mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
synced 2024-12-28 16:52:18 +00:00
fs: use guard for namespace_sem in statmount()
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
parent
a7ebb0fe43
commit
d842379313
262
fs/namespace.c
262
fs/namespace.c
@ -5040,104 +5040,6 @@ static int copy_statmount_to_user(struct kstatmount *s)
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return 0;
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}
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static int do_statmount(struct kstatmount *s)
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{
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struct mount *m = real_mount(s->mnt);
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struct mnt_namespace *ns = m->mnt_ns;
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int err;
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/*
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* Don't trigger audit denials. We just want to determine what
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* mounts to show users.
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*/
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if (!is_path_reachable(m, m->mnt.mnt_root, &s->root) &&
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!ns_capable_noaudit(ns->user_ns, CAP_SYS_ADMIN))
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return -EPERM;
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err = security_sb_statfs(s->mnt->mnt_root);
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if (err)
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return err;
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if (s->mask & STATMOUNT_SB_BASIC)
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statmount_sb_basic(s);
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if (s->mask & STATMOUNT_MNT_BASIC)
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statmount_mnt_basic(s);
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if (s->mask & STATMOUNT_PROPAGATE_FROM)
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statmount_propagate_from(s);
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if (s->mask & STATMOUNT_FS_TYPE)
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err = statmount_string(s, STATMOUNT_FS_TYPE);
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if (!err && s->mask & STATMOUNT_MNT_ROOT)
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err = statmount_string(s, STATMOUNT_MNT_ROOT);
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if (!err && s->mask & STATMOUNT_MNT_POINT)
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err = statmount_string(s, STATMOUNT_MNT_POINT);
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if (!err && s->mask & STATMOUNT_MNT_NS_ID)
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statmount_mnt_ns_id(s, ns);
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if (err)
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return err;
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return 0;
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}
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static inline bool retry_statmount(const long ret, size_t *seq_size)
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{
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if (likely(ret != -EAGAIN))
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return false;
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if (unlikely(check_mul_overflow(*seq_size, 2, seq_size)))
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return false;
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if (unlikely(*seq_size > MAX_RW_COUNT))
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return false;
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return true;
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}
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static int prepare_kstatmount(struct kstatmount *ks, struct mnt_id_req *kreq,
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struct statmount __user *buf, size_t bufsize,
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size_t seq_size)
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{
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if (!access_ok(buf, bufsize))
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return -EFAULT;
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memset(ks, 0, sizeof(*ks));
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ks->mask = kreq->param;
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ks->buf = buf;
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ks->bufsize = bufsize;
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ks->seq.size = seq_size;
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ks->seq.buf = kvmalloc(seq_size, GFP_KERNEL_ACCOUNT);
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if (!ks->seq.buf)
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return -ENOMEM;
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return 0;
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}
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static int copy_mnt_id_req(const struct mnt_id_req __user *req,
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struct mnt_id_req *kreq)
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{
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int ret;
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size_t usize;
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BUILD_BUG_ON(sizeof(struct mnt_id_req) != MNT_ID_REQ_SIZE_VER1);
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ret = get_user(usize, &req->size);
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if (ret)
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return -EFAULT;
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if (unlikely(usize > PAGE_SIZE))
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return -E2BIG;
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if (unlikely(usize < MNT_ID_REQ_SIZE_VER0))
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return -EINVAL;
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memset(kreq, 0, sizeof(*kreq));
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ret = copy_struct_from_user(kreq, sizeof(*kreq), req, usize);
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if (ret)
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return ret;
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if (kreq->spare != 0)
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return -EINVAL;
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return 0;
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}
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static struct mount *listmnt_next(struct mount *curr, bool reverse)
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{
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struct rb_node *node;
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@ -5177,6 +5079,130 @@ static int grab_requested_root(struct mnt_namespace *ns, struct path *root)
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return 0;
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}
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static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id,
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struct mnt_namespace *ns)
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{
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struct path root __free(path_put) = {};
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struct mount *m;
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int err;
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/* Has the namespace already been emptied? */
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if (mnt_ns_id && RB_EMPTY_ROOT(&ns->mounts))
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return -ENOENT;
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s->mnt = lookup_mnt_in_ns(mnt_id, ns);
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if (!s->mnt)
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return -ENOENT;
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err = grab_requested_root(ns, &root);
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if (err)
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return err;
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/*
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* Don't trigger audit denials. We just want to determine what
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* mounts to show users.
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*/
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m = real_mount(s->mnt);
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if (!is_path_reachable(m, m->mnt.mnt_root, &root) &&
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!ns_capable_noaudit(ns->user_ns, CAP_SYS_ADMIN))
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return -EPERM;
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err = security_sb_statfs(s->mnt->mnt_root);
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if (err)
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return err;
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s->root = root;
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if (s->mask & STATMOUNT_SB_BASIC)
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statmount_sb_basic(s);
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if (s->mask & STATMOUNT_MNT_BASIC)
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statmount_mnt_basic(s);
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if (s->mask & STATMOUNT_PROPAGATE_FROM)
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statmount_propagate_from(s);
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if (s->mask & STATMOUNT_FS_TYPE)
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err = statmount_string(s, STATMOUNT_FS_TYPE);
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if (!err && s->mask & STATMOUNT_MNT_ROOT)
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err = statmount_string(s, STATMOUNT_MNT_ROOT);
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if (!err && s->mask & STATMOUNT_MNT_POINT)
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err = statmount_string(s, STATMOUNT_MNT_POINT);
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if (!err && s->mask & STATMOUNT_MNT_NS_ID)
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statmount_mnt_ns_id(s, ns);
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if (err)
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return err;
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return 0;
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}
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static inline bool retry_statmount(const long ret, size_t *seq_size)
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{
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if (likely(ret != -EAGAIN))
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return false;
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if (unlikely(check_mul_overflow(*seq_size, 2, seq_size)))
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return false;
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if (unlikely(*seq_size > MAX_RW_COUNT))
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return false;
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return true;
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}
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#define STATMOUNT_STRING_REQ (STATMOUNT_MNT_ROOT | STATMOUNT_MNT_POINT | \
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STATMOUNT_FS_TYPE)
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static int prepare_kstatmount(struct kstatmount *ks, struct mnt_id_req *kreq,
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struct statmount __user *buf, size_t bufsize,
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size_t seq_size)
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{
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if (!access_ok(buf, bufsize))
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return -EFAULT;
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memset(ks, 0, sizeof(*ks));
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ks->mask = kreq->param;
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ks->buf = buf;
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ks->bufsize = bufsize;
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if (ks->mask & STATMOUNT_STRING_REQ) {
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if (bufsize == sizeof(ks->sm))
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return -EOVERFLOW;
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ks->seq.buf = kvmalloc(seq_size, GFP_KERNEL_ACCOUNT);
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if (!ks->seq.buf)
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return -ENOMEM;
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ks->seq.size = seq_size;
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}
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return 0;
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}
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static int copy_mnt_id_req(const struct mnt_id_req __user *req,
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struct mnt_id_req *kreq)
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{
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int ret;
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size_t usize;
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BUILD_BUG_ON(sizeof(struct mnt_id_req) != MNT_ID_REQ_SIZE_VER1);
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ret = get_user(usize, &req->size);
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if (ret)
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return -EFAULT;
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if (unlikely(usize > PAGE_SIZE))
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return -E2BIG;
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if (unlikely(usize < MNT_ID_REQ_SIZE_VER0))
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return -EINVAL;
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memset(kreq, 0, sizeof(*kreq));
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ret = copy_struct_from_user(kreq, sizeof(*kreq), req, usize);
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if (ret)
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return ret;
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if (kreq->spare != 0)
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return -EINVAL;
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return 0;
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}
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/*
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* If the user requested a specific mount namespace id, look that up and return
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* that, or if not simply grab a passive reference on our mount namespace and
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@ -5195,9 +5221,8 @@ SYSCALL_DEFINE4(statmount, const struct mnt_id_req __user *, req,
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unsigned int, flags)
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{
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struct mnt_namespace *ns __free(mnt_ns_release) = NULL;
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struct vfsmount *mnt;
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struct kstatmount *ks __free(kfree) = NULL;
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struct mnt_id_req kreq;
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struct kstatmount ks;
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/* We currently support retrieval of 3 strings. */
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size_t seq_size = 3 * PATH_MAX;
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int ret;
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@ -5217,40 +5242,21 @@ SYSCALL_DEFINE4(statmount, const struct mnt_id_req __user *, req,
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!ns_capable_noaudit(ns->user_ns, CAP_SYS_ADMIN))
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return -ENOENT;
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ks = kmalloc(sizeof(*ks), GFP_KERNEL_ACCOUNT);
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if (!ks)
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return -ENOMEM;
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retry:
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ret = prepare_kstatmount(&ks, &kreq, buf, bufsize, seq_size);
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ret = prepare_kstatmount(ks, &kreq, buf, bufsize, seq_size);
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if (ret)
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return ret;
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down_read(&namespace_sem);
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/* Has the namespace already been emptied? */
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if (kreq.mnt_ns_id && RB_EMPTY_ROOT(&ns->mounts)) {
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up_read(&namespace_sem);
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kvfree(ks.seq.buf);
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return -ENOENT;
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}
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mnt = lookup_mnt_in_ns(kreq.mnt_id, ns);
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if (!mnt) {
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up_read(&namespace_sem);
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kvfree(ks.seq.buf);
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return -ENOENT;
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}
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ks.mnt = mnt;
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ret = grab_requested_root(ns, &ks.root);
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if (ret) {
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up_read(&namespace_sem);
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kvfree(ks.seq.buf);
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return ret;
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}
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ret = do_statmount(&ks);
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path_put(&ks.root);
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up_read(&namespace_sem);
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scoped_guard(rwsem_read, &namespace_sem)
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ret = do_statmount(ks, kreq.mnt_id, kreq.mnt_ns_id, ns);
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if (!ret)
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ret = copy_statmount_to_user(&ks);
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kvfree(ks.seq.buf);
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ret = copy_statmount_to_user(ks);
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kvfree(ks->seq.buf);
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if (retry_statmount(ret, &seq_size))
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goto retry;
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return ret;
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