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apparmor: use the dfa to do label parse string splitting

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The current split scheme is actually wrong in that it splits
  ///&

where that is invalid and should fail. Use the dfa to do a proper
bounded split without having to worry about getting the string
processing right in code.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Seth Arnold <seth.arnold@canonical.com>
This commit is contained in:
John Johansen 2017-09-06 14:57:59 -07:00
parent cf65fabc2a
commit 6e0654d20e
5 changed files with 170 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
security/apparmor/include/label.h
View File

@ -330,6 +330,31 @@ void aa_label_printk(struct aa_label *label, gfp_t gfp);
struct aa_label *aa_label_parse(struct aa_label *base, const char *str, struct aa_label *aa_label_parse(struct aa_label *base, const char *str,
gfp_t gfp, bool create, bool force_stack); gfp_t gfp, bool create, bool force_stack);
static inline const char *aa_label_strn_split(const char *str, int n)
{
const char *pos;
unsigned int state;
state = aa_dfa_matchn_until(stacksplitdfa, DFA_START, str, n, &pos);
if (!ACCEPT_TABLE(stacksplitdfa)[state])
return NULL;
return pos - 3;
}
static inline const char *aa_label_str_split(const char *str)
{
const char *pos;
unsigned int state;
state = aa_dfa_match_until(stacksplitdfa, DFA_START, str, &pos);
if (!ACCEPT_TABLE(stacksplitdfa)[state])
return NULL;
return pos - 3;
}
struct aa_perms; struct aa_perms;
int aa_label_match(struct aa_profile *profile, struct aa_label *label, int aa_label_match(struct aa_profile *profile, struct aa_label *label,

1
security/apparmor/include/match.h
View File

@ -101,6 +101,7 @@ struct aa_dfa {
}; };
extern struct aa_dfa *nulldfa; extern struct aa_dfa *nulldfa;
extern struct aa_dfa *stacksplitdfa;
#define byte_to_byte(X) (X) #define byte_to_byte(X) (X)

12
security/apparmor/label.c
View File

@ -1815,7 +1815,9 @@ static int label_count_str_entries(const char *str)
AA_BUG(!str); AA_BUG(!str);
for (split = strstr(str, "//&"); split; split = strstr(str, "//&")) { for (split = aa_label_str_split(str);
split;
split = aa_label_str_split(str)) {
count++; count++;
str = split + 3; str = split + 3;
} }
@ -1859,7 +1861,7 @@ struct aa_label *aa_label_parse(struct aa_label *base, const char *str,
DEFINE_VEC(profile, vec); DEFINE_VEC(profile, vec);
struct aa_label *label, *currbase = base; struct aa_label *label, *currbase = base;
int i, len, stack = 0, error; int i, len, stack = 0, error;
char *split; const char *split;
AA_BUG(!base); AA_BUG(!base);
AA_BUG(!str); AA_BUG(!str);
@ -1883,7 +1885,8 @@ struct aa_label *aa_label_parse(struct aa_label *base, const char *str,
for (i = 0; i < stack; i++) for (i = 0; i < stack; i++)
vec[i] = aa_get_profile(base->vec[i]); vec[i] = aa_get_profile(base->vec[i]);
for (split = strstr(str, "//&"), i = stack; split && i < len; i++) { for (split = aa_label_str_split(str), i = stack;
split && i < len; i++) {
vec[i] = fqlookupn_profile(base, currbase, str, split - str); vec[i] = fqlookupn_profile(base, currbase, str, split - str);
if (!vec[i]) if (!vec[i])
goto fail; goto fail;
@ -1894,7 +1897,7 @@ struct aa_label *aa_label_parse(struct aa_label *base, const char *str,
if (vec[i]->ns != labels_ns(currbase)) if (vec[i]->ns != labels_ns(currbase))
currbase = &vec[i]->label; currbase = &vec[i]->label;
str = split + 3; str = split + 3;
split = strstr(str, "//&"); split = aa_label_str_split(str);
} }
/* last element doesn't have a split */ /* last element doesn't have a split */
if (i < len) { if (i < len) {
@ -1930,7 +1933,6 @@ fail:
goto out; goto out;
} }
/** /**
* aa_labelset_destroy - remove all labels from the label set * aa_labelset_destroy - remove all labels from the label set
* @ls: label set to cleanup (NOT NULL) * @ls: label set to cleanup (NOT NULL)

29
security/apparmor/match.c
View File

@ -30,6 +30,11 @@ static char nulldfa_src[] = {
}; };
struct aa_dfa *nulldfa; struct aa_dfa *nulldfa;
static char stacksplitdfa_src[] = {
#include "stacksplitdfa.in"
};
struct aa_dfa *stacksplitdfa;
int aa_setup_dfa_engine(void) int aa_setup_dfa_engine(void)
{ {
int error; int error;
@ -37,19 +42,31 @@ int aa_setup_dfa_engine(void)
nulldfa = aa_dfa_unpack(nulldfa_src, sizeof(nulldfa_src), nulldfa = aa_dfa_unpack(nulldfa_src, sizeof(nulldfa_src),
TO_ACCEPT1_FLAG(YYTD_DATA32) | TO_ACCEPT1_FLAG(YYTD_DATA32) |
TO_ACCEPT2_FLAG(YYTD_DATA32)); TO_ACCEPT2_FLAG(YYTD_DATA32));
if (!IS_ERR(nulldfa)) if (IS_ERR(nulldfa)) {
return 0; error = PTR_ERR(nulldfa);
nulldfa = NULL;
return error;
}
error = PTR_ERR(nulldfa); stacksplitdfa = aa_dfa_unpack(stacksplitdfa_src,
nulldfa = NULL; sizeof(stacksplitdfa_src),
TO_ACCEPT1_FLAG(YYTD_DATA32) |
TO_ACCEPT2_FLAG(YYTD_DATA32));
if (IS_ERR(stacksplitdfa)) {
aa_put_dfa(nulldfa);
nulldfa = NULL;
error = PTR_ERR(stacksplitdfa);
stacksplitdfa = NULL;
return error;
}
return error; return 0;
} }
void aa_teardown_dfa_engine(void) void aa_teardown_dfa_engine(void)
{ {
aa_put_dfa(stacksplitdfa);
aa_put_dfa(nulldfa); aa_put_dfa(nulldfa);
nulldfa = NULL;
} }
/** /**

114
security/apparmor/stacksplitdfa.in Normal file
View File

@ -0,0 +1,114 @@
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