From patchwork Thu May 13 20:08:06 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Casey Schaufler X-Patchwork-Id: 12256593 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0ACF6C43460 for ; Thu, 13 May 2021 20:34:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F182E611BF for ; Thu, 13 May 2021 20:34:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233046AbhEMUf5 (ORCPT ); Thu, 13 May 2021 16:35:57 -0400 Received: from sonic317-38.consmr.mail.ne1.yahoo.com ([66.163.184.49]:38564 "EHLO sonic317-38.consmr.mail.ne1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233023AbhEMUf5 (ORCPT ); Thu, 13 May 2021 16:35:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1620938087; bh=9nWli++yPqHl27Goa6bURc9CsVwE8MmqYdqxhZMz39A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From:Subject:Reply-To; b=gF4h0U2hoZaxyr/hyVPLzHkgLqnWX3gw7kldVffscVFo22ExlpS3CQikaJXirk2G1dusXaxXcu7DyYxl2bwSk9idInVPZ9vAQjVMzOiW2AmubHskePQ+46F7G8GHd5YTgs/4x/06Kykxf6O7u6di9Hs5RcBKo/n34HZBP8RsB/xaDvMEPVg5u2FVJLUyQQoLnTOwTr4BL77HH7GWj9jMmrYFNR6hf7PXMzp8kP2fufk4mL9T0QgvPjYMrxVRTGnZgkSh7x9zJa0mML0ygmP0ik9g9ENn6mRHnTUDMc6RRX7KsNDvZNSBY/23HrJRI12ogpIoJ3Rw8ROxDh/WvvRiXA== X-SONIC-DKIM-SIGN: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1620938087; bh=r7ZBJr3XdtjThE7Wr9BjH32WLz6tafr/HakW6IsEvpX=; h=X-Sonic-MF:From:To:Subject:Date:From:Subject; b=i/XDprN6yQUcSYHohVmag9yXwK5lo1++VdTuY0Zo0jDoH95bT0ur/OLB1xDEx9iRfjPA+cXTrWFkgGZYexc9YLKBSJ5PeCfWgy/+EJTygHjpWFLnZz0VZ99QKh1IBn10nfBhmcJ4ypq6Rgu/w++tVasZRI3DURKTMVwiv0DkBz4vm+40eW9tVb12PzAEdCtNczPVGVHJ5PWw/S6cIsqJ3RxOWehR0jrYDwSx3Uwg5bkC4aIWjd/+zU8WyjOdvXVaGgdAhTfJyPc6AZZGCL68a0aZm4D2LQBzNOh3EoMAAth+fK09aghvvSEOpqGYKMmi8NrNoGYOPdLdqO0Xe+qkiA== X-YMail-OSG: t5xQN4oVM1lT6Dgs0u0LqeqtZZbA60HG2LV0x1NZDsEffWyoS7ip4fi01R_x7Bk lUu1P870ZTUkoLwh8A22c4QkFDwEnfhooYSvBXos2M5GxD9zluzeQhG6AGRGlhqp9w070hHm.Tjt Ri9XiWT4GYmuuXWXkY.ecRelc_6j_fQiXO9VnCvNrBse4iLXraZO0R3HE8SJpr6CASZtio9cPR3n Avg5Ba5upf12j2G9Fgc2rov__hr7AcQkY4fl4jDiN3w4NqPQRmgu9Vd9QrX_H3HInv9.rTWMl8jP 2Tr8PCl4y5PzmfaohWvO_oM3AfcuXzh_KwORQTG18rgX2eBSMj2tDX19ZENQIcRQX9D7lT9m.p67 elopRUjkPq7lDJjCTo2VjzzuR3LlEpulQNDUkTX3PyPF8hWhfRYKWsh4lgwJP1uSzVWjZAebS9eJ 184XG.zkurjsvqpltd6OyVScTBp2WnRpqkAq2afov2IoSgd1gPqer8K6pHRWLjIRkUYwGHd_pi6j ZnJBBJem.In6m8Kgadq5gJW75_HlYUXwJCkwd0mblfR9uSTQHTc.EC20ZHpvxokRYTxuYVsuoZc. 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This entry is not writable. A security module may decide that its policy does not allow this information to be displayed. In this case none of the information will be displayed. Reviewed-by: Kees Cook Signed-off-by: Casey Schaufler Cc: linux-api@vger.kernel.org Cc: linux-doc@vger.kernel.org --- Documentation/ABI/testing/procfs-attr-context | 14 ++++ Documentation/security/lsm.rst | 14 ++++ fs/proc/base.c | 1 + include/linux/lsm_hooks.h | 6 ++ security/apparmor/include/procattr.h | 2 +- security/apparmor/lsm.c | 8 +- security/apparmor/procattr.c | 22 +++--- security/security.c | 79 +++++++++++++++++++ security/selinux/hooks.c | 2 +- security/smack/smack_lsm.c | 2 +- 10 files changed, 135 insertions(+), 15 deletions(-) create mode 100644 Documentation/ABI/testing/procfs-attr-context diff --git a/Documentation/ABI/testing/procfs-attr-context b/Documentation/ABI/testing/procfs-attr-context new file mode 100644 index 000000000000..40da1c397c30 --- /dev/null +++ b/Documentation/ABI/testing/procfs-attr-context @@ -0,0 +1,14 @@ +What: /proc/*/attr/context +Contact: linux-security-module@vger.kernel.org, +Description: The current security information used by all Linux + security module (LSMs) that are active on the system. + The details of permissions required to read from + this interface and hence obtain the security state + of the task identified is dependent on the LSMs that + are active on the system. + A process cannot write to this interface. + The data provided by this interface will have the form: + lsm_name\0lsm_data\0[lsm_name\0lsm_data\0]... + where lsm_name is the name of the LSM and the following + lsm_data is the process data for that LSM. +Users: LSM user-space diff --git a/Documentation/security/lsm.rst b/Documentation/security/lsm.rst index b77b4a540391..070225ae6ceb 100644 --- a/Documentation/security/lsm.rst +++ b/Documentation/security/lsm.rst @@ -143,3 +143,17 @@ separated list of the active security modules. The file ``/proc/pid/attr/interface_lsm`` contains the name of the security module for which the ``/proc/pid/attr/current`` interface will apply. This interface can be written to. + +The infrastructure does provide an interface for the special +case where multiple security modules provide a process context. +This is provided in compound context format. + +- `lsm\0value\0lsm\0value\0` + +The `lsm` and `value` fields are NUL-terminated bytestrings. +Each field may contain whitespace or non-printable characters. +The NUL bytes are included in the size of a compound context. +The context ``Bell\0Secret\0Biba\0Loose\0`` has a size of 23. + +The file ``/proc/pid/attr/context`` provides the security +context of the identified process. diff --git a/fs/proc/base.c b/fs/proc/base.c index 10de522f3112..23ebfc35435c 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2808,6 +2808,7 @@ static const struct pid_entry attr_dir_stuff[] = { ATTR(NULL, "keycreate", 0666), ATTR(NULL, "sockcreate", 0666), ATTR(NULL, "interface_lsm", 0666), + ATTR(NULL, "context", 0444), #ifdef CONFIG_SECURITY_SMACK DIR("smack", 0555, proc_smack_attr_dir_inode_ops, proc_smack_attr_dir_ops), diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index d2c4bc94d47f..f6ffe8b069e2 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -1397,6 +1397,12 @@ * @pages contains the number of pages. * Return 0 if permission is granted. * + * @getprocattr: + * Provide the named process attribute for display in special files in + * the /proc/.../attr directory. Attribute naming and the data displayed + * is at the discretion of the security modules. The exception is the + * "context" attribute, which will contain the security context of the + * task as a nul terminated text string without trailing whitespace. * @ismaclabel: * Check if the extended attribute specified by @name * represents a MAC label. Returns 1 if name is a MAC diff --git a/security/apparmor/include/procattr.h b/security/apparmor/include/procattr.h index 31689437e0e1..03dbfdb2f2c0 100644 --- a/security/apparmor/include/procattr.h +++ b/security/apparmor/include/procattr.h @@ -11,7 +11,7 @@ #ifndef __AA_PROCATTR_H #define __AA_PROCATTR_H -int aa_getprocattr(struct aa_label *label, char **string); +int aa_getprocattr(struct aa_label *label, char **string, bool newline); int aa_setprocattr_changehat(char *args, size_t size, int flags); #endif /* __AA_PROCATTR_H */ diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c index 4237536106aa..65a004597e53 100644 --- a/security/apparmor/lsm.c +++ b/security/apparmor/lsm.c @@ -602,6 +602,7 @@ static int apparmor_getprocattr(struct task_struct *task, char *name, const struct cred *cred = get_task_cred(task); struct aa_task_ctx *ctx = task_ctx(current); struct aa_label *label = NULL; + bool newline = true; if (strcmp(name, "current") == 0) label = aa_get_newest_label(cred_label(cred)); @@ -609,11 +610,14 @@ static int apparmor_getprocattr(struct task_struct *task, char *name, label = aa_get_newest_label(ctx->previous); else if (strcmp(name, "exec") == 0 && ctx->onexec) label = aa_get_newest_label(ctx->onexec); - else + else if (strcmp(name, "context") == 0) { + label = aa_get_newest_label(cred_label(cred)); + newline = false; + } else error = -EINVAL; if (label) - error = aa_getprocattr(label, value); + error = aa_getprocattr(label, value, newline); aa_put_label(label); put_cred(cred); diff --git a/security/apparmor/procattr.c b/security/apparmor/procattr.c index c929bf4a3df1..be3b083d9b74 100644 --- a/security/apparmor/procattr.c +++ b/security/apparmor/procattr.c @@ -20,6 +20,7 @@ * aa_getprocattr - Return the profile information for @profile * @profile: the profile to print profile info about (NOT NULL) * @string: Returns - string containing the profile info (NOT NULL) + * @newline: Should a newline be added to @string. * * Returns: length of @string on success else error on failure * @@ -30,20 +31,21 @@ * * Returns: size of string placed in @string else error code on failure */ -int aa_getprocattr(struct aa_label *label, char **string) +int aa_getprocattr(struct aa_label *label, char **string, bool newline) { struct aa_ns *ns = labels_ns(label); struct aa_ns *current_ns = aa_get_current_ns(); + int flags = FLAG_VIEW_SUBNS | FLAG_HIDDEN_UNCONFINED; int len; if (!aa_ns_visible(current_ns, ns, true)) { aa_put_ns(current_ns); return -EACCES; } + if (newline) + flags |= FLAG_SHOW_MODE; - len = aa_label_snxprint(NULL, 0, current_ns, label, - FLAG_SHOW_MODE | FLAG_VIEW_SUBNS | - FLAG_HIDDEN_UNCONFINED); + len = aa_label_snxprint(NULL, 0, current_ns, label, flags); AA_BUG(len < 0); *string = kmalloc(len + 2, GFP_KERNEL); @@ -52,19 +54,19 @@ int aa_getprocattr(struct aa_label *label, char **string) return -ENOMEM; } - len = aa_label_snxprint(*string, len + 2, current_ns, label, - FLAG_SHOW_MODE | FLAG_VIEW_SUBNS | - FLAG_HIDDEN_UNCONFINED); + len = aa_label_snxprint(*string, len + 2, current_ns, label, flags); if (len < 0) { aa_put_ns(current_ns); return len; } - (*string)[len] = '\n'; - (*string)[len + 1] = 0; + if (newline) { + (*string)[len] = '\n'; + (*string)[++len] = 0; + } aa_put_ns(current_ns); - return len + 1; + return len; } /** diff --git a/security/security.c b/security/security.c index bb4c7f6c62ec..d3ff61442877 100644 --- a/security/security.c +++ b/security/security.c @@ -799,6 +799,57 @@ static int lsm_superblock_alloc(struct super_block *sb) return 0; } +/** + * append_ctx - append a lsm/context pair to a compound context + * @ctx: the existing compound context + * @ctxlen: size of the old context, including terminating nul byte + * @lsm: new lsm name, nul terminated + * @new: new context, possibly nul terminated + * @newlen: maximum size of @new + * + * replace @ctx with a new compound context, appending @newlsm and @new + * to @ctx. On exit the new data replaces the old, which is freed. + * @ctxlen is set to the new size, which includes a trailing nul byte. + * + * Returns 0 on success, -ENOMEM if no memory is available. + */ +static int append_ctx(char **ctx, int *ctxlen, const char *lsm, char *new, + int newlen) +{ + char *final; + size_t llen; + size_t nlen; + size_t flen; + + llen = strlen(lsm) + 1; + /* + * A security module may or may not provide a trailing nul on + * when returning a security context. There is no definition + * of which it should be, and there are modules that do it + * each way. + */ + nlen = strnlen(new, newlen); + + flen = *ctxlen + llen + nlen + 1; + final = kzalloc(flen, GFP_KERNEL); + + if (final == NULL) + return -ENOMEM; + + if (*ctxlen) + memcpy(final, *ctx, *ctxlen); + + memcpy(final + *ctxlen, lsm, llen); + memcpy(final + *ctxlen + llen, new, nlen); + + kfree(*ctx); + + *ctx = final; + *ctxlen = flen; + + return 0; +} + /* * The default value of the LSM hook is defined in linux/lsm_hook_defs.h and * can be accessed with: @@ -2232,6 +2283,10 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name, char **value) { struct security_hook_list *hp; + char *final = NULL; + char *cp; + int rc = 0; + int finallen = 0; int ilsm = lsm_task_ilsm(current); int slot = 0; @@ -2259,6 +2314,30 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name, return -ENOMEM; } + if (!strcmp(name, "context")) { + hlist_for_each_entry(hp, &security_hook_heads.getprocattr, + list) { + rc = hp->hook.getprocattr(p, "context", &cp); + if (rc == -EINVAL) + continue; + if (rc < 0) { + kfree(final); + return rc; + } + rc = append_ctx(&final, &finallen, hp->lsmid->lsm, + cp, rc); + kfree(cp); + if (rc < 0) { + kfree(final); + return rc; + } + } + if (final == NULL) + return -EINVAL; + *value = final; + return finallen; + } + hlist_for_each_entry(hp, &security_hook_heads.getprocattr, list) { if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm)) continue; diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index b7800fa55a34..0a9af748f77c 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -6468,7 +6468,7 @@ static int selinux_getprocattr(struct task_struct *p, goto bad; } - if (!strcmp(name, "current")) + if (!strcmp(name, "current") || !strcmp(name, "context")) sid = __tsec->sid; else if (!strcmp(name, "prev")) sid = __tsec->osid; diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index e65497a5c095..1618d7d6154b 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -3477,7 +3477,7 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value) char *cp; int slen; - if (strcmp(name, "current") != 0) + if (strcmp(name, "current") != 0 && strcmp(name, "context") != 0) return -EINVAL; cp = kstrdup(skp->smk_known, GFP_KERNEL);