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imapd: track characters used in IMAP tags #5055

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imapd: track characters used in IMAP tags #5055

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2f94fec
imapd: track characters used in IMAP tags
elliefm Sep 25, 2024
1867d90
imapd: log all unusual tags
elliefm Sep 25, 2024
5292501
imapd: log unusual tags at LOG_INFO not LOG_DEBUG
elliefm Nov 3, 2024
e176ec1
imapd: counter for single dot tags, not unusual
elliefm Nov 3, 2024
2ba2745
imapd: better differentiate exclusive/inclusive tag behaviours
elliefm Nov 4, 2024
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150 changes: 148 additions & 2 deletions imap/imapd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -891,7 +891,10 @@ static void imapd_log_client_behavior(void)
"%s%s%s%s"
"%s%s%s%s"
"%s%s%s%s"
"%s%s",
"%s%s"
"%s%s%s%s%s%s"
"%s%s%s%s%s%s"
"%s%s%s%s%s",

session_id(),
imapd_userid ? imapd_userid : "",
Expand Down Expand Up @@ -925,7 +928,27 @@ static void imapd_log_client_behavior(void)
client_behavior.did_unselect ? " unselect=<1>" : "",

client_behavior.did_utf8_accept ? " utf8_accept=<1>" : "",
client_behavior.did_xlist ? " xlist=<1>" : "");
client_behavior.did_xlist ? " xlist=<1>" : "",

client_behavior.did_tag_only_num ? " tag_only_num=<1>" : "",
client_behavior.did_tag_only_alpha ? " tag_only_alpha=<1>" : "",
client_behavior.did_tag_only_alnum ? " tag_only_alnum=<1>" : "",
client_behavior.did_tag_only_alnumdot? " tag_only_alnumdot=<1>" : "",
client_behavior.did_tag_only_base64 ? " tag_only_base64=<1>" : "",
client_behavior.did_tag_only_onedot ? " tag_only_onedot=<1>" : "",

client_behavior.did_tag_num ? " tag_num=<1>" : "",
client_behavior.did_tag_alpha ? " tag_alpha=<1>" : "",
client_behavior.did_tag_dot ? " tag_dot=<1>" : "",
client_behavior.did_tag_sep ? " tag_sep=<1>" : "",
client_behavior.did_tag_colon ? " tag_colon=<1>" : "",
client_behavior.did_tag_angle ? " tag_angle=<1>" : "",

client_behavior.did_tag_base64 ? " tag_bases64=<1>" : "",
client_behavior.did_tag_other ? " tag_other=<1>" : "",
client_behavior.did_tag_POST ? " tag_POST=<1>" : "",
client_behavior.did_tag_PUT ? " tag_PUT=<1>" : "",
client_behavior.did_tag_inv ? " tag_inv=<1>" : "");
}

static void imapd_reset(void)
Expand Down Expand Up @@ -1473,6 +1496,127 @@ static void imapd_check(struct backend *be, unsigned tell_flags)
}
}

static void record_client_tag_behaviour(const char *tag)
{
#define TAG_SAW_NUM (1<<0)
#define TAG_SAW_ALPHA (1<<1)
#define TAG_SAW_DOT (1<<2)
#define TAG_SAW_ANGLE (1<<3)
#define TAG_SAW_SEP (1<<4)
#define TAG_SAW_COLON (1<<5)
#define TAG_SAW_B64EXTRA (1<<6)
#define TAG_SAW_OTHER (1<<31)

#define TAG_BASE64 (TAG_SAW_NUM | TAG_SAW_ALPHA \
| TAG_SAW_SEP | TAG_SAW_B64EXTRA)
uint32_t saw = 0;
const char *p;

/* whole string checks */
if (strcmp(tag, "POST") == 0) {
client_behavior.did_tag_POST = 1;
client_behavior.did_tag_only_alpha = 1;
return;
}
else if (strcmp(tag, "PUT") == 0) {
client_behavior.did_tag_PUT = 1;
client_behavior.did_tag_only_alpha = 1;
return;
}

/* collect character classes */
for (p = tag; p && *p; p++) {
if (*p >= '0' && *p <= '9') {
saw |= TAG_SAW_NUM;
}
else if ((*p >= 'a' && *p <= 'z') || (*p >= 'A' && *p <= 'Z')) {
saw |= TAG_SAW_ALPHA;
}
else if (*p == '.') {
saw |= TAG_SAW_DOT;
}
else if (*p == '<' || *p == '>') {
saw |= TAG_SAW_ANGLE;
}
else if (*p == '-' || *p == '_') {
saw |= TAG_SAW_SEP;
}
else if (*p == ':') {
saw |= TAG_SAW_COLON;
}
else if (*p == '+' || *p == '/' || *p == ',' || *p == '=') {
saw |= TAG_SAW_B64EXTRA;
}
else {
saw |= TAG_SAW_OTHER;
}
}

/* exclusive checks */
if (saw == TAG_SAW_NUM) {
client_behavior.did_tag_only_num = 1;
return;
}
else if (saw == TAG_SAW_ALPHA) {
client_behavior.did_tag_only_alpha = 1;
return;
}
else if (saw == TAG_SAW_DOT && !tag[1]) {
client_behavior.did_tag_only_onedot = 1;
return;
}
else if (saw == (TAG_SAW_NUM | TAG_SAW_ALPHA)) {
client_behavior.did_tag_only_alnum = 1;
return;
}
else if ((saw & (TAG_SAW_NUM | TAG_SAW_ALPHA))
&& (saw & ~(TAG_SAW_NUM | TAG_SAW_ALPHA | TAG_SAW_DOT)) == 0)
{
client_behavior.did_tag_only_alnumdot = 1;
return;
}
else if (saw && (saw & ~TAG_BASE64) == 0) {
client_behavior.did_tag_only_base64 = 1;
return;
}

/* if we haven't returned yet there's some odd stuff in there */
xsyslog(LOG_INFO, "saw an unusual tag", "tag=<%s>", tag);

/* inclusive checks */
if ((saw & TAG_SAW_NUM)) {
client_behavior.did_tag_num = 1;
}

if ((saw & TAG_SAW_ALPHA)) {
client_behavior.did_tag_alpha = 1;
}

if ((saw & TAG_SAW_DOT)) {
client_behavior.did_tag_dot = 1;
}

if ((saw & TAG_SAW_SEP)) {
client_behavior.did_tag_sep = 1;
}

if ((saw & TAG_SAW_COLON)) {
client_behavior.did_tag_colon = 1;
}

if ((saw & TAG_SAW_ANGLE)) {
client_behavior.did_tag_angle = 1;
}

if ((saw & TAG_SAW_B64EXTRA)) {
client_behavior.did_tag_base64 = 1;
}

if ((saw & TAG_SAW_OTHER)) {
client_behavior.did_tag_other = 1;
}
}

#define IS_EOL(c, pin) ((c = (c == '\r') ? prot_getc(pin) : c) == '\n')

/*
Expand Down Expand Up @@ -1590,10 +1734,12 @@ static void cmdloop(void)
goto done;
}
if (c != ' ' || !imparse_isatom(tag.s) || (tag.s[0] == '*' && !tag.s[1])) {
client_behavior.did_tag_inv = 1;
prot_printf(imapd_out, "* BAD Invalid tag\r\n");
eatline(imapd_in, c);
continue;
}
record_client_tag_behaviour(buf_cstring(&tag));

/* Parse command name */
c = getword(imapd_in, &cmd);
Expand Down
19 changes: 19 additions & 0 deletions imap/imapd.h
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Original file line number Diff line number Diff line change
Expand Up @@ -474,6 +474,25 @@ struct client_behavior_registry {

/* non-standard - track for possible deprecation */
uint32_t did_xlist : 1; /* used XLIST */

/* what kinds of tags is this client using? */
uint32_t did_tag_only_num : 1; /* only numbers */
uint32_t did_tag_only_alpha : 1; /* only letters */
uint32_t did_tag_only_alnum : 1; /* only numbers and letters */
uint32_t did_tag_only_alnumdot : 1; /* only numbers, letters, and dots */
uint32_t did_tag_only_base64 : 1; /* only base64 characters */
uint32_t did_tag_only_onedot : 1; /* single dot */
uint32_t did_tag_num : 1; /* tags contain numbers */
uint32_t did_tag_alpha : 1; /* tags contain letters */
uint32_t did_tag_dot : 1; /* tags contain dots */
uint32_t did_tag_sep : 1; /* tags contain - or _ */
uint32_t did_tag_colon : 1; /* tags contain : */
uint32_t did_tag_angle : 1; /* tags contain < or > */
uint32_t did_tag_base64 : 1; /* tags contains base64 punc characters */
uint32_t did_tag_other : 1; /* tags contains other characters */
uint32_t did_tag_POST : 1; /* used string "POST" as a tag */
uint32_t did_tag_PUT : 1; /* used string "PUT" as a tag */
uint32_t did_tag_inv : 1; /* we rejected an invalid tag */
};

#endif /* INCLUDED_IMAPD_H */