[PATCH v4 2/2] LSM: SafeSetID: gate setgid transitions

Micah Morton mortonm at chromium.org
Mon Mar 11 17:25:34 UTC 2019


Is this ready to be merged if there are no further comments?

On Tue, Mar 5, 2019 at 7:52 AM <mortonm at chromium.org> wrote:
>
> From: Micah Morton <mortonm at chromium.org>
>
> The SafeSetID LSM already gates setuid transitions for UIDs on the
> system whose use of CAP_SETUID has been 'restricted'. This patch
> implements the analogous functionality for setgid transitions, in order
> to restrict the use of CAP_SETGID for certain UIDs on the system. One
> notable consequence of this addition is that a process running under a
> restricted UID (i.e. one that is only allowed to setgid to certain
> approved GIDs) will not be allowed to call the setgroups() syscall to
> set its supplementary group IDs. For now, we leave such support for
> restricted setgroups() to future work, as it would require hooking the
> logic in setgroups() and verifying that the array of GIDs passed in from
> userspace only consists of approved GIDs.
>
> Signed-off-by: Micah Morton <mortonm at chromium.org>
> ---
> Changes since the last patch: Minor updates since patch 1/2 combined the
> 'task_fix_setuid' and 'task_fix_setgid' hooks into one hook called
> 'task_fix_setid'.
>
>  Documentation/admin-guide/LSM/SafeSetID.rst |   9 +-
>  security/safesetid/lsm.c                    | 272 +++++++++++++++++---
>  security/safesetid/lsm.h                    |  11 +-
>  security/safesetid/securityfs.c             | 105 +++++---
>  4 files changed, 320 insertions(+), 77 deletions(-)
>
> diff --git a/Documentation/admin-guide/LSM/SafeSetID.rst b/Documentation/admin-guide/LSM/SafeSetID.rst
> index 670a6544fd39..33307a8e9555 100644
> --- a/Documentation/admin-guide/LSM/SafeSetID.rst
> +++ b/Documentation/admin-guide/LSM/SafeSetID.rst
> @@ -98,10 +98,13 @@ Directions for use
>  ==================
>  This LSM hooks the setid syscalls to make sure transitions are allowed if an
>  applicable restriction policy is in place. Policies are configured through
> -securityfs by writing to the safesetid/add_whitelist_policy and
> +securityfs by writing to the safesetid/add_whitelist_{uid/gid}_policy* and
>  safesetid/flush_whitelist_policies files at the location where securityfs is
> -mounted. The format for adding a policy is '<UID>:<UID>', using literal
> +mounted. The format for adding a policy is '<ID>:<ID>', using literal
>  numbers, such as '123:456'. To flush the policies, any write to the file is
>  sufficient. Again, configuring a policy for a UID will prevent that UID from
>  obtaining auxiliary setid privileges, such as allowing a user to set up user
> -namespace UID mappings.
> +namespace ID mappings.
> +
> +*safesetid/add_whitelist_policy can also be used for UID policies, since it is
> +an alias for safesetid/add_whitelist_uid_policy
> diff --git a/security/safesetid/lsm.c b/security/safesetid/lsm.c
> index 5deffa92f25f..95c6f35b29f3 100644
> --- a/security/safesetid/lsm.c
> +++ b/security/safesetid/lsm.c
> @@ -26,27 +26,30 @@ int safesetid_initialized;
>
>  #define NUM_BITS 8 /* 128 buckets in hash table */
>
> -static DEFINE_HASHTABLE(safesetid_whitelist_hashtable, NUM_BITS);
> +static DEFINE_HASHTABLE(safesetid_whitelist_uid_hashtable, NUM_BITS);
> +static DEFINE_HASHTABLE(safesetid_whitelist_gid_hashtable, NUM_BITS);
> +
> +static DEFINE_SPINLOCK(safesetid_whitelist_uid_hashtable_spinlock);
> +static DEFINE_SPINLOCK(safesetid_whitelist_gid_hashtable_spinlock);
>
>  /*
>   * Hash table entry to store safesetid policy signifying that 'parent' user
> - * can setid to 'child' user.
> + * can setid to 'child' user. This struct is used in both the uid and gid
> + * hashtables.
>   */
> -struct entry {
> +struct id_entry {
>         struct hlist_node next;
>         struct hlist_node dlist; /* for deletion cleanup */
>         uint64_t parent_kuid;
> -       uint64_t child_kuid;
> +       uint64_t child_kid; /* Represents either a UID or a GID */
>  };
>
> -static DEFINE_SPINLOCK(safesetid_whitelist_hashtable_spinlock);
> -
>  static bool check_setuid_policy_hashtable_key(kuid_t parent)
>  {
> -       struct entry *entry;
> +       struct id_entry *entry;
>
>         rcu_read_lock();
> -       hash_for_each_possible_rcu(safesetid_whitelist_hashtable,
> +       hash_for_each_possible_rcu(safesetid_whitelist_uid_hashtable,
>                                    entry, next, __kuid_val(parent)) {
>                 if (entry->parent_kuid == __kuid_val(parent)) {
>                         rcu_read_unlock();
> @@ -61,13 +64,49 @@ static bool check_setuid_policy_hashtable_key(kuid_t parent)
>  static bool check_setuid_policy_hashtable_key_value(kuid_t parent,
>                                                     kuid_t child)
>  {
> -       struct entry *entry;
> +       struct id_entry *entry;
> +
> +       rcu_read_lock();
> +       hash_for_each_possible_rcu(safesetid_whitelist_uid_hashtable,
> +                                  entry, next, __kuid_val(parent)) {
> +               if (entry->parent_kuid == __kuid_val(parent) &&
> +                   entry->child_kid == __kuid_val(child)) {
> +                       rcu_read_unlock();
> +                       return true;
> +               }
> +       }
> +       rcu_read_unlock();
> +
> +       return false;
> +}
> +
> +static bool check_setgid_policy_hashtable_key(kuid_t parent)
> +{
> +       struct id_entry *entry;
> +
> +       rcu_read_lock();
> +       hash_for_each_possible_rcu(safesetid_whitelist_gid_hashtable,
> +                                  entry, next, __kuid_val(parent)) {
> +               if (entry->parent_kuid == __kuid_val(parent)) {
> +                       rcu_read_unlock();
> +                       return true;
> +               }
> +       }
> +       rcu_read_unlock();
> +
> +       return false;
> +}
> +
> +static bool check_setgid_policy_hashtable_key_value(kuid_t parent,
> +                                                   kgid_t child)
> +{
> +       struct id_entry *entry;
>
>         rcu_read_lock();
> -       hash_for_each_possible_rcu(safesetid_whitelist_hashtable,
> +       hash_for_each_possible_rcu(safesetid_whitelist_gid_hashtable,
>                                    entry, next, __kuid_val(parent)) {
>                 if (entry->parent_kuid == __kuid_val(parent) &&
> -                   entry->child_kuid == __kuid_val(child)) {
> +                   entry->child_kid == __kgid_val(child)) {
>                         rcu_read_unlock();
>                         return true;
>                 }
> @@ -77,6 +116,12 @@ static bool check_setuid_policy_hashtable_key_value(kuid_t parent,
>         return false;
>  }
>
> +/*
> + * This hook causes the security_capable check to fail when there are
> + * restriction policies for a UID and the process is trying to do something
> + * (other than a setid transition) that is gated by CAP_SETUID/CAP_SETGID
> + * (e.g. allowing user to set up userns UID/GID mappings).
> + */
>  static int safesetid_security_capable(const struct cred *cred,
>                                       struct user_namespace *ns,
>                                       int cap,
> @@ -85,17 +130,19 @@ static int safesetid_security_capable(const struct cred *cred,
>         if (cap == CAP_SETUID &&
>             check_setuid_policy_hashtable_key(cred->uid)) {
>                 if (!(opts & CAP_OPT_INSETID)) {
> -                       /*
> -                        * Deny if we're not in a set*uid() syscall to avoid
> -                        * giving powers gated by CAP_SETUID that are related
> -                        * to functionality other than calling set*uid() (e.g.
> -                        * allowing user to set up userns uid mappings).
> -                        */
>                         pr_warn("Operation requires CAP_SETUID, which is not available to UID %u for operations besides approved set*uid transitions",
>                                 __kuid_val(cred->uid));
>                         return -1;
>                 }
>         }
> +       if (cap == CAP_SETGID &&
> +           check_setgid_policy_hashtable_key(cred->uid)) {
> +               if (!(opts & CAP_OPT_INSETID)) {
> +                       pr_warn("Operation requires CAP_SETGID, which is not available to UID %u for operations besides approved set*gid transitions",
> +                               __kuid_val(cred->uid));
> +                       return -1;
> +               }
> +       }
>         return 0;
>  }
>
> @@ -115,19 +162,48 @@ static int check_uid_transition(kuid_t parent, kuid_t child)
>         return -EACCES;
>  }
>
> +static int check_gid_transition(kuid_t parent, kgid_t child)
> +{
> +       if (check_setgid_policy_hashtable_key_value(parent, child))
> +               return 0;
> +       pr_warn("Denied UID %d setting GID to %d",
> +               __kuid_val(parent),
> +               __kgid_val(child));
> +       /*
> +        * Kill this process to avoid potential security vulnerabilities
> +        * that could arise from a missing whitelist entry preventing a
> +        * privileged process from dropping to a lesser-privileged one.
> +        */
> +       force_sig(SIGKILL, current);
> +       return -EACCES;
> +}
> +
>  /*
>   * Check whether there is either an exception for user under old cred struct to
> - * set*uid to user under new cred struct, or the UID transition is allowed (by
> - * Linux set*uid rules) even without CAP_SETUID.
> + * set*id to user under new cred struct, or the ID transition is allowed (by
> + * Linux set*id rules) even without CAP_SET*ID.
>   */
>  static int safesetid_task_fix_setid(struct cred *new,
>                                      const struct cred *old,
>                                      int flags)
>  {
> +       if (flags == LSM_SETUID_RE ||
> +           flags == LSM_SETUID_ID ||
> +           flags == LSM_SETUID_RES ||
> +           flags == LSM_SETUID_FS) {
> +               /* Do nothing if there are no setuid restrictions for this UID. */
> +               if (!check_setuid_policy_hashtable_key(old->uid))
> +               return 0;
> +       }
>
> -       /* Do nothing if there are no setuid restrictions for this UID. */
> -       if (!check_setuid_policy_hashtable_key(old->uid))
> +       if (flags == LSM_SETGID_RE ||
> +           flags == LSM_SETGID_ID ||
> +           flags == LSM_SETGID_RES ||
> +           flags == LSM_SETGID_FS) {
> +               /* Do nothing if there are no setgid restrictions for this UID. */
> +               if (!check_setgid_policy_hashtable_key(old->uid))
>                 return 0;
> +       }
>
>         switch (flags) {
>         case LSM_SETUID_RE:
> @@ -201,6 +277,77 @@ static int safesetid_task_fix_setid(struct cred *new,
>                         return check_uid_transition(old->fsuid, new->fsuid);
>                 }
>                 break;
> +       case LSM_SETGID_RE:
> +               /*
> +                * Users for which setgid restrictions exist can only set the
> +                * real GID to the real GID or the effective GID, unless an
> +                * explicit whitelist policy allows the transition.
> +                */
> +               if (!gid_eq(old->gid, new->gid) &&
> +                       !gid_eq(old->egid, new->gid)) {
> +                       return check_gid_transition(old->uid, new->gid);
> +               }
> +               /*
> +                * Users for which setgid restrictions exist can only set the
> +                * effective GID to the real GID, the effective GID, or the
> +                * saved set-GID, unless an explicit whitelist policy allows
> +                * the transition.
> +                */
> +               if (!gid_eq(old->gid, new->egid) &&
> +                       !gid_eq(old->egid, new->egid) &&
> +                       !gid_eq(old->sgid, new->egid)) {
> +                       return check_gid_transition(old->euid, new->egid);
> +               }
> +               break;
> +       case LSM_SETGID_ID:
> +               /*
> +                * Users for which setgid restrictions exist cannot change the
> +                * real GID or saved set-GID unless an explicit whitelist
> +                * policy allows the transition.
> +                */
> +               if (!gid_eq(old->gid, new->gid))
> +                       return check_gid_transition(old->uid, new->gid);
> +               if (!gid_eq(old->sgid, new->sgid))
> +                       return check_gid_transition(old->suid, new->sgid);
> +               break;
> +       case LSM_SETGID_RES:
> +               /*
> +                * Users for which setgid restrictions exist cannot change the
> +                * real GID, effective GID, or saved set-GID to anything but
> +                * one of: the current real GID, the current effective GID or
> +                * the current saved set-user-ID unless an explicit whitelist
> +                * policy allows the transition.
> +                */
> +               if (!gid_eq(new->gid, old->gid) &&
> +                       !gid_eq(new->gid, old->egid) &&
> +                       !gid_eq(new->gid, old->sgid)) {
> +                       return check_gid_transition(old->uid, new->gid);
> +               }
> +               if (!gid_eq(new->egid, old->gid) &&
> +                       !gid_eq(new->egid, old->egid) &&
> +                       !gid_eq(new->egid, old->sgid)) {
> +                       return check_gid_transition(old->euid, new->egid);
> +               }
> +               if (!gid_eq(new->sgid, old->gid) &&
> +                       !gid_eq(new->sgid, old->egid) &&
> +                       !gid_eq(new->sgid, old->sgid)) {
> +                       return check_gid_transition(old->suid, new->sgid);
> +               }
> +               break;
> +       case LSM_SETGID_FS:
> +               /*
> +                * Users for which setgid restrictions exist cannot change the
> +                * filesystem GID to anything but one of: the current real GID,
> +                * the current effective GID or the current saved set-GID
> +                * unless an explicit whitelist policy allows the transition.
> +                */
> +               if (!gid_eq(new->fsgid, old->gid)  &&
> +                       !gid_eq(new->fsgid, old->egid)  &&
> +                       !gid_eq(new->fsgid, old->sgid) &&
> +                       !gid_eq(new->fsgid, old->fsgid)) {
> +                       return check_gid_transition(old->fsuid, new->fsgid);
> +               }
> +               break;
>         default:
>                 pr_warn("Unknown setid state %d\n", flags);
>                 force_sig(SIGKILL, current);
> @@ -209,49 +356,96 @@ static int safesetid_task_fix_setid(struct cred *new,
>         return 0;
>  }
>
> -int add_safesetid_whitelist_entry(kuid_t parent, kuid_t child)
> +int add_safesetid_whitelist_uid_entry(kuid_t parent, kuid_t child)
>  {
> -       struct entry *new;
> +       struct id_entry *new;
>
>         /* Return if entry already exists */
>         if (check_setuid_policy_hashtable_key_value(parent, child))
>                 return 0;
>
> -       new = kzalloc(sizeof(struct entry), GFP_KERNEL);
> +       new = kzalloc(sizeof(struct id_entry), GFP_KERNEL);
> +       if (!new)
> +               return -ENOMEM;
> +       new->parent_kuid = __kuid_val(parent);
> +       new->child_kid = __kuid_val(child);
> +       spin_lock(&safesetid_whitelist_uid_hashtable_spinlock);
> +       /* Return if the entry got added since we checked above */
> +       if (check_setuid_policy_hashtable_key_value(parent, child)) {
> +               spin_unlock(&safesetid_whitelist_uid_hashtable_spinlock);
> +               kfree(new);
> +               return 0;
> +       }
> +       hash_add_rcu(safesetid_whitelist_uid_hashtable,
> +                    &new->next,
> +                    __kuid_val(parent));
> +       spin_unlock(&safesetid_whitelist_uid_hashtable_spinlock);
> +       return 0;
> +}
> +
> +int add_safesetid_whitelist_gid_entry(kuid_t parent, kgid_t child)
> +{
> +       struct id_entry *new;
> +
> +       /* Return if entry already exists */
> +       if (check_setgid_policy_hashtable_key_value(parent, child))
> +               return 0;
> +
> +       new = kzalloc(sizeof(struct id_entry), GFP_KERNEL);
>         if (!new)
>                 return -ENOMEM;
>         new->parent_kuid = __kuid_val(parent);
> -       new->child_kuid = __kuid_val(child);
> -       spin_lock(&safesetid_whitelist_hashtable_spinlock);
> -       hash_add_rcu(safesetid_whitelist_hashtable,
> +       new->child_kid = __kgid_val(child);
> +       spin_lock(&safesetid_whitelist_gid_hashtable_spinlock);
> +       /* Return if the entry got added since we checked above */
> +       if (check_setgid_policy_hashtable_key_value(parent, child)) {
> +               spin_unlock(&safesetid_whitelist_gid_hashtable_spinlock);
> +               kfree(new);
> +               return 0;
> +       }
> +       hash_add_rcu(safesetid_whitelist_gid_hashtable,
>                      &new->next,
>                      __kuid_val(parent));
> -       spin_unlock(&safesetid_whitelist_hashtable_spinlock);
> +       spin_unlock(&safesetid_whitelist_gid_hashtable_spinlock);
>         return 0;
>  }
>
>  void flush_safesetid_whitelist_entries(void)
>  {
> -       struct entry *entry;
> +       struct id_entry *id_entry;
>         struct hlist_node *hlist_node;
>         unsigned int bkt_loop_cursor;
> -       HLIST_HEAD(free_list);
> +       HLIST_HEAD(uid_free_list);
> +       HLIST_HEAD(gid_free_list);
>
>         /*
>          * Could probably use hash_for_each_rcu here instead, but this should
>          * be fine as well.
>          */
> -       spin_lock(&safesetid_whitelist_hashtable_spinlock);
> -       hash_for_each_safe(safesetid_whitelist_hashtable, bkt_loop_cursor,
> -                          hlist_node, entry, next) {
> -               hash_del_rcu(&entry->next);
> -               hlist_add_head(&entry->dlist, &free_list);
> +       spin_lock(&safesetid_whitelist_uid_hashtable_spinlock);
> +       hash_for_each_safe(safesetid_whitelist_uid_hashtable, bkt_loop_cursor,
> +                          hlist_node, id_entry, next) {
> +               hash_del_rcu(&id_entry->next);
> +               hlist_add_head(&id_entry->dlist, &uid_free_list);
> +       }
> +       spin_unlock(&safesetid_whitelist_uid_hashtable_spinlock);
> +       synchronize_rcu();
> +       hlist_for_each_entry_safe(id_entry, hlist_node, &uid_free_list, dlist) {
> +               hlist_del(&id_entry->dlist);
> +               kfree(id_entry);
> +       }
> +
> +       spin_lock(&safesetid_whitelist_gid_hashtable_spinlock);
> +       hash_for_each_safe(safesetid_whitelist_gid_hashtable, bkt_loop_cursor,
> +                          hlist_node, id_entry, next) {
> +               hash_del_rcu(&id_entry->next);
> +               hlist_add_head(&id_entry->dlist, &gid_free_list);
>         }
> -       spin_unlock(&safesetid_whitelist_hashtable_spinlock);
> +       spin_unlock(&safesetid_whitelist_gid_hashtable_spinlock);
>         synchronize_rcu();
> -       hlist_for_each_entry_safe(entry, hlist_node, &free_list, dlist) {
> -               hlist_del(&entry->dlist);
> -               kfree(entry);
> +       hlist_for_each_entry_safe(id_entry, hlist_node, &gid_free_list, dlist) {
> +               hlist_del(&id_entry->dlist);
> +               kfree(id_entry);
>         }
>  }
>
> diff --git a/security/safesetid/lsm.h b/security/safesetid/lsm.h
> index c1ea3c265fcf..e9ae192caff2 100644
> --- a/security/safesetid/lsm.h
> +++ b/security/safesetid/lsm.h
> @@ -21,13 +21,16 @@ extern int safesetid_initialized;
>
>  /* Function type. */
>  enum safesetid_whitelist_file_write_type {
> -       SAFESETID_WHITELIST_ADD, /* Add whitelist policy. */
> +       SAFESETID_WHITELIST_ADD_UID, /* Add UID whitelist policy. */
> +       SAFESETID_WHITELIST_ADD_GID, /* Add GID whitelist policy. */
>         SAFESETID_WHITELIST_FLUSH, /* Flush whitelist policies. */
>  };
>
> -/* Add entry to safesetid whitelist to allow 'parent' to setid to 'child'. */
> -int add_safesetid_whitelist_entry(kuid_t parent, kuid_t child);
> -
> +/* Add entry to safesetid whitelist to allow 'parent' to setuid to 'child'. */
> +int add_safesetid_whitelist_uid_entry(kuid_t parent, kuid_t child);
> +/* Add entry to safesetid whitelist to allow 'parent' to setgid to 'child'. */
> +int add_safesetid_whitelist_gid_entry(kgid_t parent, kgid_t child);
> +/* Flush all UID/GID whitelist policies. */
>  void flush_safesetid_whitelist_entries(void);
>
>  #endif /* _SAFESETID_H */
> diff --git a/security/safesetid/securityfs.c b/security/safesetid/securityfs.c
> index 2c6c829be044..c4c25ba7275f 100644
> --- a/security/safesetid/securityfs.c
> +++ b/security/safesetid/securityfs.c
> @@ -26,20 +26,19 @@ struct safesetid_file_entry {
>
>  static struct safesetid_file_entry safesetid_files[] = {
>         {.name = "add_whitelist_policy",
> -        .type = SAFESETID_WHITELIST_ADD},
> +        .type = SAFESETID_WHITELIST_ADD_UID},
> +       {.name = "add_whitelist_uid_policy",
> +        .type = SAFESETID_WHITELIST_ADD_UID},
> +       {.name = "add_whitelist_gid_policy",
> +        .type = SAFESETID_WHITELIST_ADD_GID},
>         {.name = "flush_whitelist_policies",
>          .type = SAFESETID_WHITELIST_FLUSH},
>  };
>
> -/*
> - * In the case the input buffer contains one or more invalid UIDs, the kuid_t
> - * variables pointed to by 'parent' and 'child' will get updated but this
> - * function will return an error.
> - */
> -static int parse_safesetid_whitelist_policy(const char __user *buf,
> +static int parse_userbuf_to_longs(const char __user *buf,
>                                             size_t len,
> -                                           kuid_t *parent,
> -                                           kuid_t *child)
> +                                           long *parent,
> +                                           long *child)
>  {
>         char *kern_buf;
>         char *parent_buf;
> @@ -47,8 +46,6 @@ static int parse_safesetid_whitelist_policy(const char __user *buf,
>         const char separator[] = ":";
>         int ret;
>         size_t first_substring_length;
> -       long parsed_parent;
> -       long parsed_child;
>
>         /* Duplicate string from user memory and NULL-terminate */
>         kern_buf = memdup_user_nul(buf, len);
> @@ -71,27 +68,15 @@ static int parse_safesetid_whitelist_policy(const char __user *buf,
>                 goto free_kern;
>         }
>
> -       ret = kstrtol(parent_buf, 0, &parsed_parent);
> +       ret = kstrtol(parent_buf, 0, parent);
>         if (ret)
>                 goto free_both;
>
>         child_buf = kern_buf + first_substring_length + 1;
> -       ret = kstrtol(child_buf, 0, &parsed_child);
> +       ret = kstrtol(child_buf, 0, child);
>         if (ret)
>                 goto free_both;
>
> -       *parent = make_kuid(current_user_ns(), parsed_parent);
> -       if (!uid_valid(*parent)) {
> -               ret = -EINVAL;
> -               goto free_both;
> -       }
> -
> -       *child = make_kuid(current_user_ns(), parsed_child);
> -       if (!uid_valid(*child)) {
> -               ret = -EINVAL;
> -               goto free_both;
> -       }
> -
>  free_both:
>         kfree(parent_buf);
>  free_kern:
> @@ -99,6 +84,52 @@ static int parse_safesetid_whitelist_policy(const char __user *buf,
>         return ret;
>  }
>
> +static int parse_safesetid_whitelist_uid_policy(const char __user *buf,
> +                                           size_t len,
> +                                           kuid_t *parent_uid,
> +                                           kuid_t *child_uid)
> +{
> +       int ret;
> +       long parent, child;
> +
> +       ret = parse_userbuf_to_longs(buf, len, &parent, &child);
> +       if (ret)
> +               return ret;
> +
> +       *parent_uid = make_kuid(current_user_ns(), parent);
> +       if (!uid_valid(*parent_uid))
> +               return -EINVAL;
> +
> +       *child_uid = make_kuid(current_user_ns(), child);
> +       if (!uid_valid(*child_uid))
> +               return -EINVAL;
> +
> +       return 0;
> +}
> +
> +static int parse_safesetid_whitelist_gid_policy(const char __user *buf,
> +                                           size_t len,
> +                                           kgid_t *parent_gid,
> +                                           kgid_t *child_gid)
> +{
> +       int ret;
> +       long parent, child;
> +
> +       ret = parse_userbuf_to_longs(buf, len, &parent, &child);
> +       if (ret)
> +               return ret;
> +
> +       *parent_gid = make_kgid(current_user_ns(), parent);
> +       if (!gid_valid(*parent_gid))
> +               return -EINVAL;
> +
> +       *child_gid = make_kgid(current_user_ns(), child);
> +       if (!gid_valid(*child_gid))
> +               return -EINVAL;
> +
> +       return 0;
> +}
> +
>  static ssize_t safesetid_file_write(struct file *file,
>                                     const char __user *buf,
>                                     size_t len,
> @@ -106,8 +137,10 @@ static ssize_t safesetid_file_write(struct file *file,
>  {
>         struct safesetid_file_entry *file_entry =
>                 file->f_inode->i_private;
> -       kuid_t parent;
> -       kuid_t child;
> +       kuid_t uid_parent;
> +       kuid_t uid_child;
> +       kgid_t gid_parent;
> +       kgid_t gid_child;
>         int ret;
>
>         if (!ns_capable(current_user_ns(), CAP_MAC_ADMIN))
> @@ -120,13 +153,23 @@ static ssize_t safesetid_file_write(struct file *file,
>         case SAFESETID_WHITELIST_FLUSH:
>                 flush_safesetid_whitelist_entries();
>                 break;
> -       case SAFESETID_WHITELIST_ADD:
> -               ret = parse_safesetid_whitelist_policy(buf, len, &parent,
> -                                                                &child);
> +       case SAFESETID_WHITELIST_ADD_UID:
> +               ret = parse_safesetid_whitelist_uid_policy(buf, len, &uid_parent,
> +                                                                &uid_child);
> +               if (ret)
> +                       return ret;
> +
> +               ret = add_safesetid_whitelist_uid_entry(uid_parent, uid_child);
> +               if (ret)
> +                       return ret;
> +               break;
> +       case SAFESETID_WHITELIST_ADD_GID:
> +               ret = parse_safesetid_whitelist_gid_policy(buf, len, &gid_parent,
> +                                                                &gid_child);
>                 if (ret)
>                         return ret;
>
> -               ret = add_safesetid_whitelist_entry(parent, child);
> +               ret = add_safesetid_whitelist_gid_entry(gid_parent, gid_child);
>                 if (ret)
>                         return ret;
>                 break;
> --
> 2.21.0.352.gf09ad66450-goog
>



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