Host users might want to access overlayfs owned by CT. In such case
ve_capable checks will fail - they will perform VE cred checks against
host user_ns.
Modify ovl_override_creds so that it returns both old cred and old VE.
This will also protect us from future rebase issues - all new users of
old_cred and ovl_override_creds will fail with compilation error.
This fixes an observed crash in overlayfs when checkpointing
a container with a docker running inside:
[ 2300.870181] BUG: kernel NULL pointer dereference, address: 0000000000000005
[ 2300.871537] #PF: supervisor read access in kernel mode
[ 2300.872577] #PF: error_code(0x0000) - not-present page
[ 2300.873595] PGD 800000010a18f067 P4D 800000010a18f067 PUD 10730c067 PMD 0
[ 2300.874900] Oops: Oops: 0000 [#1] SMP PTI
[ 2300.875742] CPU: 1 UID: 0 PID: 5419 Comm: criu ve: 0 Kdump: loaded Not
tainted 6.12.0-211.39.1.16.6.vz10.x86_64 #1 16.6 PREEMPT(voluntary)
[ 2300.878057] Hardware name: Acronis OpenStack Compute/Virtuozzo, BIOS
1.16.1-1.vz9.2 04/01/2014
[ 2300.879684] RIP: 0010:ovl_get_index_name_fh+0x18/0x70 [overlay]
[ 2300.880859] Code: ...
[ 2300.884128] RSP: 0018:ffffd32582e0f7c0 EFLAGS: 00010246
[ 2300.885153] RAX: ...
[ 2300.895807] Call Trace:
[ 2300.896397]
[ 2300.903298] ? ovl_get_index_name_fh+0x18/0x70 [overlay]
[ 2300.904435] ovl_create_index+0x82/0x260 [overlay]
[ 2300.905406] ovl_copy_up_workdir+0x30a/0x330 [overlay]
[ 2300.906427] ovl_do_copy_up+0x10d/0x2e0 [overlay]
[ 2300.907387] ovl_copy_up_one+0x456/0x720 [overlay]
[ 2300.910736] ovl_copy_up_flags+0x81/0x110 [overlay]
[ 2300.911740] ovl_create_object+0x51/0x130 [overlay]
[ 2300.912719] vfs_mkdir+0x194/0x250
[ 2300.913470] do_mkdirat+0x14c/0x180
[ 2300.914223] __x64_sys_mkdir+0x46/0x70
[ 2300.915019] do_syscall_64+0x7d/0x160
[ 2300.922814] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 2300.923823] RIP: 0033:0x7f5a2f8de3eb
Overlayfs was created inside CT, so ovl_fill_super stored
in-container credentials to ofs->creator_cred.
Those creds were later used in ovl_override_creds to temporarily
swich creds and perform checks using them.
One of these checks happened in ovl_get_origin_fh/ovl_can_decode_fh.
On fs creation this check passed because we had container VE
and container creds, so overlayfs thought that we support
file handles (ovl_can_decode_fh call in ovl_make_workdir).
When we tried to do something with the overlayfs from host VE,
ve_capable check was performed with credentials from CT
and with host VE.
ovl_get_origin_fh returned unexpected NULL and all exploded.
Stroing ve_capable check result on creation is a possible fix,
but it just masks the problem. We have other paths from overlay to
ve_capable checks:
ovl_fileattr_set
ovl_override_creds
ovl_real_fileattr_set
vfs_fileattr_set
fileattr_set_prepare
ve_capable
And storing capability check result will make rebase dangerous - we
would have to track new added code - not funny.
https://virtuozzo.atlassian.net/browse/VSTOR-142405
Signed-off-by: Vladimir Riabchun <[email protected]>
---
fs/overlayfs/copy_up.c | 6 ++--
fs/overlayfs/dir.c | 59 ++++++++++++++++++------------
fs/overlayfs/file.c | 65 +++++++++++++++++++--------------
fs/overlayfs/inode.c | 94 +++++++++++++++++++++++++++++++-----------------
fs/overlayfs/namei.c | 39 +++++++++++++-------
fs/overlayfs/overlayfs.h | 9 ++++-
fs/overlayfs/readdir.c | 36 ++++++++++++-------
fs/overlayfs/util.c | 41 ++++++++++++++++-----
fs/overlayfs/xattrs.c | 35 +++++++++++-------
9 files changed, 252 insertions(+), 132 deletions(-)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 4388004a319d..f478d1b51af9 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -1215,7 +1215,7 @@ static int ovl_copy_up_one(struct dentry *parent, struct
dentry *dentry,
static int ovl_copy_up_flags(struct dentry *dentry, int flags)
{
int err = 0;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
bool disconnected = (dentry->d_flags & DCACHE_DISCONNECTED);
/*
@@ -1235,7 +1235,7 @@ static int ovl_copy_up_flags(struct dentry *dentry, int
flags)
if (err)
return err;
- old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
while (!err) {
struct dentry *next;
struct dentry *parent = NULL;
@@ -1260,7 +1260,7 @@ static int ovl_copy_up_flags(struct dentry *dentry, int
flags)
dput(parent);
dput(next);
}
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return err;
}
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 1c8009bf194b..23897fabe9d5 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -554,7 +554,7 @@ static int ovl_create_over_whiteout(struct dentry *dentry,
struct inode *inode,
}
static int ovl_setup_cred_for_create(struct dentry *dentry, struct inode
*inode,
- umode_t mode, const struct cred *old_cred)
+ umode_t mode, const struct ovl_creds_desc
*old_cred)
{
int err;
struct cred *override_cred;
@@ -566,7 +566,7 @@ static int ovl_setup_cred_for_create(struct dentry *dentry,
struct inode *inode,
override_cred->fsuid = inode->i_uid;
override_cred->fsgid = inode->i_gid;
err = security_dentry_create_files_as(dentry, mode, &dentry->d_name,
- old_cred, override_cred);
+ old_cred->cred, override_cred);
if (err) {
put_cred(override_cred);
return err;
@@ -581,10 +581,12 @@ static int ovl_create_or_link(struct dentry *dentry,
struct inode *inode,
struct ovl_cattr *attr, bool origin)
{
int err;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
struct dentry *parent = dentry->d_parent;
- old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ return err;
/*
* When linking a file with copy up origin into a new parent, mark the
@@ -610,7 +612,7 @@ static int ovl_create_or_link(struct dentry *dentry, struct
inode *inode,
* create a new inode, so just use the ovl mounter's
* fs{u,g}id.
*/
- err = ovl_setup_cred_for_create(dentry, inode, attr->mode,
old_cred);
+ err = ovl_setup_cred_for_create(dentry, inode, attr->mode,
&old_cred);
if (err)
goto out_revert_creds;
}
@@ -621,7 +623,7 @@ static int ovl_create_or_link(struct dentry *dentry, struct
inode *inode,
err = ovl_create_over_whiteout(dentry, inode, attr);
out_revert_creds:
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return err;
}
@@ -697,12 +699,15 @@ static int ovl_symlink(struct mnt_idmap *idmap, struct
inode *dir,
static int ovl_set_link_redirect(struct dentry *dentry)
{
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
int err;
- old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ return err;
+
err = ovl_set_redirect(dentry, false);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return err;
}
@@ -888,7 +893,7 @@ static void ovl_drop_nlink(struct dentry *dentry)
static int ovl_do_remove(struct dentry *dentry, bool is_dir)
{
int err;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
bool lower_positive = ovl_lower_positive(dentry);
LIST_HEAD(list);
@@ -907,12 +912,15 @@ static int ovl_do_remove(struct dentry *dentry, bool
is_dir)
if (err)
goto out;
- old_cred = ovl_override_creds(dentry->d_sb);
- if (!lower_positive)
- err = ovl_remove_upper(dentry, is_dir, &list);
- else
- err = ovl_remove_and_whiteout(dentry, &list);
- revert_creds(old_cred);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (!err) {
+ if (!lower_positive)
+ err = ovl_remove_upper(dentry, is_dir, &list);
+ else
+ err = ovl_remove_and_whiteout(dentry, &list);
+ ovl_revert_creds(&old_cred);
+ }
+
if (!err) {
if (is_dir)
clear_nlink(dentry->d_inode);
@@ -1095,7 +1103,7 @@ static int ovl_rename(struct mnt_idmap *idmap, struct
inode *olddir,
bool new_is_dir = d_is_dir(new);
bool samedir = olddir == newdir;
struct dentry *opaquedir = NULL;
- const struct cred *old_cred = NULL;
+ struct ovl_creds_desc old_cred = {};
struct ovl_fs *ofs = OVL_FS(old->d_sb);
LIST_HEAD(list);
@@ -1159,7 +1167,9 @@ static int ovl_rename(struct mnt_idmap *idmap, struct
inode *olddir,
goto out;
}
- old_cred = ovl_override_creds(old->d_sb);
+ err = ovl_override_creds(old->d_sb, &old_cred);
+ if (err)
+ goto out_revert_creds;
if (!list_empty(&list)) {
opaquedir = ovl_clear_empty(new, &list);
@@ -1292,7 +1302,7 @@ static int ovl_rename(struct mnt_idmap *idmap, struct
inode *olddir,
out_unlock:
unlock_rename(new_upperdir, old_upperdir);
out_revert_creds:
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
if (update_nlink)
ovl_nlink_end(new);
else
@@ -1306,7 +1316,7 @@ static int ovl_rename(struct mnt_idmap *idmap, struct
inode *olddir,
static int ovl_create_tmpfile(struct file *file, struct dentry *dentry,
struct inode *inode, umode_t mode)
{
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
struct path realparentpath;
struct file *realfile;
struct dentry *newdentry;
@@ -1314,8 +1324,11 @@ static int ovl_create_tmpfile(struct file *file, struct
dentry *dentry,
int flags = file->f_flags | OVL_OPEN_FLAGS;
int err;
- old_cred = ovl_override_creds(dentry->d_sb);
- err = ovl_setup_cred_for_create(dentry, inode, mode, old_cred);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ return err;
+
+ err = ovl_setup_cred_for_create(dentry, inode, mode, &old_cred);
if (err)
goto out_revert_creds;
@@ -1337,7 +1350,7 @@ static int ovl_create_tmpfile(struct file *file, struct
dentry *dentry,
fput(realfile);
}
out_revert_creds:
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return err;
}
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 84aad9d19bdd..3762998be706 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -31,7 +31,7 @@ static struct file *ovl_open_realfile(const struct file *file,
struct inode *inode = file_inode(file);
struct mnt_idmap *real_idmap;
struct file *realfile;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
int flags = file->f_flags | OVL_OPEN_FLAGS;
int acc_mode = ACC_MODE(flags);
int err;
@@ -39,7 +39,10 @@ static struct file *ovl_open_realfile(const struct file
*file,
if (flags & O_APPEND)
acc_mode |= MAY_APPEND;
- old_cred = ovl_override_creds(inode->i_sb);
+ err = ovl_override_creds(inode->i_sb, &old_cred);
+ if (err)
+ return ERR_PTR(err);
+
real_idmap = mnt_idmap(realpath->mnt);
err = inode_permission(real_idmap, realinode, MAY_OPEN | acc_mode);
if (err) {
@@ -51,7 +54,7 @@ static struct file *ovl_open_realfile(const struct file *file,
realfile = backing_file_open(file, flags, realpath,
current_cred());
}
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
file, file, ovl_whatisit(inode, realinode), file->f_flags,
@@ -184,7 +187,7 @@ static loff_t ovl_llseek(struct file *file, loff_t offset,
int whence)
{
struct inode *inode = file_inode(file);
struct fd real;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
loff_t ret;
/*
@@ -213,9 +216,10 @@ static loff_t ovl_llseek(struct file *file, loff_t offset,
int whence)
ovl_inode_lock(inode);
fd_file(real)->f_pos = file->f_pos;
- old_cred = ovl_override_creds(inode->i_sb);
- ret = vfs_llseek(fd_file(real), offset, whence);
- revert_creds(old_cred);
+ ret = ovl_override_creds(inode->i_sb, &old_cred);
+ if (!ret)
+ ret = vfs_llseek(fd_file(real), offset, whence);
+ ovl_revert_creds(&old_cred);
file->f_pos = fd_file(real)->f_pos;
ovl_inode_unlock(inode);
@@ -392,7 +396,7 @@ static ssize_t ovl_splice_write(struct pipe_inode_info
*pipe, struct file *out,
static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
struct fd real;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
int ret;
ret = ovl_sync_status(OVL_FS(file_inode(file)->i_sb));
@@ -405,9 +409,10 @@ static int ovl_fsync(struct file *file, loff_t start,
loff_t end, int datasync)
/* Don't sync lower file for fear of receiving EROFS error */
if (file_inode(fd_file(real)) == ovl_inode_upper(file_inode(file))) {
- old_cred = ovl_override_creds(file_inode(file)->i_sb);
- ret = vfs_fsync_range(fd_file(real), start, end, datasync);
- revert_creds(old_cred);
+ ret = ovl_override_creds(file_inode(file)->i_sb, &old_cred);
+ if (!ret)
+ ret = vfs_fsync_range(fd_file(real), start, end,
datasync);
+ ovl_revert_creds(&old_cred);
}
fdput(real);
@@ -431,7 +436,7 @@ static long ovl_fallocate(struct file *file, int mode,
loff_t offset, loff_t len
{
struct inode *inode = file_inode(file);
struct fd real;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
int ret;
inode_lock(inode);
@@ -445,9 +450,10 @@ static long ovl_fallocate(struct file *file, int mode,
loff_t offset, loff_t len
if (ret)
goto out_unlock;
- old_cred = ovl_override_creds(file_inode(file)->i_sb);
- ret = vfs_fallocate(fd_file(real), mode, offset, len);
- revert_creds(old_cred);
+ ret = ovl_override_creds(file_inode(file)->i_sb, &old_cred);
+ if (!ret)
+ ret = vfs_fallocate(fd_file(real), mode, offset, len);
+ ovl_revert_creds(&old_cred);
/* Update size */
ovl_file_modified(file);
@@ -463,16 +469,17 @@ static long ovl_fallocate(struct file *file, int mode,
loff_t offset, loff_t len
static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int
advice)
{
struct fd real;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
int ret;
ret = ovl_real_fdget(file, &real);
if (ret)
return ret;
- old_cred = ovl_override_creds(file_inode(file)->i_sb);
- ret = vfs_fadvise(fd_file(real), offset, len, advice);
- revert_creds(old_cred);
+ ret = ovl_override_creds(file_inode(file)->i_sb, &old_cred);
+ if (!ret)
+ ret = vfs_fadvise(fd_file(real), offset, len, advice);
+ ovl_revert_creds(&old_cred);
fdput(real);
@@ -491,7 +498,7 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t
pos_in,
{
struct inode *inode_out = file_inode(file_out);
struct fd real_in, real_out;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
loff_t ret;
inode_lock(inode_out);
@@ -513,7 +520,10 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t
pos_in,
goto out_unlock;
}
- old_cred = ovl_override_creds(file_inode(file_out)->i_sb);
+ ret = ovl_override_creds(file_inode(file_out)->i_sb, &old_cred);
+ if (ret)
+ goto skip_switch;
+
switch (op) {
case OVL_COPY:
ret = vfs_copy_file_range(fd_file(real_in), pos_in,
@@ -531,7 +541,9 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t
pos_in,
flags);
break;
}
- revert_creds(old_cred);
+
+skip_switch:
+ ovl_revert_creds(&old_cred);
/* Update size */
ovl_file_modified(file_out);
@@ -583,7 +595,7 @@ static loff_t ovl_remap_file_range(struct file *file_in,
loff_t pos_in,
static int ovl_flush(struct file *file, fl_owner_t id)
{
struct fd real;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
int err;
err = ovl_real_fdget(file, &real);
@@ -591,9 +603,10 @@ static int ovl_flush(struct file *file, fl_owner_t id)
return err;
if (fd_file(real)->f_op->flush) {
- old_cred = ovl_override_creds(file_inode(file)->i_sb);
- err = fd_file(real)->f_op->flush(fd_file(real), id);
- revert_creds(old_cred);
+ err = ovl_override_creds(file_inode(file)->i_sb, &old_cred);
+ if (!err)
+ err = fd_file(real)->f_op->flush(fd_file(real), id);
+ ovl_revert_creds(&old_cred);
}
fdput(real);
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 8b31f44c12cd..2d27bafad986 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -25,7 +25,7 @@ int ovl_setattr(struct mnt_idmap *idmap, struct dentry
*dentry,
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
bool full_copy_up = false;
struct dentry *upperdentry;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
err = setattr_prepare(&nop_mnt_idmap, dentry, attr);
if (err)
@@ -78,9 +78,10 @@ int ovl_setattr(struct mnt_idmap *idmap, struct dentry
*dentry,
goto out_put_write;
inode_lock(upperdentry->d_inode);
- old_cred = ovl_override_creds(dentry->d_sb);
- err = ovl_do_notify_change(ofs, upperdentry, attr);
- revert_creds(old_cred);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (!err)
+ err = ovl_do_notify_change(ofs, upperdentry, attr);
+ ovl_revert_creds(&old_cred);
if (!err)
ovl_copyattr(dentry->d_inode);
inode_unlock(upperdentry->d_inode);
@@ -159,7 +160,7 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path
*path,
struct dentry *dentry = path->dentry;
enum ovl_path_type type;
struct path realpath;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
struct inode *inode = d_inode(dentry);
bool is_dir = S_ISDIR(inode->i_mode);
int fsid = 0;
@@ -169,8 +170,10 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path
*path,
metacopy_blocks = ovl_is_metacopy_dentry(dentry);
type = ovl_path_real(dentry, &realpath);
- old_cred = ovl_override_creds(dentry->d_sb);
- err = vfs_getattr_nosec(&realpath, stat, request_mask, flags);
+
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (!err)
+ err = vfs_getattr_nosec(&realpath, stat, request_mask, flags);
if (err)
goto out;
@@ -280,7 +283,7 @@ int ovl_getattr(struct mnt_idmap *idmap, const struct path
*path,
stat->nlink = dentry->d_inode->i_nlink;
out:
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return err;
}
@@ -291,7 +294,7 @@ int ovl_permission(struct mnt_idmap *idmap,
struct inode *upperinode = ovl_inode_upper(inode);
struct inode *realinode;
struct path realpath;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
int err;
/* Careful in RCU walk mode */
@@ -309,7 +312,10 @@ int ovl_permission(struct mnt_idmap *idmap,
if (err)
return err;
- old_cred = ovl_override_creds(inode->i_sb);
+ err = ovl_override_creds(inode->i_sb, &old_cred);
+ if (err)
+ return err;
+
if (!upperinode &&
!special_file(realinode->i_mode) && mask & MAY_WRITE) {
mask &= ~(MAY_WRITE | MAY_APPEND);
@@ -317,7 +323,7 @@ int ovl_permission(struct mnt_idmap *idmap,
mask |= MAY_READ;
}
err = inode_permission(mnt_idmap(realpath.mnt), realinode, mask);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return err;
}
@@ -326,15 +332,19 @@ static const char *ovl_get_link(struct dentry *dentry,
struct inode *inode,
struct delayed_call *done)
{
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
const char *p;
+ int err;
if (!dentry)
return ERR_PTR(-ECHILD);
- old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ return ERR_PTR(err);
+
p = vfs_get_link(ovl_dentry_real(dentry), done);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return p;
}
@@ -465,11 +475,15 @@ struct posix_acl *do_ovl_get_acl(struct mnt_idmap *idmap,
acl = get_cached_acl_rcu(realinode, type);
} else {
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
+ int err;
+
+ err = ovl_override_creds(inode->i_sb, &old_cred);
+ if (err)
+ return ERR_PTR(err);
- old_cred = ovl_override_creds(inode->i_sb);
acl = ovl_get_acl_path(&realpath, posix_acl_xattr_name(type),
noperm);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
}
return acl;
@@ -481,7 +495,7 @@ static int ovl_set_or_remove_acl(struct dentry *dentry,
struct inode *inode,
int err;
struct path realpath;
const char *acl_name;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct dentry *upperdentry = ovl_dentry_upper(dentry);
struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
@@ -495,10 +509,14 @@ static int ovl_set_or_remove_acl(struct dentry *dentry,
struct inode *inode,
struct posix_acl *real_acl;
ovl_path_lower(dentry, &realpath);
- old_cred = ovl_override_creds(dentry->d_sb);
+
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ return err;
+
real_acl = vfs_get_acl(mnt_idmap(realpath.mnt), realdentry,
acl_name);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
if (IS_ERR(real_acl)) {
err = PTR_ERR(real_acl);
goto out;
@@ -518,12 +536,17 @@ static int ovl_set_or_remove_acl(struct dentry *dentry,
struct inode *inode,
if (err)
goto out;
- old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ goto out_revert;
+
if (acl)
err = ovl_do_set_acl(ofs, realdentry, acl_name, acl);
else
err = ovl_do_remove_acl(ofs, realdentry, acl_name);
- revert_creds(old_cred);
+
+out_revert:
+ ovl_revert_creds(&old_cred);
ovl_drop_write(dentry);
/* copy c/mtime */
@@ -590,7 +613,7 @@ static int ovl_fiemap(struct inode *inode, struct
fiemap_extent_info *fieinfo,
{
int err;
struct inode *realinode = ovl_inode_realdata(inode);
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
if (!realinode)
return -EIO;
@@ -598,9 +621,10 @@ static int ovl_fiemap(struct inode *inode, struct
fiemap_extent_info *fieinfo,
if (!realinode->i_op->fiemap)
return -EOPNOTSUPP;
- old_cred = ovl_override_creds(inode->i_sb);
- err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
- revert_creds(old_cred);
+ err = ovl_override_creds(inode->i_sb, &old_cred);
+ if (!err)
+ err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
+ ovl_revert_creds(&old_cred);
return err;
}
@@ -648,7 +672,7 @@ int ovl_fileattr_set(struct mnt_idmap *idmap,
{
struct inode *inode = d_inode(dentry);
struct path upperpath;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
unsigned int flags;
int err;
@@ -660,7 +684,7 @@ int ovl_fileattr_set(struct mnt_idmap *idmap,
if (err)
goto out;
- old_cred = ovl_override_creds(inode->i_sb);
+ err = ovl_override_creds(inode->i_sb, &old_cred);
/*
* Store immutable/append-only flags in xattr and clear them
* in upper fileattr (in case they were set by older kernel)
@@ -668,10 +692,11 @@ int ovl_fileattr_set(struct mnt_idmap *idmap,
* "ovl-immutable" hardlinks could be copied up.
* Clear xattr when flags are cleared.
*/
- err = ovl_set_protattr(inode, upperpath.dentry, fa);
+ if (!err)
+ err = ovl_set_protattr(inode, upperpath.dentry, fa);
if (!err)
err = ovl_real_fileattr_set(&upperpath, fa);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
ovl_drop_write(dentry);
/*
@@ -725,15 +750,18 @@ int ovl_fileattr_get(struct dentry *dentry, struct
fileattr *fa)
{
struct inode *inode = d_inode(dentry);
struct path realpath;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
int err;
ovl_path_real(dentry, &realpath);
- old_cred = ovl_override_creds(inode->i_sb);
+ err = ovl_override_creds(inode->i_sb, &old_cred);
+ if (err)
+ return err;
+
err = ovl_real_fileattr_get(&realpath, fa);
ovl_fileattr_prot_flags(inode, fa);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return err;
}
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index efa2a072aa69..edc11a7b27ee 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -969,15 +969,19 @@ static int ovl_maybe_validate_verity(struct dentry
*dentry)
return err;
if (!ovl_test_flag(OVL_VERIFIED_DIGEST, inode)) {
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
- old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err) {
+ ovl_inode_unlock(inode);
+ return err;
+ }
err = ovl_validate_verity(ofs, &metapath, &datapath);
if (err == 0)
ovl_set_flag(OVL_VERIFIED_DIGEST, inode);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
}
ovl_inode_unlock(inode);
@@ -991,7 +995,7 @@ static int ovl_maybe_lookup_lowerdata(struct dentry *dentry)
struct inode *inode = d_inode(dentry);
const char *redirect = ovl_lowerdata_redirect(inode);
struct ovl_path datapath = {};
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
int err;
if (!redirect || ovl_dentry_lowerdata(dentry))
@@ -1009,9 +1013,12 @@ static int ovl_maybe_lookup_lowerdata(struct dentry
*dentry)
if (ovl_dentry_lowerdata(dentry))
goto out;
- old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ goto out_err;
+
err = ovl_lookup_data_layers(dentry, redirect, &datapath);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
if (err)
goto out_err;
@@ -1071,7 +1078,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct
dentry *dentry,
unsigned int flags)
{
struct ovl_entry *oe = NULL;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct ovl_entry *poe = OVL_E(dentry->d_parent);
struct ovl_entry *roe = OVL_E(dentry->d_sb->s_root);
@@ -1104,7 +1111,10 @@ struct dentry *ovl_lookup(struct inode *dir, struct
dentry *dentry,
if (dentry->d_name.len > ofs->namelen)
return ERR_PTR(-ENAMETOOLONG);
- old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ return ERR_PTR(err);
+
upperdir = ovl_dentry_upper(dentry->d_parent);
if (upperdir) {
d.layer = &ofs->layers[0];
@@ -1378,7 +1388,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct
dentry *dentry,
ovl_dentry_init_reval(dentry, upperdentry, OVL_I_E(inode));
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
if (origin_path) {
dput(origin_path->dentry);
kfree(origin_path);
@@ -1402,7 +1412,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct
dentry *dentry,
kfree(d.upperredirect);
out:
kfree(d.redirect);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return ERR_PTR(err);
}
@@ -1410,7 +1420,7 @@ bool ovl_lower_positive(struct dentry *dentry)
{
struct ovl_entry *poe = OVL_E(dentry->d_parent);
const struct qstr *name = &dentry->d_name;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
unsigned int i;
bool positive = false;
bool done = false;
@@ -1426,7 +1436,10 @@ bool ovl_lower_positive(struct dentry *dentry)
if (!ovl_dentry_upper(dentry))
return true;
- old_cred = ovl_override_creds(dentry->d_sb);
+ /* Ugh, hard - we can't pass an error from here. */
+ if (ovl_override_creds(dentry->d_sb, &old_cred))
+ return false;
+
/* Positive upper -> have to look up lower to see whether it exists */
for (i = 0; !done && !positive && i < ovl_numlower(poe); i++) {
struct dentry *this;
@@ -1459,7 +1472,7 @@ bool ovl_lower_positive(struct dentry *dentry)
dput(this);
}
}
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return positive;
}
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 8577c7884fb9..4297912b0cc4 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -164,6 +164,12 @@ struct ovl_metacopy {
u8 digest[FS_VERITY_MAX_DIGEST_SIZE]; /* Only the used part on disk */
} __packed;
+/* Credential information used by overlay */
+struct ovl_creds_desc {
+ const struct cred *cred;
+ struct ve_struct *ve;
+};
+
#define OVL_METACOPY_MAX_SIZE (sizeof(struct ovl_metacopy))
#define OVL_METACOPY_MIN_SIZE (OVL_METACOPY_MAX_SIZE -
FS_VERITY_MAX_DIGEST_SIZE)
#define OVL_METACOPY_INIT { 0, OVL_METACOPY_MIN_SIZE }
@@ -420,7 +426,8 @@ void ovl_end_write(struct dentry *dentry);
int ovl_want_write(struct dentry *dentry);
void ovl_drop_write(struct dentry *dentry);
struct dentry *ovl_workdir(struct dentry *dentry);
-const struct cred *ovl_override_creds(struct super_block *sb);
+int ovl_override_creds(struct super_block *sb, struct ovl_creds_desc *desc);
+void ovl_revert_creds(struct ovl_creds_desc *old_creds);
static inline const struct cred *ovl_creds(struct super_block *sb)
{
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 0ca8af060b0c..478b0a32ff64 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -273,9 +273,11 @@ static int ovl_check_whiteouts(const struct path *path,
struct ovl_readdir_data
int err;
struct ovl_cache_entry *p;
struct dentry *dentry, *dir = path->dentry;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
- old_cred = ovl_override_creds(rdd->dentry->d_sb);
+ err = ovl_override_creds(rdd->dentry->d_sb, &old_cred);
+ if (err)
+ return err;
err = down_write_killable(&dir->d_inode->i_rwsem);
if (!err) {
@@ -290,7 +292,7 @@ static int ovl_check_whiteouts(const struct path *path,
struct ovl_readdir_data
}
inode_unlock(dir->d_inode);
}
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return err;
}
@@ -753,10 +755,13 @@ static int ovl_iterate(struct file *file, struct
dir_context *ctx)
struct dentry *dentry = file->f_path.dentry;
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
struct ovl_cache_entry *p;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
int err;
- old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ return err;
+
if (!ctx->pos)
ovl_dir_reset(file);
@@ -808,7 +813,7 @@ static int ovl_iterate(struct file *file, struct
dir_context *ctx)
}
err = 0;
out:
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return err;
}
@@ -856,11 +861,15 @@ static struct file *ovl_dir_open_realfile(const struct
file *file,
const struct path *realpath)
{
struct file *res;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
+ int err;
+
+ err = ovl_override_creds(file_inode(file)->i_sb, &old_cred);
+ if (err)
+ return ERR_PTR(err);
- old_cred = ovl_override_creds(file_inode(file)->i_sb);
res = ovl_path_open(realpath, O_RDONLY | (file->f_flags & O_LARGEFILE));
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
return res;
}
@@ -983,11 +992,14 @@ int ovl_check_empty_dir(struct dentry *dentry, struct
list_head *list)
int err;
struct ovl_cache_entry *p, *n;
struct rb_root root = RB_ROOT;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
+
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ return err;
- old_cred = ovl_override_creds(dentry->d_sb);
err = ovl_dir_read_merged(dentry, list, &root);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
if (err)
return err;
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index f95090f0d29c..d28d572d6099 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -63,11 +63,27 @@ struct dentry *ovl_workdir(struct dentry *dentry)
return ofs->workdir;
}
-const struct cred *ovl_override_creds(struct super_block *sb)
+/* On error no revert is needed. */
+int ovl_override_creds(struct super_block *sb, struct ovl_creds_desc *desc)
{
struct ovl_fs *ofs = OVL_FS(sb);
- return override_creds(ofs->creator_cred);
+ desc->ve = override_ve(ofs->creator_ve);
+ if (IS_ERR(desc->ve))
+ return PTR_ERR(desc->ve);
+
+ desc->cred = override_creds(ofs->creator_cred);
+ return 0;
+}
+
+/* Accepts desc from a failed ovl_override_creds and does nothing. */
+void ovl_revert_creds(struct ovl_creds_desc *old_creds)
+{
+ if (IS_ERR(old_creds->ve))
+ return;
+
+ revert_creds(old_creds->cred);
+ revert_ve(old_creds->ve);
}
/*
@@ -1150,7 +1166,7 @@ static void ovl_cleanup_index(struct dentry *dentry)
int ovl_nlink_start(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
int err;
if (WARN_ON(!inode))
@@ -1187,7 +1203,10 @@ int ovl_nlink_start(struct dentry *dentry)
if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, inode))
return 0;
- old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ goto out_drop_write;
+
/*
* The overlay inode nlink should be incremented/decremented IFF the
* upper operation succeeds, along with nlink change of upper inode.
@@ -1195,7 +1214,7 @@ int ovl_nlink_start(struct dentry *dentry)
* value relative to the upper inode nlink in an upper inode xattr.
*/
err = ovl_set_nlink_upper(dentry);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
if (err)
goto out_drop_write;
@@ -1216,11 +1235,15 @@ void ovl_nlink_end(struct dentry *dentry)
ovl_drop_write(dentry);
if (ovl_test_flag(OVL_INDEX, inode) && inode->i_nlink == 0) {
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
+ int err;
- old_cred = ovl_override_creds(dentry->d_sb);
- ovl_cleanup_index(dentry);
- revert_creds(old_cred);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ pr_err("%s: skipping ovl_cleanup_index.\n", __func__);
+ else
+ ovl_cleanup_index(dentry);
+ ovl_revert_creds(&old_cred);
}
ovl_inode_unlock(inode);
diff --git a/fs/overlayfs/xattrs.c b/fs/overlayfs/xattrs.c
index 0ed2b049056d..7528ec76868d 100644
--- a/fs/overlayfs/xattrs.c
+++ b/fs/overlayfs/xattrs.c
@@ -41,13 +41,16 @@ static int ovl_xattr_set(struct dentry *dentry, struct
inode *inode, const char
struct dentry *upperdentry = ovl_i_dentry_upper(inode);
struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
struct path realpath;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
if (!value && !upperdentry) {
ovl_path_lower(dentry, &realpath);
- old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err)
+ return err;
+
err = vfs_getxattr(mnt_idmap(realpath.mnt), realdentry, name,
NULL, 0);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
if (err < 0)
goto out;
}
@@ -64,7 +67,12 @@ static int ovl_xattr_set(struct dentry *dentry, struct inode
*inode, const char
if (err)
goto out;
- old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (err) {
+ ovl_drop_write(dentry);
+ return err;
+ }
+
if (value) {
err = ovl_do_setxattr(ofs, realdentry, name, value, size,
flags);
@@ -72,7 +80,7 @@ static int ovl_xattr_set(struct dentry *dentry, struct inode
*inode, const char
WARN_ON(flags != XATTR_REPLACE);
err = ovl_do_removexattr(ofs, realdentry, name);
}
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
ovl_drop_write(dentry);
/* copy c/mtime */
@@ -85,13 +93,14 @@ static int ovl_xattr_get(struct dentry *dentry, struct
inode *inode, const char
void *value, size_t size)
{
ssize_t res;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
struct path realpath;
ovl_i_path_real(inode, &realpath);
- old_cred = ovl_override_creds(dentry->d_sb);
- res = vfs_getxattr(mnt_idmap(realpath.mnt), realpath.dentry, name,
value, size);
- revert_creds(old_cred);
+ res = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (!res)
+ res = vfs_getxattr(mnt_idmap(realpath.mnt), realpath.dentry,
name, value, size);
+ ovl_revert_creds(&old_cred);
return res;
}
@@ -116,12 +125,14 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list,
size_t size)
ssize_t res;
size_t len;
char *s;
- const struct cred *old_cred;
+ struct ovl_creds_desc old_cred;
size_t prefix_len, name_len;
- old_cred = ovl_override_creds(dentry->d_sb);
+ res = ovl_override_creds(dentry->d_sb, &old_cred);
+ if (res)
+ return res;
res = vfs_listxattr(realdentry, list, size);
- revert_creds(old_cred);
+ ovl_revert_creds(&old_cred);
if (res <= 0 || size == 0)
return res;
--
2.52.0
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