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linux/security/tomoyo/condition.c
Tetsuo Handa 2ca9bf453b TOMOYO: Allow using executable's realpath and symlink's target as conditions. 
This patch adds support for permission checks using executable file's realpath
upon execve() and symlink's target upon symlink(). Hooks are in the last patch
of this pathset.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>
2011-07-11 11:05:33 +10:00

707 lines
18 KiB
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/*
* security/tomoyo/condition.c
*
* Copyright (C) 2005-2011 NTT DATA CORPORATION
*/
#include "common.h"
#include <linux/slab.h>
/* List of "struct tomoyo_condition". */
LIST_HEAD(tomoyo_condition_list);
/**
* tomoyo_scan_exec_realpath - Check "exec.realpath" parameter of "struct tomoyo_condition".
*
* @file: Pointer to "struct file".
* @ptr: Pointer to "struct tomoyo_name_union".
* @match: True if "exec.realpath=", false if "exec.realpath!=".
*
* Returns true on success, false otherwise.
*/
static bool tomoyo_scan_exec_realpath(struct file *file,
const struct tomoyo_name_union *ptr,
const bool match)
{
bool result;
struct tomoyo_path_info exe;
if (!file)
return false;
exe.name = tomoyo_realpath_from_path(&file->f_path);
if (!exe.name)
return false;
tomoyo_fill_path_info(&exe);
result = tomoyo_compare_name_union(&exe, ptr);
kfree(exe.name);
return result == match;
}
/**
* tomoyo_get_dqword - tomoyo_get_name() for a quoted string.
*
* @start: String to save.
*
* Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
*/
static const struct tomoyo_path_info *tomoyo_get_dqword(char *start)
{
char *cp = start + strlen(start) - 1;
if (cp == start || *start++ != '"' || *cp != '"')
return NULL;
*cp = '\0';
if (*start && !tomoyo_correct_word(start))
return NULL;
return tomoyo_get_name(start);
}
/**
* tomoyo_parse_name_union_quoted - Parse a quoted word.
*
* @param: Pointer to "struct tomoyo_acl_param".
* @ptr: Pointer to "struct tomoyo_name_union".
*
* Returns true on success, false otherwise.
*/
static bool tomoyo_parse_name_union_quoted(struct tomoyo_acl_param *param,
struct tomoyo_name_union *ptr)
{
char *filename = param->data;
if (*filename == '@')
return tomoyo_parse_name_union(param, ptr);
ptr->filename = tomoyo_get_dqword(filename);
return ptr->filename != NULL;
}
/**
* tomoyo_same_condition - Check for duplicated "struct tomoyo_condition" entry.
*
* @a: Pointer to "struct tomoyo_condition".
* @b: Pointer to "struct tomoyo_condition".
*
* Returns true if @a == @b, false otherwise.
*/
static inline bool tomoyo_same_condition(const struct tomoyo_condition *a,
const struct tomoyo_condition *b)
{
return a->size == b->size && a->condc == b->condc &&
a->numbers_count == b->numbers_count &&
a->names_count == b->names_count &&
!memcmp(a + 1, b + 1, a->size - sizeof(*a));
}
/**
* tomoyo_condition_type - Get condition type.
*
* @word: Keyword string.
*
* Returns one of values in "enum tomoyo_conditions_index" on success,
* TOMOYO_MAX_CONDITION_KEYWORD otherwise.
*/
static u8 tomoyo_condition_type(const char *word)
{
u8 i;
for (i = 0; i < TOMOYO_MAX_CONDITION_KEYWORD; i++) {
if (!strcmp(word, tomoyo_condition_keyword[i]))
break;
}
return i;
}
/* Define this to enable debug mode. */
/* #define DEBUG_CONDITION */
#ifdef DEBUG_CONDITION
#define dprintk printk
#else
#define dprintk(...) do { } while (0)
#endif
/**
* tomoyo_commit_condition - Commit "struct tomoyo_condition".
*
* @entry: Pointer to "struct tomoyo_condition".
*
* Returns pointer to "struct tomoyo_condition" on success, NULL otherwise.
*
* This function merges duplicated entries. This function returns NULL if
* @entry is not duplicated but memory quota for policy has exceeded.
*/
static struct tomoyo_condition *tomoyo_commit_condition
(struct tomoyo_condition *entry)
{
struct tomoyo_condition *ptr;
bool found = false;
if (mutex_lock_interruptible(&tomoyo_policy_lock)) {
dprintk(KERN_WARNING "%u: %s failed\n", __LINE__, __func__);
ptr = NULL;
found = true;
goto out;
}
list_for_each_entry_rcu(ptr, &tomoyo_condition_list, head.list) {
if (!tomoyo_same_condition(ptr, entry))
continue;
/* Same entry found. Share this entry. */
atomic_inc(&ptr->head.users);
found = true;
break;
}
if (!found) {
if (tomoyo_memory_ok(entry)) {
atomic_set(&entry->head.users, 1);
list_add_rcu(&entry->head.list,
&tomoyo_condition_list);
} else {
found = true;
ptr = NULL;
}
}
mutex_unlock(&tomoyo_policy_lock);
out:
if (found) {
tomoyo_del_condition(&entry->head.list);
kfree(entry);
entry = ptr;
}
return entry;
}
/**
* tomoyo_get_condition - Parse condition part.
*
* @param: Pointer to "struct tomoyo_acl_param".
*
* Returns pointer to "struct tomoyo_condition" on success, NULL otherwise.
*/
struct tomoyo_condition *tomoyo_get_condition(struct tomoyo_acl_param *param)
{
struct tomoyo_condition *entry = NULL;
struct tomoyo_condition_element *condp = NULL;
struct tomoyo_number_union *numbers_p = NULL;
struct tomoyo_name_union *names_p = NULL;
struct tomoyo_condition e = { };
char * const start_of_string = param->data;
char * const end_of_string = start_of_string + strlen(start_of_string);
char *pos;
rerun:
pos = start_of_string;
while (1) {
u8 left = -1;
u8 right = -1;
char *left_word = pos;
char *cp;
char *right_word;
bool is_not;
if (!*left_word)
break;
/*
* Since left-hand condition does not allow use of "path_group"
* or "number_group" and environment variable's names do not
* accept '=', it is guaranteed that the original line consists
* of one or more repetition of $left$operator$right blocks
* where "$left is free from '=' and ' '" and "$operator is
* either '=' or '!='" and "$right is free from ' '".
* Therefore, we can reconstruct the original line at the end
* of dry run even if we overwrite $operator with '\0'.
*/
cp = strchr(pos, ' ');
if (cp) {
*cp = '\0'; /* Will restore later. */
pos = cp + 1;
} else {
pos = "";
}
right_word = strchr(left_word, '=');
if (!right_word || right_word == left_word)
goto out;
is_not = *(right_word - 1) == '!';
if (is_not)
*(right_word++ - 1) = '\0'; /* Will restore later. */
else if (*(right_word + 1) != '=')
*right_word++ = '\0'; /* Will restore later. */
else
goto out;
dprintk(KERN_WARNING "%u: <%s>%s=<%s>\n", __LINE__, left_word,
is_not ? "!" : "", right_word);
left = tomoyo_condition_type(left_word);
dprintk(KERN_WARNING "%u: <%s> left=%u\n", __LINE__, left_word,
left);
if (left == TOMOYO_MAX_CONDITION_KEYWORD) {
if (!numbers_p) {
e.numbers_count++;
} else {
e.numbers_count--;
left = TOMOYO_NUMBER_UNION;
param->data = left_word;
if (*left_word == '@' ||
!tomoyo_parse_number_union(param,
numbers_p++))
goto out;
}
}
if (!condp)
e.condc++;
else
e.condc--;
if (left == TOMOYO_EXEC_REALPATH ||
left == TOMOYO_SYMLINK_TARGET) {
if (!names_p) {
e.names_count++;
} else {
e.names_count--;
right = TOMOYO_NAME_UNION;
param->data = right_word;
if (!tomoyo_parse_name_union_quoted(param,
names_p++))
goto out;
}
goto store_value;
}
right = tomoyo_condition_type(right_word);
if (right == TOMOYO_MAX_CONDITION_KEYWORD) {
if (!numbers_p) {
e.numbers_count++;
} else {
e.numbers_count--;
right = TOMOYO_NUMBER_UNION;
param->data = right_word;
if (!tomoyo_parse_number_union(param,
numbers_p++))
goto out;
}
}
store_value:
if (!condp) {
dprintk(KERN_WARNING "%u: dry_run left=%u right=%u "
"match=%u\n", __LINE__, left, right, !is_not);
continue;
}
condp->left = left;
condp->right = right;
condp->equals = !is_not;
dprintk(KERN_WARNING "%u: left=%u right=%u match=%u\n",
__LINE__, condp->left, condp->right,
condp->equals);
condp++;
}
dprintk(KERN_INFO "%u: cond=%u numbers=%u names=%u\n",
__LINE__, e.condc, e.numbers_count, e.names_count);
if (entry) {
BUG_ON(e.names_count | e.numbers_count | e.condc);
return tomoyo_commit_condition(entry);
}
e.size = sizeof(*entry)
+ e.condc * sizeof(struct tomoyo_condition_element)
+ e.numbers_count * sizeof(struct tomoyo_number_union)
+ e.names_count * sizeof(struct tomoyo_name_union);
entry = kzalloc(e.size, GFP_NOFS);
if (!entry)
return NULL;
*entry = e;
condp = (struct tomoyo_condition_element *) (entry + 1);
numbers_p = (struct tomoyo_number_union *) (condp + e.condc);
names_p = (struct tomoyo_name_union *) (numbers_p + e.numbers_count);
{
bool flag = false;
for (pos = start_of_string; pos < end_of_string; pos++) {
if (*pos)
continue;
if (flag) /* Restore " ". */
*pos = ' ';
else if (*(pos + 1) == '=') /* Restore "!=". */
*pos = '!';
else /* Restore "=". */
*pos = '=';
flag = !flag;
}
}
goto rerun;
out:
dprintk(KERN_WARNING "%u: %s failed\n", __LINE__, __func__);
if (entry) {
tomoyo_del_condition(&entry->head.list);
kfree(entry);
}
return NULL;
}
/**
* tomoyo_get_attributes - Revalidate "struct inode".
*
* @obj: Pointer to "struct tomoyo_obj_info".
*
* Returns nothing.
*/
void tomoyo_get_attributes(struct tomoyo_obj_info *obj)
{
u8 i;
struct dentry *dentry = NULL;
for (i = 0; i < TOMOYO_MAX_PATH_STAT; i++) {
struct inode *inode;
switch (i) {
case TOMOYO_PATH1:
dentry = obj->path1.dentry;
if (!dentry)
continue;
break;
case TOMOYO_PATH2:
dentry = obj->path2.dentry;
if (!dentry)
continue;
break;
default:
if (!dentry)
continue;
dentry = dget_parent(dentry);
break;
}
inode = dentry->d_inode;
if (inode) {
struct tomoyo_mini_stat *stat = &obj->stat[i];
stat->uid = inode->i_uid;
stat->gid = inode->i_gid;
stat->ino = inode->i_ino;
stat->mode = inode->i_mode;
stat->dev = inode->i_sb->s_dev;
stat->rdev = inode->i_rdev;
obj->stat_valid[i] = true;
}
if (i & 1) /* i == TOMOYO_PATH1_PARENT ||
i == TOMOYO_PATH2_PARENT */
dput(dentry);
}
}
/**
* tomoyo_condition - Check condition part.
*
* @r: Pointer to "struct tomoyo_request_info".
* @cond: Pointer to "struct tomoyo_condition". Maybe NULL.
*
* Returns true on success, false otherwise.
*
* Caller holds tomoyo_read_lock().
*/
bool tomoyo_condition(struct tomoyo_request_info *r,
const struct tomoyo_condition *cond)
{
u32 i;
unsigned long min_v[2] = { 0, 0 };
unsigned long max_v[2] = { 0, 0 };
const struct tomoyo_condition_element *condp;
const struct tomoyo_number_union *numbers_p;
const struct tomoyo_name_union *names_p;
struct tomoyo_obj_info *obj;
u16 condc;
if (!cond)
return true;
condc = cond->condc;
obj = r->obj;
condp = (struct tomoyo_condition_element *) (cond + 1);
numbers_p = (const struct tomoyo_number_union *) (condp + condc);
names_p = (const struct tomoyo_name_union *)
(numbers_p + cond->numbers_count);
for (i = 0; i < condc; i++) {
const bool match = condp->equals;
const u8 left = condp->left;
const u8 right = condp->right;
bool is_bitop[2] = { false, false };
u8 j;
condp++;
/* Check string expressions. */
if (right == TOMOYO_NAME_UNION) {
const struct tomoyo_name_union *ptr = names_p++;
switch (left) {
struct tomoyo_path_info *symlink;
struct tomoyo_execve *ee;
struct file *file;
case TOMOYO_SYMLINK_TARGET:
symlink = obj ? obj->symlink_target : NULL;
if (!symlink ||
!tomoyo_compare_name_union(symlink, ptr)
== match)
goto out;
break;
case TOMOYO_EXEC_REALPATH:
ee = r->ee;
file = ee ? ee->bprm->file : NULL;
if (!tomoyo_scan_exec_realpath(file, ptr,
match))
goto out;
break;
}
continue;
}
/* Check numeric or bit-op expressions. */
for (j = 0; j < 2; j++) {
const u8 index = j ? right : left;
unsigned long value = 0;
switch (index) {
case TOMOYO_TASK_UID:
value = current_uid();
break;
case TOMOYO_TASK_EUID:
value = current_euid();
break;
case TOMOYO_TASK_SUID:
value = current_suid();
break;
case TOMOYO_TASK_FSUID:
value = current_fsuid();
break;
case TOMOYO_TASK_GID:
value = current_gid();
break;
case TOMOYO_TASK_EGID:
value = current_egid();
break;
case TOMOYO_TASK_SGID:
value = current_sgid();
break;
case TOMOYO_TASK_FSGID:
value = current_fsgid();
break;
case TOMOYO_TASK_PID:
value = tomoyo_sys_getpid();
break;
case TOMOYO_TASK_PPID:
value = tomoyo_sys_getppid();
break;
case TOMOYO_TYPE_IS_SOCKET:
value = S_IFSOCK;
break;
case TOMOYO_TYPE_IS_SYMLINK:
value = S_IFLNK;
break;
case TOMOYO_TYPE_IS_FILE:
value = S_IFREG;
break;
case TOMOYO_TYPE_IS_BLOCK_DEV:
value = S_IFBLK;
break;
case TOMOYO_TYPE_IS_DIRECTORY:
value = S_IFDIR;
break;
case TOMOYO_TYPE_IS_CHAR_DEV:
value = S_IFCHR;
break;
case TOMOYO_TYPE_IS_FIFO:
value = S_IFIFO;
break;
case TOMOYO_MODE_SETUID:
value = S_ISUID;
break;
case TOMOYO_MODE_SETGID:
value = S_ISGID;
break;
case TOMOYO_MODE_STICKY:
value = S_ISVTX;
break;
case TOMOYO_MODE_OWNER_READ:
value = S_IRUSR;
break;
case TOMOYO_MODE_OWNER_WRITE:
value = S_IWUSR;
break;
case TOMOYO_MODE_OWNER_EXECUTE:
value = S_IXUSR;
break;
case TOMOYO_MODE_GROUP_READ:
value = S_IRGRP;
break;
case TOMOYO_MODE_GROUP_WRITE:
value = S_IWGRP;
break;
case TOMOYO_MODE_GROUP_EXECUTE:
value = S_IXGRP;
break;
case TOMOYO_MODE_OTHERS_READ:
value = S_IROTH;
break;
case TOMOYO_MODE_OTHERS_WRITE:
value = S_IWOTH;
break;
case TOMOYO_MODE_OTHERS_EXECUTE:
value = S_IXOTH;
break;
case TOMOYO_NUMBER_UNION:
/* Fetch values later. */
break;
default:
if (!obj)
goto out;
if (!obj->validate_done) {
tomoyo_get_attributes(obj);
obj->validate_done = true;
}
{
u8 stat_index;
struct tomoyo_mini_stat *stat;
switch (index) {
case TOMOYO_PATH1_UID:
case TOMOYO_PATH1_GID:
case TOMOYO_PATH1_INO:
case TOMOYO_PATH1_MAJOR:
case TOMOYO_PATH1_MINOR:
case TOMOYO_PATH1_TYPE:
case TOMOYO_PATH1_DEV_MAJOR:
case TOMOYO_PATH1_DEV_MINOR:
case TOMOYO_PATH1_PERM:
stat_index = TOMOYO_PATH1;
break;
case TOMOYO_PATH2_UID:
case TOMOYO_PATH2_GID:
case TOMOYO_PATH2_INO:
case TOMOYO_PATH2_MAJOR:
case TOMOYO_PATH2_MINOR:
case TOMOYO_PATH2_TYPE:
case TOMOYO_PATH2_DEV_MAJOR:
case TOMOYO_PATH2_DEV_MINOR:
case TOMOYO_PATH2_PERM:
stat_index = TOMOYO_PATH2;
break;
case TOMOYO_PATH1_PARENT_UID:
case TOMOYO_PATH1_PARENT_GID:
case TOMOYO_PATH1_PARENT_INO:
case TOMOYO_PATH1_PARENT_PERM:
stat_index =
TOMOYO_PATH1_PARENT;
break;
case TOMOYO_PATH2_PARENT_UID:
case TOMOYO_PATH2_PARENT_GID:
case TOMOYO_PATH2_PARENT_INO:
case TOMOYO_PATH2_PARENT_PERM:
stat_index =
TOMOYO_PATH2_PARENT;
break;
default:
goto out;
}
if (!obj->stat_valid[stat_index])
goto out;
stat = &obj->stat[stat_index];
switch (index) {
case TOMOYO_PATH1_UID:
case TOMOYO_PATH2_UID:
case TOMOYO_PATH1_PARENT_UID:
case TOMOYO_PATH2_PARENT_UID:
value = stat->uid;
break;
case TOMOYO_PATH1_GID:
case TOMOYO_PATH2_GID:
case TOMOYO_PATH1_PARENT_GID:
case TOMOYO_PATH2_PARENT_GID:
value = stat->gid;
break;
case TOMOYO_PATH1_INO:
case TOMOYO_PATH2_INO:
case TOMOYO_PATH1_PARENT_INO:
case TOMOYO_PATH2_PARENT_INO:
value = stat->ino;
break;
case TOMOYO_PATH1_MAJOR:
case TOMOYO_PATH2_MAJOR:
value = MAJOR(stat->dev);
break;
case TOMOYO_PATH1_MINOR:
case TOMOYO_PATH2_MINOR:
value = MINOR(stat->dev);
break;
case TOMOYO_PATH1_TYPE:
case TOMOYO_PATH2_TYPE:
value = stat->mode & S_IFMT;
break;
case TOMOYO_PATH1_DEV_MAJOR:
case TOMOYO_PATH2_DEV_MAJOR:
value = MAJOR(stat->rdev);
break;
case TOMOYO_PATH1_DEV_MINOR:
case TOMOYO_PATH2_DEV_MINOR:
value = MINOR(stat->rdev);
break;
case TOMOYO_PATH1_PERM:
case TOMOYO_PATH2_PERM:
case TOMOYO_PATH1_PARENT_PERM:
case TOMOYO_PATH2_PARENT_PERM:
value = stat->mode & S_IALLUGO;
break;
}
}
break;
}
max_v[j] = value;
min_v[j] = value;
switch (index) {
case TOMOYO_MODE_SETUID:
case TOMOYO_MODE_SETGID:
case TOMOYO_MODE_STICKY:
case TOMOYO_MODE_OWNER_READ:
case TOMOYO_MODE_OWNER_WRITE:
case TOMOYO_MODE_OWNER_EXECUTE:
case TOMOYO_MODE_GROUP_READ:
case TOMOYO_MODE_GROUP_WRITE:
case TOMOYO_MODE_GROUP_EXECUTE:
case TOMOYO_MODE_OTHERS_READ:
case TOMOYO_MODE_OTHERS_WRITE:
case TOMOYO_MODE_OTHERS_EXECUTE:
is_bitop[j] = true;
}
}
if (left == TOMOYO_NUMBER_UNION) {
/* Fetch values now. */
const struct tomoyo_number_union *ptr = numbers_p++;
min_v[0] = ptr->values[0];
max_v[0] = ptr->values[1];
}
if (right == TOMOYO_NUMBER_UNION) {
/* Fetch values now. */
const struct tomoyo_number_union *ptr = numbers_p++;
if (ptr->group) {
if (tomoyo_number_matches_group(min_v[0],
max_v[0],
ptr->group)
== match)
continue;
} else {
if ((min_v[0] <= ptr->values[1] &&
max_v[0] >= ptr->values[0]) == match)
continue;
}
goto out;
}
/*
* Bit operation is valid only when counterpart value
* represents permission.
*/
if (is_bitop[0] && is_bitop[1]) {
goto out;
} else if (is_bitop[0]) {
switch (right) {
case TOMOYO_PATH1_PERM:
case TOMOYO_PATH1_PARENT_PERM:
case TOMOYO_PATH2_PERM:
case TOMOYO_PATH2_PARENT_PERM:
if (!(max_v[0] & max_v[1]) == !match)
continue;
}
goto out;
} else if (is_bitop[1]) {
switch (left) {
case TOMOYO_PATH1_PERM:
case TOMOYO_PATH1_PARENT_PERM:
case TOMOYO_PATH2_PERM:
case TOMOYO_PATH2_PARENT_PERM:
if (!(max_v[0] & max_v[1]) == !match)
continue;
}
goto out;
}
/* Normal value range comparison. */
if ((min_v[0] <= max_v[1] && max_v[0] >= min_v[1]) == match)
continue;
out:
return false;
}
return true;
}
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