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phunix/minix/servers/vfs/path.c
David van Moolenbroek 27852ebe53 UDS: full rewrite 
This new implementation of the UDS service is built on top of the
libsockevent library.  It thereby inherits all the advantages that
libsockevent brings.  However, the fundamental restructuring
required for that change also paved the way for resolution of a
number of other important open issues with the old UDS code.  Most
importantly, the rewrite brings the behavior of the service much
closer to POSIX compliance and NetBSD compatibility.  These are the
most important changes:

- due to the use of libsockevent, UDS now supports multiple suspending
  calls per socket and a large number of standard socket flags and
  options;
- socket address matching is now based on <device,inode> lookups
  instead of canonized path names, and socket addresses are no longer
  altered either due to canonization or at connect time;
- the socket state machine is now well defined, most importantly
  resolving the erroneous reset-on-EOF semantics of the old UDS, but
  also allowing socket reuse;
- sockets are now connected before being accepted instead of being
  held in connecting state, unless the LOCAL_CONNWAIT option is set
  on either the connecting or the listening socket;
- connect(2) on datagram sockets is now supported (needed by syslog),
  and proper datagram socket disconnect notification is provided;
- the receive queue now supports segmentation, associating ancillary
  data (in-flight file descriptors and credentials) with each segment
  instead of being kept fully separately; this is a POSIX requirement
  (and needed by tmux);
- as part of the segmentation support, the receive queue can now hold
  as many packets as can fit, instead of one;
- in addition to the flags supported by libsockevent, the MSG_PEEK,
  MSG_WAITALL, MSG_CMSG_CLOEXEC, MSG_TRUNC, and MSG_CTRUNC send and
  receive flags are now supported;
- the SO_PASSCRED and SO_PEERCRED socket options are replaced by
  LOCAL_CREDS and LOCAL_PEEREID respectively, now following NetBSD
  semantics and allowing use of NetBSD libc's getpeereid(3);
- memory usage is reduced by about 250 KB due to centralized in-flight
  file descriptor tracking, with a limit of OPEN_MAX total rather than
  of OPEN_MAX per socket;
- memory usage is reduced by another ~50 KB due to removal of state
  redundancy, despite the fact that socket path names may now be up to
  253 bytes rather than the previous 104 bytes;
- compared to the old UDS, there is now very little direct indexing on
  the static array of sockets, thus allowing dynamic allocation of
  sockets more easily in the future;
- the UDS service now has RMIB support for the net.local sysctl tree,
  implementing preliminary support for NetBSD netstat(1).

Change-Id: I4a9b6fe4aaeef0edf2547eee894e6c14403fcb32
2017-03-09 23:39:56 +00:00

934 lines
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/* 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/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);
/*===========================================================================*
* advance *
*===========================================================================*/
struct vnode *
advance(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(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(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(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 == start_node->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(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(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(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);
}
/*===========================================================================*
* do_socketpath *
*===========================================================================*/
int do_socketpath(void)
{
/*
* Perform a path action on an on-disk socket file. This call may be performed
* by the UDS service only. The action is always on behalf of a user process
* that is currently making a socket call to the UDS service, and thus, VFS may
* rely on the fact that the user process is blocked. TODO: there should be
* checks in place to prevent (even accidental) abuse of this function, though.
*/
int r, what, slot;
endpoint_t ep;
cp_grant_id_t io_gr;
size_t pathlen;
struct vnode *dirp, *vp;
struct vmnt *vmp, *vmp2;
struct fproc *rfp;
char path[PATH_MAX];
struct lookup resolve, resolve2;
mode_t bits;
/* This should be replaced by an ACL check. */
if (!super_user) return EPERM;
ep = job_m_in.m_lsys_vfs_socketpath.endpt;
io_gr = job_m_in.m_lsys_vfs_socketpath.grant;
pathlen = job_m_in.m_lsys_vfs_socketpath.count;
what = job_m_in.m_lsys_vfs_socketpath.what;
if (isokendpt(ep, &slot) != OK) return(EINVAL);
rfp = &fproc[slot];
/* Copy in the path name, which must not be empty. It is typically not null
* terminated.
*/
if (pathlen < 1 || pathlen >= sizeof(path)) return(EINVAL);
r = sys_safecopyfrom(who_e, io_gr, (vir_bytes)0, (vir_bytes)path, pathlen);
if (r != OK) return(r);
path[pathlen] = '\0';
/* Now perform the requested action. For the SPATH_CHECK action, a socket
* file is expected to exist already, and we should check whether the given
* user process has access to it. For the SPATH_CREATE action, no file is
* expected to exist yet, and a socket file should be created on behalf of
* the user process. In both cases, on success, return the socket file's
* device and inode numbers to the caller.
*
* Since the above canonicalization releases all locks once done, we need to
* recheck absolutely everything now. TODO: do not release locks in between.
*/
switch (what) {
case SPATH_CHECK:
lookup_init(&resolve, 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 file type and permissions. */
if (!S_ISSOCK(vp->v_mode))
r = ENOTSOCK; /* not in POSIX spec; this is what NetBSD does */
else
r = forbidden(rfp, vp, R_BIT | W_BIT);
if (r == OK) {
job_m_out.m_vfs_lsys_socketpath.device = vp->v_dev;
job_m_out.m_vfs_lsys_socketpath.inode = vp->v_inode_nr;
}
unlock_vnode(vp);
unlock_vmnt(vmp);
put_vnode(vp);
break;
case SPATH_CREATE:
/* This is effectively simulating a mknod(2) call by the user process,
* including the application of its umask to the file permissions.
*/
lookup_init(&resolve, path, PATH_RET_SYMLINK, &vmp, &dirp);
resolve.l_vmnt_lock = VMNT_WRITE;
resolve.l_vnode_lock = VNODE_WRITE;
if ((dirp = last_dir(&resolve, rfp)) == NULL) return(err_code);
bits = S_IFSOCK | (ACCESSPERMS & rfp->fp_umask);
if (!S_ISDIR(dirp->v_mode))
r = ENOTDIR;
else if ((r = forbidden(rfp, dirp, W_BIT | X_BIT)) == OK) {
r = req_mknod(dirp->v_fs_e, dirp->v_inode_nr, path,
rfp->fp_effuid, rfp->fp_effgid, bits, NO_DEV);
if (r == OK) {
/* Now we need to find out the device and inode number
* of the socket file we just created. The vmnt lock
* should prevent any trouble here.
*/
lookup_init(&resolve2, resolve.l_path,
PATH_RET_SYMLINK, &vmp2, &vp);
resolve2.l_vmnt_lock = VMNT_READ;
resolve2.l_vnode_lock = VNODE_READ;
vp = advance(dirp, &resolve2, rfp);
assert(vmp2 == NULL);
if (vp != NULL) {
job_m_out.m_vfs_lsys_socketpath.device =
vp->v_dev;
job_m_out.m_vfs_lsys_socketpath.inode =
vp->v_inode_nr;
unlock_vnode(vp);
put_vnode(vp);
} else {
/* Huh. This should never happen. If it does,
* we assume the socket file has somehow been
* lost, so we do not try to unlink it.
*/
printf("VFS: socketpath did not find created "
"node at %s (%d)\n", path, err_code);
r = err_code;
}
} else if (r == EEXIST)
r = EADDRINUSE;
}
unlock_vnode(dirp);
unlock_vmnt(vmp);
put_vnode(dirp);
break;
default:
r = ENOSYS;
}
return(r);
}
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