[PATCH] tomoyo: Swicth from cred->security to task_struct->security.
Casey Schaufler
casey at schaufler-ca.com
Fri Jan 18 17:01:05 UTC 2019
On 1/18/2019 2:18 AM, Tetsuo Handa wrote:
> TOMOYO security module is designed to use "struct task_struct"->security
> in order to allow per "struct task_struct" tracking without being disturbed
> by unable to update "struct cred"->security due to override mechanism.
>
> Now that infrastructure-managed security blob is ready, this patch updates
> TOMOYO to use "struct task_struct"->security.
>
> Signed-off-by: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
> ---
> security/tomoyo/common.c | 4 +-
> security/tomoyo/common.h | 43 ++++--------
> security/tomoyo/domain.c | 11 +--
> security/tomoyo/securityfs_if.c | 22 +++---
> security/tomoyo/tomoyo.c | 144 ++++++++++++++++++----------------------
> 5 files changed, 95 insertions(+), 129 deletions(-)
>
> diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
> index c598aa0..877cf8a 100644
> --- a/security/tomoyo/common.c
> +++ b/security/tomoyo/common.c
> @@ -986,7 +986,7 @@ static bool tomoyo_select_domain(struct tomoyo_io_buffer *head,
> else
> p = find_task_by_vpid(pid);
> if (p)
> - domain = tomoyo_real_domain(p);
> + domain = tomoyo_security(p)->domain_info;
> rcu_read_unlock();
> } else if (!strncmp(data, "domain=", 7)) {
> if (tomoyo_domain_def(data + 7))
> @@ -1668,7 +1668,7 @@ static void tomoyo_read_pid(struct tomoyo_io_buffer *head)
> else
> p = find_task_by_vpid(pid);
> if (p)
> - domain = tomoyo_real_domain(p);
> + domain = tomoyo_security(p)->domain_info;
> rcu_read_unlock();
> if (!domain)
> return;
> diff --git a/security/tomoyo/common.h b/security/tomoyo/common.h
> index 4fc1729..f19ed53 100644
> --- a/security/tomoyo/common.h
> +++ b/security/tomoyo/common.h
> @@ -686,7 +686,7 @@ struct tomoyo_domain_info {
> u8 group; /* Group number to use. */
> bool is_deleted; /* Delete flag. */
> bool flags[TOMOYO_MAX_DOMAIN_INFO_FLAGS];
> - atomic_t users; /* Number of referring credentials. */
> + atomic_t users; /* Number of referring tasks. */
> };
>
> /*
> @@ -913,6 +913,12 @@ struct tomoyo_policy_namespace {
> const char *name;
> };
>
> +/* Structure for "struct task_struct"->security. */
> +struct tomoyo_security {
> + struct tomoyo_domain_info *domain_info;
> + struct tomoyo_domain_info *old_domain_info;
> +};
> +
> /********** Function prototypes. **********/
>
> bool tomoyo_address_matches_group(const bool is_ipv6, const __be32 *address,
> @@ -1021,6 +1027,7 @@ ssize_t tomoyo_write_control(struct tomoyo_io_buffer *head,
> struct tomoyo_condition *tomoyo_get_condition(struct tomoyo_acl_param *param);
> struct tomoyo_domain_info *tomoyo_assign_domain(const char *domainname,
> const bool transit);
> +struct tomoyo_domain_info *tomoyo_domain(void);
> struct tomoyo_domain_info *tomoyo_find_domain(const char *domainname);
> struct tomoyo_group *tomoyo_get_group(struct tomoyo_acl_param *param,
> const u8 idx);
> @@ -1200,41 +1207,15 @@ static inline void tomoyo_put_group(struct tomoyo_group *group)
> }
>
> /**
> - * tomoyo_cred - Get a pointer to the tomoyo cred security blob
> - * @cred - the relevant cred
> - *
> - * Returns pointer to the tomoyo cred blob.
> - */
> -static inline struct tomoyo_domain_info **tomoyo_cred(const struct cred *cred)
> -{
> - return cred->security + tomoyo_blob_sizes.lbs_cred;
> -}
> -
> -/**
> - * tomoyo_domain - Get "struct tomoyo_domain_info" for current thread.
> + * tomoyo_security - Get "struct tomoyo_security" for specified thread.
> *
> - * Returns pointer to "struct tomoyo_domain_info" for current thread.
> - */
> -static inline struct tomoyo_domain_info *tomoyo_domain(void)
> -{
> - struct tomoyo_domain_info **blob = tomoyo_cred(current_cred());
> -
> - return *blob;
> -}
> -
> -/**
> - * tomoyo_real_domain - Get "struct tomoyo_domain_info" for specified thread.
> - *
> - * @task: Pointer to "struct task_struct".
> + * @task - Pointer to "struct task_struct".
> *
> * Returns pointer to "struct tomoyo_security" for specified thread.
> */
> -static inline struct tomoyo_domain_info *tomoyo_real_domain(struct task_struct
> - *task)
> +static inline struct tomoyo_security *tomoyo_security(struct task_struct *task)
Could you use tomoyo_task() instead of tomoyo_security()?
To the extent that it's been possible I've worked to add
consistency in the security modules, and this breaks it.
> {
> - struct tomoyo_domain_info **blob = tomoyo_cred(get_task_cred(task));
> -
> - return *blob;
> + return task->security + tomoyo_blob_sizes.lbs_task;
> }
>
> /**
> diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
> index b7469fd..05f470e 100644
> --- a/security/tomoyo/domain.c
> +++ b/security/tomoyo/domain.c
> @@ -678,7 +678,6 @@ static int tomoyo_environ(struct tomoyo_execve *ee)
> */
> int tomoyo_find_next_domain(struct linux_binprm *bprm)
> {
> - struct tomoyo_domain_info **blob;
> struct tomoyo_domain_info *old_domain = tomoyo_domain();
> struct tomoyo_domain_info *domain = NULL;
> const char *original_name = bprm->filename;
> @@ -843,9 +842,13 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
> if (!domain)
> domain = old_domain;
> /* Update reference count on "struct tomoyo_domain_info". */
> - atomic_inc(&domain->users);
> - blob = tomoyo_cred(bprm->cred);
> - *blob = domain;
> + {
> + struct tomoyo_security *s = tomoyo_security(current);
> +
> + s->old_domain_info = s->domain_info;
> + s->domain_info = domain;
> + atomic_inc(&domain->users);
> + }
> kfree(exename.name);
> if (!retval) {
> ee->r.domain = domain;
> diff --git a/security/tomoyo/securityfs_if.c b/security/tomoyo/securityfs_if.c
> index 768dff9..2bf634c 100644
> --- a/security/tomoyo/securityfs_if.c
> +++ b/security/tomoyo/securityfs_if.c
> @@ -67,21 +67,15 @@ static ssize_t tomoyo_write_self(struct file *file, const char __user *buf,
> if (!new_domain) {
> error = -ENOENT;
> } else {
> - struct cred *cred = prepare_creds();
> - if (!cred) {
> - error = -ENOMEM;
> - } else {
> - struct tomoyo_domain_info **blob;
> - struct tomoyo_domain_info *old_domain;
> + struct tomoyo_security *s =
> + tomoyo_security(current);
> + struct tomoyo_domain_info *old_domain =
> + s->domain_info;
>
> - blob = tomoyo_cred(cred);
> - old_domain = *blob;
> - *blob = new_domain;
> - atomic_inc(&new_domain->users);
> - atomic_dec(&old_domain->users);
> - commit_creds(cred);
> - error = 0;
> - }
> + s->domain_info = new_domain;
> + atomic_inc(&new_domain->users);
> + atomic_dec(&old_domain->users);
> + error = 0;
> }
> }
> tomoyo_read_unlock(idx);
> diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
> index 2b3eee0..77da989 100644
> --- a/security/tomoyo/tomoyo.c
> +++ b/security/tomoyo/tomoyo.c
> @@ -9,19 +9,19 @@
> #include "common.h"
>
> /**
> - * tomoyo_cred_alloc_blank - Target for security_cred_alloc_blank().
> + * tomoyo_domain - Get "struct tomoyo_domain_info" for current thread.
> *
> - * @new: Pointer to "struct cred".
> - * @gfp: Memory allocation flags.
> - *
> - * Returns 0.
> + * Returns pointer to "struct tomoyo_domain_info" for current thread.
> */
> -static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
> +struct tomoyo_domain_info *tomoyo_domain(void)
> {
> - struct tomoyo_domain_info **blob = tomoyo_cred(new);
> + struct tomoyo_security *s = tomoyo_security(current);
>
> - *blob = NULL;
> - return 0;
> + if (s->old_domain_info && !current->in_execve) {
> + atomic_dec(&s->old_domain_info->users);
> + s->old_domain_info = NULL;
> + }
> + return s->domain_info;
> }
>
> /**
> @@ -36,85 +36,36 @@ static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
> static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
> gfp_t gfp)
> {
> - struct tomoyo_domain_info **old_blob = tomoyo_cred(old);
> - struct tomoyo_domain_info **new_blob = tomoyo_cred(new);
> - struct tomoyo_domain_info *domain;
> -
> - domain = *old_blob;
> - *new_blob = domain;
> -
> - if (domain)
> - atomic_inc(&domain->users);
> + /* To clear old_domain_info saved by previous execve() request. */
> + tomoyo_domain();
> return 0;
> }
>
> -/**
> - * tomoyo_cred_transfer - Target for security_transfer_creds().
> - *
> - * @new: Pointer to "struct cred".
> - * @old: Pointer to "struct cred".
> - */
> -static void tomoyo_cred_transfer(struct cred *new, const struct cred *old)
> -{
> - tomoyo_cred_prepare(new, old, 0);
> -}
> -
> -/**
> - * tomoyo_cred_free - Target for security_cred_free().
> - *
> - * @cred: Pointer to "struct cred".
> - */
> -static void tomoyo_cred_free(struct cred *cred)
> -{
> - struct tomoyo_domain_info **blob = tomoyo_cred(cred);
> - struct tomoyo_domain_info *domain = *blob;
> -
> - if (domain)
> - atomic_dec(&domain->users);
> -}
> -
> +#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
> /**
> * tomoyo_bprm_set_creds - Target for security_bprm_set_creds().
> *
> * @bprm: Pointer to "struct linux_binprm".
> *
> - * Returns 0 on success, negative value otherwise.
> + * Returns 0.
> */
> static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
> {
> - struct tomoyo_domain_info **blob;
> - struct tomoyo_domain_info *domain;
> -
> /*
> * Do only if this function is called for the first time of an execve
> * operation.
> */
> if (bprm->called_set_creds)
> return 0;
> -#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
> /*
> * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
> * for the first time.
> */
> if (!tomoyo_policy_loaded)
> tomoyo_load_policy(bprm->filename);
> -#endif
> - /*
> - * Release reference to "struct tomoyo_domain_info" stored inside
> - * "bprm->cred->security". New reference to "struct tomoyo_domain_info"
> - * stored inside "bprm->cred->security" will be acquired later inside
> - * tomoyo_find_next_domain().
> - */
> - blob = tomoyo_cred(bprm->cred);
> - domain = *blob;
> - atomic_dec(&domain->users);
> - /*
> - * Tell tomoyo_bprm_check_security() is called for the first time of an
> - * execve operation.
> - */
> - *blob = NULL;
> return 0;
> }
> +#endif
>
> /**
> * tomoyo_bprm_check_security - Target for security_bprm_check().
> @@ -125,16 +76,13 @@ static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
> */
> static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
> {
> - struct tomoyo_domain_info **blob;
> - struct tomoyo_domain_info *domain;
> + struct tomoyo_security *s = tomoyo_security(current);
>
> - blob = tomoyo_cred(bprm->cred);
> - domain = *blob;
> /*
> * Execute permission is checked against pathname passed to do_execve()
> * using current domain.
> */
> - if (!domain) {
> + if (!s->old_domain_info) {
> const int idx = tomoyo_read_lock();
> const int err = tomoyo_find_next_domain(bprm);
> tomoyo_read_unlock(idx);
> @@ -143,8 +91,8 @@ static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
> /*
> * Read permission is checked against interpreters using next domain.
> */
> - return tomoyo_check_open_permission(domain, &bprm->file->f_path,
> - O_RDONLY);
> + return tomoyo_check_open_permission(s->domain_info,
> + &bprm->file->f_path, O_RDONLY);
> }
>
> /**
> @@ -510,19 +458,59 @@ static int tomoyo_socket_sendmsg(struct socket *sock, struct msghdr *msg,
> }
>
> struct lsm_blob_sizes tomoyo_blob_sizes __lsm_ro_after_init = {
> - .lbs_cred = sizeof(struct tomoyo_domain_info *),
> + .lbs_task = sizeof(struct tomoyo_security),
> };
>
> +/**
> + * tomoyo_task_alloc - Target for security_task_alloc().
> + *
> + * @task: Pointer to "struct task_struct".
> + * @flags: clone() flags.
> + *
> + * Returns 0.
> + */
> +static int tomoyo_task_alloc(struct task_struct *task,
> + unsigned long clone_flags)
> +{
> + struct tomoyo_security *old = tomoyo_security(current);
> + struct tomoyo_security *new = tomoyo_security(task);
> +
> + new->domain_info = old->domain_info;
> + atomic_inc(&new->domain_info->users);
> + new->old_domain_info = NULL;
> + return 0;
> +}
> +
> +/**
> + * tomoyo_task_free - Target for security_task_free().
> + *
> + * @task: Pointer to "struct task_struct".
> + */
> +static void tomoyo_task_free(struct task_struct *task)
> +{
> + struct tomoyo_security *s = tomoyo_security(task);
> +
> + if (s->domain_info) {
> + atomic_dec(&s->domain_info->users);
> + s->domain_info = NULL;
> + }
> + if (s->old_domain_info) {
> + atomic_dec(&s->old_domain_info->users);
> + s->old_domain_info = NULL;
> + }
> +}
> +
> /*
> * tomoyo_security_ops is a "struct security_operations" which is used for
> * registering TOMOYO.
> */
> static struct security_hook_list tomoyo_hooks[] __lsm_ro_after_init = {
> - LSM_HOOK_INIT(cred_alloc_blank, tomoyo_cred_alloc_blank),
> LSM_HOOK_INIT(cred_prepare, tomoyo_cred_prepare),
> - LSM_HOOK_INIT(cred_transfer, tomoyo_cred_transfer),
> - LSM_HOOK_INIT(cred_free, tomoyo_cred_free),
> + LSM_HOOK_INIT(task_alloc, tomoyo_task_alloc),
> + LSM_HOOK_INIT(task_free, tomoyo_task_free),
> +#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
> LSM_HOOK_INIT(bprm_set_creds, tomoyo_bprm_set_creds),
> +#endif
> LSM_HOOK_INIT(bprm_check_security, tomoyo_bprm_check_security),
> LSM_HOOK_INIT(file_fcntl, tomoyo_file_fcntl),
> LSM_HOOK_INIT(file_open, tomoyo_file_open),
> @@ -560,14 +548,14 @@ struct lsm_blob_sizes tomoyo_blob_sizes __lsm_ro_after_init = {
> */
> static int __init tomoyo_init(void)
> {
> - struct cred *cred = (struct cred *) current_cred();
> - struct tomoyo_domain_info **blob;
> + struct tomoyo_security *s = tomoyo_security(current);
>
> /* register ourselves with the security framework */
> security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo");
> printk(KERN_INFO "TOMOYO Linux initialized\n");
> - blob = tomoyo_cred(cred);
> - *blob = &tomoyo_kernel_domain;
> + s->domain_info = &tomoyo_kernel_domain;
> + atomic_inc(&tomoyo_kernel_domain.users);
> + s->old_domain_info = NULL;
> tomoyo_mm_init();
>
> return 0;
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