diff options
Diffstat (limited to 'security')
| -rw-r--r-- | security/safesetid/lsm.c | 39 | ||||
| -rw-r--r-- | security/security.c | 5 |
2 files changed, 35 insertions, 9 deletions
diff --git a/security/safesetid/lsm.c b/security/safesetid/lsm.c index 963f4ad9cb66..e806739f7868 100644 --- a/security/safesetid/lsm.c +++ b/security/safesetid/lsm.c @@ -97,15 +97,9 @@ static int safesetid_security_capable(const struct cred *cred, return 0; /* - * If CAP_SET{U/G}ID is currently used for a setid() syscall, we want to - * let it go through here; the real security check happens later, in the - * task_fix_set{u/g}id hook. - * - * NOTE: - * Until we add support for restricting setgroups() calls, GID security - * policies offer no meaningful security since we always return 0 here - * when called from within the setgroups() syscall and there is no - * additional hook later on to enforce security policies for setgroups(). + * If CAP_SET{U/G}ID is currently used for a setid or setgroups syscall, we + * want to let it go through here; the real security check happens later, in + * the task_fix_set{u/g}id or task_fix_setgroups hooks. */ if ((opts & CAP_OPT_INSETID) != 0) return 0; @@ -241,9 +235,36 @@ static int safesetid_task_fix_setgid(struct cred *new, return -EACCES; } +static int safesetid_task_fix_setgroups(struct cred *new, const struct cred *old) +{ + int i; + + /* Do nothing if there are no setgid restrictions for our old RGID. */ + if (setid_policy_lookup((kid_t){.gid = old->gid}, INVALID_ID, GID) == SIDPOL_DEFAULT) + return 0; + + get_group_info(new->group_info); + for (i = 0; i < new->group_info->ngroups; i++) { + if (!id_permitted_for_cred(old, (kid_t){.gid = new->group_info->gid[i]}, GID)) { + put_group_info(new->group_info); + /* + * Kill this process to avoid potential security vulnerabilities + * that could arise from a missing allowlist entry preventing a + * privileged process from dropping to a lesser-privileged one. + */ + force_sig(SIGKILL); + return -EACCES; + } + } + + put_group_info(new->group_info); + return 0; +} + static struct security_hook_list safesetid_security_hooks[] = { LSM_HOOK_INIT(task_fix_setuid, safesetid_task_fix_setuid), LSM_HOOK_INIT(task_fix_setgid, safesetid_task_fix_setgid), + LSM_HOOK_INIT(task_fix_setgroups, safesetid_task_fix_setgroups), LSM_HOOK_INIT(capable, safesetid_security_capable) }; diff --git a/security/security.c b/security/security.c index f85afb02ea1c..14d30fec8a00 100644 --- a/security/security.c +++ b/security/security.c @@ -1804,6 +1804,11 @@ int security_task_fix_setgid(struct cred *new, const struct cred *old, return call_int_hook(task_fix_setgid, 0, new, old, flags); } +int security_task_fix_setgroups(struct cred *new, const struct cred *old) +{ + return call_int_hook(task_fix_setgroups, 0, new, old); +} + int security_task_setpgid(struct task_struct *p, pid_t pgid) { return call_int_hook(task_setpgid, 0, p, pgid); |