selinux/libselinux/utils/sefcontext_compile.c

441 lines
10 KiB
C
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#include <ctype.h>
#include <errno.h>
#include <pcre.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <getopt.h>
#include <limits.h>
#include <selinux/selinux.h>
#include <sepol/sepol.h>
#include "../src/label_file.h"
const char *policy_file;
static int ctx_err;
static int validate_context(char **ctxp)
{
char *ctx = *ctxp;
if (policy_file && sepol_check_context(ctx) < 0) {
ctx_err = -1;
return ctx_err;
}
return 0;
}
static int process_file(struct selabel_handle *rec, const char *filename)
{
unsigned int line_num;
int rc;
char *line_buf = NULL;
size_t line_len = 0;
FILE *context_file;
const char *prefix = NULL;
context_file = fopen(filename, "r");
if (!context_file) {
fprintf(stderr, "Error opening %s: %s\n",
filename, strerror(errno));
return -1;
}
line_num = 0;
rc = 0;
while (getline(&line_buf, &line_len, context_file) > 0) {
rc = process_line(rec, filename, prefix, line_buf, ++line_num);
if (rc || ctx_err) {
/* With -p option need to check and fail if ctx err as
* process_line() context validation on Linux does not
* return an error, but does print the error line to
* stderr. Android will set both to error and print
* the error line. */
rc = -1;
goto out;
}
}
out:
free(line_buf);
fclose(context_file);
return rc;
}
/*
* File Format
*
* u32 - magic number
* u32 - version
* u32 - length of pcre version EXCLUDING nul
* char - pcre version string EXCLUDING nul
* u32 - number of stems
* ** Stems
* u32 - length of stem EXCLUDING nul
* char - stem char array INCLUDING nul
* u32 - number of regexs
* ** Regexes
* u32 - length of upcoming context INCLUDING nul
* char - char array of the raw context
* u32 - length of the upcoming regex_str
* char - char array of the original regex string including the stem.
* u32 - mode bits for >= SELINUX_COMPILED_FCONTEXT_MODE
* mode_t for <= SELINUX_COMPILED_FCONTEXT_PCRE_VERS
* s32 - stemid associated with the regex
* u32 - spec has meta characters
* u32 - The specs prefix_len if >= SELINUX_COMPILED_FCONTEXT_PREFIX_LEN
* u32 - data length of the pcre regex
* char - a bufer holding the raw pcre regex info
* u32 - data length of the pcre regex study daya
* char - a buffer holding the raw pcre regex study data
*/
static int write_binary_file(struct saved_data *data, int fd)
{
struct spec *specs = data->spec_arr;
FILE *bin_file;
size_t len;
uint32_t magic = SELINUX_MAGIC_COMPILED_FCONTEXT;
uint32_t section_len;
uint32_t i;
int rc;
bin_file = fdopen(fd, "w");
if (!bin_file) {
perror("fopen output_file");
exit(EXIT_FAILURE);
}
/* write some magic number */
len = fwrite(&magic, sizeof(uint32_t), 1, bin_file);
if (len != 1)
goto err;
/* write the version */
section_len = SELINUX_COMPILED_FCONTEXT_MAX_VERS;
len = fwrite(&section_len, sizeof(uint32_t), 1, bin_file);
if (len != 1)
goto err;
/* write the pcre version */
section_len = strlen(pcre_version());
len = fwrite(&section_len, sizeof(uint32_t), 1, bin_file);
if (len != 1)
goto err;
len = fwrite(pcre_version(), sizeof(char), section_len, bin_file);
if (len != section_len)
goto err;
/* write the number of stems coming */
section_len = data->num_stems;
len = fwrite(&section_len, sizeof(uint32_t), 1, bin_file);
if (len != 1)
goto err;
for (i = 0; i < section_len; i++) {
char *stem = data->stem_arr[i].buf;
uint32_t stem_len = data->stem_arr[i].len;
/* write the strlen (aka no nul) */
len = fwrite(&stem_len, sizeof(uint32_t), 1, bin_file);
if (len != 1)
goto err;
/* include the nul in the file */
stem_len += 1;
len = fwrite(stem, sizeof(char), stem_len, bin_file);
if (len != stem_len)
goto err;
}
/* write the number of regexes coming */
section_len = data->nspec;
len = fwrite(&section_len, sizeof(uint32_t), 1, bin_file);
if (len != 1)
goto err;
for (i = 0; i < section_len; i++) {
char *context = specs[i].lr.ctx_raw;
char *regex_str = specs[i].regex_str;
mode_t mode = specs[i].mode;
size_t prefix_len = specs[i].prefix_len;
int32_t stem_id = specs[i].stem_id;
pcre *re = specs[i].regex;
pcre_extra *sd = get_pcre_extra(&specs[i]);
uint32_t to_write;
size_t size;
/* length of the context string (including nul) */
to_write = strlen(context) + 1;
len = fwrite(&to_write, sizeof(uint32_t), 1, bin_file);
if (len != 1)
goto err;
/* original context strin (including nul) */
len = fwrite(context, sizeof(char), to_write, bin_file);
if (len != to_write)
goto err;
/* length of the original regex string (including nul) */
to_write = strlen(regex_str) + 1;
len = fwrite(&to_write, sizeof(uint32_t), 1, bin_file);
if (len != 1)
goto err;
/* original regex string */
len = fwrite(regex_str, sizeof(char), to_write, bin_file);
if (len != to_write)
goto err;
/* binary F_MODE bits */
to_write = mode;
len = fwrite(&to_write, sizeof(uint32_t), 1, bin_file);
if (len != 1)
goto err;
/* stem for this regex (could be -1) */
len = fwrite(&stem_id, sizeof(stem_id), 1, bin_file);
if (len != 1)
goto err;
/* does this spec have a metaChar? */
to_write = specs[i].hasMetaChars;
len = fwrite(&to_write, sizeof(to_write), 1, bin_file);
if (len != 1)
goto err;
/* For SELINUX_COMPILED_FCONTEXT_PREFIX_LEN */
to_write = prefix_len;
len = fwrite(&to_write, sizeof(to_write), 1, bin_file);
if (len != 1)
goto err;
/* determine the size of the pcre data in bytes */
rc = pcre_fullinfo(re, NULL, PCRE_INFO_SIZE, &size);
if (rc < 0)
goto err;
/* write the number of bytes in the pcre data */
to_write = size;
len = fwrite(&to_write, sizeof(uint32_t), 1, bin_file);
if (len != 1)
goto err;
/* write the actual pcre data as a char array */
len = fwrite(re, 1, to_write, bin_file);
if (len != to_write)
goto err;
/* determine the size of the pcre study info */
rc = pcre_fullinfo(re, sd, PCRE_INFO_STUDYSIZE, &size);
if (rc < 0)
goto err;
/* write the number of bytes in the pcre study data */
to_write = size;
len = fwrite(&to_write, sizeof(uint32_t), 1, bin_file);
if (len != 1)
goto err;
/* write the actual pcre study data as a char array */
len = fwrite(sd->study_data, 1, to_write, bin_file);
if (len != to_write)
goto err;
}
rc = 0;
out:
fclose(bin_file);
return rc;
err:
rc = -1;
goto out;
}
static void free_specs(struct saved_data *data)
{
struct spec *specs = data->spec_arr;
unsigned int num_entries = data->nspec;
unsigned int i;
for (i = 0; i < num_entries; i++) {
free(specs[i].lr.ctx_raw);
free(specs[i].lr.ctx_trans);
free(specs[i].regex_str);
free(specs[i].type_str);
pcre_free(specs[i].regex);
pcre_free_study(specs[i].sd);
}
free(specs);
num_entries = data->num_stems;
for (i = 0; i < num_entries; i++)
free(data->stem_arr[i].buf);
free(data->stem_arr);
memset(data, 0, sizeof(*data));
}
static void usage(const char *progname)
{
fprintf(stderr,
"usage: %s [-o out_file] [-p policy_file] fc_file\n"
"Where:\n\t"
"-o Optional file name of the PCRE formatted binary\n\t"
" file to be output. If not specified the default\n\t"
" will be fc_file with the .bin suffix appended.\n\t"
"-p Optional binary policy file that will be used to\n\t"
" validate contexts defined in the fc_file.\n\t"
"fc_file The text based file contexts file to be processed.\n",
progname);
exit(EXIT_FAILURE);
}
int main(int argc, char *argv[])
{
const char *path = NULL;
const char *out_file = NULL;
char stack_path[PATH_MAX + 1];
char *tmp = NULL;
int fd, rc, opt;
FILE *policy_fp = NULL;
struct stat buf;
struct selabel_handle *rec = NULL;
struct saved_data *data = NULL;
if (argc < 2)
usage(argv[0]);
while ((opt = getopt(argc, argv, "o:p:")) > 0) {
switch (opt) {
case 'o':
out_file = optarg;
break;
case 'p':
policy_file = optarg;
break;
default:
usage(argv[0]);
}
}
if (optind >= argc)
usage(argv[0]);
path = argv[optind];
if (stat(path, &buf) < 0) {
fprintf(stderr, "Can not stat: %s: %m\n", path);
exit(EXIT_FAILURE);
}
/* Open binary policy if supplied. */
if (policy_file) {
policy_fp = fopen(policy_file, "r");
if (!policy_fp) {
fprintf(stderr, "Failed to open policy: %s\n",
policy_file);
exit(EXIT_FAILURE);
}
if (sepol_set_policydb_from_file(policy_fp) < 0) {
fprintf(stderr, "Failed to load policy: %s\n",
policy_file);
fclose(policy_fp);
exit(EXIT_FAILURE);
}
}
/* Generate dummy handle for process_line() function */
rec = (struct selabel_handle *)calloc(1, sizeof(*rec));
if (!rec) {
fprintf(stderr, "Failed to calloc handle\n");
if (policy_fp)
fclose(policy_fp);
exit(EXIT_FAILURE);
}
rec->backend = SELABEL_CTX_FILE;
/* Need to set validation on to get the bin file generated by the
* process_line function, however as the bin file being generated
* may not be related to the currently loaded policy (that it
* would be validated against), then set callback to ignore any
* validation - unless the -p option is used in which case if an
* error is detected, the process will be aborted. */
rec->validating = 1;
selinux_set_callback(SELINUX_CB_VALIDATE,
(union selinux_callback)&validate_context);
data = (struct saved_data *)calloc(1, sizeof(*data));
if (!data) {
fprintf(stderr, "Failed to calloc saved_data\n");
free(rec);
if (policy_fp)
fclose(policy_fp);
exit(EXIT_FAILURE);
}
rec->data = data;
rc = process_file(rec, path);
if (rc < 0)
goto err;
rc = sort_specs(data);
if (rc)
goto err;
if (out_file)
rc = snprintf(stack_path, sizeof(stack_path), "%s", out_file);
else
rc = snprintf(stack_path, sizeof(stack_path), "%s.bin", path);
if (rc < 0 || rc >= (int)sizeof(stack_path))
goto err;
tmp = malloc(strlen(stack_path) + 7);
if (!tmp)
goto err;
rc = sprintf(tmp, "%sXXXXXX", stack_path);
if (rc < 0)
goto err;
fd = mkstemp(tmp);
if (fd < 0)
goto err;
rc = fchmod(fd, buf.st_mode);
if (rc < 0) {
perror("fchmod failed to set permission on compiled regexs");
goto err_unlink;
}
rc = write_binary_file(data, fd);
if (rc < 0)
goto err_unlink;
rc = rename(tmp, stack_path);
if (rc < 0)
goto err_unlink;
rc = 0;
out:
if (policy_fp)
fclose(policy_fp);
free_specs(data);
free(rec);
free(data);
free(tmp);
return rc;
err_unlink:
unlink(tmp);
err:
rc = -1;
goto out;
}