apparmor: drop cred_ctx and reference the label directly
With the task domain change information now stored in the task->security context, the cred->security context only stores the label. We can get rid of the cred_ctx and directly reference the label, removing a layer of indirection, and unneeded extra allocations. Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
John Johansen
Родитель
3b529a7600
Коммит
d9087c49d4
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@ -13,11 +13,9 @@
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* License.
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*
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*
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* AppArmor sets confinement on every task, via the the aa_cred_ctx and
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* the aa_cred_ctx.label, both of which are required and are not allowed
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* to be NULL. The aa_cred_ctx is not reference counted and is unique
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* to each cred (which is reference count). The label pointed to by
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* the cred_ctx is reference counted.
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* AppArmor sets confinement on every task, via the cred_label() which
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* is required and are not allowed to be NULL. The cred_label is
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* reference counted.
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*
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* TODO
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* If a task uses change_hat it currently does not return to the old
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@ -29,40 +27,6 @@
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#include "include/context.h"
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#include "include/policy.h"
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/**
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* aa_alloc_cred_ctx - allocate a new cred_ctx
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* @flags: gfp flags for allocation
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*
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* Returns: allocated buffer or NULL on failure
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*/
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struct aa_cred_ctx *aa_alloc_cred_ctx(gfp_t flags)
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{
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return kzalloc(sizeof(struct aa_cred_ctx), flags);
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}
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/**
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* aa_free_cred_ctx - free a cred_ctx
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* @ctx: cred_ctx to free (MAYBE NULL)
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*/
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void aa_free_cred_ctx(struct aa_cred_ctx *ctx)
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{
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if (ctx) {
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aa_put_label(ctx->label);
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kzfree(ctx);
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}
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}
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/**
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* aa_dup_cred_ctx - duplicate a task context, incrementing reference counts
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* @new: a blank task context (NOT NULL)
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* @old: the task context to copy (NOT NULL)
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*/
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void aa_dup_cred_ctx(struct aa_cred_ctx *new, const struct aa_cred_ctx *old)
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{
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*new = *old;
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aa_get_label(new->label);
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}
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/**
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* aa_get_task_label - Get another task's label
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@ -126,11 +90,12 @@ void aa_dup_task_ctx(struct aa_task_ctx *new, const struct aa_task_ctx *old)
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*/
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int aa_replace_current_label(struct aa_label *label)
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{
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struct aa_cred_ctx *ctx = current_cred_ctx();
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struct aa_label *old = aa_current_raw_label();
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struct cred *new;
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AA_BUG(!label);
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if (ctx->label == label)
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if (old == label)
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return 0;
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if (current_cred() != current_real_cred())
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@ -140,22 +105,22 @@ int aa_replace_current_label(struct aa_label *label)
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if (!new)
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return -ENOMEM;
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ctx = cred_ctx(new);
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if (unconfined(label) || (labels_ns(ctx->label) != labels_ns(label)))
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/* if switching to unconfined or a different label namespace
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if (unconfined(label) || (labels_ns(old) != labels_ns(label)))
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/*
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* if switching to unconfined or a different label namespace
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* clear out context state
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*/
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aa_clear_task_ctx_trans(current_task_ctx());
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/*
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* be careful switching ctx->profile, when racing replacement it
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* is possible that ctx->profile->proxy->profile is the reference
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* keeping @profile valid, so make sure to get its reference before
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* dropping the reference on ctx->profile
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* be careful switching cred label, when racing replacement it
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* is possible that the cred labels's->proxy->label is the reference
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* keeping @label valid, so make sure to get its reference before
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* dropping the reference on the cred's label
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*/
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aa_get_label(label);
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aa_put_label(ctx->label);
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ctx->label = label;
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aa_put_label(cred_label(new));
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cred_label(new) = label;
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commit_creds(new);
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return 0;
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@ -193,26 +158,26 @@ int aa_set_current_hat(struct aa_label *label, u64 token)
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{
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struct aa_task_ctx *tctx = current_task_ctx();
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struct aa_cred_ctx *ctx;
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struct cred *new = prepare_creds();
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struct cred *new;
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new = prepare_creds();
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if (!new)
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return -ENOMEM;
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AA_BUG(!label);
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ctx = cred_ctx(new);
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if (!tctx->previous) {
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/* transfer refcount */
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tctx->previous = ctx->label;
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tctx->previous = cred_label(new);
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tctx->token = token;
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} else if (tctx->token == token) {
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aa_put_label(ctx->label);
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aa_put_label(cred_label(new));
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} else {
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/* previous_profile && ctx->token != token */
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abort_creds(new);
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return -EACCES;
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}
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ctx->label = aa_get_newest_label(label);
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cred_label(new) = aa_get_newest_label(label);
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/* clear exec on switching context */
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aa_put_label(tctx->onexec);
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tctx->onexec = NULL;
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@ -233,7 +198,6 @@ int aa_set_current_hat(struct aa_label *label, u64 token)
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int aa_restore_previous_label(u64 token)
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{
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struct aa_task_ctx *tctx = current_task_ctx();
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struct aa_cred_ctx *ctx;
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struct cred *new;
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if (tctx->token != token)
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@ -245,11 +209,10 @@ int aa_restore_previous_label(u64 token)
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new = prepare_creds();
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if (!new)
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return -ENOMEM;
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ctx = cred_ctx(new);
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aa_put_label(ctx->label);
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ctx->label = aa_get_newest_label(tctx->previous);
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AA_BUG(!ctx->label);
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aa_put_label(cred_label(new));
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cred_label(new) = aa_get_newest_label(tctx->previous);
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AA_BUG(!cred_label(new));
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/* clear exec && prev information when restoring to previous context */
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aa_clear_task_ctx_trans(tctx);
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@ -779,7 +779,6 @@ static struct aa_label *handle_onexec(struct aa_label *label,
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*/
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int apparmor_bprm_set_creds(struct linux_binprm *bprm)
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{
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struct aa_cred_ctx *ctx;
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struct aa_task_ctx *tctx;
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struct aa_label *label, *new = NULL;
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struct aa_profile *profile;
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@ -795,12 +794,11 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
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if (bprm->called_set_creds)
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return 0;
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ctx = cred_ctx(bprm->cred);
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tctx = current_task_ctx();
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AA_BUG(!ctx);
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AA_BUG(!cred_label(bprm->cred));
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AA_BUG(!tctx);
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label = aa_get_newest_label(ctx->label);
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label = aa_get_newest_label(cred_label(bprm->cred));
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/* buffer freed below, name is pointer into buffer */
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get_buffers(buffer);
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@ -856,9 +854,9 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
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}
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bprm->per_clear |= PER_CLEAR_ON_SETID;
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}
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aa_put_label(ctx->label);
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/* transfer reference, released when ctx is freed */
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ctx->label = new;
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aa_put_label(cred_label(bprm->cred));
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/* transfer reference, released when cred is freed */
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cred_label(bprm->cred) = new;
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done:
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aa_put_label(label);
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@ -1049,7 +1047,6 @@ build:
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int aa_change_hat(const char *hats[], int count, u64 token, int flags)
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{
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const struct cred *cred;
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struct aa_cred_ctx *ctx;
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struct aa_task_ctx *tctx;
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struct aa_label *label, *previous, *new = NULL, *target = NULL;
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struct aa_profile *profile;
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@ -1070,7 +1067,6 @@ int aa_change_hat(const char *hats[], int count, u64 token, int flags)
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/* released below */
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cred = get_current_cred();
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ctx = cred_ctx(cred);
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tctx = current_task_ctx();
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label = aa_get_newest_cred_label(cred);
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previous = aa_get_newest_label(tctx->previous);
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@ -22,21 +22,11 @@
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#include "label.h"
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#include "policy_ns.h"
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#define cred_ctx(X) ((X)->security)
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#define current_cred_ctx() cred_ctx(current_cred())
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#define task_ctx(X) ((X)->security)
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#define current_task_ctx() (task_ctx(current))
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#define cred_label(X) ((X)->security)
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/**
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* struct aa_cred_ctx - primary label for confined tasks
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* @label: the current label (NOT NULL)
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*/
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struct aa_cred_ctx {
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struct aa_label *label;
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};
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/**
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/*
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* struct aa_task_ctx - information for current task label change
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* @onexec: profile to transition to on next exec (MAY BE NULL)
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* @previous: profile the task may return to (MAY BE NULL)
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@ -48,10 +38,6 @@ struct aa_task_ctx {
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u64 token;
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};
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struct aa_cred_ctx *aa_alloc_cred_ctx(gfp_t flags);
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void aa_free_cred_ctx(struct aa_cred_ctx *ctx);
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void aa_dup_cred_ctx(struct aa_cred_ctx *new, const struct aa_cred_ctx *old);
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struct aa_task_ctx *aa_alloc_task_ctx(gfp_t flags);
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void aa_free_task_ctx(struct aa_task_ctx *ctx);
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void aa_dup_task_ctx(struct aa_task_ctx *new, const struct aa_task_ctx *old);
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@ -73,10 +59,10 @@ struct aa_label *aa_get_task_label(struct task_struct *task);
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*/
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static inline struct aa_label *aa_cred_raw_label(const struct cred *cred)
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{
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struct aa_cred_ctx *ctx = cred_ctx(cred);
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struct aa_label *label = cred_label(cred);
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AA_BUG(!ctx || !ctx->label);
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return ctx->label;
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AA_BUG(!label);
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return label;
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}
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/**
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@ -51,12 +51,12 @@ DEFINE_PER_CPU(struct aa_buffers, aa_buffers);
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*/
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/*
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* free the associated aa_cred_ctx and put its labels
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* put the associated labels
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*/
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static void apparmor_cred_free(struct cred *cred)
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{
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aa_free_cred_ctx(cred_ctx(cred));
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cred_ctx(cred) = NULL;
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aa_put_label(cred_label(cred));
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cred_label(cred) = NULL;
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}
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/*
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@ -64,30 +64,17 @@ static void apparmor_cred_free(struct cred *cred)
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*/
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static int apparmor_cred_alloc_blank(struct cred *cred, gfp_t gfp)
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{
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/* freed by apparmor_cred_free */
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struct aa_cred_ctx *ctx = aa_alloc_cred_ctx(gfp);
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if (!ctx)
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return -ENOMEM;
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cred_ctx(cred) = ctx;
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cred_label(cred) = NULL;
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return 0;
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}
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/*
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* prepare new aa_cred_ctx for modification by prepare_cred block
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* prepare new cred label for modification by prepare_cred block
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*/
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static int apparmor_cred_prepare(struct cred *new, const struct cred *old,
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gfp_t gfp)
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{
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/* freed by apparmor_cred_free */
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struct aa_cred_ctx *ctx = aa_alloc_cred_ctx(gfp);
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if (!ctx)
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return -ENOMEM;
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aa_dup_cred_ctx(ctx, cred_ctx(old));
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cred_ctx(new) = ctx;
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cred_label(new) = aa_get_newest_label(cred_label(old));
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return 0;
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}
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@ -96,10 +83,7 @@ static int apparmor_cred_prepare(struct cred *new, const struct cred *old,
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*/
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static void apparmor_cred_transfer(struct cred *new, const struct cred *old)
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{
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const struct aa_cred_ctx *old_ctx = cred_ctx(old);
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struct aa_cred_ctx *new_ctx = cred_ctx(new);
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aa_dup_cred_ctx(new_ctx, old_ctx);
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cred_label(new) = aa_get_newest_label(cred_label(old));
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}
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static void apparmor_task_free(struct task_struct *task)
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@ -599,11 +583,10 @@ static int apparmor_getprocattr(struct task_struct *task, char *name,
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/* released below */
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const struct cred *cred = get_task_cred(task);
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struct aa_task_ctx *tctx = current_task_ctx();
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struct aa_cred_ctx *ctx = cred_ctx(cred);
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struct aa_label *label = NULL;
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if (strcmp(name, "current") == 0)
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label = aa_get_newest_label(ctx->label);
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label = aa_get_newest_label(cred_label(cred));
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else if (strcmp(name, "prev") == 0 && tctx->previous)
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label = aa_get_newest_label(tctx->previous);
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else if (strcmp(name, "exec") == 0 && tctx->onexec)
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@ -700,11 +683,11 @@ fail:
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static void apparmor_bprm_committing_creds(struct linux_binprm *bprm)
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{
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struct aa_label *label = aa_current_raw_label();
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struct aa_cred_ctx *new_ctx = cred_ctx(bprm->cred);
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struct aa_label *new_label = cred_label(bprm->cred);
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/* bail out if unconfined or not changing profile */
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if ((new_ctx->label->proxy == label->proxy) ||
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(unconfined(new_ctx->label)))
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if ((new_label->proxy == label->proxy) ||
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(unconfined(new_label)))
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return;
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aa_inherit_files(bprm->cred, current->files);
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@ -712,7 +695,7 @@ static void apparmor_bprm_committing_creds(struct linux_binprm *bprm)
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current->pdeath_signal = 0;
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/* reset soft limits and set hard limits for the new label */
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__aa_transition_rlimits(label, new_ctx->label);
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__aa_transition_rlimits(label, new_label);
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}
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/**
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@ -1050,26 +1033,16 @@ static int param_set_mode(const char *val, const struct kernel_param *kp)
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static int __init set_init_ctx(void)
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{
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struct cred *cred = (struct cred *)current->real_cred;
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struct aa_cred_ctx *ctx;
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struct aa_task_ctx *tctx;
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ctx = aa_alloc_cred_ctx(GFP_KERNEL);
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if (!ctx)
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goto fail_cred;
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tctx = aa_alloc_task_ctx(GFP_KERNEL);
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if (!tctx)
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goto fail_task;
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return -ENOMEM;
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ctx->label = aa_get_label(ns_unconfined(root_ns));
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cred_ctx(cred) = ctx;
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cred_label(cred) = aa_get_label(ns_unconfined(root_ns));
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task_ctx(current) = tctx;
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return 0;
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fail_task:
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aa_free_cred_ctx(ctx);
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fail_cred:
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return -ENOMEM;
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}
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static void destroy_buffers(void)
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