arno/simplesshd
1
0
Fork 0
mirror of http://galexander.org/git/simplesshd.git synced 2025-01-01 02:40:52 +00:00
Code Issues Releases Wiki Activity

When reading data from various spots in /proc to initialize the random

Browse Source 
number generator:
 * reduce timeout from 2s to 1ms
 * if timeout, abort
 * only read first 4096 bytes
this is to work around the fact that on Samsung Tab 4, /proc/timer_list
is apparently 167MB!
This commit is contained in:
Greg Alexander 2016-08-08 14:08:49 -04:00
parent 3d9a5b5ced
commit 60fcaa6ec9
1 changed files with 9 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
dropbear/dbrandom.c
View File

@ -85,8 +85,8 @@ process_file(hash_state *hs, const char *filename,
struct timeval timeout; struct timeval timeout;
fd_set read_fds; fd_set read_fds;
timeout.tv_sec = 2; timeout.tv_sec = 0;
timeout.tv_usec = 0; timeout.tv_usec = 1000;
FD_ZERO(&read_fds); FD_ZERO(&read_fds);
FD_SET(readfd, &read_fds); FD_SET(readfd, &read_fds);
@ -98,6 +98,8 @@ process_file(hash_state *hs, const char *filename,
} }
} }
if (already_blocked) break;
if (len == 0) if (len == 0)
{ {
wantread = sizeof(readbuf); wantread = sizeof(readbuf);
@ -205,12 +207,12 @@ void seedrandom() {
#ifdef __linux__ #ifdef __linux__
/* Seems to be a reasonable source of entropy from timers. Possibly hard /* Seems to be a reasonable source of entropy from timers. Possibly hard
* for even local attackers to reproduce */ * for even local attackers to reproduce */
process_file(&hs, "/proc/timer_list", 0, 0); process_file(&hs, "/proc/timer_list", 4096, 0);
/* Might help on systems with wireless */ /* Might help on systems with wireless */
process_file(&hs, "/proc/interrupts", 0, 0); process_file(&hs, "/proc/interrupts", 4096, 0);
process_file(&hs, "/proc/loadavg", 0, 0); process_file(&hs, "/proc/loadavg", 4096, 0);
process_file(&hs, "/proc/sys/kernel/random/entropy_avail", 0, 0); process_file(&hs, "/proc/sys/kernel/random/entropy_avail", 4096, 0);
/* Mostly network visible but useful in some situations. /* Mostly network visible but useful in some situations.
* Limit size to avoid slowdowns on systems with lots of routes */ * Limit size to avoid slowdowns on systems with lots of routes */
@ -219,7 +221,7 @@ void seedrandom() {
process_file(&hs, "/proc/net/tcp", 4096, 0); process_file(&hs, "/proc/net/tcp", 4096, 0);
/* Also includes interface lo */ /* Also includes interface lo */
process_file(&hs, "/proc/net/rt_cache", 4096, 0); process_file(&hs, "/proc/net/rt_cache", 4096, 0);
process_file(&hs, "/proc/vmstat", 0, 0); process_file(&hs, "/proc/vmstat", 4096, 0);
#endif #endif
pid = getpid(); pid = getpid();