diff options
Diffstat (limited to 'security/selinux/ss/conditional.c')
| -rw-r--r-- | security/selinux/ss/conditional.c | 758 |
1 files changed, 758 insertions, 0 deletions
diff --git a/security/selinux/ss/conditional.c b/security/selinux/ss/conditional.c new file mode 100644 index 000000000..865611127 --- /dev/null +++ b/security/selinux/ss/conditional.c @@ -0,0 +1,758 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Authors: Karl MacMillan <kmacmillan@tresys.com> + * Frank Mayer <mayerf@tresys.com> + * + * Copyright (C) 2003 - 2004 Tresys Technology, LLC + */ + +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/string.h> +#include <linux/spinlock.h> +#include <linux/slab.h> + +#include "security.h" +#include "conditional.h" +#include "services.h" + +/* + * cond_evaluate_expr evaluates a conditional expr + * in reverse polish notation. It returns true (1), false (0), + * or undefined (-1). Undefined occurs when the expression + * exceeds the stack depth of COND_EXPR_MAXDEPTH. + */ +static int cond_evaluate_expr(struct policydb *p, struct cond_expr *expr) +{ + u32 i; + int s[COND_EXPR_MAXDEPTH]; + int sp = -1; + + if (expr->len == 0) + return -1; + + for (i = 0; i < expr->len; i++) { + struct cond_expr_node *node = &expr->nodes[i]; + + switch (node->expr_type) { + case COND_BOOL: + if (sp == (COND_EXPR_MAXDEPTH - 1)) + return -1; + sp++; + s[sp] = p->bool_val_to_struct[node->bool - 1]->state; + break; + case COND_NOT: + if (sp < 0) + return -1; + s[sp] = !s[sp]; + break; + case COND_OR: + if (sp < 1) + return -1; + sp--; + s[sp] |= s[sp + 1]; + break; + case COND_AND: + if (sp < 1) + return -1; + sp--; + s[sp] &= s[sp + 1]; + break; + case COND_XOR: + if (sp < 1) + return -1; + sp--; + s[sp] ^= s[sp + 1]; + break; + case COND_EQ: + if (sp < 1) + return -1; + sp--; + s[sp] = (s[sp] == s[sp + 1]); + break; + case COND_NEQ: + if (sp < 1) + return -1; + sp--; + s[sp] = (s[sp] != s[sp + 1]); + break; + default: + return -1; + } + } + return s[0]; +} + +/* + * evaluate_cond_node evaluates the conditional stored in + * a struct cond_node and if the result is different than the + * current state of the node it sets the rules in the true/false + * list appropriately. If the result of the expression is undefined + * all of the rules are disabled for safety. + */ +static void evaluate_cond_node(struct policydb *p, struct cond_node *node) +{ + struct avtab_node *avnode; + int new_state; + u32 i; + + new_state = cond_evaluate_expr(p, &node->expr); + if (new_state != node->cur_state) { + node->cur_state = new_state; + if (new_state == -1) + pr_err("SELinux: expression result was undefined - disabling all rules.\n"); + /* turn the rules on or off */ + for (i = 0; i < node->true_list.len; i++) { + avnode = node->true_list.nodes[i]; + if (new_state <= 0) + avnode->key.specified &= ~AVTAB_ENABLED; + else + avnode->key.specified |= AVTAB_ENABLED; + } + + for (i = 0; i < node->false_list.len; i++) { + avnode = node->false_list.nodes[i]; + /* -1 or 1 */ + if (new_state) + avnode->key.specified &= ~AVTAB_ENABLED; + else + avnode->key.specified |= AVTAB_ENABLED; + } + } +} + +void evaluate_cond_nodes(struct policydb *p) +{ + u32 i; + + for (i = 0; i < p->cond_list_len; i++) + evaluate_cond_node(p, &p->cond_list[i]); +} + +void cond_policydb_init(struct policydb *p) +{ + p->bool_val_to_struct = NULL; + p->cond_list = NULL; + p->cond_list_len = 0; + + avtab_init(&p->te_cond_avtab); +} + +static void cond_node_destroy(struct cond_node *node) +{ + kfree(node->expr.nodes); + /* the avtab_ptr_t nodes are destroyed by the avtab */ + kfree(node->true_list.nodes); + kfree(node->false_list.nodes); +} + +static void cond_list_destroy(struct policydb *p) +{ + u32 i; + + for (i = 0; i < p->cond_list_len; i++) + cond_node_destroy(&p->cond_list[i]); + kfree(p->cond_list); + p->cond_list = NULL; + p->cond_list_len = 0; +} + +void cond_policydb_destroy(struct policydb *p) +{ + kfree(p->bool_val_to_struct); + avtab_destroy(&p->te_cond_avtab); + cond_list_destroy(p); +} + +int cond_init_bool_indexes(struct policydb *p) +{ + kfree(p->bool_val_to_struct); + p->bool_val_to_struct = kmalloc_array(p->p_bools.nprim, + sizeof(*p->bool_val_to_struct), + GFP_KERNEL); + if (!p->bool_val_to_struct) + return -ENOMEM; + return 0; +} + +int cond_destroy_bool(void *key, void *datum, void *p) +{ + kfree(key); + kfree(datum); + return 0; +} + +int cond_index_bool(void *key, void *datum, void *datap) +{ + struct policydb *p; + struct cond_bool_datum *booldatum; + + booldatum = datum; + p = datap; + + if (!booldatum->value || booldatum->value > p->p_bools.nprim) + return -EINVAL; + + p->sym_val_to_name[SYM_BOOLS][booldatum->value - 1] = key; + p->bool_val_to_struct[booldatum->value - 1] = booldatum; + + return 0; +} + +static int bool_isvalid(struct cond_bool_datum *b) +{ + if (!(b->state == 0 || b->state == 1)) + return 0; + return 1; +} + +int cond_read_bool(struct policydb *p, struct symtab *s, void *fp) +{ + char *key = NULL; + struct cond_bool_datum *booldatum; + __le32 buf[3]; + u32 len; + int rc; + + booldatum = kzalloc(sizeof(*booldatum), GFP_KERNEL); + if (!booldatum) + return -ENOMEM; + + rc = next_entry(buf, fp, sizeof(buf)); + if (rc) + goto err; + + booldatum->value = le32_to_cpu(buf[0]); + booldatum->state = le32_to_cpu(buf[1]); + + rc = -EINVAL; + if (!bool_isvalid(booldatum)) + goto err; + + len = le32_to_cpu(buf[2]); + if (((len == 0) || (len == (u32)-1))) + goto err; + + rc = -ENOMEM; + key = kmalloc(len + 1, GFP_KERNEL); + if (!key) + goto err; + rc = next_entry(key, fp, len); + if (rc) + goto err; + key[len] = '\0'; + rc = symtab_insert(s, key, booldatum); + if (rc) + goto err; + + return 0; +err: + cond_destroy_bool(key, booldatum, NULL); + return rc; +} + +struct cond_insertf_data { + struct policydb *p; + struct avtab_node **dst; + struct cond_av_list *other; +}; + +static int cond_insertf(struct avtab *a, struct avtab_key *k, struct avtab_datum *d, void *ptr) +{ + struct cond_insertf_data *data = ptr; + struct policydb *p = data->p; + struct cond_av_list *other = data->other; + struct avtab_node *node_ptr; + u32 i; + bool found; + + /* + * For type rules we have to make certain there aren't any + * conflicting rules by searching the te_avtab and the + * cond_te_avtab. + */ + if (k->specified & AVTAB_TYPE) { + if (avtab_search(&p->te_avtab, k)) { + pr_err("SELinux: type rule already exists outside of a conditional.\n"); + return -EINVAL; + } + /* + * If we are reading the false list other will be a pointer to + * the true list. We can have duplicate entries if there is only + * 1 other entry and it is in our true list. + * + * If we are reading the true list (other == NULL) there shouldn't + * be any other entries. + */ + if (other) { + node_ptr = avtab_search_node(&p->te_cond_avtab, k); + if (node_ptr) { + if (avtab_search_node_next(node_ptr, k->specified)) { + pr_err("SELinux: too many conflicting type rules.\n"); + return -EINVAL; + } + found = false; + for (i = 0; i < other->len; i++) { + if (other->nodes[i] == node_ptr) { + found = true; + break; + } + } + if (!found) { + pr_err("SELinux: conflicting type rules.\n"); + return -EINVAL; + } + } + } else { + if (avtab_search(&p->te_cond_avtab, k)) { + pr_err("SELinux: conflicting type rules when adding type rule for true.\n"); + return -EINVAL; + } + } + } + + node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, k, d); + if (!node_ptr) { + pr_err("SELinux: could not insert rule.\n"); + return -ENOMEM; + } + + *data->dst = node_ptr; + return 0; +} + +static int cond_read_av_list(struct policydb *p, void *fp, + struct cond_av_list *list, + struct cond_av_list *other) +{ + int rc; + __le32 buf[1]; + u32 i, len; + struct cond_insertf_data data; + + rc = next_entry(buf, fp, sizeof(u32)); + if (rc) + return rc; + + len = le32_to_cpu(buf[0]); + if (len == 0) + return 0; + + list->nodes = kcalloc(len, sizeof(*list->nodes), GFP_KERNEL); + if (!list->nodes) + return -ENOMEM; + + data.p = p; + data.other = other; + for (i = 0; i < len; i++) { + data.dst = &list->nodes[i]; + rc = avtab_read_item(&p->te_cond_avtab, fp, p, cond_insertf, + &data); + if (rc) { + kfree(list->nodes); + list->nodes = NULL; + return rc; + } + } + + list->len = len; + return 0; +} + +static int expr_node_isvalid(struct policydb *p, struct cond_expr_node *expr) +{ + if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) { + pr_err("SELinux: conditional expressions uses unknown operator.\n"); + return 0; + } + + if (expr->bool > p->p_bools.nprim) { + pr_err("SELinux: conditional expressions uses unknown bool.\n"); + return 0; + } + return 1; +} + +static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp) +{ + __le32 buf[2]; + u32 i, len; + int rc; + + rc = next_entry(buf, fp, sizeof(u32) * 2); + if (rc) + return rc; + + node->cur_state = le32_to_cpu(buf[0]); + + /* expr */ + len = le32_to_cpu(buf[1]); + node->expr.nodes = kcalloc(len, sizeof(*node->expr.nodes), GFP_KERNEL); + if (!node->expr.nodes) + return -ENOMEM; + + node->expr.len = len; + + for (i = 0; i < len; i++) { + struct cond_expr_node *expr = &node->expr.nodes[i]; + + rc = next_entry(buf, fp, sizeof(u32) * 2); + if (rc) + return rc; + + expr->expr_type = le32_to_cpu(buf[0]); + expr->bool = le32_to_cpu(buf[1]); + + if (!expr_node_isvalid(p, expr)) + return -EINVAL; + } + + rc = cond_read_av_list(p, fp, &node->true_list, NULL); + if (rc) + return rc; + return cond_read_av_list(p, fp, &node->false_list, &node->true_list); +} + +int cond_read_list(struct policydb *p, void *fp) +{ + __le32 buf[1]; + u32 i, len; + int rc; + + rc = next_entry(buf, fp, sizeof(buf)); + if (rc) + return rc; + + len = le32_to_cpu(buf[0]); + + p->cond_list = kcalloc(len, sizeof(*p->cond_list), GFP_KERNEL); + if (!p->cond_list) + return -ENOMEM; + + rc = avtab_alloc(&(p->te_cond_avtab), p->te_avtab.nel); + if (rc) + goto err; + + p->cond_list_len = len; + + for (i = 0; i < len; i++) { + rc = cond_read_node(p, &p->cond_list[i], fp); + if (rc) + goto err; + } + return 0; +err: + cond_list_destroy(p); + return rc; +} + +int cond_write_bool(void *vkey, void *datum, void *ptr) +{ + char *key = vkey; + struct cond_bool_datum *booldatum = datum; + struct policy_data *pd = ptr; + void *fp = pd->fp; + __le32 buf[3]; + u32 len; + int rc; + + len = strlen(key); + buf[0] = cpu_to_le32(booldatum->value); + buf[1] = cpu_to_le32(booldatum->state); + buf[2] = cpu_to_le32(len); + rc = put_entry(buf, sizeof(u32), 3, fp); + if (rc) + return rc; + rc = put_entry(key, 1, len, fp); + if (rc) + return rc; + return 0; +} + +/* + * cond_write_cond_av_list doesn't write out the av_list nodes. + * Instead it writes out the key/value pairs from the avtab. This + * is necessary because there is no way to uniquely identifying rules + * in the avtab so it is not possible to associate individual rules + * in the avtab with a conditional without saving them as part of + * the conditional. This means that the avtab with the conditional + * rules will not be saved but will be rebuilt on policy load. + */ +static int cond_write_av_list(struct policydb *p, + struct cond_av_list *list, struct policy_file *fp) +{ + __le32 buf[1]; + u32 i; + int rc; + + buf[0] = cpu_to_le32(list->len); + rc = put_entry(buf, sizeof(u32), 1, fp); + if (rc) + return rc; + + for (i = 0; i < list->len; i++) { + rc = avtab_write_item(p, list->nodes[i], fp); + if (rc) + return rc; + } + + return 0; +} + +static int cond_write_node(struct policydb *p, struct cond_node *node, + struct policy_file *fp) +{ + __le32 buf[2]; + int rc; + u32 i; + + buf[0] = cpu_to_le32(node->cur_state); + rc = put_entry(buf, sizeof(u32), 1, fp); + if (rc) + return rc; + + buf[0] = cpu_to_le32(node->expr.len); + rc = put_entry(buf, sizeof(u32), 1, fp); + if (rc) + return rc; + + for (i = 0; i < node->expr.len; i++) { + buf[0] = cpu_to_le32(node->expr.nodes[i].expr_type); + buf[1] = cpu_to_le32(node->expr.nodes[i].bool); + rc = put_entry(buf, sizeof(u32), 2, fp); + if (rc) + return rc; + } + + rc = cond_write_av_list(p, &node->true_list, fp); + if (rc) + return rc; + rc = cond_write_av_list(p, &node->false_list, fp); + if (rc) + return rc; + + return 0; +} + +int cond_write_list(struct policydb *p, void *fp) +{ + u32 i; + __le32 buf[1]; + int rc; + + buf[0] = cpu_to_le32(p->cond_list_len); + rc = put_entry(buf, sizeof(u32), 1, fp); + if (rc) + return rc; + + for (i = 0; i < p->cond_list_len; i++) { + rc = cond_write_node(p, &p->cond_list[i], fp); + if (rc) + return rc; + } + + return 0; +} + +void cond_compute_xperms(struct avtab *ctab, struct avtab_key *key, + struct extended_perms_decision *xpermd) +{ + struct avtab_node *node; + + if (!ctab || !key || !xpermd) + return; + + for (node = avtab_search_node(ctab, key); node; + node = avtab_search_node_next(node, key->specified)) { + if (node->key.specified & AVTAB_ENABLED) + services_compute_xperms_decision(xpermd, node); + } + return; + +} +/* Determine whether additional permissions are granted by the conditional + * av table, and if so, add them to the result + */ +void cond_compute_av(struct avtab *ctab, struct avtab_key *key, + struct av_decision *avd, struct extended_perms *xperms) +{ + struct avtab_node *node; + + if (!ctab || !key || !avd) + return; + + for (node = avtab_search_node(ctab, key); node; + node = avtab_search_node_next(node, key->specified)) { + if ((u16)(AVTAB_ALLOWED|AVTAB_ENABLED) == + (node->key.specified & (AVTAB_ALLOWED|AVTAB_ENABLED))) + avd->allowed |= node->datum.u.data; + if ((u16)(AVTAB_AUDITDENY|AVTAB_ENABLED) == + (node->key.specified & (AVTAB_AUDITDENY|AVTAB_ENABLED))) + /* Since a '0' in an auditdeny mask represents a + * permission we do NOT want to audit (dontaudit), we use + * the '&' operand to ensure that all '0's in the mask + * are retained (much unlike the allow and auditallow cases). + */ + avd->auditdeny &= node->datum.u.data; + if ((u16)(AVTAB_AUDITALLOW|AVTAB_ENABLED) == + (node->key.specified & (AVTAB_AUDITALLOW|AVTAB_ENABLED))) + avd->auditallow |= node->datum.u.data; + if (xperms && (node->key.specified & AVTAB_ENABLED) && + (node->key.specified & AVTAB_XPERMS)) + services_compute_xperms_drivers(xperms, node); + } +} + +static int cond_dup_av_list(struct cond_av_list *new, + struct cond_av_list *orig, + struct avtab *avtab) +{ + u32 i; + + memset(new, 0, sizeof(*new)); + + new->nodes = kcalloc(orig->len, sizeof(*new->nodes), GFP_KERNEL); + if (!new->nodes) + return -ENOMEM; + + for (i = 0; i < orig->len; i++) { + new->nodes[i] = avtab_insert_nonunique(avtab, + &orig->nodes[i]->key, + &orig->nodes[i]->datum); + if (!new->nodes[i]) + return -ENOMEM; + new->len++; + } + + return 0; +} + +static int duplicate_policydb_cond_list(struct policydb *newp, + struct policydb *origp) +{ + int rc, i, j; + + rc = avtab_alloc_dup(&newp->te_cond_avtab, &origp->te_cond_avtab); + if (rc) + return rc; + + newp->cond_list_len = 0; + newp->cond_list = kcalloc(origp->cond_list_len, + sizeof(*newp->cond_list), + GFP_KERNEL); + if (!newp->cond_list) + goto error; + + for (i = 0; i < origp->cond_list_len; i++) { + struct cond_node *newn = &newp->cond_list[i]; + struct cond_node *orign = &origp->cond_list[i]; + + newp->cond_list_len++; + + newn->cur_state = orign->cur_state; + newn->expr.nodes = kcalloc(orign->expr.len, + sizeof(*newn->expr.nodes), GFP_KERNEL); + if (!newn->expr.nodes) + goto error; + for (j = 0; j < orign->expr.len; j++) + newn->expr.nodes[j] = orign->expr.nodes[j]; + newn->expr.len = orign->expr.len; + + rc = cond_dup_av_list(&newn->true_list, &orign->true_list, + &newp->te_cond_avtab); + if (rc) + goto error; + + rc = cond_dup_av_list(&newn->false_list, &orign->false_list, + &newp->te_cond_avtab); + if (rc) + goto error; + } + + return 0; + +error: + avtab_destroy(&newp->te_cond_avtab); + cond_list_destroy(newp); + return -ENOMEM; +} + +static int cond_bools_destroy(void *key, void *datum, void *args) +{ + /* key was not copied so no need to free here */ + kfree(datum); + return 0; +} + +static int cond_bools_copy(struct hashtab_node *new, struct hashtab_node *orig, void *args) +{ + struct cond_bool_datum *datum; + + datum = kmemdup(orig->datum, sizeof(struct cond_bool_datum), + GFP_KERNEL); + if (!datum) + return -ENOMEM; + + new->key = orig->key; /* No need to copy, never modified */ + new->datum = datum; + return 0; +} + +static int cond_bools_index(void *key, void *datum, void *args) +{ + struct cond_bool_datum *booldatum, **cond_bool_array; + + booldatum = datum; + cond_bool_array = args; + cond_bool_array[booldatum->value - 1] = booldatum; + + return 0; +} + +static int duplicate_policydb_bools(struct policydb *newdb, + struct policydb *orig) +{ + struct cond_bool_datum **cond_bool_array; + int rc; + + cond_bool_array = kmalloc_array(orig->p_bools.nprim, + sizeof(*orig->bool_val_to_struct), + GFP_KERNEL); + if (!cond_bool_array) + return -ENOMEM; + + rc = hashtab_duplicate(&newdb->p_bools.table, &orig->p_bools.table, + cond_bools_copy, cond_bools_destroy, NULL); + if (rc) { + kfree(cond_bool_array); + return -ENOMEM; + } + + hashtab_map(&newdb->p_bools.table, cond_bools_index, cond_bool_array); + newdb->bool_val_to_struct = cond_bool_array; + + newdb->p_bools.nprim = orig->p_bools.nprim; + + return 0; +} + +void cond_policydb_destroy_dup(struct policydb *p) +{ + hashtab_map(&p->p_bools.table, cond_bools_destroy, NULL); + hashtab_destroy(&p->p_bools.table); + cond_policydb_destroy(p); +} + +int cond_policydb_dup(struct policydb *new, struct policydb *orig) +{ + cond_policydb_init(new); + + if (duplicate_policydb_bools(new, orig)) + return -ENOMEM; + + if (duplicate_policydb_cond_list(new, orig)) { + cond_policydb_destroy_dup(new); + return -ENOMEM; + } + + return 0; +} |