diff options
| -rw-r--r-- | security/apparmor/context.c | 216 | ||||
| -rw-r--r-- | security/apparmor/include/context.h | 154 |
2 files changed, 370 insertions, 0 deletions
diff --git a/security/apparmor/context.c b/security/apparmor/context.c new file mode 100644 index 000000000000..8a9b5027c813 --- /dev/null +++ b/security/apparmor/context.c @@ -0,0 +1,216 @@ +/* + * AppArmor security module + * + * This file contains AppArmor functions used to manipulate object security + * contexts. + * + * Copyright (C) 1998-2008 Novell/SUSE + * Copyright 2009-2010 Canonical Ltd. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation, version 2 of the + * License. + * + * + * AppArmor sets confinement on every task, via the the aa_task_cxt and + * the aa_task_cxt.profile, both of which are required and are not allowed + * to be NULL. The aa_task_cxt is not reference counted and is unique + * to each cred (which is reference count). The profile pointed to by + * the task_cxt is reference counted. + * + * TODO + * If a task uses change_hat it currently does not return to the old + * cred or task context but instead creates a new one. Ideally the task + * should return to the previous cred if it has not been modified. + * + */ + +#include "include/context.h" +#include "include/policy.h" + +/** + * aa_alloc_task_context - allocate a new task_cxt + * @flags: gfp flags for allocation + * + * Returns: allocated buffer or NULL on failure + */ +struct aa_task_cxt *aa_alloc_task_context(gfp_t flags) +{ + return kzalloc(sizeof(struct aa_task_cxt), flags); +} + +/** + * aa_free_task_context - free a task_cxt + * @cxt: task_cxt to free (MAYBE NULL) + */ +void aa_free_task_context(struct aa_task_cxt *cxt) +{ + if (cxt) { + aa_put_profile(cxt->profile); + aa_put_profile(cxt->previous); + aa_put_profile(cxt->onexec); + + kzfree(cxt); + } +} + +/** + * aa_dup_task_context - duplicate a task context, incrementing reference counts + * @new: a blank task context (NOT NULL) + * @old: the task context to copy (NOT NULL) + */ +void aa_dup_task_context(struct aa_task_cxt *new, const struct aa_task_cxt *old) +{ + *new = *old; + aa_get_profile(new->profile); + aa_get_profile(new->previous); + aa_get_profile(new->onexec); +} + +/** + * aa_replace_current_profile - replace the current tasks profiles + * @profile: new profile (NOT NULL) + * + * Returns: 0 or error on failure + */ +int aa_replace_current_profile(struct aa_profile *profile) +{ + struct aa_task_cxt *cxt = current_cred()->security; + struct cred *new; + BUG_ON(!profile); + + if (cxt->profile == profile) + return 0; + + new = prepare_creds(); + if (!new) + return -ENOMEM; + + cxt = new->security; + if (unconfined(profile) || (cxt->profile->ns != profile->ns)) { + /* if switching to unconfined or a different profile namespace + * clear out context state + */ + aa_put_profile(cxt->previous); + aa_put_profile(cxt->onexec); + cxt->previous = NULL; + cxt->onexec = NULL; + cxt->token = 0; + } + /* be careful switching cxt->profile, when racing replacement it + * is possible that cxt->profile->replacedby is the reference keeping + * @profile valid, so make sure to get its reference before dropping + * the reference on cxt->profile */ + aa_get_profile(profile); + aa_put_profile(cxt->profile); + cxt->profile = profile; + + commit_creds(new); + return 0; +} + +/** + * aa_set_current_onexec - set the tasks change_profile to happen onexec + * @profile: system profile to set at exec (MAYBE NULL to clear value) + * + * Returns: 0 or error on failure + */ +int aa_set_current_onexec(struct aa_profile *profile) +{ + struct aa_task_cxt *cxt; + struct cred *new = prepare_creds(); + if (!new) + return -ENOMEM; + + cxt = new->security; + aa_get_profile(profile); + aa_put_profile(cxt->onexec); + cxt->onexec = profile; + + commit_creds(new); + return 0; +} + +/** + * aa_set_current_hat - set the current tasks hat + * @profile: profile to set as the current hat (NOT NULL) + * @token: token value that must be specified to change from the hat + * + * Do switch of tasks hat. If the task is currently in a hat + * validate the token to match. + * + * Returns: 0 or error on failure + */ +int aa_set_current_hat(struct aa_profile *profile, u64 token) +{ + struct aa_task_cxt *cxt; + struct cred *new = prepare_creds(); + if (!new) + return -ENOMEM; + BUG_ON(!profile); + + cxt = new->security; + if (!cxt->previous) { + /* transfer refcount */ + cxt->previous = cxt->profile; + cxt->token = token; + } else if (cxt->token == token) { + aa_put_profile(cxt->profile); + } else { + /* previous_profile && cxt->token != token */ + abort_creds(new); + return -EACCES; + } + cxt->profile = aa_get_profile(aa_newest_version(profile)); + /* clear exec on switching context */ + aa_put_profile(cxt->onexec); + cxt->onexec = NULL; + + commit_creds(new); + return 0; +} + +/** + * aa_restore_previous_profile - exit from hat context restoring the profile + * @token: the token that must be matched to exit hat context + * + * Attempt to return out of a hat to the previous profile. The token + * must match the stored token value. + * + * Returns: 0 or error of failure + */ +int aa_restore_previous_profile(u64 token) +{ + struct aa_task_cxt *cxt; + struct cred *new = prepare_creds(); + if (!new) + return -ENOMEM; + + cxt = new->security; + if (cxt->token != token) { + abort_creds(new); + return -EACCES; + } + /* ignore restores when there is no saved profile */ + if (!cxt->previous) { + abort_creds(new); + return 0; + } + + aa_put_profile(cxt->profile); + cxt->profile = aa_newest_version(cxt->previous); + BUG_ON(!cxt->profile); + if (unlikely(cxt->profile != cxt->previous)) { + aa_get_profile(cxt->profile); + aa_put_profile(cxt->previous); + } + /* clear exec && prev information when restoring to previous context */ + cxt->previous = NULL; + cxt->token = 0; + aa_put_profile(cxt->onexec); + cxt->onexec = NULL; + + commit_creds(new); + return 0; +} diff --git a/security/apparmor/include/context.h b/security/apparmor/include/context.h new file mode 100644 index 000000000000..a9cbee4d9e48 --- /dev/null +++ b/security/apparmor/include/context.h @@ -0,0 +1,154 @@ +/* + * AppArmor security module + * + * This file contains AppArmor contexts used to associate "labels" to objects. + * + * Copyright (C) 1998-2008 Novell/SUSE + * Copyright 2009-2010 Canonical Ltd. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation, version 2 of the + * License. + */ + +#ifndef __AA_CONTEXT_H +#define __AA_CONTEXT_H + +#include <linux/cred.h> +#include <linux/slab.h> +#include <linux/sched.h> + +#include "policy.h" + +/* struct aa_file_cxt - the AppArmor context the file was opened in + * @perms: the permission the file was opened with + * + * The file_cxt could currently be directly stored in file->f_security + * as the profile reference is now stored in the f_cred. However the + * cxt struct will expand in the future so we keep the struct. + */ +struct aa_file_cxt { + u16 allow; +}; + +/** + * aa_alloc_file_context - allocate file_cxt + * @gfp: gfp flags for allocation + * + * Returns: file_cxt or NULL on failure + */ +static inline struct aa_file_cxt *aa_alloc_file_context(gfp_t gfp) +{ + return kzalloc(sizeof(struct aa_file_cxt), gfp); +} + +/** + * aa_free_file_context - free a file_cxt + * @cxt: file_cxt to free (MAYBE_NULL) + */ +static inline void aa_free_file_context(struct aa_file_cxt *cxt) +{ + if (cxt) + kzfree(cxt); +} + +/** + * struct aa_task_cxt - primary label for confined tasks + * @profile: the current profile (NOT NULL) + * @exec: profile to transition to on next exec (MAYBE NULL) + * @previous: profile the task may return to (MAYBE NULL) + * @token: magic value the task must know for returning to @previous_profile + * + * Contains the task's current profile (which could change due to + * change_hat). Plus the hat_magic needed during change_hat. + * + * TODO: make so a task can be confined by a stack of contexts + */ +struct aa_task_cxt { + struct aa_profile *profile; + struct aa_profile *onexec; + struct aa_profile *previous; + u64 token; +}; + +struct aa_task_cxt *aa_alloc_task_context(gfp_t flags); +void aa_free_task_context(struct aa_task_cxt *cxt); +void aa_dup_task_context(struct aa_task_cxt *new, + const struct aa_task_cxt *old); +int aa_replace_current_profile(struct aa_profile *profile); +int aa_set_current_onexec(struct aa_profile *profile); +int aa_set_current_hat(struct aa_profile *profile, u64 token); +int aa_restore_previous_profile(u64 cookie); + +/** + * __aa_task_is_confined - determine if @task has any confinement + * @task: task to check confinement of (NOT NULL) + * + * If @task != current needs to be called in RCU safe critical section + */ +static inline bool __aa_task_is_confined(struct task_struct *task) +{ + struct aa_task_cxt *cxt = __task_cred(task)->security; + + BUG_ON(!cxt || !cxt->profile); + if (unconfined(aa_newest_version(cxt->profile))) + return 0; + + return 1; +} + +/** + * aa_cred_profile - obtain cred's profiles + * @cred: cred to obtain profiles from (NOT NULL) + * + * Returns: confining profile + * + * does NOT increment reference count + */ +static inline struct aa_profile *aa_cred_profile(const struct cred *cred) +{ + struct aa_task_cxt *cxt = cred->security; + BUG_ON(!cxt || !cxt->profile); + return aa_newest_version(cxt->profile); +} + +/** + * __aa_current_profile - find the current tasks confining profile + * + * Returns: up to date confining profile or the ns unconfined profile (NOT NULL) + * + * This fn will not update the tasks cred to the most up to date version + * of the profile so it is safe to call when inside of locks. + */ +static inline struct aa_profile *__aa_current_profile(void) +{ + return aa_cred_profile(current_cred()); +} + +/** + * aa_current_profile - find the current tasks confining profile and do updates + * + * Returns: up to date confining profile or the ns unconfined profile (NOT NULL) + * + * This fn will update the tasks cred structure if the profile has been + * replaced. Not safe to call inside locks + */ +static inline struct aa_profile *aa_current_profile(void) +{ + const struct aa_task_cxt *cxt = current_cred()->security; + struct aa_profile *profile; + BUG_ON(!cxt || !cxt->profile); + + profile = aa_newest_version(cxt->profile); + /* + * Whether or not replacement succeeds, use newest profile so + * there is no need to update it after replacement. + */ + if (unlikely((cxt->profile != profile))) + aa_replace_current_profile(profile); + + return profile; +} + +#endif /* __AA_CONTEXT_H */ |