From: Scott Mayhew smayhew@redhat.com
[ Upstream commit eae00c5d6e48ccb2d78ae5873743d7d1a572951b ]
After calling security_sb_clone_mnt_opts() in nfs_get_root(), it's necessary to copy the value of has_sec_mnt_opts from the cloned super_block's nfs_server. Otherwise, calls to nfs_compare_super() using this super_block may not return the correct result, leading to mount failures.
For example, mounting an nfs server with the following in /etc/exports: /export *(rw,insecure,crossmnt,no_root_squash,security_label) and having /export/scratch on a separate block device.
mount -o v4.2,context=system_u:object_r:root_t:s0 server:/export/test /mnt/test mount -o v4.2,context=system_u:object_r:swapfile_t:s0 server:/export/scratch /mnt/scratch
The second mount would fail with "mount.nfs: /mnt/scratch is busy or already mounted or sharecache fail" and "SELinux: mount invalid. Same superblock, different security settings for..." would appear in the syslog.
Also while we're in there, replace several instances of "NFS_SB(s)" with "server", which was already declared at the top of the nfs_get_root().
Fixes: ec1ade6a0448 ("nfs: account for selinux security context when deciding to share superblock") Signed-off-by: Scott Mayhew smayhew@redhat.com Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nfs/getroot.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c index aaeeb4659bff..59355c106ece 100644 --- a/fs/nfs/getroot.c +++ b/fs/nfs/getroot.c @@ -67,7 +67,7 @@ static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *i int nfs_get_root(struct super_block *s, struct fs_context *fc) { struct nfs_fs_context *ctx = nfs_fc2context(fc); - struct nfs_server *server = NFS_SB(s); + struct nfs_server *server = NFS_SB(s), *clone_server; struct nfs_fsinfo fsinfo; struct dentry *root; struct inode *inode; @@ -127,7 +127,7 @@ int nfs_get_root(struct super_block *s, struct fs_context *fc) } spin_unlock(&root->d_lock); fc->root = root; - if (NFS_SB(s)->caps & NFS_CAP_SECURITY_LABEL) + if (server->caps & NFS_CAP_SECURITY_LABEL) kflags |= SECURITY_LSM_NATIVE_LABELS; if (ctx->clone_data.sb) { if (d_inode(fc->root)->i_fop != &nfs_dir_operations) { @@ -137,15 +137,19 @@ int nfs_get_root(struct super_block *s, struct fs_context *fc) /* clone lsm security options from the parent to the new sb */ error = security_sb_clone_mnt_opts(ctx->clone_data.sb, s, kflags, &kflags_out); + if (error) + goto error_splat_root; + clone_server = NFS_SB(ctx->clone_data.sb); + server->has_sec_mnt_opts = clone_server->has_sec_mnt_opts; } else { error = security_sb_set_mnt_opts(s, fc->security, kflags, &kflags_out); } if (error) goto error_splat_root; - if (NFS_SB(s)->caps & NFS_CAP_SECURITY_LABEL && + if (server->caps & NFS_CAP_SECURITY_LABEL && !(kflags_out & SECURITY_LSM_NATIVE_LABELS)) - NFS_SB(s)->caps &= ~NFS_CAP_SECURITY_LABEL; + server->caps &= ~NFS_CAP_SECURITY_LABEL;
nfs_setsecurity(inode, fsinfo.fattr, fsinfo.fattr->label); error = 0;