| Message ID | 20241111114351.200984-1-budhirajaritviksmb@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | CIFS: New mount option for cifs.upcall namespace resolution | expand |
tentatively merged into cifs-2.6.git for-next pending testing and additional review. Any suggestions on whether there would be a better mount parm name? On Mon, Nov 11, 2024 at 5:44 AM <budhirajaritviksmb@gmail.com> wrote: > > From: Ritvik Budhiraja <rbudhiraja@microsoft.com> > > In the current implementation, the SMB filesystem on a mount point can > trigger upcalls from the kernel to the userspace to enable certain > functionalities like spnego, dns_resolution, amongst others. These upcalls > usually either happen in the context of the mount or in the context of an > application/user. The upcall handler for cifs, cifs.upcall already has > existing code which switches the namespaces to the caller's namespace > before handling the upcall. This behaviour is expected for scenarios like > multiuser mounts, but might not cover all single user scenario with > services such as Kubernetes, where the mount can happen from different > locations such as on the host, from an app container, or a driver pod > which does the mount on behalf of a different pod. > > This patch introduces a new mount option called upcall_target, to > customise the upcall behaviour. upcall_target can take 'mount' and 'app' > as possible values. This aids use cases like Kubernetes where the mount > happens on behalf of the application in another container altogether. > Having this new mount option allows the mount command to specify where the > upcall should happen: 'mount' for resolving the upcall to the host > namespace, and 'app' for resolving the upcall to the ns of the calling > thread. This will enable both the scenarios where the Kerberos credentials > can be found on the application namespace or the host namespace to which > just the mount operation is "delegated". > > Reviewed-by: Shyam Prasad <shyam.prasad@microsoft.com> > Reviewed-by: Bharath S M <bharathsm@microsoft.com> > Signed-off-by: Ritvik Budhiraja <rbudhiraja@microsoft.com> > --- > fs/smb/client/cifs_spnego.c | 16 +++++++++++++++ > fs/smb/client/cifsfs.c | 25 ++++++++++++++++++++++++ > fs/smb/client/cifsglob.h | 7 +++++++ > fs/smb/client/connect.c | 20 +++++++++++++++++++ > fs/smb/client/fs_context.c | 39 +++++++++++++++++++++++++++++++++++++ > fs/smb/client/fs_context.h | 10 ++++++++++ > 6 files changed, 117 insertions(+) > > diff --git a/fs/smb/client/cifs_spnego.c b/fs/smb/client/cifs_spnego.c > index af7849e59..28f568b5f 100644 > --- a/fs/smb/client/cifs_spnego.c > +++ b/fs/smb/client/cifs_spnego.c > @@ -82,6 +82,9 @@ struct key_type cifs_spnego_key_type = { > /* strlen of ";pid=0x" */ > #define PID_KEY_LEN 7 > > +/* strlen of ";upcall_target=" */ > +#define UPCALL_TARGET_KEY_LEN 15 > + > /* get a key struct with a SPNEGO security blob, suitable for session setup */ > struct key * > cifs_get_spnego_key(struct cifs_ses *sesInfo, > @@ -108,6 +111,11 @@ cifs_get_spnego_key(struct cifs_ses *sesInfo, > if (sesInfo->user_name) > desc_len += USER_KEY_LEN + strlen(sesInfo->user_name); > > + if (sesInfo->upcall_target == UPTARGET_MOUNT) > + desc_len += UPCALL_TARGET_KEY_LEN + 5; // strlen("mount") > + else > + desc_len += UPCALL_TARGET_KEY_LEN + 3; // strlen("app") > + > spnego_key = ERR_PTR(-ENOMEM); > description = kzalloc(desc_len, GFP_KERNEL); > if (description == NULL) > @@ -156,6 +164,14 @@ cifs_get_spnego_key(struct cifs_ses *sesInfo, > dp = description + strlen(description); > sprintf(dp, ";pid=0x%x", current->pid); > > + if (sesInfo->upcall_target == UPTARGET_MOUNT) { > + dp = description + strlen(description); > + sprintf(dp, ";upcall_target=mount"); > + } else { > + dp = description + strlen(description); > + sprintf(dp, ";upcall_target=app"); > + } > + > cifs_dbg(FYI, "key description = %s\n", description); > saved_cred = override_creds(spnego_cred); > spnego_key = request_key(&cifs_spnego_key_type, description, ""); > diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c > index 2a2523c93..ac89bd199 100644 > --- a/fs/smb/client/cifsfs.c > +++ b/fs/smb/client/cifsfs.c > @@ -535,6 +535,30 @@ static int cifs_show_devname(struct seq_file *m, struct dentry *root) > return 0; > } > > +static void > +cifs_show_upcall_target(struct seq_file *s, struct cifs_sb_info *cifs_sb) > +{ > + if (cifs_sb->ctx->upcall_target == UPTARGET_UNSPECIFIED) { > + seq_puts(s, ",upcall_target=app"); > + return; > + } > + > + seq_puts(s, ",upcall_target="); > + > + switch (cifs_sb->ctx->upcall_target) { > + case UPTARGET_APP: > + seq_puts(s, "app"); > + break; > + case UPTARGET_MOUNT: > + seq_puts(s, "mount"); > + break; > + default: > + /* shouldn't ever happen */ > + seq_puts(s, "unknown"); > + break; > + } > +} > + > /* > * cifs_show_options() is for displaying mount options in /proc/mounts. > * Not all settable options are displayed but most of the important > @@ -551,6 +575,7 @@ cifs_show_options(struct seq_file *s, struct dentry *root) > seq_show_option(s, "vers", tcon->ses->server->vals->version_string); > cifs_show_security(s, tcon->ses); > cifs_show_cache_flavor(s, cifs_sb); > + cifs_show_upcall_target(s, cifs_sb); > > if (tcon->no_lease) > seq_puts(s, ",nolease"); > diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h > index 9eae8649f..7878d1197 100644 > --- a/fs/smb/client/cifsglob.h > +++ b/fs/smb/client/cifsglob.h > @@ -153,6 +153,12 @@ enum securityEnum { > Kerberos, /* Kerberos via SPNEGO */ > }; > > +enum upcall_target_enum { > + UPTARGET_UNSPECIFIED, /* not specified, defaults to app */ > + UPTARGET_MOUNT, /* upcall to the mount namespace */ > + UPTARGET_APP, /* upcall to the application namespace which did the mount */ > +}; > + > enum cifs_reparse_type { > CIFS_REPARSE_TYPE_NFS, > CIFS_REPARSE_TYPE_WSL, > @@ -1083,6 +1089,7 @@ struct cifs_ses { > struct session_key auth_key; > struct ntlmssp_auth *ntlmssp; /* ciphertext, flags, server challenge */ > enum securityEnum sectype; /* what security flavor was specified? */ > + enum upcall_target_enum upcall_target; /* what upcall target was specified? */ > bool sign; /* is signing required? */ > bool domainAuto:1; > bool expired_pwd; /* track if access denied or expired pwd so can know if need to update */ > diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c > index 5375b0c1d..57766bca0 100644 > --- a/fs/smb/client/connect.c > +++ b/fs/smb/client/connect.c > @@ -2352,6 +2352,26 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx) > > ses->sectype = ctx->sectype; > ses->sign = ctx->sign; > + > + /* > + *Explicitly marking upcall_target mount option for easier handling > + * by cifs_spnego.c and eventually cifs.upcall.c > + */ > + > + switch (ctx->upcall_target) { > + case UPTARGET_UNSPECIFIED: /* default to app */ > + case UPTARGET_APP: > + ses->upcall_target = UPTARGET_APP; > + break; > + case UPTARGET_MOUNT: > + ses->upcall_target = UPTARGET_MOUNT; > + break; > + default: > + // should never happen > + ses->upcall_target = UPTARGET_APP; > + break; > + } > + > ses->local_nls = load_nls(ctx->local_nls->charset); > > /* add server as first channel */ > diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c > index bc926ab25..2bae49507 100644 > --- a/fs/smb/client/fs_context.c > +++ b/fs/smb/client/fs_context.c > @@ -67,6 +67,12 @@ static const match_table_t cifs_secflavor_tokens = { > { Opt_sec_err, NULL } > }; > > +static const match_table_t cifs_upcall_target = { > + { Opt_upcall_target_mount, "mount" }, > + { Opt_upcall_target_application, "app" }, > + { Opt_upcall_target_err, NULL } > +}; > + > const struct fs_parameter_spec smb3_fs_parameters[] = { > /* Mount options that take no arguments */ > fsparam_flag_no("user_xattr", Opt_user_xattr), > @@ -178,6 +184,7 @@ const struct fs_parameter_spec smb3_fs_parameters[] = { > fsparam_string("sec", Opt_sec), > fsparam_string("cache", Opt_cache), > fsparam_string("reparse", Opt_reparse), > + fsparam_string("upcall_target", Opt_upcalltarget), > > /* Arguments that should be ignored */ > fsparam_flag("guest", Opt_ignore), > @@ -248,6 +255,29 @@ cifs_parse_security_flavors(struct fs_context *fc, char *value, struct smb3_fs_c > return 0; > } > > +static int > +cifs_parse_upcall_target(struct fs_context *fc, char *value, struct smb3_fs_context *ctx) > +{ > + substring_t args[MAX_OPT_ARGS]; > + > + ctx->upcall_target = UPTARGET_UNSPECIFIED; > + > + switch (match_token(value, cifs_upcall_target, args)) { > + case Opt_upcall_target_mount: > + ctx->upcall_target = UPTARGET_MOUNT; > + break; > + case Opt_upcall_target_application: > + ctx->upcall_target = UPTARGET_APP; > + break; > + > + default: > + cifs_errorf(fc, "bad upcall target: %s\n", value); > + return 1; > + } > + > + return 0; > +} > + > static const match_table_t cifs_cacheflavor_tokens = { > { Opt_cache_loose, "loose" }, > { Opt_cache_strict, "strict" }, > @@ -1440,6 +1470,10 @@ static int smb3_fs_context_parse_param(struct fs_context *fc, > if (cifs_parse_security_flavors(fc, param->string, ctx) != 0) > goto cifs_parse_mount_err; > break; > + case Opt_upcalltarget: > + if (cifs_parse_upcall_target(fc, param->string, ctx) != 0) > + goto cifs_parse_mount_err; > + break; > case Opt_cache: > if (cifs_parse_cache_flavor(fc, param->string, ctx) != 0) > goto cifs_parse_mount_err; > @@ -1617,6 +1651,11 @@ static int smb3_fs_context_parse_param(struct fs_context *fc, > } > /* case Opt_ignore: - is ignored as expected ... */ > > + if (ctx->multiuser && ctx->upcall_target == UPTARGET_MOUNT) { > + cifs_errorf(fc, "multiuser mount option not supported with upcalltarget set as 'mount'\n"); > + goto cifs_parse_mount_err; > + } > + > return 0; > > cifs_parse_mount_err: > diff --git a/fs/smb/client/fs_context.h b/fs/smb/client/fs_context.h > index cf577ec0d..e3ceed48c 100644 > --- a/fs/smb/client/fs_context.h > +++ b/fs/smb/client/fs_context.h > @@ -61,6 +61,12 @@ enum cifs_sec_param { > Opt_sec_err > }; > > +enum cifs_upcall_target_param { > + Opt_upcall_target_mount, > + Opt_upcall_target_application, > + Opt_upcall_target_err > +}; > + > enum cifs_param { > /* Mount options that take no arguments */ > Opt_user_xattr, > @@ -114,6 +120,8 @@ enum cifs_param { > Opt_multichannel, > Opt_compress, > Opt_witness, > + Opt_is_upcall_target_mount, > + Opt_is_upcall_target_application, > > /* Mount options which take numeric value */ > Opt_backupuid, > @@ -157,6 +165,7 @@ enum cifs_param { > Opt_sec, > Opt_cache, > Opt_reparse, > + Opt_upcalltarget, > > /* Mount options to be ignored */ > Opt_ignore, > @@ -198,6 +207,7 @@ struct smb3_fs_context { > umode_t file_mode; > umode_t dir_mode; > enum securityEnum sectype; /* sectype requested via mnt opts */ > + enum upcall_target_enum upcall_target; /* where to upcall for mount */ > bool sign; /* was signing requested via mnt opts? */ > bool ignore_signature:1; > bool retry:1; > -- > 2.43.0 >
diff --git a/fs/smb/client/cifs_spnego.c b/fs/smb/client/cifs_spnego.c index af7849e59..28f568b5f 100644 --- a/fs/smb/client/cifs_spnego.c +++ b/fs/smb/client/cifs_spnego.c @@ -82,6 +82,9 @@ struct key_type cifs_spnego_key_type = { /* strlen of ";pid=0x" */ #define PID_KEY_LEN 7 +/* strlen of ";upcall_target=" */ +#define UPCALL_TARGET_KEY_LEN 15 + /* get a key struct with a SPNEGO security blob, suitable for session setup */ struct key * cifs_get_spnego_key(struct cifs_ses *sesInfo, @@ -108,6 +111,11 @@ cifs_get_spnego_key(struct cifs_ses *sesInfo, if (sesInfo->user_name) desc_len += USER_KEY_LEN + strlen(sesInfo->user_name); + if (sesInfo->upcall_target == UPTARGET_MOUNT) + desc_len += UPCALL_TARGET_KEY_LEN + 5; // strlen("mount") + else + desc_len += UPCALL_TARGET_KEY_LEN + 3; // strlen("app") + spnego_key = ERR_PTR(-ENOMEM); description = kzalloc(desc_len, GFP_KERNEL); if (description == NULL) @@ -156,6 +164,14 @@ cifs_get_spnego_key(struct cifs_ses *sesInfo, dp = description + strlen(description); sprintf(dp, ";pid=0x%x", current->pid); + if (sesInfo->upcall_target == UPTARGET_MOUNT) { + dp = description + strlen(description); + sprintf(dp, ";upcall_target=mount"); + } else { + dp = description + strlen(description); + sprintf(dp, ";upcall_target=app"); + } + cifs_dbg(FYI, "key description = %s\n", description); saved_cred = override_creds(spnego_cred); spnego_key = request_key(&cifs_spnego_key_type, description, ""); diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c index 2a2523c93..ac89bd199 100644 --- a/fs/smb/client/cifsfs.c +++ b/fs/smb/client/cifsfs.c @@ -535,6 +535,30 @@ static int cifs_show_devname(struct seq_file *m, struct dentry *root) return 0; } +static void +cifs_show_upcall_target(struct seq_file *s, struct cifs_sb_info *cifs_sb) +{ + if (cifs_sb->ctx->upcall_target == UPTARGET_UNSPECIFIED) { + seq_puts(s, ",upcall_target=app"); + return; + } + + seq_puts(s, ",upcall_target="); + + switch (cifs_sb->ctx->upcall_target) { + case UPTARGET_APP: + seq_puts(s, "app"); + break; + case UPTARGET_MOUNT: + seq_puts(s, "mount"); + break; + default: + /* shouldn't ever happen */ + seq_puts(s, "unknown"); + break; + } +} + /* * cifs_show_options() is for displaying mount options in /proc/mounts. * Not all settable options are displayed but most of the important @@ -551,6 +575,7 @@ cifs_show_options(struct seq_file *s, struct dentry *root) seq_show_option(s, "vers", tcon->ses->server->vals->version_string); cifs_show_security(s, tcon->ses); cifs_show_cache_flavor(s, cifs_sb); + cifs_show_upcall_target(s, cifs_sb); if (tcon->no_lease) seq_puts(s, ",nolease"); diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h index 9eae8649f..7878d1197 100644 --- a/fs/smb/client/cifsglob.h +++ b/fs/smb/client/cifsglob.h @@ -153,6 +153,12 @@ enum securityEnum { Kerberos, /* Kerberos via SPNEGO */ }; +enum upcall_target_enum { + UPTARGET_UNSPECIFIED, /* not specified, defaults to app */ + UPTARGET_MOUNT, /* upcall to the mount namespace */ + UPTARGET_APP, /* upcall to the application namespace which did the mount */ +}; + enum cifs_reparse_type { CIFS_REPARSE_TYPE_NFS, CIFS_REPARSE_TYPE_WSL, @@ -1083,6 +1089,7 @@ struct cifs_ses { struct session_key auth_key; struct ntlmssp_auth *ntlmssp; /* ciphertext, flags, server challenge */ enum securityEnum sectype; /* what security flavor was specified? */ + enum upcall_target_enum upcall_target; /* what upcall target was specified? */ bool sign; /* is signing required? */ bool domainAuto:1; bool expired_pwd; /* track if access denied or expired pwd so can know if need to update */ diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c index 5375b0c1d..57766bca0 100644 --- a/fs/smb/client/connect.c +++ b/fs/smb/client/connect.c @@ -2352,6 +2352,26 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx) ses->sectype = ctx->sectype; ses->sign = ctx->sign; + + /* + *Explicitly marking upcall_target mount option for easier handling + * by cifs_spnego.c and eventually cifs.upcall.c + */ + + switch (ctx->upcall_target) { + case UPTARGET_UNSPECIFIED: /* default to app */ + case UPTARGET_APP: + ses->upcall_target = UPTARGET_APP; + break; + case UPTARGET_MOUNT: + ses->upcall_target = UPTARGET_MOUNT; + break; + default: + // should never happen + ses->upcall_target = UPTARGET_APP; + break; + } + ses->local_nls = load_nls(ctx->local_nls->charset); /* add server as first channel */ diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c index bc926ab25..2bae49507 100644 --- a/fs/smb/client/fs_context.c +++ b/fs/smb/client/fs_context.c @@ -67,6 +67,12 @@ static const match_table_t cifs_secflavor_tokens = { { Opt_sec_err, NULL } }; +static const match_table_t cifs_upcall_target = { + { Opt_upcall_target_mount, "mount" }, + { Opt_upcall_target_application, "app" }, + { Opt_upcall_target_err, NULL } +}; + const struct fs_parameter_spec smb3_fs_parameters[] = { /* Mount options that take no arguments */ fsparam_flag_no("user_xattr", Opt_user_xattr), @@ -178,6 +184,7 @@ const struct fs_parameter_spec smb3_fs_parameters[] = { fsparam_string("sec", Opt_sec), fsparam_string("cache", Opt_cache), fsparam_string("reparse", Opt_reparse), + fsparam_string("upcall_target", Opt_upcalltarget), /* Arguments that should be ignored */ fsparam_flag("guest", Opt_ignore), @@ -248,6 +255,29 @@ cifs_parse_security_flavors(struct fs_context *fc, char *value, struct smb3_fs_c return 0; } +static int +cifs_parse_upcall_target(struct fs_context *fc, char *value, struct smb3_fs_context *ctx) +{ + substring_t args[MAX_OPT_ARGS]; + + ctx->upcall_target = UPTARGET_UNSPECIFIED; + + switch (match_token(value, cifs_upcall_target, args)) { + case Opt_upcall_target_mount: + ctx->upcall_target = UPTARGET_MOUNT; + break; + case Opt_upcall_target_application: + ctx->upcall_target = UPTARGET_APP; + break; + + default: + cifs_errorf(fc, "bad upcall target: %s\n", value); + return 1; + } + + return 0; +} + static const match_table_t cifs_cacheflavor_tokens = { { Opt_cache_loose, "loose" }, { Opt_cache_strict, "strict" }, @@ -1440,6 +1470,10 @@ static int smb3_fs_context_parse_param(struct fs_context *fc, if (cifs_parse_security_flavors(fc, param->string, ctx) != 0) goto cifs_parse_mount_err; break; + case Opt_upcalltarget: + if (cifs_parse_upcall_target(fc, param->string, ctx) != 0) + goto cifs_parse_mount_err; + break; case Opt_cache: if (cifs_parse_cache_flavor(fc, param->string, ctx) != 0) goto cifs_parse_mount_err; @@ -1617,6 +1651,11 @@ static int smb3_fs_context_parse_param(struct fs_context *fc, } /* case Opt_ignore: - is ignored as expected ... */ + if (ctx->multiuser && ctx->upcall_target == UPTARGET_MOUNT) { + cifs_errorf(fc, "multiuser mount option not supported with upcalltarget set as 'mount'\n"); + goto cifs_parse_mount_err; + } + return 0; cifs_parse_mount_err: diff --git a/fs/smb/client/fs_context.h b/fs/smb/client/fs_context.h index cf577ec0d..e3ceed48c 100644 --- a/fs/smb/client/fs_context.h +++ b/fs/smb/client/fs_context.h @@ -61,6 +61,12 @@ enum cifs_sec_param { Opt_sec_err }; +enum cifs_upcall_target_param { + Opt_upcall_target_mount, + Opt_upcall_target_application, + Opt_upcall_target_err +}; + enum cifs_param { /* Mount options that take no arguments */ Opt_user_xattr, @@ -114,6 +120,8 @@ enum cifs_param { Opt_multichannel, Opt_compress, Opt_witness, + Opt_is_upcall_target_mount, + Opt_is_upcall_target_application, /* Mount options which take numeric value */ Opt_backupuid, @@ -157,6 +165,7 @@ enum cifs_param { Opt_sec, Opt_cache, Opt_reparse, + Opt_upcalltarget, /* Mount options to be ignored */ Opt_ignore, @@ -198,6 +207,7 @@ struct smb3_fs_context { umode_t file_mode; umode_t dir_mode; enum securityEnum sectype; /* sectype requested via mnt opts */ + enum upcall_target_enum upcall_target; /* where to upcall for mount */ bool sign; /* was signing requested via mnt opts? */ bool ignore_signature:1; bool retry:1;