488 lines
11 KiB
C
488 lines
11 KiB
C
#include <unistd.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <ctype.h>
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#include <pwd.h>
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#include "selinux_internal.h"
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#include "context_internal.h"
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#include "get_context_list_internal.h"
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int get_default_context_with_role(const char* user,
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const char *role,
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security_context_t fromcon,
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security_context_t *newcon)
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{
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security_context_t *conary;
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char **ptr;
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context_t con;
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const char *role2;
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int rc;
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rc = get_ordered_context_list(user, fromcon, &conary);
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if (rc <= 0)
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return -1;
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for (ptr = conary; *ptr; ptr++) {
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con = context_new(*ptr);
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if (!con)
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continue;
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role2 = context_role_get(con);
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if (role2 && !strcmp(role, role2)) {
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context_free(con);
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break;
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}
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context_free(con);
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}
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rc = -1;
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if (!(*ptr))
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goto out;
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*newcon = strdup(*ptr);
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if (!(*newcon))
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goto out;
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rc = 0;
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out:
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freeconary(conary);
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return rc;
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}
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int get_default_context(const char* user,
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security_context_t fromcon,
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security_context_t *newcon)
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{
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security_context_t *conary;
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int rc;
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rc = get_ordered_context_list(user, fromcon, &conary);
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if (rc <= 0)
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return -1;
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*newcon = strdup(conary[0]);
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freeconary(conary);
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if (!(*newcon))
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return -1;
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return 0;
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}
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static int find_partialcon(security_context_t *list,
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unsigned int nreach,
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char *part)
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{
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const char *conrole, *contype;
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char *partrole, *parttype, *ptr;
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context_t con;
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unsigned int i;
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partrole = part;
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ptr = part;
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while (*ptr && !isspace(*ptr) && *ptr != ':')
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ptr++;
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if (*ptr != ':')
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return -1;
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*ptr++ = 0;
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parttype = ptr;
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while (*ptr && !isspace(*ptr) && *ptr != ':')
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ptr++;
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*ptr = 0;
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for (i = 0; i < nreach; i++) {
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con = context_new(list[i]);
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if (!con)
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return -1;
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conrole = context_role_get(con);
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contype = context_type_get(con);
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if (!conrole || !contype) {
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context_free(con);
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return -1;
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}
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if (!strcmp(conrole, partrole) && !strcmp(contype, parttype)) {
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context_free(con);
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return i;
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}
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context_free(con);
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}
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return -1;
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}
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static int get_context_order(FILE *fp,
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security_context_t fromcon,
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security_context_t *reachable,
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unsigned int nreach,
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unsigned int *ordering,
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unsigned int *nordered)
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{
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char *start, *end = NULL;
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char *line = NULL;
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size_t line_len = 0, len;
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int found = 0;
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const char *fromrole, *fromtype;
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char *linerole, *linetype;
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unsigned int i;
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context_t con;
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int rc;
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errno = -EINVAL;
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/* Extract the role and type of the fromcon for matching.
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User identity and MLS range can be variable. */
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con = context_new(fromcon);
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if (!con)
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return -1;
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fromrole = context_role_get(con);
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fromtype = context_type_get(con);
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if (!fromrole || !fromtype) {
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context_free(con);
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return -1;
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}
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while (getline(&line, &line_len, fp) > 0) {
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len = strlen(line);
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if (line[len - 1] == '\n')
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line[len - 1] = 0;
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/* Skip leading whitespace. */
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start = line;
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while (*start && isspace(*start))
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start++;
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if (!(*start))
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continue;
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/* Find the end of the (partial) fromcon in the line. */
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end = start;
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while (*end && !isspace(*end))
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end++;
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if (!(*end))
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continue;
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/* Check for a match. */
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linerole = start;
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while (*start && !isspace(*start) && *start != ':')
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start++;
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if (*start != ':')
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continue;
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*start = 0;
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linetype = ++start;
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while (*start && !isspace(*start) && *start != ':')
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start++;
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if (!(*start))
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continue;
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*start = 0;
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if (!strcmp(fromrole, linerole) && !strcmp(fromtype, linetype)) {
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found = 1;
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break;
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}
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}
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if (!found) {
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errno = ENOENT;
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rc = -1;
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goto out;
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}
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start = ++end;
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while (*start) {
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/* Skip leading whitespace */
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while (*start && isspace(*start))
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start++;
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if (!(*start))
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break;
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/* Find the end of this partial context. */
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end = start;
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while (*end && !isspace(*end))
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end++;
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if (*end)
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*end++ = 0;
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/* Check for a match in the reachable list. */
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rc = find_partialcon(reachable, nreach, start);
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if (rc < 0) {
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/* No match, skip it. */
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start = end;
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continue;
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}
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/* If a match is found and the entry is not already ordered
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(e.g. due to prior match in prior config file), then set
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the ordering for it. */
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i = rc;
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if (ordering[i] == nreach)
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ordering[i] = (*nordered)++;
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start = end;
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}
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rc = 0;
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out:
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context_free(con);
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free(line);
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return rc;
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}
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static int get_failsafe_context(const char* user,
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security_context_t *newcon)
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{
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FILE *fp;
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char buf[255], *ptr;
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size_t plen, nlen;
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int rc;
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fp = fopen(selinux_failsafe_context_path(), "r");
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if (!fp)
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return -1;
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ptr = fgets_unlocked(buf, sizeof buf, fp);
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fclose(fp);
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if (!ptr)
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return -1;
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plen = strlen(ptr);
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if (buf[plen-1] == '\n')
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buf[plen-1] = 0;
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retry:
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nlen = strlen(user)+1+plen+1;
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*newcon = malloc(nlen);
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if(!(*newcon))
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return -1;
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rc = snprintf(*newcon, nlen, "%s:%s", user, ptr);
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if (rc < 0 || (size_t) rc >= nlen) {
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free(*newcon);
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*newcon = 0;
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return -1;
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}
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/* If possible, check the context to catch
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errors early rather than waiting until the
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caller tries to use setexeccon on the context.
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But this may not always be possible, e.g. if
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selinuxfs isn't mounted. */
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if (security_check_context(*newcon) && errno != ENOENT) {
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free(*newcon);
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*newcon = 0;
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if (strcmp(user, SELINUX_DEFAULTUSER)) {
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user = SELINUX_DEFAULTUSER;
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goto retry;
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}
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return -1;
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}
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return 0;
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}
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struct context_order {
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security_context_t con;
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unsigned int order;
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};
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static int order_compare(const void *A, const void *B)
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{
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const struct context_order *c1 = A, *c2 = B;
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if (c1->order < c2->order)
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return -1;
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else if (c1->order > c2->order)
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return 1;
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return strcmp(c1->con, c2->con);
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}
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int get_ordered_context_list_with_level (const char *user,
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const char *level,
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security_context_t fromcon,
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security_context_t **list)
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{
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int rc;
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int freefrom = 0;
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context_t con;
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char *newfromcon;
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if (!level)
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return get_ordered_context_list (user, fromcon, list);
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if (!fromcon) {
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rc = getcon(&fromcon);
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if (rc < 0)
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return rc;
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freefrom = 1;
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}
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rc = -1;
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con=context_new(fromcon);
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if (!con)
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goto out;
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if (context_range_set(con, level))
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goto out;
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newfromcon = context_str(con);
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if (!newfromcon)
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goto out;
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rc = get_ordered_context_list (user, newfromcon, list);
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out:
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context_free(con);
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if (freefrom)
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freecon(fromcon);
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return rc;
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}
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hidden_def(get_ordered_context_list_with_level)
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int get_default_context_with_level(const char *user,
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const char *level,
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security_context_t fromcon,
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security_context_t *newcon)
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{
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security_context_t *conary;
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int rc;
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rc = get_ordered_context_list_with_level(user, level, fromcon, &conary);
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if (rc <= 0)
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return -1;
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*newcon = strdup(conary[0]);
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freeconary(conary);
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if (!(*newcon))
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return -1;
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return 0;
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}
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int get_ordered_context_list (const char *user,
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security_context_t fromcon,
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security_context_t **list)
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{
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security_context_t *reachable = NULL;
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unsigned int *ordering = NULL;
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struct context_order *co = NULL;
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char **ptr;
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int rc = 0;
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unsigned int nreach = 0, nordered = 0, freefrom = 0, i;
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FILE *fp;
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char *fname = NULL;
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size_t fname_len;
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const char *user_contexts_path = selinux_user_contexts_path();
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if (!fromcon) {
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/* Get the current context and use it for the starting context */
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rc = getcon(&fromcon);
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if (rc < 0)
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return rc;
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freefrom = 1;
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}
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/* Determine the set of reachable contexts for the user. */
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rc = security_compute_user(fromcon, user, &reachable);
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if (rc < 0) {
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/* Retry with the default SELinux user identity. */
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user = SELINUX_DEFAULTUSER;
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rc = security_compute_user(fromcon, user, &reachable);
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if (rc < 0)
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goto failsafe;
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}
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nreach = 0;
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for (ptr = reachable; *ptr; ptr++)
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nreach++;
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if (!nreach)
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goto failsafe;
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/* Initialize ordering array. */
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ordering = malloc(nreach * sizeof(unsigned int));
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if (!ordering)
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goto oom_order;
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for (i = 0; i < nreach; i++)
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ordering[i] = nreach;
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/* Determine the ordering to apply from the optional per-user config
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and from the global config. */
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fname_len = strlen(user_contexts_path) + strlen(user) + 2;
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fname = malloc(fname_len);
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if (!fname)
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goto oom_order;
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snprintf(fname, fname_len, "%s%s", user_contexts_path, user);
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fp = fopen(fname, "r");
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if (fp) {
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rc = get_context_order(fp, fromcon, reachable, nreach, ordering, &nordered);
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fclose(fp);
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if (rc < 0 && errno != ENOENT) {
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fprintf(stderr, "%s: error in processing configuration file %s\n", __FUNCTION__, fname);
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/* Fall through, try global config */
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}
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}
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free(fname);
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fp = fopen(selinux_default_context_path(), "r");
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if (fp) {
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rc = get_context_order(fp, fromcon, reachable, nreach, ordering, &nordered);
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fclose(fp);
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if (rc < 0 && errno != ENOENT) {
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fprintf(stderr, "%s: error in processing configuration file %s\n", __FUNCTION__, selinux_default_context_path());
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/* Fall through */
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}
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}
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/* Apply the ordering. */
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if (nordered) {
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co = malloc(nreach * sizeof(struct context_order));
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if (!co)
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goto oom_order;
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for (i = 0; i < nreach; i++) {
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co[i].con = reachable[i];
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co[i].order = ordering[i];
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}
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qsort(co, nreach, sizeof(struct context_order), order_compare);
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for (i = 0; i < nreach; i++)
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reachable[i] = co[i].con;
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free(co);
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}
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/* Return the ordered list.
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If we successfully ordered it, then only report the ordered entries
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to the caller. Otherwise, fall back to the entire reachable list. */
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if (nordered && nordered < nreach) {
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for (i = nordered; i < nreach; i++)
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free(reachable[i]);
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reachable[nordered] = NULL;
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rc = nordered;
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} else {
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rc = nreach;
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}
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out:
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*list = reachable;
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free(ordering);
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if (freefrom)
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freecon(fromcon);
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return rc;
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failsafe:
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/* Unable to determine a reachable context list, try to fall back to
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the "failsafe" context to at least permit root login
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for emergency recovery if possible. */
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freeconary(reachable);
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reachable = malloc(2*sizeof(security_context_t));
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if (!reachable) {
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rc = -1;
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goto out;
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}
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reachable[0] = reachable[1] = 0;
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rc = get_failsafe_context(user, &reachable[0]);
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if (rc < 0) {
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freeconary(reachable);
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reachable = NULL;
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goto out;
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}
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rc = 1; /* one context in the list */
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goto out;
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oom_order:
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/* Unable to order context list due to OOM condition.
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Fall back to unordered reachable context list. */
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fprintf(stderr, "%s: out of memory, unable to order list\n", __FUNCTION__);
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rc = nreach;
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goto out;
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}
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hidden_def(get_ordered_context_list)
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