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    Subject[PATCH v38 19/39] LSM: Use lsmblob in security_cred_getsecid
    Date
    Change the security_cred_getsecid() interface to fill in a
    lsmblob instead of a u32 secid. The associated data elements
    in the audit sub-system are changed from a secid to a lsmblob
    to accommodate multiple possible LSM audit users.

    Reviewed-by: Kees Cook <keescook@chromium.org>
    Reviewed-by: John Johansen <john.johansen@canonical.com>
    Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
    Acked-by: Paul Moore <paul@paul-moore.com>
    Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
    Cc: linux-integrity@vger.kernel.org
    Cc: linux-audit@redhat.com
    ---
    drivers/android/binder.c | 12 +----------
    include/linux/security.h | 7 ++++---
    kernel/audit.c | 25 +++++++----------------
    kernel/audit.h | 3 ++-
    kernel/auditsc.c | 33 +++++++++++--------------------
    security/integrity/ima/ima_main.c | 4 +---
    security/security.c | 12 ++++++++---
    7 files changed, 36 insertions(+), 60 deletions(-)

    diff --git a/drivers/android/binder.c b/drivers/android/binder.c
    index 0ab1d5179fc4..6e1e35de1fcb 100644
    --- a/drivers/android/binder.c
    +++ b/drivers/android/binder.c
    @@ -3171,18 +3171,8 @@ static void binder_transaction(struct binder_proc *proc,
    if (target_node && target_node->txn_security_ctx) {
    struct lsmblob blob;
    size_t added_size;
    - u32 secid;

    - security_cred_getsecid(proc->cred, &secid);
    - /*
    - * Later in this patch set security_cred_getsecid() will
    - * provide a lsmblob instead of a secid. lsmblob_init
    - * is used to ensure that all the secids in the lsmblob
    - * get the value returned from security_cred_getsecid(),
    - * which means that the one expected by
    - * security_secid_to_secctx() will be set.
    - */
    - lsmblob_init(&blob, secid);
    + security_cred_getsecid(proc->cred, &blob);
    ret = security_secid_to_secctx(&blob, &secctx, &secctx_sz);
    if (ret) {
    binder_txn_error("%d:%d failed to get security context\n",
    diff --git a/include/linux/security.h b/include/linux/security.h
    index ca5dcaee7c23..9f80b685542d 100644
    --- a/include/linux/security.h
    +++ b/include/linux/security.h
    @@ -521,7 +521,7 @@ int security_cred_alloc_blank(struct cred *cred, gfp_t gfp);
    void security_cred_free(struct cred *cred);
    int security_prepare_creds(struct cred *new, const struct cred *old, gfp_t gfp);
    void security_transfer_creds(struct cred *new, const struct cred *old);
    -void security_cred_getsecid(const struct cred *c, u32 *secid);
    +void security_cred_getsecid(const struct cred *c, struct lsmblob *blob);
    int security_kernel_act_as(struct cred *new, struct lsmblob *blob);
    int security_kernel_create_files_as(struct cred *new, struct inode *inode);
    int security_kernel_module_request(char *kmod_name);
    @@ -1162,9 +1162,10 @@ static inline void security_transfer_creds(struct cred *new,
    {
    }

    -static inline void security_cred_getsecid(const struct cred *c, u32 *secid)
    +static inline void security_cred_getsecid(const struct cred *c,
    + struct lsmblob *blob)
    {
    - *secid = 0;
    + lsmblob_init(blob, 0);
    }

    static inline int security_kernel_act_as(struct cred *cred,
    diff --git a/kernel/audit.c b/kernel/audit.c
    index 4e13e48afc06..3d026013e6eb 100644
    --- a/kernel/audit.c
    +++ b/kernel/audit.c
    @@ -125,7 +125,7 @@ static u32 audit_backlog_wait_time = AUDIT_BACKLOG_WAIT_TIME;
    /* The identity of the user shutting down the audit system. */
    static kuid_t audit_sig_uid = INVALID_UID;
    static pid_t audit_sig_pid = -1;
    -static u32 audit_sig_sid;
    +static struct lsmblob audit_sig_lsm;

    /* Records can be lost in several ways:
    0) [suppressed in audit_alloc]
    @@ -1463,29 +1463,21 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
    }
    case AUDIT_SIGNAL_INFO:
    len = 0;
    - if (audit_sig_sid) {
    - struct lsmblob blob;
    -
    - /*
    - * lsmblob_init sets all values in the lsmblob
    - * to audit_sig_sid. This is temporary until
    - * audit_sig_sid is converted to a lsmblob, which
    - * happens later in this patch set.
    - */
    - lsmblob_init(&blob, audit_sig_sid);
    - err = security_secid_to_secctx(&blob, &ctx, &len);
    + if (lsmblob_is_set(&audit_sig_lsm)) {
    + err = security_secid_to_secctx(&audit_sig_lsm, &ctx,
    + &len);
    if (err)
    return err;
    }
    sig_data = kmalloc(struct_size(sig_data, ctx, len), GFP_KERNEL);
    if (!sig_data) {
    - if (audit_sig_sid)
    + if (lsmblob_is_set(&audit_sig_lsm))
    security_release_secctx(ctx, len);
    return -ENOMEM;
    }
    sig_data->uid = from_kuid(&init_user_ns, audit_sig_uid);
    sig_data->pid = audit_sig_pid;
    - if (audit_sig_sid) {
    + if (lsmblob_is_set(&audit_sig_lsm)) {
    memcpy(sig_data->ctx, ctx, len);
    security_release_secctx(ctx, len);
    }
    @@ -2392,7 +2384,6 @@ int audit_set_loginuid(kuid_t loginuid)
    int audit_signal_info(int sig, struct task_struct *t)
    {
    kuid_t uid = current_uid(), auid;
    - struct lsmblob blob;

    if (auditd_test_task(t) &&
    (sig == SIGTERM || sig == SIGHUP ||
    @@ -2403,9 +2394,7 @@ int audit_signal_info(int sig, struct task_struct *t)
    audit_sig_uid = auid;
    else
    audit_sig_uid = uid;
    - security_current_getsecid_subj(&blob);
    - /* scaffolding until audit_sig_sid is converted */
    - audit_sig_sid = lsmblob_first(&blob);
    + security_current_getsecid_subj(&audit_sig_lsm);
    }

    return audit_signal_info_syscall(t);
    diff --git a/kernel/audit.h b/kernel/audit.h
    index 58b66543b4d5..316fac62d5f7 100644
    --- a/kernel/audit.h
    +++ b/kernel/audit.h
    @@ -12,6 +12,7 @@
    #include <linux/fs.h>
    #include <linux/audit.h>
    #include <linux/skbuff.h>
    +#include <linux/security.h>
    #include <uapi/linux/mqueue.h>
    #include <linux/tty.h>
    #include <uapi/linux/openat2.h> // struct open_how
    @@ -143,7 +144,7 @@ struct audit_context {
    kuid_t target_auid;
    kuid_t target_uid;
    unsigned int target_sessionid;
    - u32 target_sid;
    + struct lsmblob target_lsm;
    char target_comm[TASK_COMM_LEN];

    struct audit_tree_refs *trees, *first_trees;
    diff --git a/kernel/auditsc.c b/kernel/auditsc.c
    index ad5f33af3b50..092aba46a9b3 100644
    --- a/kernel/auditsc.c
    +++ b/kernel/auditsc.c
    @@ -99,7 +99,7 @@ struct audit_aux_data_pids {
    kuid_t target_auid[AUDIT_AUX_PIDS];
    kuid_t target_uid[AUDIT_AUX_PIDS];
    unsigned int target_sessionid[AUDIT_AUX_PIDS];
    - u32 target_sid[AUDIT_AUX_PIDS];
    + struct lsmblob target_lsm[AUDIT_AUX_PIDS];
    char target_comm[AUDIT_AUX_PIDS][TASK_COMM_LEN];
    int pid_count;
    };
    @@ -1018,7 +1018,7 @@ static void audit_reset_context(struct audit_context *ctx)
    ctx->target_pid = 0;
    ctx->target_auid = ctx->target_uid = KUIDT_INIT(0);
    ctx->target_sessionid = 0;
    - ctx->target_sid = 0;
    + lsmblob_init(&ctx->target_lsm, 0);
    ctx->target_comm[0] = '\0';
    unroll_tree_refs(ctx, NULL, 0);
    WARN_ON(!list_empty(&ctx->killed_trees));
    @@ -1091,14 +1091,14 @@ static inline void audit_free_context(struct audit_context *context)
    }

    static int audit_log_pid_context(struct audit_context *context, pid_t pid,
    - kuid_t auid, kuid_t uid, unsigned int sessionid,
    - u32 sid, char *comm)
    + kuid_t auid, kuid_t uid,
    + unsigned int sessionid,
    + struct lsmblob *blob, char *comm)
    {
    struct audit_buffer *ab;
    char *ctx = NULL;
    u32 len;
    int rc = 0;
    - struct lsmblob blob;

    ab = audit_log_start(context, GFP_KERNEL, AUDIT_OBJ_PID);
    if (!ab)
    @@ -1107,9 +1107,8 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
    audit_log_format(ab, "opid=%d oauid=%d ouid=%d oses=%d", pid,
    from_kuid(&init_user_ns, auid),
    from_kuid(&init_user_ns, uid), sessionid);
    - if (sid) {
    - lsmblob_init(&blob, sid);
    - if (security_secid_to_secctx(&blob, &ctx, &len)) {
    + if (lsmblob_is_set(blob)) {
    + if (security_secid_to_secctx(blob, &ctx, &len)) {
    audit_log_format(ab, " obj=(none)");
    rc = 1;
    } else {
    @@ -1789,7 +1788,7 @@ static void audit_log_exit(void)
    axs->target_auid[i],
    axs->target_uid[i],
    axs->target_sessionid[i],
    - axs->target_sid[i],
    + &axs->target_lsm[i],
    axs->target_comm[i]))
    call_panic = 1;
    }
    @@ -1798,7 +1797,7 @@ static void audit_log_exit(void)
    audit_log_pid_context(context, context->target_pid,
    context->target_auid, context->target_uid,
    context->target_sessionid,
    - context->target_sid, context->target_comm))
    + &context->target_lsm, context->target_comm))
    call_panic = 1;

    if (context->pwd.dentry && context->pwd.mnt) {
    @@ -2740,15 +2739,12 @@ int __audit_sockaddr(int len, void *a)
    void __audit_ptrace(struct task_struct *t)
    {
    struct audit_context *context = audit_context();
    - struct lsmblob blob;

    context->target_pid = task_tgid_nr(t);
    context->target_auid = audit_get_loginuid(t);
    context->target_uid = task_uid(t);
    context->target_sessionid = audit_get_sessionid(t);
    - security_task_getsecid_obj(t, &blob);
    - /* scaffolding - until target_sid is converted */
    - context->target_sid = lsmblob_first(&blob);
    + security_task_getsecid_obj(t, &context->target_lsm);
    memcpy(context->target_comm, t->comm, TASK_COMM_LEN);
    }

    @@ -2764,7 +2760,6 @@ int audit_signal_info_syscall(struct task_struct *t)
    struct audit_aux_data_pids *axp;
    struct audit_context *ctx = audit_context();
    kuid_t t_uid = task_uid(t);
    - struct lsmblob blob;

    if (!audit_signals || audit_dummy_context())
    return 0;
    @@ -2776,9 +2771,7 @@ int audit_signal_info_syscall(struct task_struct *t)
    ctx->target_auid = audit_get_loginuid(t);
    ctx->target_uid = t_uid;
    ctx->target_sessionid = audit_get_sessionid(t);
    - security_task_getsecid_obj(t, &blob);
    - /* scaffolding until target_sid is converted */
    - ctx->target_sid = lsmblob_first(&blob);
    + security_task_getsecid_obj(t, &ctx->target_lsm);
    memcpy(ctx->target_comm, t->comm, TASK_COMM_LEN);
    return 0;
    }
    @@ -2799,9 +2792,7 @@ int audit_signal_info_syscall(struct task_struct *t)
    axp->target_auid[axp->pid_count] = audit_get_loginuid(t);
    axp->target_uid[axp->pid_count] = t_uid;
    axp->target_sessionid[axp->pid_count] = audit_get_sessionid(t);
    - security_task_getsecid_obj(t, &blob);
    - /* scaffolding until target_sid is converted */
    - axp->target_sid[axp->pid_count] = lsmblob_first(&blob);
    + security_task_getsecid_obj(t, &axp->target_lsm[axp->pid_count]);
    memcpy(axp->target_comm[axp->pid_count], t->comm, TASK_COMM_LEN);
    axp->pid_count++;

    diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
    index 25870eb422d9..ecaa0b96bb26 100644
    --- a/security/integrity/ima/ima_main.c
    +++ b/security/integrity/ima/ima_main.c
    @@ -488,7 +488,6 @@ int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot)
    int ima_bprm_check(struct linux_binprm *bprm)
    {
    int ret;
    - u32 secid;
    struct lsmblob blob;

    security_current_getsecid_subj(&blob);
    @@ -497,8 +496,7 @@ int ima_bprm_check(struct linux_binprm *bprm)
    if (ret)
    return ret;

    - security_cred_getsecid(bprm->cred, &secid);
    - lsmblob_init(&blob, secid);
    + security_cred_getsecid(bprm->cred, &blob);
    return process_measurement(bprm->file, bprm->cred, &blob, NULL, 0,
    MAY_EXEC, CREDS_CHECK);
    }
    diff --git a/security/security.c b/security/security.c
    index 563452000729..80133d6e982c 100644
    --- a/security/security.c
    +++ b/security/security.c
    @@ -1829,10 +1829,16 @@ void security_transfer_creds(struct cred *new, const struct cred *old)
    call_void_hook(cred_transfer, new, old);
    }

    -void security_cred_getsecid(const struct cred *c, u32 *secid)
    +void security_cred_getsecid(const struct cred *c, struct lsmblob *blob)
    {
    - *secid = 0;
    - call_void_hook(cred_getsecid, c, secid);
    + struct security_hook_list *hp;
    +
    + lsmblob_init(blob, 0);
    + hlist_for_each_entry(hp, &security_hook_heads.cred_getsecid, list) {
    + if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
    + continue;
    + hp->hook.cred_getsecid(c, &blob->secid[hp->lsmid->slot]);
    + }
    }
    EXPORT_SYMBOL(security_cred_getsecid);

    --
    2.37.3
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