When an ID has no dquot on disk, Q_XGETQUOTA returns -ENOENT even though default quota limits are configured and enforced against that ID. This means unprivileged users who have never used any resources cannot see the limits that apply to them. When xfs_qm_dqget() returns -ENOENT for a non-zero ID, return a zero-usage response with the default limits filled in from m_quotainfo rather than propagating the error. This is consistent with the enforcement behavior in xfs_qm_adjust_dqlimits(), which pushes the same default limits into a dquot when it is first allocated. Signed-off-by: Ravi Singh --- v2: - Moved fix from VFS (fs/quota/quota.c) to XFS (fs/xfs/xfs_qm_syscalls.c) per review feedback - Return default limits on ENOENT instead of granting unprivileged access to ID 0's dquot fs/xfs/xfs_qm_syscalls.c | 36 +++++++++++++++++++++++++++++++++++- 1 file changed, 35 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_qm_syscalls.c b/fs/xfs/xfs_qm_syscalls.c index d50b7318c..2176dc617 100644 --- a/fs/xfs/xfs_qm_syscalls.c +++ b/fs/xfs/xfs_qm_syscalls.c @@ -391,6 +391,30 @@ xfs_qm_scall_setqlim( return error; } +/* + * Fill out the default quota limits for an ID that has no dquot on disk. + * The default limits are enforced against such IDs by + * xfs_qm_adjust_dqlimits() when a dquot is first allocated. + */ +static void +xfs_qm_scall_getquota_fill_defaults( + struct xfs_mount *mp, + xfs_dqtype_t type, + struct qc_dqblk *dst) +{ + struct xfs_def_quota *defq; + + defq = xfs_get_defquota(mp->m_quotainfo, type); + + memset(dst, 0, sizeof(*dst)); + dst->d_spc_softlimit = XFS_FSB_TO_B(mp, defq->blk.soft); + dst->d_spc_hardlimit = XFS_FSB_TO_B(mp, defq->blk.hard); + dst->d_ino_softlimit = defq->ino.soft; + dst->d_ino_hardlimit = defq->ino.hard; + dst->d_rt_spc_softlimit = XFS_FSB_TO_B(mp, defq->rtb.soft); + dst->d_rt_spc_hardlimit = XFS_FSB_TO_B(mp, defq->rtb.hard); +} + /* Fill out the quota context. */ static void xfs_qm_scall_getquota_fill_qc( @@ -451,8 +475,18 @@ xfs_qm_scall_getquota( * set doalloc. If it doesn't exist, we'll get ENOENT back. */ error = xfs_qm_dqget(mp, id, type, false, &dqp); - if (error) + if (error) { + /* + * If there is no dquot for this ID and it is not ID 0, + * return the default limits with zero usage so that + * unprivileged users can see what limits apply to them. + */ + if (error == -ENOENT && id != 0) { + xfs_qm_scall_getquota_fill_defaults(mp, type, dst); + return 0; + } return error; + } /* * If everything's NULL, this dquot doesn't quite exist as far as -- 2.49.0