6.6-stable review patch. If anyone has any objections, please let me know.
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From: Paulo Alcantara pc@manguebit.com
commit 5e2fd17f434d2fed78efb123e2fc6711e4f598f1 upstream.
There was a wrong assumption that with CONFIG_CIFS_DFS_UPCALL=y there would always be a dns_resolver key set up so we could unconditionally upcall to resolve UNC hostname rather than using the value provided by mount(2).
Only require it when performing automount of junctions within a DFS share so users that don't have dns_resolver key still can mount their regular shares with server hostname resolved by mount.cifs(8).
Fixes: 348a04a8d113 ("smb: client: get rid of dfs code dep in namespace.c") Cc: stable@vger.kernel.org Tested-by: Eduard Bachmakov e.bachmakov@gmail.com Reported-by: Eduard Bachmakov e.bachmakov@gmail.com Closes: https://lore.kernel.org/all/CADCRUiNvZuiUZ0VGZZO9HRyPyw6x92kiA7o7Q4tsX5FkZqU... Signed-off-by: Paulo Alcantara (SUSE) pc@manguebit.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/smb/client/dfs.c | 18 +++++++++++++----- fs/smb/client/fs_context.h | 1 + fs/smb/client/namespace.c | 17 +++++++++++++++-- 3 files changed, 29 insertions(+), 7 deletions(-)
--- a/fs/smb/client/dfs.c +++ b/fs/smb/client/dfs.c @@ -263,15 +263,23 @@ out: return rc; }
-/* Resolve UNC hostname in @ctx->source and set ip addr in @ctx->dstaddr */ +/* + * If @ctx->dfs_automount, then update @ctx->dstaddr earlier with the DFS root + * server from where we'll start following any referrals. Otherwise rely on the + * value provided by mount(2) as the user might not have dns_resolver key set up + * and therefore failing to upcall to resolve UNC hostname under @ctx->source. + */ static int update_fs_context_dstaddr(struct smb3_fs_context *ctx) { struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr; - int rc; + int rc = 0;
- rc = dns_resolve_server_name_to_ip(ctx->source, addr, NULL); - if (!rc) - cifs_set_port(addr, ctx->port); + if (!ctx->nodfs && ctx->dfs_automount) { + rc = dns_resolve_server_name_to_ip(ctx->source, addr, NULL); + if (!rc) + cifs_set_port(addr, ctx->port); + ctx->dfs_automount = false; + } return rc; }
--- a/fs/smb/client/fs_context.h +++ b/fs/smb/client/fs_context.h @@ -268,6 +268,7 @@ struct smb3_fs_context { bool witness:1; /* use witness protocol */ char *leaf_fullpath; struct cifs_ses *dfs_root_ses; + bool dfs_automount:1; /* set for dfs automount only */ };
extern const struct fs_parameter_spec smb3_fs_parameters[]; --- a/fs/smb/client/namespace.c +++ b/fs/smb/client/namespace.c @@ -117,6 +117,18 @@ cifs_build_devname(char *nodename, const return dev; }
+static bool is_dfs_mount(struct dentry *dentry) +{ + struct cifs_sb_info *cifs_sb = CIFS_SB(dentry->d_sb); + struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb); + bool ret; + + spin_lock(&tcon->tc_lock); + ret = !!tcon->origin_fullpath; + spin_unlock(&tcon->tc_lock); + return ret; +} + /* Return full path out of a dentry set for automount */ static char *automount_fullpath(struct dentry *dentry, void *page) { @@ -212,8 +224,9 @@ static struct vfsmount *cifs_do_automoun ctx->source = NULL; goto out; } - cifs_dbg(FYI, "%s: ctx: source=%s UNC=%s prepath=%s\n", - __func__, ctx->source, ctx->UNC, ctx->prepath); + ctx->dfs_automount = is_dfs_mount(mntpt); + cifs_dbg(FYI, "%s: ctx: source=%s UNC=%s prepath=%s dfs_automount=%d\n", + __func__, ctx->source, ctx->UNC, ctx->prepath, ctx->dfs_automount);
mnt = fc_mount(fc); out: