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ceph: don't allow type or device number to change on non-I_NEW inodes

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Al pointed out that a malicious or broken MDS could change the type or
device number of a given inode number. It may also be possible for the
MDS to reuse an old inode number.

Ensure that we never allow fill_inode to change the type part of the
i_mode or the i_rdev unless I_NEW is set. Throw warnings if the MDS ever
changes these on us mid-stream, and return an error.

Don't set i_rdev directly, and rely on init_special_inode to do it.
Also, fix up error handling in the callers of ceph_get_inode.

In handle_cap_grant, check for and warn if the inode type changes, and
only overwrite the mode if it didn't.

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Jeff Layton 2021-02-25 15:04:16 -05:00 committed by Al Viro
parent 3e10a15ffc
commit ed94f87c2b
2 changed files with 30 additions and 5 deletions
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8
fs/ceph/caps.c
View File

@ -3358,7 +3358,13 @@ static void handle_cap_grant(struct inode *inode,
if ((newcaps & CEPH_CAP_AUTH_SHARED) &&
(extra_info->issued & CEPH_CAP_AUTH_EXCL) == 0) {
inode->i_mode = le32_to_cpu(grant->mode);
umode_t mode = le32_to_cpu(grant->mode);
if (inode_wrong_type(inode, mode))
pr_warn_once("inode type changed! (ino %llx.%llx is 0%o, mds says 0%o)\n",
ceph_vinop(inode), inode->i_mode, mode);
else
inode->i_mode = mode;
inode->i_uid = make_kuid(&init_user_ns, le32_to_cpu(grant->uid));
inode->i_gid = make_kgid(&init_user_ns, le32_to_cpu(grant->gid));
ci->i_btime = extra_info->btime;

27
fs/ceph/inode.c
View File

@ -769,11 +769,32 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page,
bool queue_trunc = false;
bool new_version = false;
bool fill_inline = false;
umode_t mode = le32_to_cpu(info->mode);
dev_t rdev = le32_to_cpu(info->rdev);
dout("%s %p ino %llx.%llx v %llu had %llu\n", __func__,
inode, ceph_vinop(inode), le64_to_cpu(info->version),
ci->i_version);
/* Once I_NEW is cleared, we can't change type or dev numbers */
if (inode->i_state & I_NEW) {
inode->i_mode = mode;
} else {
if (inode_wrong_type(inode, mode)) {
pr_warn_once("inode type changed! (ino %llx.%llx is 0%o, mds says 0%o)\n",
ceph_vinop(inode), inode->i_mode, mode);
return -ESTALE;
}
if ((S_ISCHR(mode) || S_ISBLK(mode)) && inode->i_rdev != rdev) {
pr_warn_once("dev inode rdev changed! (ino %llx.%llx is %u:%u, mds says %u:%u)\n",
ceph_vinop(inode), MAJOR(inode->i_rdev),
MINOR(inode->i_rdev), MAJOR(rdev),
MINOR(rdev));
return -ESTALE;
}
}
info_caps = le32_to_cpu(info->cap.caps);
/* prealloc new cap struct */
@ -827,8 +848,6 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page,
issued |= __ceph_caps_dirty(ci);
new_issued = ~issued & info_caps;
/* update inode */
inode->i_rdev = le32_to_cpu(info->rdev);
/* directories have fl_stripe_unit set to zero */
if (le32_to_cpu(info->layout.fl_stripe_unit))
inode->i_blkbits =
@ -840,7 +859,7 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page,
if ((new_version || (new_issued & CEPH_CAP_AUTH_SHARED)) &&
(issued & CEPH_CAP_AUTH_EXCL) == 0) {
inode->i_mode = le32_to_cpu(info->mode);
inode->i_mode = mode;
inode->i_uid = make_kuid(&init_user_ns, le32_to_cpu(info->uid));
inode->i_gid = make_kgid(&init_user_ns, le32_to_cpu(info->gid));
dout("%p mode 0%o uid.gid %d.%d\n", inode, inode->i_mode,
@ -938,7 +957,7 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page,
case S_IFCHR:
case S_IFSOCK:
inode->i_blkbits = PAGE_SHIFT;
init_special_inode(inode, inode->i_mode, inode->i_rdev);
init_special_inode(inode, inode->i_mode, rdev);
inode->i_op = &ceph_file_iops;
break;
case S_IFREG: