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b=H4sIAPrPwGUC/6tWKk4tykwtVrJSqFYqSi3LLM7MzwNyDHUUlJIzE vPSU3UzU4B8JSMDIxMDIKGbVGVkZGJhYWyga2CcapZsbmpgZm5gqgRUX1CUmpZZATYrOra2FgC +MPxdWwAAAA== To: Alexander Viro , Christian Brauner , Jan Kara , Chuck Lever , Neil Brown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, =?utf-8?b?T25kcmVqIE1vc27DocSNZWs=?= , Zdenek Pytela , Jeff Layton X-Mailer: b4 0.12.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=7870; i=jlayton@kernel.org; h=from:subject:message-id; bh=rhLn0KVRJ18boZjsfYPOuNLIVNG/FOTLR0EenwS0/J0=; b=owEBbQKS/ZANAwAIAQAOaEEZVoIVAcsmYgBlwNASW7Z2b4lT4W5V3fZaQ7gstoWwscL/2Oapl NLuBngXaduJAjMEAAEIAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCZcDQEgAKCRAADmhBGVaC FRalD/4y8GxrCyO4fl0X3p17gLzPFUyHuj6kfrt1C/3zu1PUyqodEXWf3cI7yYosdoMQLvrc5yj 9VdmeuRzAxydNQZffWPDAiIM/O3Z8OG+1B9zZbQccFLQB/hh2YUXtQd++DWf3aDtprNu77siSVv 8MUdZXc+9rO/60NXZNXpR8zyufSt6+MDQAlOTjeSMfjzEsdLeXqJ5Hll0AE1n/ncy1ioDnFPfUJ ur4PGNZ6ifS0Qzgdhucz3+x7T2sM4bEifdFZWuVeJrv6TT1+j9VWyxx+lAL3/zh7wJUQdDlYAAe tmStu2SircP2WnZbD6pAs01PEqxXrJKyiRehal2BunTrAxcwCZleEvtxt/iB4DQj0DwV+5V9V30 RqEz1fzR8lWdqmTyi3ilz5BiOt+XCAI0FobxGjcP/4fhL7dyZVa6QUqrcG0sLQ2x9muQZzZ6sZQ QJtzTPQR7p5hCDpbpiRqvAXfjj3q6Msg/n3lhtowT5anKKXANb+BNOL+cLCDxdL0/c1eD94M7Cw 4JqpNa4hJWCmpRtqQBgseKi+tkOptcrL4KPGzlIoTAXW6itEIzPU9pr56qP2Jb0vVl9wo0Bvf3K 7BgHiLMoOYp5T3WUjOR0u0ErHw6B7TyKb+SJKEZnKppeRGjblMlVYBvY85AVLiZxuFuLx8iN2M+ yoadsJcfsRsuz1g== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1790062664066649390 X-GMAIL-MSGID: 1790062664066649390 Zdenek reported seeing some AVC denials due to nfsd trying to set delegations: type=AVC msg=audit(09.11.2023 09:03:46.411:496) : avc: denied { lease } for pid=5127 comm=rpc.nfsd capability=lease scontext=system_u:system_r:nfsd_t:s0 tcontext=system_u:system_r:nfsd_t:s0 tclass=capability permissive=0 When setting delegations on behalf of nfsd, we don't want to do all of the normal capabilty and LSM checks. nfsd is a kernel thread and runs with CAP_LEASE set, so the uid checks end up being a no-op in most cases anyway. Some nfsd functions can end up running in normal process context when tearing down the server. At that point, the CAP_LEASE check can fail and cause the client to not tear down delegations when expected. Also, the way the per-fs ->setlease handlers work today is a little convoluted. The non-trivial ones are wrappers around generic_setlease, so when they fail due to permission problems they usually they end up doing a little extra work only to determine that they can't set the lease anyway. It would be more efficient to do those checks earlier. Transplant the permission checking from generic_setlease to vfs_setlease, which will make the permission checking happen earlier on filesystems that have a ->setlease operation. Add a new kernel_setlease function that bypasses these checks, and switch nfsd to use that instead of vfs_setlease. There is one behavioral change here: prior this patch the setlease_notifier would fire even if the lease attempt was going to fail the security checks later. With this change, it doesn't fire until the caller has passed them. I think this is a desirable change overall. nfsd is the only user of the setlease_notifier and it doesn't benefit from being notified about failed attempts. Cc: Ondrej Mosnáček Reported-by: Zdenek Pytela Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2248830 Signed-off-by: Jeff Layton Reviewed-by: NeilBrown Acked-by: Tom Talpey Acked-by: Tom Talpey Signed-off-by: NeilBrown Signed-off-by: Christian Brauner --- This patch is based on top of a merge of Christian's vfs.file branch (which has the file_lock/lease split). There is a small merge confict with Chuck's nfsd-next patch, but it should be fairly simple to resolve. --- fs/locks.c | 43 +++++++++++++++++++++++++------------------ fs/nfsd/nfs4layouts.c | 5 ++--- fs/nfsd/nfs4state.c | 8 ++++---- include/linux/filelock.h | 7 +++++++ 4 files changed, 38 insertions(+), 25 deletions(-) --- base-commit: 1499e59af376949b062cdc039257f811f6c1697f change-id: 20240202-bz2248830-03e6c7506705 Best regards, diff --git a/fs/locks.c b/fs/locks.c index 33c7f4a8c729..26d52ef5314a 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -1925,18 +1925,6 @@ static int generic_delete_lease(struct file *filp, void *owner) int generic_setlease(struct file *filp, int arg, struct file_lease **flp, void **priv) { - struct inode *inode = file_inode(filp); - vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(filp), inode); - int error; - - if ((!vfsuid_eq_kuid(vfsuid, current_fsuid())) && !capable(CAP_LEASE)) - return -EACCES; - if (!S_ISREG(inode->i_mode)) - return -EINVAL; - error = security_file_lock(filp, arg); - if (error) - return error; - switch (arg) { case F_UNLCK: return generic_delete_lease(filp, *priv); @@ -1987,6 +1975,19 @@ void lease_unregister_notifier(struct notifier_block *nb) } EXPORT_SYMBOL_GPL(lease_unregister_notifier); + +int +kernel_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv) +{ + if (lease) + setlease_notifier(arg, *lease); + if (filp->f_op->setlease) + return filp->f_op->setlease(filp, arg, lease, priv); + else + return generic_setlease(filp, arg, lease, priv); +} +EXPORT_SYMBOL_GPL(kernel_setlease); + /** * vfs_setlease - sets a lease on an open file * @filp: file pointer @@ -2007,12 +2008,18 @@ EXPORT_SYMBOL_GPL(lease_unregister_notifier); int vfs_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv) { - if (lease) - setlease_notifier(arg, *lease); - if (filp->f_op->setlease) - return filp->f_op->setlease(filp, arg, lease, priv); - else - return generic_setlease(filp, arg, lease, priv); + struct inode *inode = file_inode(filp); + vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(filp), inode); + int error; + + if ((!vfsuid_eq_kuid(vfsuid, current_fsuid())) && !capable(CAP_LEASE)) + return -EACCES; + if (!S_ISREG(inode->i_mode)) + return -EINVAL; + error = security_file_lock(filp, arg); + if (error) + return error; + return kernel_setlease(filp, arg, lease, priv); } EXPORT_SYMBOL_GPL(vfs_setlease); diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c index 4fa21b74a981..4c0d00bdfbb1 100644 --- a/fs/nfsd/nfs4layouts.c +++ b/fs/nfsd/nfs4layouts.c @@ -170,7 +170,7 @@ nfsd4_free_layout_stateid(struct nfs4_stid *stid) spin_unlock(&fp->fi_lock); if (!nfsd4_layout_ops[ls->ls_layout_type]->disable_recalls) - vfs_setlease(ls->ls_file->nf_file, F_UNLCK, NULL, (void **)&ls); + kernel_setlease(ls->ls_file->nf_file, F_UNLCK, NULL, (void **)&ls); nfsd_file_put(ls->ls_file); if (ls->ls_recalled) @@ -199,8 +199,7 @@ nfsd4_layout_setlease(struct nfs4_layout_stateid *ls) fl->c.flc_pid = current->tgid; fl->c.flc_file = ls->ls_file->nf_file; - status = vfs_setlease(fl->c.flc_file, fl->c.flc_type, &fl, - NULL); + status = kernel_setlease(fl->c.flc_file, fl->c.flc_type, &fl, NULL); if (status) { locks_free_lease(fl); return status; diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index b2c8efb5f793..6d52ecba8e9c 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1249,7 +1249,7 @@ static void nfs4_unlock_deleg_lease(struct nfs4_delegation *dp) WARN_ON_ONCE(!fp->fi_delegees); - vfs_setlease(nf->nf_file, F_UNLCK, NULL, (void **)&dp); + kernel_setlease(nf->nf_file, F_UNLCK, NULL, (void **)&dp); put_deleg_file(fp); } @@ -5532,8 +5532,8 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp, if (!fl) goto out_clnt_odstate; - status = vfs_setlease(fp->fi_deleg_file->nf_file, - fl->c.flc_type, &fl, NULL); + status = kernel_setlease(fp->fi_deleg_file->nf_file, + fl->c.flc_type, &fl, NULL); if (fl) locks_free_lease(fl); if (status) @@ -5571,7 +5571,7 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp, return dp; out_unlock: - vfs_setlease(fp->fi_deleg_file->nf_file, F_UNLCK, NULL, (void **)&dp); + kernel_setlease(fp->fi_deleg_file->nf_file, F_UNLCK, NULL, (void **)&dp); out_clnt_odstate: put_clnt_odstate(dp->dl_clnt_odstate); nfs4_put_stid(&dp->dl_stid); diff --git a/include/linux/filelock.h b/include/linux/filelock.h index 4a5ad26962c1..cd6c1c291de9 100644 --- a/include/linux/filelock.h +++ b/include/linux/filelock.h @@ -208,6 +208,7 @@ struct file_lease *locks_alloc_lease(void); int __break_lease(struct inode *inode, unsigned int flags, unsigned int type); void lease_get_mtime(struct inode *, struct timespec64 *time); int generic_setlease(struct file *, int, struct file_lease **, void **priv); +int kernel_setlease(struct file *, int, struct file_lease **, void **); int vfs_setlease(struct file *, int, struct file_lease **, void **); int lease_modify(struct file_lease *, int, struct list_head *); @@ -357,6 +358,12 @@ static inline int generic_setlease(struct file *filp, int arg, return -EINVAL; } +static inline int kernel_setlease(struct file *filp, int arg, + struct file_lease **lease, void **priv) +{ + return -EINVAL; +} + static inline int vfs_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv) {