| Message ID | 1370745294-19933-1-git-send-email-famz@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Sun, Jun 09, 2013 at 10:34:54AM +0800, Fam Zheng wrote: > @@ -110,14 +111,14 @@ static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action, > return 0; > } > > -static size_t curl_size_cb(void *ptr, size_t size, size_t nmemb, void *opaque) > +static size_t curl_header_cb(void *ptr, size_t size, size_t nmemb, void *opaque) > { > - CURLState *s = ((CURLState*)opaque); > + BDRVCURLState *s = opaque; > size_t realsize = size * nmemb; > - size_t fsize; > + const char *accept_line = "Accept-Ranges: bytes"; > > - if(sscanf(ptr, "Content-Length: %zd", &fsize) == 1) { > - s->s->len = fsize; > + if (strncmp((char *)ptr, accept_line, strlen(accept_line)) == 0) { > + s->accept_range = true; > } This still assumes ptr is NUL-terminated. You need to pass size * nmemb instead of strlen(accept_line).
On Mon, Jun 10, 2013 at 5:21 PM, Stefan Hajnoczi <stefanha@gmail.com> wrote: > On Sun, Jun 09, 2013 at 10:34:54AM +0800, Fam Zheng wrote: >> @@ -110,14 +111,14 @@ static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action, >> return 0; >> } >> >> -static size_t curl_size_cb(void *ptr, size_t size, size_t nmemb, void *opaque) >> +static size_t curl_header_cb(void *ptr, size_t size, size_t nmemb, void *opaque) >> { >> - CURLState *s = ((CURLState*)opaque); >> + BDRVCURLState *s = opaque; >> size_t realsize = size * nmemb; >> - size_t fsize; >> + const char *accept_line = "Accept-Ranges: bytes"; >> >> - if(sscanf(ptr, "Content-Length: %zd", &fsize) == 1) { >> - s->s->len = fsize; >> + if (strncmp((char *)ptr, accept_line, strlen(accept_line)) == 0) { >> + s->accept_range = true; >> } > > This still assumes ptr is NUL-terminated. You need to pass size * nmemb > instead of strlen(accept_line). > OK, the case is so corner, only when : - realsize < strlen(accept_line) and - ptr is the first part of accept_line, without NUL-termination strncpm will possibly access no more than (strlen(accept_line) - realsize) bytes after ptr buffer. I'll need to check if realsize >= strlen(accept_line), not passing realsize.
On Tue, Jun 11, 2013 at 11:15:15AM +0800, Fam Zheng wrote: > On Mon, Jun 10, 2013 at 5:21 PM, Stefan Hajnoczi <stefanha@gmail.com> wrote: > > On Sun, Jun 09, 2013 at 10:34:54AM +0800, Fam Zheng wrote: > >> @@ -110,14 +111,14 @@ static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action, > >> return 0; > >> } > >> > >> -static size_t curl_size_cb(void *ptr, size_t size, size_t nmemb, void *opaque) > >> +static size_t curl_header_cb(void *ptr, size_t size, size_t nmemb, void *opaque) > >> { > >> - CURLState *s = ((CURLState*)opaque); > >> + BDRVCURLState *s = opaque; > >> size_t realsize = size * nmemb; > >> - size_t fsize; > >> + const char *accept_line = "Accept-Ranges: bytes"; > >> > >> - if(sscanf(ptr, "Content-Length: %zd", &fsize) == 1) { > >> - s->s->len = fsize; > >> + if (strncmp((char *)ptr, accept_line, strlen(accept_line)) == 0) { > >> + s->accept_range = true; > >> } > > > > This still assumes ptr is NUL-terminated. You need to pass size * nmemb > > instead of strlen(accept_line). > > > OK, the case is so corner, only when : > - realsize < strlen(accept_line) and > - ptr is the first part of accept_line, without NUL-termination > strncpm will possibly access no more than (strlen(accept_line) - > realsize) bytes after ptr buffer. > > I'll need to check if realsize >= strlen(accept_line), not passing realsize. You can just pass size * nmemb because strncmp() does check for NUL in both strings. Therefore strlen(accept_line) is not needed - you know accept_line is NUL-terminated. Stefan
Am 11.06.2013 um 09:40 hat Stefan Hajnoczi geschrieben: > On Tue, Jun 11, 2013 at 11:15:15AM +0800, Fam Zheng wrote: > > On Mon, Jun 10, 2013 at 5:21 PM, Stefan Hajnoczi <stefanha@gmail.com> wrote: > > > On Sun, Jun 09, 2013 at 10:34:54AM +0800, Fam Zheng wrote: > > >> @@ -110,14 +111,14 @@ static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action, > > >> return 0; > > >> } > > >> > > >> -static size_t curl_size_cb(void *ptr, size_t size, size_t nmemb, void *opaque) > > >> +static size_t curl_header_cb(void *ptr, size_t size, size_t nmemb, void *opaque) > > >> { > > >> - CURLState *s = ((CURLState*)opaque); > > >> + BDRVCURLState *s = opaque; > > >> size_t realsize = size * nmemb; > > >> - size_t fsize; > > >> + const char *accept_line = "Accept-Ranges: bytes"; > > >> > > >> - if(sscanf(ptr, "Content-Length: %zd", &fsize) == 1) { > > >> - s->s->len = fsize; > > >> + if (strncmp((char *)ptr, accept_line, strlen(accept_line)) == 0) { > > >> + s->accept_range = true; > > >> } > > > > > > This still assumes ptr is NUL-terminated. You need to pass size * nmemb > > > instead of strlen(accept_line). > > > > > OK, the case is so corner, only when : > > - realsize < strlen(accept_line) and > > - ptr is the first part of accept_line, without NUL-termination > > strncpm will possibly access no more than (strlen(accept_line) - > > realsize) bytes after ptr buffer. > > > > I'll need to check if realsize >= strlen(accept_line), not passing realsize. > > You can just pass size * nmemb because strncmp() does check for NUL in > both strings. Therefore strlen(accept_line) is not needed - you know > accept_line is NUL-terminated. Don't you just want to check that ptr _starts_ with accept_line rather than requiring an exact match? Kevin
On Tue, 06/11 09:40, Stefan Hajnoczi wrote: > On Tue, Jun 11, 2013 at 11:15:15AM +0800, Fam Zheng wrote: > > On Mon, Jun 10, 2013 at 5:21 PM, Stefan Hajnoczi <stefanha@gmail.com> wrote: > > > On Sun, Jun 09, 2013 at 10:34:54AM +0800, Fam Zheng wrote: > > >> @@ -110,14 +111,14 @@ static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action, > > >> return 0; > > >> } > > >> > > >> -static size_t curl_size_cb(void *ptr, size_t size, size_t nmemb, void *opaque) > > >> +static size_t curl_header_cb(void *ptr, size_t size, size_t nmemb, void *opaque) > > >> { > > >> - CURLState *s = ((CURLState*)opaque); > > >> + BDRVCURLState *s = opaque; > > >> size_t realsize = size * nmemb; > > >> - size_t fsize; > > >> + const char *accept_line = "Accept-Ranges: bytes"; > > >> > > >> - if(sscanf(ptr, "Content-Length: %zd", &fsize) == 1) { > > >> - s->s->len = fsize; > > >> + if (strncmp((char *)ptr, accept_line, strlen(accept_line)) == 0) { > > >> + s->accept_range = true; > > >> } > > > > > > This still assumes ptr is NUL-terminated. You need to pass size * nmemb > > > instead of strlen(accept_line). > > > > > OK, the case is so corner, only when : > > - realsize < strlen(accept_line) and > > - ptr is the first part of accept_line, without NUL-termination > > strncpm will possibly access no more than (strlen(accept_line) - > > realsize) bytes after ptr buffer. > > > > I'll need to check if realsize >= strlen(accept_line), not passing realsize. > > You can just pass size * nmemb because strncmp() does check for NUL in > both strings. Therefore strlen(accept_line) is not needed - you know > accept_line is NUL-terminated. > No, e.g. size * nmemb is 5, and *ptr is "Conte", passing size * nmemb to strncmp gets zero. We need to: * Ensure size * nmemb is no less than needed * Only compare needed, not whole (first strlen(accept_line) bytes).
On Thu, Jun 13, 2013 at 4:13 AM, Fam Zheng <famz@redhat.com> wrote: > On Tue, 06/11 09:40, Stefan Hajnoczi wrote: >> On Tue, Jun 11, 2013 at 11:15:15AM +0800, Fam Zheng wrote: >> > On Mon, Jun 10, 2013 at 5:21 PM, Stefan Hajnoczi <stefanha@gmail.com> wrote: >> > > On Sun, Jun 09, 2013 at 10:34:54AM +0800, Fam Zheng wrote: >> > >> @@ -110,14 +111,14 @@ static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action, >> > >> return 0; >> > >> } >> > >> >> > >> -static size_t curl_size_cb(void *ptr, size_t size, size_t nmemb, void *opaque) >> > >> +static size_t curl_header_cb(void *ptr, size_t size, size_t nmemb, void *opaque) >> > >> { >> > >> - CURLState *s = ((CURLState*)opaque); >> > >> + BDRVCURLState *s = opaque; >> > >> size_t realsize = size * nmemb; >> > >> - size_t fsize; >> > >> + const char *accept_line = "Accept-Ranges: bytes"; >> > >> >> > >> - if(sscanf(ptr, "Content-Length: %zd", &fsize) == 1) { >> > >> - s->s->len = fsize; >> > >> + if (strncmp((char *)ptr, accept_line, strlen(accept_line)) == 0) { >> > >> + s->accept_range = true; >> > >> } >> > > >> > > This still assumes ptr is NUL-terminated. You need to pass size * nmemb >> > > instead of strlen(accept_line). >> > > >> > OK, the case is so corner, only when : >> > - realsize < strlen(accept_line) and >> > - ptr is the first part of accept_line, without NUL-termination >> > strncpm will possibly access no more than (strlen(accept_line) - >> > realsize) bytes after ptr buffer. >> > >> > I'll need to check if realsize >= strlen(accept_line), not passing realsize. >> >> You can just pass size * nmemb because strncmp() does check for NUL in >> both strings. Therefore strlen(accept_line) is not needed - you know >> accept_line is NUL-terminated. >> > > No, e.g. size * nmemb is 5, and *ptr is "Conte", passing size * nmemb to > strncmp gets zero. We need to: > * Ensure size * nmemb is no less than needed That's true, it would match "Accept-". The libcurl docs do say that only complete headers are provided but the server could return junk so we need to be careful.
diff --git a/block/curl.c b/block/curl.c index b8935fd..b46de69 100644 --- a/block/curl.c +++ b/block/curl.c @@ -81,6 +81,7 @@ typedef struct BDRVCURLState { CURLState states[CURL_NUM_STATES]; char *url; size_t readahead_size; + bool accept_range; } BDRVCURLState; static void curl_clean_state(CURLState *s); @@ -110,14 +111,14 @@ static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action, return 0; } -static size_t curl_size_cb(void *ptr, size_t size, size_t nmemb, void *opaque) +static size_t curl_header_cb(void *ptr, size_t size, size_t nmemb, void *opaque) { - CURLState *s = ((CURLState*)opaque); + BDRVCURLState *s = opaque; size_t realsize = size * nmemb; - size_t fsize; + const char *accept_line = "Accept-Ranges: bytes"; - if(sscanf(ptr, "Content-Length: %zd", &fsize) == 1) { - s->s->len = fsize; + if (strncmp((char *)ptr, accept_line, strlen(accept_line)) == 0) { + s->accept_range = true; } return realsize; @@ -441,8 +442,11 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags) // Get file size + s->accept_range = false; curl_easy_setopt(state->curl, CURLOPT_NOBODY, 1); - curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION, (void *)curl_size_cb); + curl_easy_setopt(state->curl, CURLOPT_HEADERFUNCTION, + curl_header_cb); + curl_easy_setopt(state->curl, CURLOPT_HEADERDATA, s); if (curl_easy_perform(state->curl)) goto out; curl_easy_getinfo(state->curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &d); @@ -452,6 +456,12 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags) s->len = (size_t)d; else if(!s->len) goto out; + if ((!strncasecmp(s->url, "http://", strlen("http://")) + || !strncasecmp(s->url, "https://", strlen("https://"))) + && !s->accept_range) { + pstrcpy(state->errmsg, CURL_ERROR_SIZE, "Server not supporting range."); + goto out; + } DPRINTF("CURL: Size = %zd\n", s->len); curl_clean_state(state);
CURL driver requests partial data from server on guest IO req. For HTTP and HTTPS, it uses "Range: ***" in requests, and this will not work if server not accepting range. This patch does this check when open. * Removed curl_size_cb, which is not used: On one hand it's registered to libcurl as CURLOPT_WRITEFUNCTION, instead of CURLOPT_HEADERFUNCTION, which will get called with *data*, not *header*. On the other hand the s->len is assigned unconditionally later. In this gone function, the sscanf for "Content-Length: %zd", on (void *)ptr, which is not guaranteed to be zero-terminated, is potentially a security bug. So this patch fixes it as a side-effect. The bug is reported as: https://bugs.launchpad.net/qemu/+bug/1188943 (Note the bug is marked "private" so you might not be able to see it) * Introduced curl_header_cb, which is used to parse header and mark the server as accepting range if "Accept-Ranges: bytes" line is seen from response header. If protocol is HTTP or HTTPS, but server response has no not this support, refuse to open this URL. Note that python builtin module SimpleHTTPServer is an example of not supporting range, if you need to test this driver, get a better server or use internet URLs. Cc: "Richard W.M. Jones" <rjones@redhat.com> Signed-off-by: Fam Zheng <famz@redhat.com> --- block/curl.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)