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authorMiklos Szeredi <mszeredi@redhat.com>2021-01-28 10:22:48 +0100
committerMiklos Szeredi <mszeredi@redhat.com>2021-01-28 10:22:48 +0100
commitf2b00be488730522d0fb7a8a5de663febdcefe0a (patch)
treec343be25749cf1c5d809dbbbb56495fd7d652445 /security
parent554677b97257b0b69378bd74e521edb7e94769ff (diff)
cap: fix conversions on getxattr
If a capability is stored on disk in v2 format cap_inode_getsecurity() will currently return in v2 format unconditionally. This is wrong: v2 cap should be equivalent to a v3 cap with zero rootid, and so the same conversions performed on it. If the rootid cannot be mapped, v3 is returned unconverted. Fix this so that both v2 and v3 return -EOVERFLOW if the rootid (or the owner of the fs user namespace in case of v2) cannot be mapped into the current user namespace. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'security')
-rw-r--r--security/commoncap.c67
1 files changed, 43 insertions, 24 deletions
diff --git a/security/commoncap.c b/security/commoncap.c
index bacc1111d871..26c1cb725dcb 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -371,10 +371,11 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer,
{
int size, ret;
kuid_t kroot;
+ u32 nsmagic, magic;
uid_t root, mappedroot;
char *tmpbuf = NULL;
struct vfs_cap_data *cap;
- struct vfs_ns_cap_data *nscap;
+ struct vfs_ns_cap_data *nscap = NULL;
struct dentry *dentry;
struct user_namespace *fs_ns;
@@ -396,46 +397,61 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer,
fs_ns = inode->i_sb->s_user_ns;
cap = (struct vfs_cap_data *) tmpbuf;
if (is_v2header((size_t) ret, cap)) {
- /* If this is sizeof(vfs_cap_data) then we're ok with the
- * on-disk value, so return that. */
- if (alloc)
- *buffer = tmpbuf;
- else
- kfree(tmpbuf);
- return ret;
- } else if (!is_v3header((size_t) ret, cap)) {
- kfree(tmpbuf);
- return -EINVAL;
+ root = 0;
+ } else if (is_v3header((size_t) ret, cap)) {
+ nscap = (struct vfs_ns_cap_data *) tmpbuf;
+ root = le32_to_cpu(nscap->rootid);
+ } else {
+ size = -EINVAL;
+ goto out_free;
}
- nscap = (struct vfs_ns_cap_data *) tmpbuf;
- root = le32_to_cpu(nscap->rootid);
kroot = make_kuid(fs_ns, root);
/* If the root kuid maps to a valid uid in current ns, then return
* this as a nscap. */
mappedroot = from_kuid(current_user_ns(), kroot);
if (mappedroot != (uid_t)-1 && mappedroot != (uid_t)0) {
+ size = sizeof(struct vfs_ns_cap_data);
if (alloc) {
- *buffer = tmpbuf;
+ if (!nscap) {
+ /* v2 -> v3 conversion */
+ nscap = kzalloc(size, GFP_ATOMIC);
+ if (!nscap) {
+ size = -ENOMEM;
+ goto out_free;
+ }
+ nsmagic = VFS_CAP_REVISION_3;
+ magic = le32_to_cpu(cap->magic_etc);
+ if (magic & VFS_CAP_FLAGS_EFFECTIVE)
+ nsmagic |= VFS_CAP_FLAGS_EFFECTIVE;
+ memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
+ nscap->magic_etc = cpu_to_le32(nsmagic);
+ } else {
+ /* use allocated v3 buffer */
+ tmpbuf = NULL;
+ }
nscap->rootid = cpu_to_le32(mappedroot);
- } else
- kfree(tmpbuf);
- return size;
+ *buffer = nscap;
+ }
+ goto out_free;
}
if (!rootid_owns_currentns(kroot)) {
- kfree(tmpbuf);
- return -EOPNOTSUPP;
+ size = -EOVERFLOW;
+ goto out_free;
}
/* This comes from a parent namespace. Return as a v2 capability */
size = sizeof(struct vfs_cap_data);
if (alloc) {
- *buffer = kmalloc(size, GFP_ATOMIC);
- if (*buffer) {
- struct vfs_cap_data *cap = *buffer;
- __le32 nsmagic, magic;
+ if (nscap) {
+ /* v3 -> v2 conversion */
+ cap = kzalloc(size, GFP_ATOMIC);
+ if (!cap) {
+ size = -ENOMEM;
+ goto out_free;
+ }
magic = VFS_CAP_REVISION_2;
nsmagic = le32_to_cpu(nscap->magic_etc);
if (nsmagic & VFS_CAP_FLAGS_EFFECTIVE)
@@ -443,9 +459,12 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer,
memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
cap->magic_etc = cpu_to_le32(magic);
} else {
- size = -ENOMEM;
+ /* use unconverted v2 */
+ tmpbuf = NULL;
}
+ *buffer = cap;
}
+out_free:
kfree(tmpbuf);
return size;
}