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1183 lines
28 KiB
1183 lines
28 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
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* Copyright (C) 2011 Novell Inc. |
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* Copyright (C) 2016 Red Hat, Inc. |
|
*/ |
|
|
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#include <linux/fs.h> |
|
#include <linux/cred.h> |
|
#include <linux/ctype.h> |
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#include <linux/namei.h> |
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#include <linux/xattr.h> |
|
#include <linux/ratelimit.h> |
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#include <linux/mount.h> |
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#include <linux/exportfs.h> |
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#include "overlayfs.h" |
|
|
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struct ovl_lookup_data { |
|
struct super_block *sb; |
|
struct qstr name; |
|
bool is_dir; |
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bool opaque; |
|
bool stop; |
|
bool last; |
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char *redirect; |
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bool metacopy; |
|
}; |
|
|
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static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d, |
|
size_t prelen, const char *post) |
|
{ |
|
int res; |
|
char *buf; |
|
struct ovl_fs *ofs = OVL_FS(d->sb); |
|
|
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buf = ovl_get_redirect_xattr(ofs, dentry, prelen + strlen(post)); |
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if (IS_ERR_OR_NULL(buf)) |
|
return PTR_ERR(buf); |
|
|
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if (buf[0] == '/') { |
|
/* |
|
* One of the ancestor path elements in an absolute path |
|
* lookup in ovl_lookup_layer() could have been opaque and |
|
* that will stop further lookup in lower layers (d->stop=true) |
|
* But we have found an absolute redirect in decendant path |
|
* element and that should force continue lookup in lower |
|
* layers (reset d->stop). |
|
*/ |
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d->stop = false; |
|
} else { |
|
res = strlen(buf) + 1; |
|
memmove(buf + prelen, buf, res); |
|
memcpy(buf, d->name.name, prelen); |
|
} |
|
|
|
strcat(buf, post); |
|
kfree(d->redirect); |
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d->redirect = buf; |
|
d->name.name = d->redirect; |
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d->name.len = strlen(d->redirect); |
|
|
|
return 0; |
|
} |
|
|
|
static int ovl_acceptable(void *ctx, struct dentry *dentry) |
|
{ |
|
/* |
|
* A non-dir origin may be disconnected, which is fine, because |
|
* we only need it for its unique inode number. |
|
*/ |
|
if (!d_is_dir(dentry)) |
|
return 1; |
|
|
|
/* Don't decode a deleted empty directory */ |
|
if (d_unhashed(dentry)) |
|
return 0; |
|
|
|
/* Check if directory belongs to the layer we are decoding from */ |
|
return is_subdir(dentry, ((struct vfsmount *)ctx)->mnt_root); |
|
} |
|
|
|
/* |
|
* Check validity of an overlay file handle buffer. |
|
* |
|
* Return 0 for a valid file handle. |
|
* Return -ENODATA for "origin unknown". |
|
* Return <0 for an invalid file handle. |
|
*/ |
|
int ovl_check_fb_len(struct ovl_fb *fb, int fb_len) |
|
{ |
|
if (fb_len < sizeof(struct ovl_fb) || fb_len < fb->len) |
|
return -EINVAL; |
|
|
|
if (fb->magic != OVL_FH_MAGIC) |
|
return -EINVAL; |
|
|
|
/* Treat larger version and unknown flags as "origin unknown" */ |
|
if (fb->version > OVL_FH_VERSION || fb->flags & ~OVL_FH_FLAG_ALL) |
|
return -ENODATA; |
|
|
|
/* Treat endianness mismatch as "origin unknown" */ |
|
if (!(fb->flags & OVL_FH_FLAG_ANY_ENDIAN) && |
|
(fb->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN) |
|
return -ENODATA; |
|
|
|
return 0; |
|
} |
|
|
|
static struct ovl_fh *ovl_get_fh(struct ovl_fs *ofs, struct dentry *dentry, |
|
enum ovl_xattr ox) |
|
{ |
|
int res, err; |
|
struct ovl_fh *fh = NULL; |
|
|
|
res = ovl_do_getxattr(ofs, dentry, ox, NULL, 0); |
|
if (res < 0) { |
|
if (res == -ENODATA || res == -EOPNOTSUPP) |
|
return NULL; |
|
goto fail; |
|
} |
|
/* Zero size value means "copied up but origin unknown" */ |
|
if (res == 0) |
|
return NULL; |
|
|
|
fh = kzalloc(res + OVL_FH_WIRE_OFFSET, GFP_KERNEL); |
|
if (!fh) |
|
return ERR_PTR(-ENOMEM); |
|
|
|
res = ovl_do_getxattr(ofs, dentry, ox, fh->buf, res); |
|
if (res < 0) |
|
goto fail; |
|
|
|
err = ovl_check_fb_len(&fh->fb, res); |
|
if (err < 0) { |
|
if (err == -ENODATA) |
|
goto out; |
|
goto invalid; |
|
} |
|
|
|
return fh; |
|
|
|
out: |
|
kfree(fh); |
|
return NULL; |
|
|
|
fail: |
|
pr_warn_ratelimited("failed to get origin (%i)\n", res); |
|
goto out; |
|
invalid: |
|
pr_warn_ratelimited("invalid origin (%*phN)\n", res, fh); |
|
goto out; |
|
} |
|
|
|
struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt, |
|
bool connected) |
|
{ |
|
struct dentry *real; |
|
int bytes; |
|
|
|
/* |
|
* Make sure that the stored uuid matches the uuid of the lower |
|
* layer where file handle will be decoded. |
|
*/ |
|
if (!uuid_equal(&fh->fb.uuid, &mnt->mnt_sb->s_uuid)) |
|
return NULL; |
|
|
|
bytes = (fh->fb.len - offsetof(struct ovl_fb, fid)); |
|
real = exportfs_decode_fh(mnt, (struct fid *)fh->fb.fid, |
|
bytes >> 2, (int)fh->fb.type, |
|
connected ? ovl_acceptable : NULL, mnt); |
|
if (IS_ERR(real)) { |
|
/* |
|
* Treat stale file handle to lower file as "origin unknown". |
|
* upper file handle could become stale when upper file is |
|
* unlinked and this information is needed to handle stale |
|
* index entries correctly. |
|
*/ |
|
if (real == ERR_PTR(-ESTALE) && |
|
!(fh->fb.flags & OVL_FH_FLAG_PATH_UPPER)) |
|
real = NULL; |
|
return real; |
|
} |
|
|
|
if (ovl_dentry_weird(real)) { |
|
dput(real); |
|
return NULL; |
|
} |
|
|
|
return real; |
|
} |
|
|
|
static bool ovl_is_opaquedir(struct super_block *sb, struct dentry *dentry) |
|
{ |
|
return ovl_check_dir_xattr(sb, dentry, OVL_XATTR_OPAQUE); |
|
} |
|
|
|
static struct dentry *ovl_lookup_positive_unlocked(const char *name, |
|
struct dentry *base, int len, |
|
bool drop_negative) |
|
{ |
|
struct dentry *ret = lookup_one_len_unlocked(name, base, len); |
|
|
|
if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { |
|
if (drop_negative && ret->d_lockref.count == 1) { |
|
spin_lock(&ret->d_lock); |
|
/* Recheck condition under lock */ |
|
if (d_is_negative(ret) && ret->d_lockref.count == 1) |
|
__d_drop(ret); |
|
spin_unlock(&ret->d_lock); |
|
} |
|
dput(ret); |
|
ret = ERR_PTR(-ENOENT); |
|
} |
|
return ret; |
|
} |
|
|
|
static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d, |
|
const char *name, unsigned int namelen, |
|
size_t prelen, const char *post, |
|
struct dentry **ret, bool drop_negative) |
|
{ |
|
struct dentry *this; |
|
int err; |
|
bool last_element = !post[0]; |
|
|
|
this = ovl_lookup_positive_unlocked(name, base, namelen, drop_negative); |
|
if (IS_ERR(this)) { |
|
err = PTR_ERR(this); |
|
this = NULL; |
|
if (err == -ENOENT || err == -ENAMETOOLONG) |
|
goto out; |
|
goto out_err; |
|
} |
|
|
|
if (ovl_dentry_weird(this)) { |
|
/* Don't support traversing automounts and other weirdness */ |
|
err = -EREMOTE; |
|
goto out_err; |
|
} |
|
if (ovl_is_whiteout(this)) { |
|
d->stop = d->opaque = true; |
|
goto put_and_out; |
|
} |
|
/* |
|
* This dentry should be a regular file if previous layer lookup |
|
* found a metacopy dentry. |
|
*/ |
|
if (last_element && d->metacopy && !d_is_reg(this)) { |
|
d->stop = true; |
|
goto put_and_out; |
|
} |
|
if (!d_can_lookup(this)) { |
|
if (d->is_dir || !last_element) { |
|
d->stop = true; |
|
goto put_and_out; |
|
} |
|
err = ovl_check_metacopy_xattr(OVL_FS(d->sb), this); |
|
if (err < 0) |
|
goto out_err; |
|
|
|
d->metacopy = err; |
|
d->stop = !d->metacopy; |
|
if (!d->metacopy || d->last) |
|
goto out; |
|
} else { |
|
if (ovl_lookup_trap_inode(d->sb, this)) { |
|
/* Caught in a trap of overlapping layers */ |
|
err = -ELOOP; |
|
goto out_err; |
|
} |
|
|
|
if (last_element) |
|
d->is_dir = true; |
|
if (d->last) |
|
goto out; |
|
|
|
if (ovl_is_opaquedir(d->sb, this)) { |
|
d->stop = true; |
|
if (last_element) |
|
d->opaque = true; |
|
goto out; |
|
} |
|
} |
|
err = ovl_check_redirect(this, d, prelen, post); |
|
if (err) |
|
goto out_err; |
|
out: |
|
*ret = this; |
|
return 0; |
|
|
|
put_and_out: |
|
dput(this); |
|
this = NULL; |
|
goto out; |
|
|
|
out_err: |
|
dput(this); |
|
return err; |
|
} |
|
|
|
static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, |
|
struct dentry **ret, bool drop_negative) |
|
{ |
|
/* Counting down from the end, since the prefix can change */ |
|
size_t rem = d->name.len - 1; |
|
struct dentry *dentry = NULL; |
|
int err; |
|
|
|
if (d->name.name[0] != '/') |
|
return ovl_lookup_single(base, d, d->name.name, d->name.len, |
|
0, "", ret, drop_negative); |
|
|
|
while (!IS_ERR_OR_NULL(base) && d_can_lookup(base)) { |
|
const char *s = d->name.name + d->name.len - rem; |
|
const char *next = strchrnul(s, '/'); |
|
size_t thislen = next - s; |
|
bool end = !next[0]; |
|
|
|
/* Verify we did not go off the rails */ |
|
if (WARN_ON(s[-1] != '/')) |
|
return -EIO; |
|
|
|
err = ovl_lookup_single(base, d, s, thislen, |
|
d->name.len - rem, next, &base, |
|
drop_negative); |
|
dput(dentry); |
|
if (err) |
|
return err; |
|
dentry = base; |
|
if (end) |
|
break; |
|
|
|
rem -= thislen + 1; |
|
|
|
if (WARN_ON(rem >= d->name.len)) |
|
return -EIO; |
|
} |
|
*ret = dentry; |
|
return 0; |
|
} |
|
|
|
|
|
int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected, |
|
struct dentry *upperdentry, struct ovl_path **stackp) |
|
{ |
|
struct dentry *origin = NULL; |
|
int i; |
|
|
|
for (i = 1; i < ofs->numlayer; i++) { |
|
/* |
|
* If lower fs uuid is not unique among lower fs we cannot match |
|
* fh->uuid to layer. |
|
*/ |
|
if (ofs->layers[i].fsid && |
|
ofs->layers[i].fs->bad_uuid) |
|
continue; |
|
|
|
origin = ovl_decode_real_fh(fh, ofs->layers[i].mnt, |
|
connected); |
|
if (origin) |
|
break; |
|
} |
|
|
|
if (!origin) |
|
return -ESTALE; |
|
else if (IS_ERR(origin)) |
|
return PTR_ERR(origin); |
|
|
|
if (upperdentry && !ovl_is_whiteout(upperdentry) && |
|
inode_wrong_type(d_inode(upperdentry), d_inode(origin)->i_mode)) |
|
goto invalid; |
|
|
|
if (!*stackp) |
|
*stackp = kmalloc(sizeof(struct ovl_path), GFP_KERNEL); |
|
if (!*stackp) { |
|
dput(origin); |
|
return -ENOMEM; |
|
} |
|
**stackp = (struct ovl_path){ |
|
.dentry = origin, |
|
.layer = &ofs->layers[i] |
|
}; |
|
|
|
return 0; |
|
|
|
invalid: |
|
pr_warn_ratelimited("invalid origin (%pd2, ftype=%x, origin ftype=%x).\n", |
|
upperdentry, d_inode(upperdentry)->i_mode & S_IFMT, |
|
d_inode(origin)->i_mode & S_IFMT); |
|
dput(origin); |
|
return -EIO; |
|
} |
|
|
|
static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry, |
|
struct ovl_path **stackp) |
|
{ |
|
struct ovl_fh *fh = ovl_get_fh(ofs, upperdentry, OVL_XATTR_ORIGIN); |
|
int err; |
|
|
|
if (IS_ERR_OR_NULL(fh)) |
|
return PTR_ERR(fh); |
|
|
|
err = ovl_check_origin_fh(ofs, fh, false, upperdentry, stackp); |
|
kfree(fh); |
|
|
|
if (err) { |
|
if (err == -ESTALE) |
|
return 0; |
|
return err; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
/* |
|
* Verify that @fh matches the file handle stored in xattr @name. |
|
* Return 0 on match, -ESTALE on mismatch, < 0 on error. |
|
*/ |
|
static int ovl_verify_fh(struct ovl_fs *ofs, struct dentry *dentry, |
|
enum ovl_xattr ox, const struct ovl_fh *fh) |
|
{ |
|
struct ovl_fh *ofh = ovl_get_fh(ofs, dentry, ox); |
|
int err = 0; |
|
|
|
if (!ofh) |
|
return -ENODATA; |
|
|
|
if (IS_ERR(ofh)) |
|
return PTR_ERR(ofh); |
|
|
|
if (fh->fb.len != ofh->fb.len || memcmp(&fh->fb, &ofh->fb, fh->fb.len)) |
|
err = -ESTALE; |
|
|
|
kfree(ofh); |
|
return err; |
|
} |
|
|
|
/* |
|
* Verify that @real dentry matches the file handle stored in xattr @name. |
|
* |
|
* If @set is true and there is no stored file handle, encode @real and store |
|
* file handle in xattr @name. |
|
* |
|
* Return 0 on match, -ESTALE on mismatch, -ENODATA on no xattr, < 0 on error. |
|
*/ |
|
int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry, |
|
enum ovl_xattr ox, struct dentry *real, bool is_upper, |
|
bool set) |
|
{ |
|
struct inode *inode; |
|
struct ovl_fh *fh; |
|
int err; |
|
|
|
fh = ovl_encode_real_fh(real, is_upper); |
|
err = PTR_ERR(fh); |
|
if (IS_ERR(fh)) { |
|
fh = NULL; |
|
goto fail; |
|
} |
|
|
|
err = ovl_verify_fh(ofs, dentry, ox, fh); |
|
if (set && err == -ENODATA) |
|
err = ovl_do_setxattr(ofs, dentry, ox, fh->buf, fh->fb.len); |
|
if (err) |
|
goto fail; |
|
|
|
out: |
|
kfree(fh); |
|
return err; |
|
|
|
fail: |
|
inode = d_inode(real); |
|
pr_warn_ratelimited("failed to verify %s (%pd2, ino=%lu, err=%i)\n", |
|
is_upper ? "upper" : "origin", real, |
|
inode ? inode->i_ino : 0, err); |
|
goto out; |
|
} |
|
|
|
/* Get upper dentry from index */ |
|
struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index) |
|
{ |
|
struct ovl_fh *fh; |
|
struct dentry *upper; |
|
|
|
if (!d_is_dir(index)) |
|
return dget(index); |
|
|
|
fh = ovl_get_fh(ofs, index, OVL_XATTR_UPPER); |
|
if (IS_ERR_OR_NULL(fh)) |
|
return ERR_CAST(fh); |
|
|
|
upper = ovl_decode_real_fh(fh, ovl_upper_mnt(ofs), true); |
|
kfree(fh); |
|
|
|
if (IS_ERR_OR_NULL(upper)) |
|
return upper ?: ERR_PTR(-ESTALE); |
|
|
|
if (!d_is_dir(upper)) { |
|
pr_warn_ratelimited("invalid index upper (%pd2, upper=%pd2).\n", |
|
index, upper); |
|
dput(upper); |
|
return ERR_PTR(-EIO); |
|
} |
|
|
|
return upper; |
|
} |
|
|
|
/* |
|
* Verify that an index entry name matches the origin file handle stored in |
|
* OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path. |
|
* Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error. |
|
*/ |
|
int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index) |
|
{ |
|
struct ovl_fh *fh = NULL; |
|
size_t len; |
|
struct ovl_path origin = { }; |
|
struct ovl_path *stack = &origin; |
|
struct dentry *upper = NULL; |
|
int err; |
|
|
|
if (!d_inode(index)) |
|
return 0; |
|
|
|
err = -EINVAL; |
|
if (index->d_name.len < sizeof(struct ovl_fb)*2) |
|
goto fail; |
|
|
|
err = -ENOMEM; |
|
len = index->d_name.len / 2; |
|
fh = kzalloc(len + OVL_FH_WIRE_OFFSET, GFP_KERNEL); |
|
if (!fh) |
|
goto fail; |
|
|
|
err = -EINVAL; |
|
if (hex2bin(fh->buf, index->d_name.name, len)) |
|
goto fail; |
|
|
|
err = ovl_check_fb_len(&fh->fb, len); |
|
if (err) |
|
goto fail; |
|
|
|
/* |
|
* Whiteout index entries are used as an indication that an exported |
|
* overlay file handle should be treated as stale (i.e. after unlink |
|
* of the overlay inode). These entries contain no origin xattr. |
|
*/ |
|
if (ovl_is_whiteout(index)) |
|
goto out; |
|
|
|
/* |
|
* Verifying directory index entries are not stale is expensive, so |
|
* only verify stale dir index if NFS export is enabled. |
|
*/ |
|
if (d_is_dir(index) && !ofs->config.nfs_export) |
|
goto out; |
|
|
|
/* |
|
* Directory index entries should have 'upper' xattr pointing to the |
|
* real upper dir. Non-dir index entries are hardlinks to the upper |
|
* real inode. For non-dir index, we can read the copy up origin xattr |
|
* directly from the index dentry, but for dir index we first need to |
|
* decode the upper directory. |
|
*/ |
|
upper = ovl_index_upper(ofs, index); |
|
if (IS_ERR_OR_NULL(upper)) { |
|
err = PTR_ERR(upper); |
|
/* |
|
* Directory index entries with no 'upper' xattr need to be |
|
* removed. When dir index entry has a stale 'upper' xattr, |
|
* we assume that upper dir was removed and we treat the dir |
|
* index as orphan entry that needs to be whited out. |
|
*/ |
|
if (err == -ESTALE) |
|
goto orphan; |
|
else if (!err) |
|
err = -ESTALE; |
|
goto fail; |
|
} |
|
|
|
err = ovl_verify_fh(ofs, upper, OVL_XATTR_ORIGIN, fh); |
|
dput(upper); |
|
if (err) |
|
goto fail; |
|
|
|
/* Check if non-dir index is orphan and don't warn before cleaning it */ |
|
if (!d_is_dir(index) && d_inode(index)->i_nlink == 1) { |
|
err = ovl_check_origin_fh(ofs, fh, false, index, &stack); |
|
if (err) |
|
goto fail; |
|
|
|
if (ovl_get_nlink(ofs, origin.dentry, index, 0) == 0) |
|
goto orphan; |
|
} |
|
|
|
out: |
|
dput(origin.dentry); |
|
kfree(fh); |
|
return err; |
|
|
|
fail: |
|
pr_warn_ratelimited("failed to verify index (%pd2, ftype=%x, err=%i)\n", |
|
index, d_inode(index)->i_mode & S_IFMT, err); |
|
goto out; |
|
|
|
orphan: |
|
pr_warn_ratelimited("orphan index entry (%pd2, ftype=%x, nlink=%u)\n", |
|
index, d_inode(index)->i_mode & S_IFMT, |
|
d_inode(index)->i_nlink); |
|
err = -ENOENT; |
|
goto out; |
|
} |
|
|
|
static int ovl_get_index_name_fh(struct ovl_fh *fh, struct qstr *name) |
|
{ |
|
char *n, *s; |
|
|
|
n = kcalloc(fh->fb.len, 2, GFP_KERNEL); |
|
if (!n) |
|
return -ENOMEM; |
|
|
|
s = bin2hex(n, fh->buf, fh->fb.len); |
|
*name = (struct qstr) QSTR_INIT(n, s - n); |
|
|
|
return 0; |
|
|
|
} |
|
|
|
/* |
|
* Lookup in indexdir for the index entry of a lower real inode or a copy up |
|
* origin inode. The index entry name is the hex representation of the lower |
|
* inode file handle. |
|
* |
|
* If the index dentry in negative, then either no lower aliases have been |
|
* copied up yet, or aliases have been copied up in older kernels and are |
|
* not indexed. |
|
* |
|
* If the index dentry for a copy up origin inode is positive, but points |
|
* to an inode different than the upper inode, then either the upper inode |
|
* has been copied up and not indexed or it was indexed, but since then |
|
* index dir was cleared. Either way, that index cannot be used to indentify |
|
* the overlay inode. |
|
*/ |
|
int ovl_get_index_name(struct dentry *origin, struct qstr *name) |
|
{ |
|
struct ovl_fh *fh; |
|
int err; |
|
|
|
fh = ovl_encode_real_fh(origin, false); |
|
if (IS_ERR(fh)) |
|
return PTR_ERR(fh); |
|
|
|
err = ovl_get_index_name_fh(fh, name); |
|
|
|
kfree(fh); |
|
return err; |
|
} |
|
|
|
/* Lookup index by file handle for NFS export */ |
|
struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh) |
|
{ |
|
struct dentry *index; |
|
struct qstr name; |
|
int err; |
|
|
|
err = ovl_get_index_name_fh(fh, &name); |
|
if (err) |
|
return ERR_PTR(err); |
|
|
|
index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len); |
|
kfree(name.name); |
|
if (IS_ERR(index)) { |
|
if (PTR_ERR(index) == -ENOENT) |
|
index = NULL; |
|
return index; |
|
} |
|
|
|
if (ovl_is_whiteout(index)) |
|
err = -ESTALE; |
|
else if (ovl_dentry_weird(index)) |
|
err = -EIO; |
|
else |
|
return index; |
|
|
|
dput(index); |
|
return ERR_PTR(err); |
|
} |
|
|
|
struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper, |
|
struct dentry *origin, bool verify) |
|
{ |
|
struct dentry *index; |
|
struct inode *inode; |
|
struct qstr name; |
|
bool is_dir = d_is_dir(origin); |
|
int err; |
|
|
|
err = ovl_get_index_name(origin, &name); |
|
if (err) |
|
return ERR_PTR(err); |
|
|
|
index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len); |
|
if (IS_ERR(index)) { |
|
err = PTR_ERR(index); |
|
if (err == -ENOENT) { |
|
index = NULL; |
|
goto out; |
|
} |
|
pr_warn_ratelimited("failed inode index lookup (ino=%lu, key=%.*s, err=%i);\n" |
|
"overlayfs: mount with '-o index=off' to disable inodes index.\n", |
|
d_inode(origin)->i_ino, name.len, name.name, |
|
err); |
|
goto out; |
|
} |
|
|
|
inode = d_inode(index); |
|
if (ovl_is_whiteout(index) && !verify) { |
|
/* |
|
* When index lookup is called with !verify for decoding an |
|
* overlay file handle, a whiteout index implies that decode |
|
* should treat file handle as stale and no need to print a |
|
* warning about it. |
|
*/ |
|
dput(index); |
|
index = ERR_PTR(-ESTALE); |
|
goto out; |
|
} else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) || |
|
inode_wrong_type(inode, d_inode(origin)->i_mode)) { |
|
/* |
|
* Index should always be of the same file type as origin |
|
* except for the case of a whiteout index. A whiteout |
|
* index should only exist if all lower aliases have been |
|
* unlinked, which means that finding a lower origin on lookup |
|
* whose index is a whiteout should be treated as an error. |
|
*/ |
|
pr_warn_ratelimited("bad index found (index=%pd2, ftype=%x, origin ftype=%x).\n", |
|
index, d_inode(index)->i_mode & S_IFMT, |
|
d_inode(origin)->i_mode & S_IFMT); |
|
goto fail; |
|
} else if (is_dir && verify) { |
|
if (!upper) { |
|
pr_warn_ratelimited("suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n", |
|
origin, index); |
|
goto fail; |
|
} |
|
|
|
/* Verify that dir index 'upper' xattr points to upper dir */ |
|
err = ovl_verify_upper(ofs, index, upper, false); |
|
if (err) { |
|
if (err == -ESTALE) { |
|
pr_warn_ratelimited("suspected multiply redirected dir found (upper=%pd2, origin=%pd2, index=%pd2).\n", |
|
upper, origin, index); |
|
} |
|
goto fail; |
|
} |
|
} else if (upper && d_inode(upper) != inode) { |
|
goto out_dput; |
|
} |
|
out: |
|
kfree(name.name); |
|
return index; |
|
|
|
out_dput: |
|
dput(index); |
|
index = NULL; |
|
goto out; |
|
|
|
fail: |
|
dput(index); |
|
index = ERR_PTR(-EIO); |
|
goto out; |
|
} |
|
|
|
/* |
|
* Returns next layer in stack starting from top. |
|
* Returns -1 if this is the last layer. |
|
*/ |
|
int ovl_path_next(int idx, struct dentry *dentry, struct path *path) |
|
{ |
|
struct ovl_entry *oe = dentry->d_fsdata; |
|
|
|
BUG_ON(idx < 0); |
|
if (idx == 0) { |
|
ovl_path_upper(dentry, path); |
|
if (path->dentry) |
|
return oe->numlower ? 1 : -1; |
|
idx++; |
|
} |
|
BUG_ON(idx > oe->numlower); |
|
path->dentry = oe->lowerstack[idx - 1].dentry; |
|
path->mnt = oe->lowerstack[idx - 1].layer->mnt; |
|
|
|
return (idx < oe->numlower) ? idx + 1 : -1; |
|
} |
|
|
|
/* Fix missing 'origin' xattr */ |
|
static int ovl_fix_origin(struct ovl_fs *ofs, struct dentry *dentry, |
|
struct dentry *lower, struct dentry *upper) |
|
{ |
|
int err; |
|
|
|
if (ovl_check_origin_xattr(ofs, upper)) |
|
return 0; |
|
|
|
err = ovl_want_write(dentry); |
|
if (err) |
|
return err; |
|
|
|
err = ovl_set_origin(dentry, lower, upper); |
|
if (!err) |
|
err = ovl_set_impure(dentry->d_parent, upper->d_parent); |
|
|
|
ovl_drop_write(dentry); |
|
return err; |
|
} |
|
|
|
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, |
|
unsigned int flags) |
|
{ |
|
struct ovl_entry *oe; |
|
const struct cred *old_cred; |
|
struct ovl_fs *ofs = dentry->d_sb->s_fs_info; |
|
struct ovl_entry *poe = dentry->d_parent->d_fsdata; |
|
struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata; |
|
struct ovl_path *stack = NULL, *origin_path = NULL; |
|
struct dentry *upperdir, *upperdentry = NULL; |
|
struct dentry *origin = NULL; |
|
struct dentry *index = NULL; |
|
unsigned int ctr = 0; |
|
struct inode *inode = NULL; |
|
bool upperopaque = false; |
|
char *upperredirect = NULL; |
|
struct dentry *this; |
|
unsigned int i; |
|
int err; |
|
bool uppermetacopy = false; |
|
struct ovl_lookup_data d = { |
|
.sb = dentry->d_sb, |
|
.name = dentry->d_name, |
|
.is_dir = false, |
|
.opaque = false, |
|
.stop = false, |
|
.last = ofs->config.redirect_follow ? false : !poe->numlower, |
|
.redirect = NULL, |
|
.metacopy = false, |
|
}; |
|
|
|
if (dentry->d_name.len > ofs->namelen) |
|
return ERR_PTR(-ENAMETOOLONG); |
|
|
|
old_cred = ovl_override_creds(dentry->d_sb); |
|
upperdir = ovl_dentry_upper(dentry->d_parent); |
|
if (upperdir) { |
|
err = ovl_lookup_layer(upperdir, &d, &upperdentry, true); |
|
if (err) |
|
goto out; |
|
|
|
if (upperdentry && upperdentry->d_flags & DCACHE_OP_REAL) { |
|
dput(upperdentry); |
|
err = -EREMOTE; |
|
goto out; |
|
} |
|
if (upperdentry && !d.is_dir) { |
|
/* |
|
* Lookup copy up origin by decoding origin file handle. |
|
* We may get a disconnected dentry, which is fine, |
|
* because we only need to hold the origin inode in |
|
* cache and use its inode number. We may even get a |
|
* connected dentry, that is not under any of the lower |
|
* layers root. That is also fine for using it's inode |
|
* number - it's the same as if we held a reference |
|
* to a dentry in lower layer that was moved under us. |
|
*/ |
|
err = ovl_check_origin(ofs, upperdentry, &origin_path); |
|
if (err) |
|
goto out_put_upper; |
|
|
|
if (d.metacopy) |
|
uppermetacopy = true; |
|
} |
|
|
|
if (d.redirect) { |
|
err = -ENOMEM; |
|
upperredirect = kstrdup(d.redirect, GFP_KERNEL); |
|
if (!upperredirect) |
|
goto out_put_upper; |
|
if (d.redirect[0] == '/') |
|
poe = roe; |
|
} |
|
upperopaque = d.opaque; |
|
} |
|
|
|
if (!d.stop && poe->numlower) { |
|
err = -ENOMEM; |
|
stack = kcalloc(ofs->numlayer - 1, sizeof(struct ovl_path), |
|
GFP_KERNEL); |
|
if (!stack) |
|
goto out_put_upper; |
|
} |
|
|
|
for (i = 0; !d.stop && i < poe->numlower; i++) { |
|
struct ovl_path lower = poe->lowerstack[i]; |
|
|
|
if (!ofs->config.redirect_follow) |
|
d.last = i == poe->numlower - 1; |
|
else |
|
d.last = lower.layer->idx == roe->numlower; |
|
|
|
err = ovl_lookup_layer(lower.dentry, &d, &this, false); |
|
if (err) |
|
goto out_put; |
|
|
|
if (!this) |
|
continue; |
|
|
|
if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) { |
|
dput(this); |
|
err = -EPERM; |
|
pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", dentry); |
|
goto out_put; |
|
} |
|
|
|
/* |
|
* If no origin fh is stored in upper of a merge dir, store fh |
|
* of lower dir and set upper parent "impure". |
|
*/ |
|
if (upperdentry && !ctr && !ofs->noxattr && d.is_dir) { |
|
err = ovl_fix_origin(ofs, dentry, this, upperdentry); |
|
if (err) { |
|
dput(this); |
|
goto out_put; |
|
} |
|
} |
|
|
|
/* |
|
* When "verify_lower" feature is enabled, do not merge with a |
|
* lower dir that does not match a stored origin xattr. In any |
|
* case, only verified origin is used for index lookup. |
|
* |
|
* For non-dir dentry, if index=on, then ensure origin |
|
* matches the dentry found using path based lookup, |
|
* otherwise error out. |
|
*/ |
|
if (upperdentry && !ctr && |
|
((d.is_dir && ovl_verify_lower(dentry->d_sb)) || |
|
(!d.is_dir && ofs->config.index && origin_path))) { |
|
err = ovl_verify_origin(ofs, upperdentry, this, false); |
|
if (err) { |
|
dput(this); |
|
if (d.is_dir) |
|
break; |
|
goto out_put; |
|
} |
|
origin = this; |
|
} |
|
|
|
if (d.metacopy && ctr) { |
|
/* |
|
* Do not store intermediate metacopy dentries in |
|
* lower chain, except top most lower metacopy dentry. |
|
* Continue the loop so that if there is an absolute |
|
* redirect on this dentry, poe can be reset to roe. |
|
*/ |
|
dput(this); |
|
this = NULL; |
|
} else { |
|
stack[ctr].dentry = this; |
|
stack[ctr].layer = lower.layer; |
|
ctr++; |
|
} |
|
|
|
/* |
|
* Following redirects can have security consequences: it's like |
|
* a symlink into the lower layer without the permission checks. |
|
* This is only a problem if the upper layer is untrusted (e.g |
|
* comes from an USB drive). This can allow a non-readable file |
|
* or directory to become readable. |
|
* |
|
* Only following redirects when redirects are enabled disables |
|
* this attack vector when not necessary. |
|
*/ |
|
err = -EPERM; |
|
if (d.redirect && !ofs->config.redirect_follow) { |
|
pr_warn_ratelimited("refusing to follow redirect for (%pd2)\n", |
|
dentry); |
|
goto out_put; |
|
} |
|
|
|
if (d.stop) |
|
break; |
|
|
|
if (d.redirect && d.redirect[0] == '/' && poe != roe) { |
|
poe = roe; |
|
/* Find the current layer on the root dentry */ |
|
i = lower.layer->idx - 1; |
|
} |
|
} |
|
|
|
/* |
|
* For regular non-metacopy upper dentries, there is no lower |
|
* path based lookup, hence ctr will be zero. If a dentry is found |
|
* using ORIGIN xattr on upper, install it in stack. |
|
* |
|
* For metacopy dentry, path based lookup will find lower dentries. |
|
* Just make sure a corresponding data dentry has been found. |
|
*/ |
|
if (d.metacopy || (uppermetacopy && !ctr)) { |
|
err = -EIO; |
|
goto out_put; |
|
} else if (!d.is_dir && upperdentry && !ctr && origin_path) { |
|
if (WARN_ON(stack != NULL)) { |
|
err = -EIO; |
|
goto out_put; |
|
} |
|
stack = origin_path; |
|
ctr = 1; |
|
origin = origin_path->dentry; |
|
origin_path = NULL; |
|
} |
|
|
|
/* |
|
* Always lookup index if there is no-upperdentry. |
|
* |
|
* For the case of upperdentry, we have set origin by now if it |
|
* needed to be set. There are basically three cases. |
|
* |
|
* For directories, lookup index by lower inode and verify it matches |
|
* upper inode. We only trust dir index if we verified that lower dir |
|
* matches origin, otherwise dir index entries may be inconsistent |
|
* and we ignore them. |
|
* |
|
* For regular upper, we already set origin if upper had ORIGIN |
|
* xattr. There is no verification though as there is no path |
|
* based dentry lookup in lower in this case. |
|
* |
|
* For metacopy upper, we set a verified origin already if index |
|
* is enabled and if upper had an ORIGIN xattr. |
|
* |
|
*/ |
|
if (!upperdentry && ctr) |
|
origin = stack[0].dentry; |
|
|
|
if (origin && ovl_indexdir(dentry->d_sb) && |
|
(!d.is_dir || ovl_index_all(dentry->d_sb))) { |
|
index = ovl_lookup_index(ofs, upperdentry, origin, true); |
|
if (IS_ERR(index)) { |
|
err = PTR_ERR(index); |
|
index = NULL; |
|
goto out_put; |
|
} |
|
} |
|
|
|
oe = ovl_alloc_entry(ctr); |
|
err = -ENOMEM; |
|
if (!oe) |
|
goto out_put; |
|
|
|
memcpy(oe->lowerstack, stack, sizeof(struct ovl_path) * ctr); |
|
dentry->d_fsdata = oe; |
|
|
|
if (upperopaque) |
|
ovl_dentry_set_opaque(dentry); |
|
|
|
if (upperdentry) |
|
ovl_dentry_set_upper_alias(dentry); |
|
else if (index) { |
|
upperdentry = dget(index); |
|
upperredirect = ovl_get_redirect_xattr(ofs, upperdentry, 0); |
|
if (IS_ERR(upperredirect)) { |
|
err = PTR_ERR(upperredirect); |
|
upperredirect = NULL; |
|
goto out_free_oe; |
|
} |
|
err = ovl_check_metacopy_xattr(ofs, upperdentry); |
|
if (err < 0) |
|
goto out_free_oe; |
|
uppermetacopy = err; |
|
} |
|
|
|
if (upperdentry || ctr) { |
|
struct ovl_inode_params oip = { |
|
.upperdentry = upperdentry, |
|
.lowerpath = stack, |
|
.index = index, |
|
.numlower = ctr, |
|
.redirect = upperredirect, |
|
.lowerdata = (ctr > 1 && !d.is_dir) ? |
|
stack[ctr - 1].dentry : NULL, |
|
}; |
|
|
|
inode = ovl_get_inode(dentry->d_sb, &oip); |
|
err = PTR_ERR(inode); |
|
if (IS_ERR(inode)) |
|
goto out_free_oe; |
|
if (upperdentry && !uppermetacopy) |
|
ovl_set_flag(OVL_UPPERDATA, inode); |
|
} |
|
|
|
ovl_dentry_update_reval(dentry, upperdentry, |
|
DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE); |
|
|
|
revert_creds(old_cred); |
|
if (origin_path) { |
|
dput(origin_path->dentry); |
|
kfree(origin_path); |
|
} |
|
dput(index); |
|
kfree(stack); |
|
kfree(d.redirect); |
|
return d_splice_alias(inode, dentry); |
|
|
|
out_free_oe: |
|
dentry->d_fsdata = NULL; |
|
kfree(oe); |
|
out_put: |
|
dput(index); |
|
for (i = 0; i < ctr; i++) |
|
dput(stack[i].dentry); |
|
kfree(stack); |
|
out_put_upper: |
|
if (origin_path) { |
|
dput(origin_path->dentry); |
|
kfree(origin_path); |
|
} |
|
dput(upperdentry); |
|
kfree(upperredirect); |
|
out: |
|
kfree(d.redirect); |
|
revert_creds(old_cred); |
|
return ERR_PTR(err); |
|
} |
|
|
|
bool ovl_lower_positive(struct dentry *dentry) |
|
{ |
|
struct ovl_entry *poe = dentry->d_parent->d_fsdata; |
|
const struct qstr *name = &dentry->d_name; |
|
const struct cred *old_cred; |
|
unsigned int i; |
|
bool positive = false; |
|
bool done = false; |
|
|
|
/* |
|
* If dentry is negative, then lower is positive iff this is a |
|
* whiteout. |
|
*/ |
|
if (!dentry->d_inode) |
|
return ovl_dentry_is_opaque(dentry); |
|
|
|
/* Negative upper -> positive lower */ |
|
if (!ovl_dentry_upper(dentry)) |
|
return true; |
|
|
|
old_cred = ovl_override_creds(dentry->d_sb); |
|
/* Positive upper -> have to look up lower to see whether it exists */ |
|
for (i = 0; !done && !positive && i < poe->numlower; i++) { |
|
struct dentry *this; |
|
struct dentry *lowerdir = poe->lowerstack[i].dentry; |
|
|
|
this = lookup_positive_unlocked(name->name, lowerdir, |
|
name->len); |
|
if (IS_ERR(this)) { |
|
switch (PTR_ERR(this)) { |
|
case -ENOENT: |
|
case -ENAMETOOLONG: |
|
break; |
|
|
|
default: |
|
/* |
|
* Assume something is there, we just couldn't |
|
* access it. |
|
*/ |
|
positive = true; |
|
break; |
|
} |
|
} else { |
|
positive = !ovl_is_whiteout(this); |
|
done = true; |
|
dput(this); |
|
} |
|
} |
|
revert_creds(old_cred); |
|
|
|
return positive; |
|
}
|
|
|