diff options
| author | Paulo Alcantara <pc@cjr.nz> | 2021-02-25 02:59:23 +0300 |
|---|---|---|
| committer | Steve French <stfrench@microsoft.com> | 2021-02-25 21:19:15 +0300 |
| commit | 5ff2836ed3a5c24420a7235be25a462594cdc4ea (patch) | |
| tree | 20bc10e8ef8c989a70266d7353f3d27b1ecc71e3 /fs/cifs/connect.c | |
| parent | ff2c54a04097dee0b8899c485360719844d923f8 (diff) | |
| download | linux-5ff2836ed3a5c24420a7235be25a462594cdc4ea.tar.xz | |
cifs: introduce helper for finding referral server to improve DFS target resolution
Some servers seem to mistakenly report different values for
capabilities and share flags, so we can't always rely on those values
to decide whether the resolved target can handle any new DFS
referrals.
Add a new helper is_referral_server() to check if all resolved targets
can handle new DFS referrals by directly looking at the
GET_DFS_REFERRAL.ReferralHeaderFlags value as specified in MS-DFSC
2.2.4 RESP_GET_DFS_REFERRAL in addition to is_tcon_dfs().
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Cc: stable@vger.kernel.org # 5.11
Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/cifs/connect.c')
| -rw-r--r-- | fs/cifs/connect.c | 35 |
1 files changed, 34 insertions, 1 deletions
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 1a6d6e1e2c71..b2447cea45ae 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -3333,6 +3333,33 @@ out: return rc; } +/* Check if resolved targets can handle any DFS referrals */ +static int is_referral_server(const char *ref_path, struct cifs_tcon *tcon, bool *ref_server) +{ + int rc; + struct dfs_info3_param ref = {0}; + + if (is_tcon_dfs(tcon)) { + *ref_server = true; + } else { + cifs_dbg(FYI, "%s: ref_path=%s\n", __func__, ref_path); + + rc = dfs_cache_noreq_find(ref_path, &ref, NULL); + if (rc) { + cifs_dbg(VFS, "%s: dfs_cache_noreq_find: failed (rc=%d)\n", __func__, rc); + return rc; + } + cifs_dbg(FYI, "%s: ref.flags=0x%x\n", __func__, ref.flags); + /* + * Check if all targets are capable of handling DFS referrals as per + * MS-DFSC 2.2.4 RESP_GET_DFS_REFERRAL. + */ + *ref_server = !!(ref.flags & DFSREF_REFERRAL_SERVER); + free_dfs_info_param(&ref); + } + return 0; +} + int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx) { int rc = 0; @@ -3344,6 +3371,7 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx) char *ref_path = NULL, *full_path = NULL; char *oldmnt = NULL; char *mntdata = NULL; + bool ref_server = false; rc = mount_get_conns(ctx, cifs_sb, &xid, &server, &ses, &tcon); /* @@ -3409,11 +3437,16 @@ int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx) break; if (!tcon) continue; + /* Make sure that requests go through new root servers */ - if (is_tcon_dfs(tcon)) { + rc = is_referral_server(ref_path + 1, tcon, &ref_server); + if (rc) + break; + if (ref_server) { put_root_ses(root_ses); set_root_ses(cifs_sb, ses, &root_ses); } + /* Get next dfs path and then continue chasing them if -EREMOTE */ rc = next_dfs_prepath(cifs_sb, ctx, xid, server, tcon, &ref_path); /* Prevent recursion on broken link referrals */ |