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selinux: rewrite selinux_sb_eat_lsm_opts() 

make it use selinux_add_opt() and avoid separate copies - gather
non-LSM options by memmove() in place

Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2018-12-14 21:56:23 -05:00
parent da3d76abb2
commit 99dbbb593f
1 changed files with 57 additions and 95 deletions
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152
security/selinux/hooks.c
View File

@ -2606,109 +2606,71 @@ static void selinux_sb_free_security(struct super_block *sb)
superblock_free_security(sb);
}
static inline int match_prefix(char *prefix, int plen, char *option, int olen)
static inline int opt_len(const char *s)
{
if (plen > olen)
return 0;
bool open_quote = false;
int len;
char c;
return !memcmp(prefix, option, plen);
}
static inline int selinux_option(char *option, int len)
{
return (match_prefix(CONTEXT_STR, sizeof(CONTEXT_STR)-1, option, len) ||
match_prefix(FSCONTEXT_STR, sizeof(FSCONTEXT_STR)-1, option, len) ||
match_prefix(DEFCONTEXT_STR, sizeof(DEFCONTEXT_STR)-1, option, len) ||
match_prefix(ROOTCONTEXT_STR, sizeof(ROOTCONTEXT_STR)-1, option, len) ||
match_prefix(LABELSUPP_STR, sizeof(LABELSUPP_STR)-1, option, len));
}
static inline void take_option(char **to, char *from, int *first, int len)
{
if (!*first) {
**to = ',';
*to += 1;
} else
*first = 0;
memcpy(*to, from, len);
*to += len;
}
static inline void take_selinux_option(char **to, char *from, int *first,
int len)
{
int current_size = 0;
if (!*first) {
**to = '|';
*to += 1;
} else
*first = 0;
while (current_size < len) {
if (*from != '"') {
**to = *from;
*to += 1;
}
from += 1;
current_size += 1;
}
}
static int selinux_sb_copy_data(char *orig, char *copy)
{
int fnosec, fsec, rc = 0;
char *in_save, *in_curr, *in_end;
char *sec_curr, *nosec_save, *nosec;
int open_quote = 0;
in_curr = orig;
sec_curr = copy;
nosec = (char *)get_zeroed_page(GFP_KERNEL);
if (!nosec) {
rc = -ENOMEM;
goto out;
}
nosec_save = nosec;
fnosec = fsec = 1;
in_save = in_end = orig;
do {
if (*in_end == '"')
for (len = 0; (c = s[len]) != '\0'; len++) {
if (c == '"')
open_quote = !open_quote;
if ((*in_end == ',' && open_quote == 0) ||
*in_end == '\0') {
int len = in_end - in_curr;
if (selinux_option(in_curr, len))
take_selinux_option(&sec_curr, in_curr, &fsec, len);
else
take_option(&nosec, in_curr, &fnosec, len);
in_curr = in_end + 1;
}
} while (*in_end++);
strcpy(in_save, nosec_save);
free_page((unsigned long)nosec_save);
out:
return rc;
if (c == ',' && !open_quote)
break;
}
return len;
}
static int selinux_sb_eat_lsm_opts(char *options, void **mnt_opts)
{
char *s = (char *)get_zeroed_page(GFP_KERNEL);
int err;
char *from = options;
char *to = options;
bool first = true;
if (!s)
return -ENOMEM;
err = selinux_sb_copy_data(options, s);
if (!err)
err = selinux_parse_opts_str(s, mnt_opts);
free_page((unsigned long)s);
return err;
while (1) {
int len = opt_len(from);
int token, rc;
char *arg = NULL;
token = match_opt_prefix(from, len, &arg);
if (token != Opt_error) {
char *p, *q;
/* strip quotes */
if (arg) {
for (p = q = arg; p < from + len; p++) {
char c = *p;
if (c != '"')
*q++ = c;
}
arg = kmemdup_nul(arg, q - arg, GFP_KERNEL);
}
rc = selinux_add_opt(token, arg, mnt_opts);
if (unlikely(rc)) {
kfree(arg);
if (*mnt_opts) {
selinux_free_mnt_opts(*mnt_opts);
*mnt_opts = NULL;
}
return rc;
}
} else {
if (!first) { // copy with preceding comma
from--;
len++;
}
if (to != from)
memmove(to, from, len);
to += len;
first = false;
}
if (!from[len])
break;
from += len + 1;
}
*to = '\0';
return 0;
}
static int selinux_sb_remount(struct super_block *sb, void *mnt_opts)