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fs: add copy_mount_setattr() helper

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Split out copy_mount_setattr() from mount_setattr() so we can use it in
later patches.

Link: https://lore.kernel.org/r/20250128-work-mnt_idmap-update-v2-v1-2-c25feb0d2eb3@kernel.org
Reviewed-by: "Seth Forshee (DigitalOcean)" <sforshee@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2025-01-28 11:33:40 +01:00
parent 901766df44
commit 474f7825d5
No known key found for this signature in database
GPG key ID: 91C61BC06578DCA2
1 changed files with 40 additions and 33 deletions
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73
fs/namespace.c
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@ -4814,7 +4814,7 @@ static int do_mount_setattr(struct path *path, struct mount_kattr *kattr)
}
static int build_mount_idmapped(const struct mount_attr *attr, size_t usize,
struct mount_kattr *kattr, unsigned int flags)
struct mount_kattr *kattr)
{
struct ns_common *ns;
struct user_namespace *mnt_userns;
@ -4865,22 +4865,8 @@ static int build_mount_idmapped(const struct mount_attr *attr, size_t usize,
}
static int build_mount_kattr(const struct mount_attr *attr, size_t usize,
struct mount_kattr *kattr, unsigned int flags)
struct mount_kattr *kattr)
{
unsigned int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW;
if (flags & AT_NO_AUTOMOUNT)
lookup_flags &= ~LOOKUP_AUTOMOUNT;
if (flags & AT_SYMLINK_NOFOLLOW)
lookup_flags &= ~LOOKUP_FOLLOW;
if (flags & AT_EMPTY_PATH)
lookup_flags |= LOOKUP_EMPTY;
*kattr = (struct mount_kattr) {
.lookup_flags = lookup_flags,
.recurse = !!(flags & AT_RECURSIVE),
};
if (attr->propagation & ~MOUNT_SETATTR_PROPAGATION_FLAGS)
return -EINVAL;
if (hweight32(attr->propagation & MOUNT_SETATTR_PROPAGATION_FLAGS) > 1)
@ -4928,7 +4914,7 @@ static int build_mount_kattr(const struct mount_attr *attr, size_t usize,
return -EINVAL;
}
return build_mount_idmapped(attr, usize, kattr, flags);
return build_mount_idmapped(attr, usize, kattr);
}
static void finish_mount_kattr(struct mount_kattr *kattr)
@ -4940,23 +4926,14 @@ static void finish_mount_kattr(struct mount_kattr *kattr)
mnt_idmap_put(kattr->mnt_idmap);
}
SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
unsigned int, flags, struct mount_attr __user *, uattr,
size_t, usize)
static int copy_mount_setattr(struct mount_attr __user *uattr, size_t usize,
struct mount_kattr *kattr)
{
int err;
struct path target;
int ret;
struct mount_attr attr;
struct mount_kattr kattr;
BUILD_BUG_ON(sizeof(struct mount_attr) != MOUNT_ATTR_SIZE_VER0);
if (flags & ~(AT_EMPTY_PATH |
AT_RECURSIVE |
AT_SYMLINK_NOFOLLOW |
AT_NO_AUTOMOUNT))
return -EINVAL;
if (unlikely(usize > PAGE_SIZE))
return -E2BIG;
if (unlikely(usize < MOUNT_ATTR_SIZE_VER0))
@ -4965,9 +4942,9 @@ SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
if (!may_mount())
return -EPERM;
err = copy_struct_from_user(&attr, sizeof(attr), uattr, usize);
if (err)
return err;
ret = copy_struct_from_user(&attr, sizeof(attr), uattr, usize);
if (ret)
return ret;
/* Don't bother walking through the mounts if this is a nop. */
if (attr.attr_set == 0 &&
@ -4975,7 +4952,37 @@ SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
attr.propagation == 0)
return 0;
err = build_mount_kattr(&attr, usize, &kattr, flags);
return build_mount_kattr(&attr, usize, kattr);
}
SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
unsigned int, flags, struct mount_attr __user *, uattr,
size_t, usize)
{
int err;
struct path target;
struct mount_kattr kattr;
unsigned int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW;
if (flags & ~(AT_EMPTY_PATH |
AT_RECURSIVE |
AT_SYMLINK_NOFOLLOW |
AT_NO_AUTOMOUNT))
return -EINVAL;
if (flags & AT_NO_AUTOMOUNT)
lookup_flags &= ~LOOKUP_AUTOMOUNT;
if (flags & AT_SYMLINK_NOFOLLOW)
lookup_flags &= ~LOOKUP_FOLLOW;
if (flags & AT_EMPTY_PATH)
lookup_flags |= LOOKUP_EMPTY;
kattr = (struct mount_kattr) {
.lookup_flags = lookup_flags,
.recurse = !!(flags & AT_RECURSIVE),
};
err = copy_mount_setattr(uattr, usize, &kattr);
if (err)
return err;