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libselinux: Fix binary file labels for regexes with metachars 

File labels assigned using the lookup_best_match() function do not
assign the best match if its regex contains metacharacters in the
binary file_contexts file version.

This change adds a new entry in the binary file with the calculated
prefix length that is then read when processing the file. This fix
also bumps SELINUX_COMPILED_FCONTEXT_MAX_VERS.

This patch relies on patch [1] that fixes the same problem
for text based file_contexts files.

[1] http://marc.info/?l=selinux&m=143576498713964&w=2

Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>
This commit is contained in:
Richard Haines 2015-07-04 11:57:09 +01:00 committed by Stephen Smalley
parent de41db98e4
commit f309a0e88c
3 changed files with 20 additions and 2 deletions
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11
libselinux/src/label_file.c
View File

@ -261,7 +261,7 @@ static int load_mmap(struct selabel_handle *rec, const char *path,
for (i = 0; i < regex_array_len; i++) {
struct spec *spec;
int32_t stem_id, meta_chars;
uint32_t mode = 0;
uint32_t mode = 0, prefix_len = 0;
rc = grow_specs(data);
if (rc < 0)
@ -337,6 +337,15 @@ static int load_mmap(struct selabel_handle *rec, const char *path,
goto err;
spec->hasMetaChars = meta_chars;
/* and prefix length for use by selabel_lookup_best_match */
if (version >= SELINUX_COMPILED_FCONTEXT_PREFIX_LEN) {
rc = next_entry(&prefix_len, mmap_area,
sizeof(uint32_t));
if (rc < 0)
goto err;
spec->prefix_len = prefix_len;
}
/* Process regex and study_data entries */
rc = next_entry(&entry_len, mmap_area, sizeof(uint32_t));

3
libselinux/src/label_file.h
View File

@ -12,8 +12,9 @@
#define SELINUX_COMPILED_FCONTEXT_NOPCRE_VERS 1
#define SELINUX_COMPILED_FCONTEXT_PCRE_VERS 2
#define SELINUX_COMPILED_FCONTEXT_MODE 3
#define SELINUX_COMPILED_FCONTEXT_PREFIX_LEN 4
#define SELINUX_COMPILED_FCONTEXT_MAX_VERS SELINUX_COMPILED_FCONTEXT_MODE
#define SELINUX_COMPILED_FCONTEXT_MAX_VERS SELINUX_COMPILED_FCONTEXT_PREFIX_LEN
/* Prior to version 8.20, libpcre did not have pcre_free_study() */
#if (PCRE_MAJOR < 8 || (PCRE_MAJOR == 8 && PCRE_MINOR < 20))

8
libselinux/utils/sefcontext_compile.c
View File

@ -68,6 +68,7 @@ out:
* 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
@ -141,6 +142,7 @@ static int write_binary_file(struct saved_data *data, int fd)
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]);
@ -186,6 +188,12 @@ static int write_binary_file(struct saved_data *data, int fd)
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)