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ifcfg-rh: fix up lowlevel ifcfg file reading code

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shvar.c was assuming it could do a single read() to read in the ifcfg
file, without taking partial reads or EINTR into account. Fix that.

Also, it was keeping the raw contents of the ifcfg file in the
shvarFile even though it never looked at it after svOpenFile().
(Presumably lineList originally consisted of pointers into arena, but
that had to be changed to support readwrite.) Fix that.

It would simplify things further to use g_file_get_contents() and
g_file_set_contents(), but the current code is perhaps more resilient
to symlink attacks because it keeps the fd open?
This commit is contained in:
Dan Winship 2014-03-17 13:32:18 -04:00
parent b104994078
commit 5bb45373d4
2 changed files with 15 additions and 7 deletions
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21
src/settings/plugins/ifcfg-rh/shvar.c
View file

@ -22,6 +22,7 @@
*
*/
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
@ -56,17 +57,27 @@ svOpenFile(const char *name, gboolean create)
if (s->fd != -1) {
struct stat buf;
char *p, *q;
char *arena, *p, *q;
ssize_t nread, total = 0;
if (fstat(s->fd, &buf) < 0) goto bail;
s->arena = g_malloc0(buf.st_size + 1);
arena = g_malloc(buf.st_size + 1);
arena[buf.st_size] = '\0';
if (read(s->fd, s->arena, buf.st_size) < 0) goto bail;
while (total < buf.st_size) {
nread = read(s->fd, arena + total, buf.st_size - total);
if (nread == -1 && errno == EINTR)
continue;
if (nread <= 0)
goto bail;
total += nread;
}
/* we'd use g_strsplit() here, but we want a list, not an array */
for(p = s->arena; (q = strchr(p, '\n')) != NULL; p = q + 1) {
for(p = arena; (q = strchr(p, '\n')) != NULL; p = q + 1) {
s->lineList = g_list_append(s->lineList, g_strndup(p, q - p));
}
g_free (arena);
/* closefd is set if we opened the file read-only, so go ahead and
close it, because we can't write to it anyway */
@ -84,7 +95,6 @@ svOpenFile(const char *name, gboolean create)
bail:
if (s->fd != -1) close(s->fd);
g_free (s->arena);
g_free (s->fileName);
g_free (s);
return NULL;
@ -374,7 +384,6 @@ svCloseFile(shvarFile *s)
if (s->fd != -1) close(s->fd);
g_free(s->arena);
g_free(s->fileName);
g_list_free_full (s->lineList, g_free); /* implicitly frees s->current */
g_free(s);

1
src/settings/plugins/ifcfg-rh/shvar.h
View file

@ -40,7 +40,6 @@ typedef struct _shvarFile shvarFile;
struct _shvarFile {
char *fileName; /* read-only */
int fd; /* read-only */
char *arena; /* ignore */
GList *lineList; /* read-only */
GList *current; /* set implicitly or explicitly,
points to element of lineList */