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Diffstat (limited to 'security/apparmor/context.c')
| -rw-r--r-- | security/apparmor/context.c | 216 |
1 files changed, 216 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; +} |