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Use pread(2) and pwrite(2) where possible.

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This commit is contained in:
Todd C. Miller
2015-09-07 06:06:08 -06:00
parent 70914b3328
commit 7d0a623fdd
5 changed files with 50 additions and 22 deletions
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52
plugins/sudoers/timestamp.c
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@@ -61,8 +61,6 @@
* The TS_LOCKEXCL entry must be unlocked before locking the actual record.
*/
/* TODO: use pread/pwrite when possible */
struct ts_cookie {
char *fname;
int fd;
@@ -274,14 +272,29 @@ ts_open(const char *path, int flags)
}
static ssize_t
ts_write(int fd, const char *fname, struct timestamp_entry *entry)
ts_write(int fd, const char *fname, struct timestamp_entry *entry, off_t offset)
{
ssize_t nwritten;
off_t old_eof;
debug_decl(ts_write, SUDOERS_DEBUG_AUTH)
old_eof = lseek(fd, (off_t)0, SEEK_CUR);
nwritten = write(fd, entry, entry->size);
if (offset == -1) {
old_eof = lseek(fd, 0, SEEK_CUR);
nwritten = write(fd, entry, entry->size);
} else {
old_eof = offset;
#ifdef HAVE_PWRITE
nwritten = pwrite(fd, entry, entry->size, offset);
#else
if (lseek(fd, offset, SEEK_SET) == -1) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO|SUDO_DEBUG_LINENO,
"unable to seek to %lld", offset);
nwritten = -1;
} else {
nwritten = write(fd, entry, entry->size);
}
#endif
}
if ((size_t)nwritten != entry->size) {
if (nwritten == -1) {
log_warning(SLOG_SEND_MAIL,
@@ -500,12 +513,16 @@ ts_read(struct ts_cookie *cookie, struct timestamp_entry *entry)
}
/* Seek to the record position and read it. */
#ifdef HAVE_PREAD
nread = pread(cookie->fd, entry, sizeof(*entry), cookie->pos);
#else
if (lseek(cookie->fd, cookie->pos, SEEK_SET) == -1) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO|SUDO_DEBUG_LINENO,
"unable to seek to %lld", (long long)cookie->pos);
goto done;
}
nread = read(cookie->fd, entry, sizeof(*entry));
#endif
if (nread != sizeof(*entry)) {
/* short read, should not happen */
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
@@ -559,14 +576,14 @@ timestamp_lock(void *vcookie, struct passwd *pw)
entry.version = TS_VERSION;
entry.size = sizeof(entry);
entry.type = TS_LOCKEXCL;
if (ts_write(cookie->fd, cookie->fname, &entry) == -1)
if (ts_write(cookie->fd, cookie->fname, &entry, -1) == -1)
debug_return_bool(false);
} else if (entry.type != TS_LOCKEXCL) {
/* Old sudo record, convert it to TS_LOCKEXCL. */
entry.type = TS_LOCKEXCL;
memset((char *)&entry + offsetof(struct timestamp_entry, type), 0,
nread - offsetof(struct timestamp_entry, type));
if (ts_write(cookie->fd, cookie->fname, &entry) == -1)
if (ts_write(cookie->fd, cookie->fname, &entry, 0) == -1)
debug_return_bool(false);
}
@@ -582,7 +599,7 @@ timestamp_lock(void *vcookie, struct passwd *pw)
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
"appending new tty time stamp record");
lock_pos = lseek(cookie->fd, 0, SEEK_CUR);
if (ts_write(cookie->fd, cookie->fname, &cookie->key) == -1)
if (ts_write(cookie->fd, cookie->fname, &cookie->key, -1) == -1)
debug_return_bool(false);
}
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
@@ -607,9 +624,9 @@ timestamp_lock(void *vcookie, struct passwd *pw)
cookie->pos = lseek(cookie->fd, 0, SEEK_CUR) - (off_t)entry.size;
} else {
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
"appending new globbal record");
"appending new global record");
cookie->pos = lseek(cookie->fd, 0, SEEK_CUR);
if (ts_write(cookie->fd, cookie->fname, &cookie->key) == -1)
if (ts_write(cookie->fd, cookie->fname, &cookie->key, -1) == -1)
debug_return_bool(false);
}
}
@@ -724,7 +741,7 @@ timestamp_status(void *vcookie, struct passwd *pw)
N_("ignoring time stamp from the future"));
status = TS_OLD;
SET(entry.flags, TS_DISABLED);
ts_write(cookie->fd, cookie->fname, &entry);
ts_write(cookie->fd, cookie->fname, &entry, cookie->pos);
}
#else
/* Check for bogus (future) time in the stampfile. */
@@ -737,7 +754,7 @@ timestamp_status(void *vcookie, struct passwd *pw)
4 + ctime(&tv_sec));
status = TS_OLD;
SET(entry.flags, TS_DISABLED);
ts_write(cookie->fd, cookie->fname, &entry);
ts_write(cookie->fd, cookie->fname, &entry, cookie->pos);
}
#endif /* CLOCK_MONOTONIC */
} else {
@@ -779,15 +796,10 @@ timestamp_update(void *vcookie, struct passwd *pw)
}
/* Write out the locked record. */
if (lseek(cookie->fd, cookie->pos, SEEK_SET) == -1) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO|SUDO_DEBUG_LINENO,
"unable to seek to %lld", (long long)cookie->pos);
goto done;
}
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
"writing %zu byte record at %lld", sizeof(cookie->key),
(long long)cookie->pos);
if (ts_write(cookie->fd, cookie->fname, &cookie->key) != -1)
if (ts_write(cookie->fd, cookie->fname, &cookie->key, cookie->pos) != -1)
rval = true;
done:
@@ -845,9 +857,9 @@ timestamp_remove(bool unlink_it)
while (ts_find_record(fd, &key, &entry)) {
/* Back up and disable the entry. */
if (!ISSET(entry.flags, TS_DISABLED)) {
lseek(fd, (off_t)0 - sizeof(entry), SEEK_CUR);
SET(entry.flags, TS_DISABLED);
if (ts_write(fd, fname, &entry) == -1)
lseek(fd, 0 - sizeof(entry), SEEK_CUR);
if (ts_write(fd, fname, &entry, -1) == -1)
rval = false;
}
}