minix/servers/vfs/path.c
Lionel Sambuc 7031438f58 Message type and related cleanup
- Intorduce and use a message type for VFS_GETDENTS, VFS_READ,
   VFS_WRITE.

 - Some cleanup to related functions where vir_bytes are replaced (and
   casted to/from, in parameter definition and local variables as well.

   This allow to see more clearly which function receives unsafe
   (pointer) values, or at least values which are not supposed to be
   valid in the address space of VFS. The current patch does so only
   for the minimal amount of functions which are concerned with the
   introduction of the new message type.

Change-Id: I0cdca97409c4016d02fae067b48bf55d37572c5c
2014-07-28 17:05:34 +02:00

878 lines
25 KiB
C

/* lookup() is the main routine that controls the path name lookup. It
* handles mountpoints and symbolic links. The actual lookup requests
* are sent through the req_lookup wrapper function.
*/
#include "fs.h"
#include <string.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/const.h>
#include <minix/endpoint.h>
#include <stddef.h>
#include <unistd.h>
#include <assert.h>
#include <minix/vfsif.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <sys/dirent.h>
#include "vmnt.h"
#include "vnode.h"
#include "path.h"
/* Set to following define to 1 if you really want to use the POSIX definition
* (IEEE Std 1003.1, 2004) of pathname resolution. POSIX requires pathnames
* with a traling slash (and that do not entirely consist of slash characters)
* to be treated as if a single dot is appended. This means that for example
* mkdir("dir/", ...) and rmdir("dir/") will fail because the call tries to
* create or remove the directory '.'. Historically, Unix systems just ignore
* trailing slashes.
*/
#define DO_POSIX_PATHNAME_RES 0
static int lookup(struct vnode *dirp, struct lookup *resolve,
node_details_t *node, struct fproc *rfp);
static int check_perms(endpoint_t ep, cp_grant_id_t io_gr, size_t
pathlen);
/*===========================================================================*
* advance *
*===========================================================================*/
struct vnode *advance(dirp, resolve, rfp)
struct vnode *dirp;
struct lookup *resolve;
struct fproc *rfp;
{
/* Resolve a path name starting at dirp to a vnode. */
int r;
int do_downgrade = 1;
struct vnode *new_vp, *vp;
struct vmnt *vmp;
struct node_details res = {0,0,0,0,0,0,0};
tll_access_t initial_locktype;
assert(dirp);
assert(resolve->l_vnode_lock != TLL_NONE);
assert(resolve->l_vmnt_lock != TLL_NONE);
if (resolve->l_vnode_lock == VNODE_READ)
initial_locktype = VNODE_OPCL;
else
initial_locktype = resolve->l_vnode_lock;
/* Get a free vnode and lock it */
if ((new_vp = get_free_vnode()) == NULL) return(NULL);
lock_vnode(new_vp, initial_locktype);
/* Lookup vnode belonging to the file. */
if ((r = lookup(dirp, resolve, &res, rfp)) != OK) {
err_code = r;
unlock_vnode(new_vp);
return(NULL);
}
/* Check whether we already have a vnode for that file */
if ((vp = find_vnode(res.fs_e, res.inode_nr)) != NULL) {
unlock_vnode(new_vp); /* Don't need this anymore */
do_downgrade = (lock_vnode(vp, initial_locktype) != EBUSY);
/* Unfortunately, by the time we get the lock, another thread might've
* rid of the vnode (e.g., find_vnode found the vnode while a
* req_putnode was being processed). */
if (vp->v_ref_count == 0) { /* vnode vanished! */
/* As the lookup before increased the usage counters in the FS,
* we can simply set the usage counters to 1 and proceed as
* normal, because the putnode resulted in a use count of 1 in
* the FS. Other data is still valid, because the vnode was
* marked as pending lock, so get_free_vnode hasn't
* reinitialized the vnode yet. */
vp->v_fs_count = 1;
if (vp->v_mapfs_e != NONE) vp->v_mapfs_count = 1;
} else {
vp->v_fs_count++; /* We got a reference from the FS */
}
} else {
/* Vnode not found, fill in the free vnode's fields */
new_vp->v_fs_e = res.fs_e;
new_vp->v_inode_nr = res.inode_nr;
new_vp->v_mode = res.fmode;
new_vp->v_size = res.fsize;
new_vp->v_uid = res.uid;
new_vp->v_gid = res.gid;
new_vp->v_sdev = res.dev;
if( (vmp = find_vmnt(new_vp->v_fs_e)) == NULL)
panic("advance: vmnt not found");
new_vp->v_vmnt = vmp;
new_vp->v_dev = vmp->m_dev;
new_vp->v_fs_count = 1;
vp = new_vp;
}
dup_vnode(vp);
if (do_downgrade) {
/* Only downgrade a lock if we managed to lock it in the first place */
*(resolve->l_vnode) = vp;
if (initial_locktype != resolve->l_vnode_lock)
tll_downgrade(&vp->v_lock);
#if LOCK_DEBUG
if (resolve->l_vnode_lock == VNODE_READ)
fp->fp_vp_rdlocks++;
#endif
}
return(vp);
}
/*===========================================================================*
* eat_path *
*===========================================================================*/
struct vnode *eat_path(resolve, rfp)
struct lookup *resolve;
struct fproc *rfp;
{
/* Resolve path to a vnode. advance does the actual work. */
struct vnode *start_dir;
start_dir = (resolve->l_path[0] == '/' ? rfp->fp_rd : rfp->fp_wd);
return advance(start_dir, resolve, rfp);
}
/*===========================================================================*
* last_dir *
*===========================================================================*/
struct vnode *last_dir(resolve, rfp)
struct lookup *resolve;
struct fproc *rfp;
{
/* Parse a path, as far as the last directory, fetch the vnode
* for the last directory into the vnode table, and return a pointer to the
* vnode. In addition, return the final component of the path in 'string'. If
* the last directory can't be opened, return NULL and the reason for
* failure in 'err_code'. We can't parse component by component as that would
* be too expensive. Alternatively, we cut off the last component of the path,
* and parse the path up to the penultimate component.
*/
size_t len;
char *cp;
char dir_entry[NAME_MAX+1];
struct vnode *start_dir, *res_vp, *sym_vp, *sym_vp_l, *loop_start;
struct vmnt *sym_vmp = NULL;
int r, symloop = 0, ret_on_symlink = 0;
struct lookup symlink;
*resolve->l_vnode = NULL;
*resolve->l_vmp = NULL;
loop_start = NULL;
sym_vp = NULL;
ret_on_symlink = !!(resolve->l_flags & PATH_RET_SYMLINK);
do {
/* Is the path absolute or relative? Initialize 'start_dir'
* accordingly. Use loop_start in case we're looping.
*/
if (loop_start != NULL)
start_dir = loop_start;
else
start_dir = (resolve->l_path[0] == '/' ? rfp->fp_rd:rfp->fp_wd);
len = strlen(resolve->l_path);
/* If path is empty, return ENOENT. */
if (len == 0) {
err_code = ENOENT;
res_vp = NULL;
break;
}
#if !DO_POSIX_PATHNAME_RES
/* Remove trailing slashes */
while (len > 1 && resolve->l_path[len-1] == '/') {
len--;
resolve->l_path[len]= '\0';
}
#endif
cp = strrchr(resolve->l_path, '/');
if (cp == NULL) {
/* Just an entry in the current working directory. Prepend
* "./" in front of the path and resolve it.
*/
if (strlcpy(dir_entry, resolve->l_path, NAME_MAX+1) >= NAME_MAX + 1) {
err_code = ENAMETOOLONG;
res_vp = NULL;
break;
}
dir_entry[NAME_MAX] = '\0';
resolve->l_path[0] = '.';
resolve->l_path[1] = '\0';
} else if (cp[1] == '\0') {
/* Path ends in a slash. The directory entry is '.' */
strlcpy(dir_entry, ".", NAME_MAX+1);
} else {
/* A path name for the directory and a directory entry */
if (strlcpy(dir_entry, cp+1, NAME_MAX+1) >= NAME_MAX + 1) {
err_code = ENAMETOOLONG;
res_vp = NULL;
break;
}
cp[1] = '\0';
dir_entry[NAME_MAX] = '\0';
}
/* Remove trailing slashes */
while (cp > resolve->l_path && cp[0] == '/') {
cp[0]= '\0';
cp--;
}
/* Resolve up to and including the last directory of the path. Turn off
* PATH_RET_SYMLINK, because we do want to follow the symlink in this
* case. That is, the flag is meant for the actual filename of the path,
* not the last directory.
*/
resolve->l_flags &= ~PATH_RET_SYMLINK;
if ((res_vp = advance(start_dir, resolve, rfp)) == NULL) {
break;
}
/* If the directory entry is not a symlink we're done now. If it is a
* symlink, then we're not at the last directory, yet. */
/* Copy the directory entry back to user_fullpath */
strlcpy(resolve->l_path, dir_entry, NAME_MAX + 1);
/* Look up the directory entry, but do not follow the symlink when it
* is one. Note: depending on the previous advance, we might not be
* able to lock the resulting vnode. For example, when we look up "./."
* and request a VNODE_WRITE lock on the result, then the previous
* advance has "./" locked. The next advance to "." will try to lock
* the same vnode with a VNODE_READ lock, and fail. When that happens,
* sym_vp_l will be NULL and we must not unlock the vnode. If we would
* unlock, we actually unlock the vnode locked by the previous advance.
*/
lookup_init(&symlink, resolve->l_path,
resolve->l_flags|PATH_RET_SYMLINK, &sym_vmp, &sym_vp_l);
symlink.l_vmnt_lock = VMNT_READ;
symlink.l_vnode_lock = VNODE_READ;
sym_vp = advance(res_vp, &symlink, rfp);
if (sym_vp == NULL) break;
if (S_ISLNK(sym_vp->v_mode)) {
/* Last component is a symlink, but if we've been asked to not
* resolve it, return now.
*/
if (ret_on_symlink) {
break;
}
r = req_rdlink(sym_vp->v_fs_e, sym_vp->v_inode_nr, NONE,
(vir_bytes) resolve->l_path, PATH_MAX - 1, 1);
if (r < 0) {
/* Failed to read link */
err_code = r;
unlock_vnode(res_vp);
unlock_vmnt(*resolve->l_vmp);
put_vnode(res_vp);
*resolve->l_vmp = NULL;
*resolve->l_vnode = NULL;
res_vp = NULL;
break;
}
resolve->l_path[r] = '\0';
if (strrchr(resolve->l_path, '/') != NULL) {
if (sym_vp_l != NULL)
unlock_vnode(sym_vp);
unlock_vmnt(*resolve->l_vmp);
if (sym_vmp != NULL)
unlock_vmnt(sym_vmp);
*resolve->l_vmp = NULL;
put_vnode(sym_vp);
sym_vp = NULL;
symloop++;
/* Relative symlinks are relative to res_vp, not cwd */
if (resolve->l_path[0] != '/') {
loop_start = res_vp;
} else {
/* Absolute symlink, forget about res_vp */
unlock_vnode(res_vp);
put_vnode(res_vp);
}
continue;
}
} else {
symloop = 0; /* Not a symlink, so restart counting */
/* If we're crossing a mount point, return root node of mount
* point on which the file resides. That's the 'real' last
* dir that holds the file we're looking for.
*/
if (sym_vp->v_fs_e != res_vp->v_fs_e) {
assert(sym_vmp != NULL);
/* Unlock final file, it might have wrong lock types */
if (sym_vp_l != NULL)
unlock_vnode(sym_vp);
unlock_vmnt(sym_vmp);
put_vnode(sym_vp);
sym_vp = NULL;
/* Also unlock and release erroneous result */
unlock_vnode(*resolve->l_vnode);
unlock_vmnt(*resolve->l_vmp);
put_vnode(res_vp);
/* Relock vmnt and vnode with correct lock types */
lock_vmnt(sym_vmp, resolve->l_vmnt_lock);
lock_vnode(sym_vmp->m_root_node, resolve->l_vnode_lock);
res_vp = sym_vmp->m_root_node;
dup_vnode(res_vp);
*resolve->l_vnode = res_vp;
*resolve->l_vmp = sym_vmp;
/* We've effectively resolved the final component, so
* change it to current directory to prevent future
* 'advances' of returning erroneous results.
*/
strlcpy(dir_entry, ".", NAME_MAX+1);
}
}
break;
} while (symloop < _POSIX_SYMLOOP_MAX);
if (symloop >= _POSIX_SYMLOOP_MAX) {
err_code = ELOOP;
res_vp = NULL;
}
if (sym_vp != NULL) {
if (sym_vp_l != NULL) {
unlock_vnode(sym_vp);
}
if (sym_vmp != NULL) {
unlock_vmnt(sym_vmp);
}
put_vnode(sym_vp);
}
if (loop_start != NULL) {
unlock_vnode(loop_start);
put_vnode(loop_start);
}
/* Copy the directory entry back to user_fullpath */
strlcpy(resolve->l_path, dir_entry, NAME_MAX + 1);
/* Turn PATH_RET_SYMLINK flag back on if it was on */
if (ret_on_symlink) resolve->l_flags |= PATH_RET_SYMLINK;
return(res_vp);
}
/*===========================================================================*
* lookup *
*===========================================================================*/
static int lookup(start_node, resolve, result_node, rfp)
struct vnode *start_node;
struct lookup *resolve;
node_details_t *result_node;
struct fproc *rfp;
{
/* Resolve a path name relative to start_node. */
int r, symloop;
endpoint_t fs_e;
size_t path_off, path_left_len;
ino_t dir_ino, root_ino;
uid_t uid;
gid_t gid;
struct vnode *dir_vp;
struct vmnt *vmp, *vmpres;
struct lookup_res res;
tll_access_t mnt_lock_type;
assert(resolve->l_vmp);
assert(resolve->l_vnode);
*(resolve->l_vmp) = vmpres = NULL; /* No vmnt found nor locked yet */
/* Empty (start) path? */
if (resolve->l_path[0] == '\0') {
result_node->inode_nr = 0;
return(ENOENT);
}
if (!rfp->fp_rd || !rfp->fp_wd) {
printf("VFS: lookup %d: no rd/wd\n", rfp->fp_endpoint);
return(ENOENT);
}
fs_e = start_node->v_fs_e;
dir_ino = start_node->v_inode_nr;
vmpres = find_vmnt(fs_e);
if (vmpres == NULL) return(EIO); /* mountpoint vanished? */
/* Is the process' root directory on the same partition?,
* if so, set the chroot directory too. */
if (rfp->fp_rd->v_dev == rfp->fp_wd->v_dev)
root_ino = rfp->fp_rd->v_inode_nr;
else
root_ino = 0;
/* Set user and group ids according to the system call */
uid = (job_call_nr == VFS_ACCESS ? rfp->fp_realuid : rfp->fp_effuid);
gid = (job_call_nr == VFS_ACCESS ? rfp->fp_realgid : rfp->fp_effgid);
symloop = 0; /* Number of symlinks seen so far */
/* Lock vmnt */
if (resolve->l_vmnt_lock == VMNT_READ)
mnt_lock_type = VMNT_WRITE;
else
mnt_lock_type = resolve->l_vmnt_lock;
if ((r = lock_vmnt(vmpres, mnt_lock_type)) != OK) {
if (r == EBUSY) /* vmnt already locked */
vmpres = NULL;
else
return(r);
}
*(resolve->l_vmp) = vmpres;
/* Issue the request */
r = req_lookup(fs_e, dir_ino, root_ino, uid, gid, resolve, &res, rfp);
if (r != OK && r != EENTERMOUNT && r != ELEAVEMOUNT && r != ESYMLINK) {
if (vmpres) unlock_vmnt(vmpres);
*(resolve->l_vmp) = NULL;
return(r); /* i.e., an error occured */
}
/* While the response is related to mount control set the
* new requests respectively */
while (r == EENTERMOUNT || r == ELEAVEMOUNT || r == ESYMLINK) {
/* Update user_fullpath to reflect what's left to be parsed. */
path_off = res.char_processed;
path_left_len = strlen(&resolve->l_path[path_off]);
memmove(resolve->l_path, &resolve->l_path[path_off], path_left_len);
resolve->l_path[path_left_len] = '\0'; /* terminate string */
/* Update the current value of the symloop counter */
symloop += res.symloop;
if (symloop > _POSIX_SYMLOOP_MAX) {
if (vmpres) unlock_vmnt(vmpres);
*(resolve->l_vmp) = NULL;
return(ELOOP);
}
/* Symlink encountered with absolute path */
if (r == ESYMLINK) {
dir_vp = rfp->fp_rd;
vmp = NULL;
} else if (r == EENTERMOUNT) {
/* Entering a new partition */
dir_vp = NULL;
/* Start node is now the mounted partition's root node */
for (vmp = &vmnt[0]; vmp != &vmnt[NR_MNTS]; ++vmp) {
if (vmp->m_dev != NO_DEV && vmp->m_mounted_on) {
if (vmp->m_mounted_on->v_inode_nr == res.inode_nr &&
vmp->m_mounted_on->v_fs_e == res.fs_e) {
dir_vp = vmp->m_root_node;
break;
}
}
}
if (dir_vp == NULL) {
printf("VFS: path lookup error; root node not found\n");
if (vmpres) unlock_vmnt(vmpres);
*(resolve->l_vmp) = NULL;
return(EIO);
}
} else {
/* Climbing up mount */
/* Find the vmnt that represents the partition on
* which we "climb up". */
if ((vmp = find_vmnt(res.fs_e)) == NULL) {
panic("VFS lookup: can't find parent vmnt");
}
/* Make sure that the child FS does not feed a bogus path
* to the parent FS. That is, when we climb up the tree, we
* must've encountered ".." in the path, and that is exactly
* what we're going to feed to the parent */
if(strncmp(resolve->l_path, "..", 2) != 0 ||
(resolve->l_path[2] != '\0' && resolve->l_path[2] != '/')) {
printf("VFS: bogus path: %s\n", resolve->l_path);
if (vmpres) unlock_vmnt(vmpres);
*(resolve->l_vmp) = NULL;
return(ENOENT);
}
/* Start node is the vnode on which the partition is
* mounted */
dir_vp = vmp->m_mounted_on;
}
/* Set the starting directories inode number and FS endpoint */
fs_e = dir_vp->v_fs_e;
dir_ino = dir_vp->v_inode_nr;
/* Is the process' root directory on the same partition?,
* if so, set the chroot directory too. */
if (dir_vp->v_dev == rfp->fp_rd->v_dev)
root_ino = rfp->fp_rd->v_inode_nr;
else
root_ino = 0;
/* Unlock a previously locked vmnt if locked and lock new vmnt */
if (vmpres) unlock_vmnt(vmpres);
vmpres = find_vmnt(fs_e);
if (vmpres == NULL) return(EIO); /* mount point vanished? */
if ((r = lock_vmnt(vmpres, mnt_lock_type)) != OK) {
if (r == EBUSY)
vmpres = NULL; /* Already locked */
else
return(r);
}
*(resolve->l_vmp) = vmpres;
r = req_lookup(fs_e, dir_ino, root_ino, uid, gid, resolve, &res, rfp);
if (r != OK && r != EENTERMOUNT && r != ELEAVEMOUNT && r != ESYMLINK) {
if (vmpres) unlock_vmnt(vmpres);
*(resolve->l_vmp) = NULL;
return(r);
}
}
if (*(resolve->l_vmp) != NULL && resolve->l_vmnt_lock != mnt_lock_type) {
/* downgrade VMNT_WRITE to VMNT_READ */
downgrade_vmnt_lock(*(resolve->l_vmp));
}
/* Fill in response fields */
result_node->inode_nr = res.inode_nr;
result_node->fmode = res.fmode;
result_node->fsize = res.fsize;
result_node->dev = res.dev;
result_node->fs_e = res.fs_e;
result_node->uid = res.uid;
result_node->gid = res.gid;
return(r);
}
/*===========================================================================*
* lookup_init *
*===========================================================================*/
void lookup_init(resolve, path, flags, vmp, vp)
struct lookup *resolve;
char *path;
int flags;
struct vmnt **vmp;
struct vnode **vp;
{
assert(vmp != NULL);
assert(vp != NULL);
resolve->l_path = path;
resolve->l_flags = flags;
resolve->l_vmp = vmp;
resolve->l_vnode = vp;
resolve->l_vmnt_lock = TLL_NONE;
resolve->l_vnode_lock = TLL_NONE;
*vmp = NULL; /* Initialize lookup result to NULL */
*vp = NULL;
}
/*===========================================================================*
* get_name *
*===========================================================================*/
int get_name(dirp, entry, ename)
struct vnode *dirp;
struct vnode *entry;
char ename[NAME_MAX + 1];
{
#define DIR_ENTRIES 8
#define DIR_ENTRY_SIZE (sizeof(struct dirent) + NAME_MAX)
off_t pos, new_pos;
int r, consumed, totalbytes, name_len;
char buf[DIR_ENTRY_SIZE * DIR_ENTRIES];
struct dirent *cur;
pos = 0;
if (!S_ISDIR(dirp->v_mode)) return(EBADF);
do {
r = req_getdents(dirp->v_fs_e, dirp->v_inode_nr, pos, (vir_bytes)buf,
sizeof(buf), &new_pos, 1);
if (r == 0) {
return(ENOENT); /* end of entries -- matching inode !found */
} else if (r < 0) {
return(r); /* error */
}
consumed = 0; /* bytes consumed */
totalbytes = r; /* number of bytes to consume */
do {
cur = (struct dirent *) (buf + consumed);
name_len = cur->d_reclen - offsetof(struct dirent, d_name) - 1;
if(cur->d_name + name_len+1 > &buf[sizeof(buf)])
return(EINVAL); /* Rubbish in dir entry */
if (entry->v_inode_nr == cur->d_fileno) {
/* found the entry we were looking for */
int copylen = MIN(name_len + 1, NAME_MAX + 1);
if (strlcpy(ename, cur->d_name, copylen) >= copylen) {
return(ENAMETOOLONG);
}
ename[NAME_MAX] = '\0';
return(OK);
}
/* not a match -- move on to the next dirent */
consumed += cur->d_reclen;
} while (consumed < totalbytes);
pos = new_pos;
} while (1);
}
/*===========================================================================*
* canonical_path *
*===========================================================================*/
int canonical_path(orig_path, rfp)
char orig_path[PATH_MAX];
struct fproc *rfp;
{
/* Find canonical path of a given path */
int len = 0;
int r, symloop = 0;
struct vnode *dir_vp, *parent_dir;
struct vmnt *dir_vmp, *parent_vmp;
char component[NAME_MAX+1]; /* NAME_MAX does /not/ include '\0' */
char temp_path[PATH_MAX];
struct lookup resolve;
parent_dir = dir_vp = NULL;
parent_vmp = dir_vmp = NULL;
strlcpy(temp_path, orig_path, PATH_MAX);
temp_path[PATH_MAX - 1] = '\0';
/* First resolve path to the last directory holding the file */
do {
if (dir_vp) {
unlock_vnode(dir_vp);
unlock_vmnt(dir_vmp);
put_vnode(dir_vp);
}
lookup_init(&resolve, temp_path, PATH_NOFLAGS, &dir_vmp, &dir_vp);
resolve.l_vmnt_lock = VMNT_READ;
resolve.l_vnode_lock = VNODE_READ;
if ((dir_vp = last_dir(&resolve, rfp)) == NULL) return(err_code);
/* dir_vp points to dir and resolve path now contains only the
* filename.
*/
strlcpy(orig_path, temp_path, NAME_MAX+1); /* Store file name */
/* If we're just crossing a mount point, our name has changed to '.' */
if (!strcmp(orig_path, ".")) orig_path[0] = '\0';
/* check if the file is a symlink, if so resolve it */
r = rdlink_direct(orig_path, temp_path, rfp);
if (r <= 0)
break;
/* encountered a symlink -- loop again */
strlcpy(orig_path, temp_path, PATH_MAX);
symloop++;
} while (symloop < _POSIX_SYMLOOP_MAX);
if (symloop >= _POSIX_SYMLOOP_MAX) {
if (dir_vp) {
unlock_vnode(dir_vp);
unlock_vmnt(dir_vmp);
put_vnode(dir_vp);
}
return(ELOOP);
}
/* We've got the filename and the actual directory holding the file. From
* here we start building up the canonical path by climbing up the tree */
while (dir_vp != rfp->fp_rd) {
strlcpy(temp_path, "..", NAME_MAX+1);
/* check if we're at the root node of the file system */
if (dir_vp->v_vmnt->m_root_node == dir_vp) {
if (dir_vp->v_vmnt->m_mounted_on == NULL) {
/* Bail out, we can't go any higher */
break;
}
unlock_vnode(dir_vp);
unlock_vmnt(dir_vmp);
put_vnode(dir_vp);
dir_vp = dir_vp->v_vmnt->m_mounted_on;
dir_vmp = dir_vp->v_vmnt;
if (lock_vmnt(dir_vmp, VMNT_READ) != OK)
panic("failed to lock vmnt");
if (lock_vnode(dir_vp, VNODE_READ) != OK)
panic("failed to lock vnode");
dup_vnode(dir_vp);
}
lookup_init(&resolve, temp_path, PATH_NOFLAGS, &parent_vmp,
&parent_dir);
resolve.l_vmnt_lock = VMNT_READ;
resolve.l_vnode_lock = VNODE_READ;
if ((parent_dir = advance(dir_vp, &resolve, rfp)) == NULL) {
unlock_vnode(dir_vp);
unlock_vmnt(dir_vmp);
put_vnode(dir_vp);
return(err_code);
}
/* now we have to retrieve the name of the parent directory */
if ((r = get_name(parent_dir, dir_vp, component)) != OK) {
unlock_vnode(parent_dir);
unlock_vmnt(parent_vmp);
unlock_vnode(dir_vp);
unlock_vmnt(dir_vmp);
put_vnode(parent_dir);
put_vnode(dir_vp);
return(r);
}
len += strlen(component) + 1;
if (len >= PATH_MAX) {
/* adding the component to orig_path would exceed PATH_MAX */
unlock_vnode(parent_dir);
unlock_vmnt(parent_vmp);
unlock_vnode(dir_vp);
unlock_vmnt(dir_vmp);
put_vnode(parent_dir);
put_vnode(dir_vp);
return(ENOMEM);
}
/* Store result of component in orig_path. First make space by moving
* the contents of orig_path to the right. Move strlen + 1 bytes to
* include the terminating '\0'. Move to strlen + 1 bytes to reserve
* space for the slash.
*/
memmove(orig_path+strlen(component)+1, orig_path, strlen(orig_path)+1);
/* Copy component into canon_path */
memmove(orig_path, component, strlen(component));
/* Put slash into place */
orig_path[strlen(component)] = '/';
/* Store parent_dir result, and continue the loop once more */
unlock_vnode(dir_vp);
unlock_vmnt(dir_vmp);
put_vnode(dir_vp);
dir_vp = parent_dir;
dir_vmp = parent_vmp;
parent_vmp = NULL;
}
unlock_vmnt(dir_vmp);
unlock_vnode(dir_vp);
put_vnode(dir_vp);
/* add the leading slash */
len = strlen(orig_path);
if (strlen(orig_path) >= PATH_MAX) return(ENAMETOOLONG);
memmove(orig_path+1, orig_path, len + 1 /* include terminating nul */);
orig_path[0] = '/';
/* remove trailing slash if there is any */
if (len > 1 && orig_path[len] == '/') orig_path[len] = '\0';
return(OK);
}
/*===========================================================================*
* check_perms *
*===========================================================================*/
static int check_perms(ep, io_gr, pathlen)
endpoint_t ep;
cp_grant_id_t io_gr;
size_t pathlen;
{
int r, slot;
struct vnode *vp;
struct vmnt *vmp;
struct fproc *rfp;
char canon_path[PATH_MAX];
struct lookup resolve;
struct sockaddr_un sun;
if (isokendpt(ep, &slot) != OK) return(EINVAL);
if (pathlen < sizeof(sun.sun_path) || pathlen >= PATH_MAX) return(EINVAL);
rfp = &(fproc[slot]);
r = sys_safecopyfrom(who_e, io_gr, (vir_bytes) 0, (vir_bytes) canon_path,
pathlen);
if (r != OK) return(r);
canon_path[pathlen] = '\0';
/* Turn path into canonical path to the socket file */
if ((r = canonical_path(canon_path, rfp)) != OK) return(r);
if (strlen(canon_path) >= pathlen) return(ENAMETOOLONG);
/* copy canon_path back to the caller */
r = sys_safecopyto(who_e, (cp_grant_id_t) io_gr, (vir_bytes) 0,
(vir_bytes) canon_path, pathlen);
if (r != OK) return(r);
/* Now do permissions checking */
lookup_init(&resolve, canon_path, PATH_NOFLAGS, &vmp, &vp);
resolve.l_vmnt_lock = VMNT_READ;
resolve.l_vnode_lock = VNODE_READ;
if ((vp = eat_path(&resolve, rfp)) == NULL) return(err_code);
/* check permissions */
r = forbidden(rfp, vp, (R_BIT | W_BIT));
unlock_vnode(vp);
unlock_vmnt(vmp);
put_vnode(vp);
return(r);
}
/*===========================================================================*
* do_checkperms *
*===========================================================================*/
int do_checkperms(void)
{
/* This should be replaced by an ACL check. */
if (!super_user) return EPERM;
return check_perms(job_m_in.m_lsys_vfs_checkperms.endpt,
job_m_in.m_lsys_vfs_checkperms.grant,
job_m_in.m_lsys_vfs_checkperms.count);
}