vnode *vp;
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off_t newsize;
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{
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/* Truncate a regular file or a pipe */
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int r, file_type;
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assert(tll_locked_by_me(&vp->v_lock));
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file_type = vp->v_mode & I_TYPE;
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if (file_type != I_REGULAR && file_type != I_NAMED_PIPE) return(EINVAL);
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if ((r = req_ftrunc(vp->v_fs_e, vp->v_inode_nr, newsize, 0)) == OK)
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vp->v_size = newsize;
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return(r);
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}
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/*===========================================================================*
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* do_slink *
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*===========================================================================*/
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PUBLIC int do_slink()
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{
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/* Perform the symlink(name1, name2) system call. */
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int r;
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struct vnode *vp;
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struct vmnt *vmp;
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char fullpath[PATH_MAX];
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struct lookup resolve;
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lookup_init(&resolve, fullpath, PATH_NOFLAGS, &vmp, &vp);
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resolve.l_vmnt_lock = VMNT_WRITE;
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resolve.l_vnode_lock = VNODE_READ;
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if (m_in.name1_length <= 1) return(ENOENT);
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if (m_in.name1_length >= SYMLINK_MAX) return(ENAMETOOLONG);
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/* Get dir inode of 'name2' */
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if (fetch_name(m_in.name2, m_in.name2_length, M1, fullpath) != OK)
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return(err_code);
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if ((vp = last_dir(&resolve, fp)) == NULL) return(err_code);
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if ((r = forbidden(vp, W_BIT|X_BIT)) == OK) {
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r = req_slink(vp->v_fs_e, vp->v_inode_nr, fullpath, who_e,
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m_in.name1, m_in.name1_length - 1, fp->fp_effuid,
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fp->fp_effgid);
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}
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unlock_vnode(vp);
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unlock_vmnt(vmp);
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put_vnode(vp);
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return(r);
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}
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/*===========================================================================*
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* rdlink_direct *
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*===========================================================================*/
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PUBLIC int rdlink_direct(orig_path, link_path, rfp)
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char *orig_path;
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char link_path[PATH_MAX]; /* should have length PATH_MAX */
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struct fproc *rfp;
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{
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/* Perform a readlink()-like call from within the VFS */
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int r;
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struct vnode *vp;
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struct vmnt *vmp;
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struct lookup resolve;
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lookup_init(&resolve, link_path, PATH_RET_SYMLINK, &vmp, &vp);
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resolve.l_vmnt_lock = VMNT_READ;
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resolve.l_vnode_lock = VNODE_READ;
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/* Temporarily open the file containing the symbolic link. Use link_path
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* for temporary storage to keep orig_path untouched. */
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strncpy(link_path, orig_path, PATH_MAX); /* PATH_MAX includes '\0' */
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link_path[PATH_MAX - 1] = '\0';
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if ((vp = eat_path(&resolve, rfp)) == NULL) return(err_code);
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/* Make sure this is a symbolic link */
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if ((vp->v_mode & I_TYPE) != I_SYMBOLIC_LINK)
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r = EINVAL;
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else
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r = req_rdlink(vp->v_fs_e, vp->v_inode_nr, NONE, link_path,
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PATH_MAX - 1, 1);
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if (r > 0) link_path[r] = '\0'; /* Terminate string when succesful */
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unlock_vnode(vp);
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unlock_vmnt(vmp);
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put_vnode(vp);
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return r;
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}
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/*===========================================================================*
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* do_rdlink *
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*===========================================================================*/
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PUBLIC int do_rdlink()
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{
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/* Perform the readlink(name, buf, bufsize) system call. */
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int r, copylen;
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struct vnode *vp;
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struct vmnt *vmp;
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char fullpath[PATH_MAX];
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struct lookup resolve;
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lookup_init(&resolve, fullpath, PATH_RET_SYMLINK, &vmp, &vp);
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resolve.l_vmnt_lock = VMNT_READ;
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resolve.l_vnode_lock = VNODE_READ;
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copylen = m_in.nbytes;
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if (copylen < 0) return(EINVAL);
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/* Temporarily open the file containing the symbolic link */
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if (fetch_name(m_in.name1, m_in.name1_length, M1, fullpath) != OK)
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return(err_code);
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if ((vp = eat_path(&resolve, fp)) == NULL) return(err_code);
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/* Make sure this is a symbolic link */
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if ((vp->v_mode & I_TYPE) != I_SYMBOLIC_LINK)
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r = EINVAL;
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else
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r = req_rdlink(vp->v_fs_e, vp->v_inode_nr, who_e, m_in.name2,
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copylen, 0);
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unlock_vnode(vp);
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unlock_vmnt(vmp);
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put_vnode(vp);
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return(r);
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}
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