d/freebsd-nq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

vfs: factor symlink traversal out of namei

Browse Source 
The intent down the road is to eliminate the loop to begin with,
pushing traversal down to vfs_lookup, all while not allocating the
extra buffer.
This commit is contained in:
Mateusz Guzik 2022-03-24 12:57:30 +00:00
parent d9ea7e2b1e
commit 3b6792d28a
1 changed files with 71 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

123
sys/kern/vfs_lookup.c
View File

@ -511,6 +511,74 @@ errout:
return (error);
}
static int __noinline
namei_follow_link(struct nameidata *ndp)
{
char *cp;
struct iovec aiov;
struct uio auio;
struct componentname *cnp;
struct thread *td;
int error, linklen;
error = 0;
cnp = &ndp->ni_cnd;
td = curthread;
if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
error = ELOOP;
goto out;
}
#ifdef MAC
if ((cnp->cn_flags & NOMACCHECK) == 0) {
error = mac_vnode_check_readlink(td->td_ucred, ndp->ni_vp);
if (error != 0)
goto out;
}
#endif
if (ndp->ni_pathlen > 1)
cp = uma_zalloc(namei_zone, M_WAITOK);
else
cp = cnp->cn_pnbuf;
aiov.iov_base = cp;
aiov.iov_len = MAXPATHLEN;
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
auio.uio_offset = 0;
auio.uio_rw = UIO_READ;
auio.uio_segflg = UIO_SYSSPACE;
auio.uio_td = td;
auio.uio_resid = MAXPATHLEN;
error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
if (error != 0) {
if (ndp->ni_pathlen > 1)
uma_zfree(namei_zone, cp);
goto out;
}
linklen = MAXPATHLEN - auio.uio_resid;
if (linklen == 0) {
if (ndp->ni_pathlen > 1)
uma_zfree(namei_zone, cp);
error = ENOENT;
goto out;
}
if (linklen + ndp->ni_pathlen > MAXPATHLEN) {
if (ndp->ni_pathlen > 1)
uma_zfree(namei_zone, cp);
error = ENAMETOOLONG;
goto out;
}
if (ndp->ni_pathlen > 1) {
bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
uma_zfree(namei_zone, cnp->cn_pnbuf);
cnp->cn_pnbuf = cp;
} else
cnp->cn_pnbuf[linklen] = '\0';
ndp->ni_pathlen += linklen;
out:
return (error);
}
/*
* Convert a pathname into a pointer to a locked vnode.
*
@ -534,14 +602,11 @@ errout:
int
namei(struct nameidata *ndp)
{
char *cp; /* pointer into pathname argument */
struct vnode *dp; /* the directory we are searching */
struct iovec aiov; /* uio for reading symbolic links */
struct componentname *cnp;
struct thread *td;
struct pwd *pwd;
struct uio auio;
int error, linklen;
int error;
enum cache_fpl_status status;
cnp = &ndp->ni_cnd;
@ -675,57 +740,9 @@ namei(struct nameidata *ndp)
NDVALIDATE(ndp);
return (error);
}
if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
error = ELOOP;
break;
}
#ifdef MAC
if ((cnp->cn_flags & NOMACCHECK) == 0) {
error = mac_vnode_check_readlink(td->td_ucred,
ndp->ni_vp);
error = namei_follow_link(ndp);
if (error != 0)
break;
}
#endif
if (ndp->ni_pathlen > 1)
cp = uma_zalloc(namei_zone, M_WAITOK);
else
cp = cnp->cn_pnbuf;
aiov.iov_base = cp;
aiov.iov_len = MAXPATHLEN;
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
auio.uio_offset = 0;
auio.uio_rw = UIO_READ;
auio.uio_segflg = UIO_SYSSPACE;
auio.uio_td = td;
auio.uio_resid = MAXPATHLEN;
error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
if (error != 0) {
if (ndp->ni_pathlen > 1)
uma_zfree(namei_zone, cp);
break;
}
linklen = MAXPATHLEN - auio.uio_resid;
if (linklen == 0) {
if (ndp->ni_pathlen > 1)
uma_zfree(namei_zone, cp);
error = ENOENT;
break;
}
if (linklen + ndp->ni_pathlen > MAXPATHLEN) {
if (ndp->ni_pathlen > 1)
uma_zfree(namei_zone, cp);
error = ENAMETOOLONG;
break;
}
if (ndp->ni_pathlen > 1) {
bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
uma_zfree(namei_zone, cnp->cn_pnbuf);
cnp->cn_pnbuf = cp;
} else
cnp->cn_pnbuf[linklen] = '\0';
ndp->ni_pathlen += linklen;
vput(ndp->ni_vp);
dp = ndp->ni_dvp;
/*