From 6e0654d20ed9679cbf75a0ff7cd786e364f7f09a Mon Sep 17 00:00:00 2001 From: John Johansen Date: Wed, 6 Sep 2017 14:57:59 -0700 Subject: apparmor: use the dfa to do label parse string splitting 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 Acked-by: Seth Arnold --- security/apparmor/include/label.h | 25 ++++++++ security/apparmor/include/match.h | 1 + security/apparmor/label.c | 12 ++-- security/apparmor/match.c | 29 ++++++++-- security/apparmor/stacksplitdfa.in | 114 +++++++++++++++++++++++++++++++++++++ 5 files changed, 170 insertions(+), 11 deletions(-) create mode 100644 security/apparmor/stacksplitdfa.in (limited to 'security') diff --git a/security/apparmor/include/label.h b/security/apparmor/include/label.h index af22dcbbcb8a..80e9ba9d172c 100644 --- a/security/apparmor/include/label.h +++ b/security/apparmor/include/label.h @@ -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, 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; int aa_label_match(struct aa_profile *profile, struct aa_label *label, diff --git a/security/apparmor/include/match.h b/security/apparmor/include/match.h index 72b9b89670e6..cd8aeab6ac57 100644 --- a/security/apparmor/include/match.h +++ b/security/apparmor/include/match.h @@ -101,6 +101,7 @@ struct aa_dfa { }; extern struct aa_dfa *nulldfa; +extern struct aa_dfa *stacksplitdfa; #define byte_to_byte(X) (X) diff --git a/security/apparmor/label.c b/security/apparmor/label.c index 324fe5c60f87..31e2f701d971 100644 --- a/security/apparmor/label.c +++ b/security/apparmor/label.c @@ -1815,7 +1815,9 @@ static int label_count_str_entries(const char *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++; str = split + 3; } @@ -1859,7 +1861,7 @@ struct aa_label *aa_label_parse(struct aa_label *base, const char *str, DEFINE_VEC(profile, vec); struct aa_label *label, *currbase = base; int i, len, stack = 0, error; - char *split; + const char *split; AA_BUG(!base); 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++) 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); if (!vec[i]) 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)) currbase = &vec[i]->label; str = split + 3; - split = strstr(str, "//&"); + split = aa_label_str_split(str); } /* last element doesn't have a split */ if (i < len) { @@ -1930,7 +1933,6 @@ fail: goto out; } - /** * aa_labelset_destroy - remove all labels from the label set * @ls: label set to cleanup (NOT NULL) diff --git a/security/apparmor/match.c b/security/apparmor/match.c index 6c6dc1a22f9a..5d95caeddebc 100644 --- a/security/apparmor/match.c +++ b/security/apparmor/match.c @@ -30,6 +30,11 @@ static char nulldfa_src[] = { }; struct aa_dfa *nulldfa; +static char stacksplitdfa_src[] = { + #include "stacksplitdfa.in" +}; +struct aa_dfa *stacksplitdfa; + int aa_setup_dfa_engine(void) { int error; @@ -37,19 +42,31 @@ int aa_setup_dfa_engine(void) nulldfa = aa_dfa_unpack(nulldfa_src, sizeof(nulldfa_src), TO_ACCEPT1_FLAG(YYTD_DATA32) | TO_ACCEPT2_FLAG(YYTD_DATA32)); - if (!IS_ERR(nulldfa)) - return 0; + if (IS_ERR(nulldfa)) { + error = PTR_ERR(nulldfa); + nulldfa = NULL; + return error; + } - error = PTR_ERR(nulldfa); - nulldfa = NULL; + stacksplitdfa = aa_dfa_unpack(stacksplitdfa_src, + 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) { + aa_put_dfa(stacksplitdfa); aa_put_dfa(nulldfa); - nulldfa = NULL; } /** diff --git a/security/apparmor/stacksplitdfa.in b/security/apparmor/stacksplitdfa.in new file mode 100644 index 000000000000..4bddd10b62a9 --- /dev/null +++ b/security/apparmor/stacksplitdfa.in @@ -0,0 +1,114 @@ +/* 0x1 [^\000]*[^/\000]//& */ 0x1B, 0x5E, 0x78, 0x3D, 0x00, 0x00, +0x00, 0x18, 0x00, 0x00, 0x04, 0xD8, 0x00, 0x00, 0x6E, 0x6F, 0x74, +0x66, 0x6C, 0x65, 0x78, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x04, +0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06, 0x00, 0x00, 0x00, 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