6.6-stable review patch. If anyone has any objections, please let me know.
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From: Shyam Prasad N sprasad@microsoft.com
[ Upstream commit 0f0e357902957fba28ed31bde0d6921c6bd1485d ]
This fixes scenarios where remount can overwrite the only currently working password, breaking reconnect.
We recently introduced a password2 field in both ses and ctx structs. This was done so as to allow the client to rotate passwords for a mount without any downtime. However, when the client transparently handles password rotation, it can swap the values of the two password fields in the ses struct, but not in smb3_fs_context struct that hangs off cifs_sb. This can lead to a situation where a remount unintentionally overwrites a working password in the ses struct.
In order to fix this, we first get the passwords in ctx struct in-sync with ses struct, before replacing them with what the passwords that could be passed as a part of remount.
Also, in order to avoid race condition between smb2_reconnect and smb3_reconfigure, we make sure to lock session_mutex before changing password and password2 fields of the ses structure.
Fixes: 35f834265e0d ("smb3: fix broken reconnect when password changing on the server by allowing password rotation") Signed-off-by: Shyam Prasad N sprasad@microsoft.com Signed-off-by: Meetakshi Setiya msetiya@microsoft.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/smb/client/fs_context.c | 83 +++++++++++++++++++++++++++++++++----- fs/smb/client/fs_context.h | 1 + 2 files changed, 75 insertions(+), 9 deletions(-)
diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c index 8d7484400fe8e..6ba38bfa645b4 100644 --- a/fs/smb/client/fs_context.c +++ b/fs/smb/client/fs_context.c @@ -888,12 +888,37 @@ do { \ cifs_sb->ctx->field = NULL; \ } while (0)
+int smb3_sync_session_ctx_passwords(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses) +{ + if (ses->password && + cifs_sb->ctx->password && + strcmp(ses->password, cifs_sb->ctx->password)) { + kfree_sensitive(cifs_sb->ctx->password); + cifs_sb->ctx->password = kstrdup(ses->password, GFP_KERNEL); + if (!cifs_sb->ctx->password) + return -ENOMEM; + } + if (ses->password2 && + cifs_sb->ctx->password2 && + strcmp(ses->password2, cifs_sb->ctx->password2)) { + kfree_sensitive(cifs_sb->ctx->password2); + cifs_sb->ctx->password2 = kstrdup(ses->password2, GFP_KERNEL); + if (!cifs_sb->ctx->password2) { + kfree_sensitive(cifs_sb->ctx->password); + cifs_sb->ctx->password = NULL; + return -ENOMEM; + } + } + return 0; +} + static int smb3_reconfigure(struct fs_context *fc) { struct smb3_fs_context *ctx = smb3_fc2context(fc); struct dentry *root = fc->root; struct cifs_sb_info *cifs_sb = CIFS_SB(root->d_sb); struct cifs_ses *ses = cifs_sb_master_tcon(cifs_sb)->ses; + char *new_password = NULL, *new_password2 = NULL; bool need_recon = false; int rc;
@@ -913,21 +938,61 @@ static int smb3_reconfigure(struct fs_context *fc) STEAL_STRING(cifs_sb, ctx, UNC); STEAL_STRING(cifs_sb, ctx, source); STEAL_STRING(cifs_sb, ctx, username); + if (need_recon == false) STEAL_STRING_SENSITIVE(cifs_sb, ctx, password); else { - kfree_sensitive(ses->password); - ses->password = kstrdup(ctx->password, GFP_KERNEL); - if (!ses->password) - return -ENOMEM; - kfree_sensitive(ses->password2); - ses->password2 = kstrdup(ctx->password2, GFP_KERNEL); - if (!ses->password2) { - kfree_sensitive(ses->password); - ses->password = NULL; + if (ctx->password) { + new_password = kstrdup(ctx->password, GFP_KERNEL); + if (!new_password) + return -ENOMEM; + } else + STEAL_STRING_SENSITIVE(cifs_sb, ctx, password); + } + + /* + * if a new password2 has been specified, then reset it's value + * inside the ses struct + */ + if (ctx->password2) { + new_password2 = kstrdup(ctx->password2, GFP_KERNEL); + if (!new_password2) { + kfree_sensitive(new_password); return -ENOMEM; } + } else + STEAL_STRING_SENSITIVE(cifs_sb, ctx, password2); + + /* + * we may update the passwords in the ses struct below. Make sure we do + * not race with smb2_reconnect + */ + mutex_lock(&ses->session_mutex); + + /* + * smb2_reconnect may swap password and password2 in case session setup + * failed. First get ctx passwords in sync with ses passwords. It should + * be okay to do this even if this function were to return an error at a + * later stage + */ + rc = smb3_sync_session_ctx_passwords(cifs_sb, ses); + if (rc) + return rc; + + /* + * now that allocations for passwords are done, commit them + */ + if (new_password) { + kfree_sensitive(ses->password); + ses->password = new_password; } + if (new_password2) { + kfree_sensitive(ses->password2); + ses->password2 = new_password2; + } + + mutex_unlock(&ses->session_mutex); + STEAL_STRING(cifs_sb, ctx, domainname); STEAL_STRING(cifs_sb, ctx, nodename); STEAL_STRING(cifs_sb, ctx, iocharset); diff --git a/fs/smb/client/fs_context.h b/fs/smb/client/fs_context.h index cf577ec0dd0ac..bbd2063ab838d 100644 --- a/fs/smb/client/fs_context.h +++ b/fs/smb/client/fs_context.h @@ -298,6 +298,7 @@ static inline struct smb3_fs_context *smb3_fc2context(const struct fs_context *f }
extern int smb3_fs_context_dup(struct smb3_fs_context *new_ctx, struct smb3_fs_context *ctx); +extern int smb3_sync_session_ctx_passwords(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses); extern void smb3_update_mnt_flags(struct cifs_sb_info *cifs_sb);
/*