Hi Erik,
Hi to all,
This is part five of the my_get*id story.
I've tweaked a bit this two functions to make them more flexible,
but this changes will not affect existing code.
Now they work so:
1) my_getpwuid( char *user, uid_t uid, int bufsize)
if bufsize is > 0 char *user cannot be set to NULL
on success username is written on static allocated buffer
on failure uid as string is written to buffer and NULL is returned
if bufsize is = 0 char *user can be set to NULL
on success username is returned
on failure NULL is returned
if bufsize is < 0 char *user can be set to NULL
on success username is returned
on failure an error message is printed and the program exits
2) 1) my_getgrgid( char *group, uid_t uid, int bufsize)
if bufsize is > 0 char *group cannot be set to NULL
on success groupname is written on static allocated buffer
on failure gid as string is written to buffer and NULL is returned
if bufsize is = 0 char *group can be set to NULL
on success groupname is returned
on failure NULL is returned
if bufsize is < 0 char *group can be set to nULL
on success groupname is returned
on failure an error message is printed and the program exits
This changes were needed mainly for my new id applet.
It is somewhat bigger then the previous but matches the behaviour of GNU id
and is capable to handle usernames of whatever length.
BTW: at a first look it seems to me that it will integrate well (with just a few changes)
with the pending patch in patches/id_groups_alias.patch.
The increase in size is balanced by the removal of my_getpwnamegid.c
from libbb as this was used only in previous id applet and by size optimizations
made possible in whoami.c and in passwd.c.
I know that we are in feature freeze but I think that i've tested it enough
(at least I hope so.......).
Hi,
I've spent the half night staring at the devilish my_getpwuid and my_getgrgid functions
trying to find out a way to avoid actual and future potential buffer overflow problems
without breaking existing code.
Finally I've found a not intrusive way to do this that surely doesn't break existing code
and fixes a couple of problems too.
The attached patch:
1) changes the behaviour of my_getpwuid and my_getgrgid to avoid potetntial buffer overflows
2) fixes all occurences of this function calls in tar.c , id.c , ls.c, whoami.c, logger.c, libbb.h.
3) The behaviour of tar, ls and logger is unchanged.
4) The behavior of ps with somewhat longer usernames messing up output is fixed.
5) The only bigger change was the increasing of size of the buffers in id.c to avoid
false negatives (unknown user: xxxxxx) with usernames longer than 8 chars.
The value i used ( 32 chars ) was taken from the tar header ( see gname and uname).
Maybe this buffers can be reduced a bit ( to 16 or whatever ), this is up to you.
6) The increase of size of the binary is not so dramatic:
size busybox
text data bss dec hex filename
239568 2300 36816 278684 4409c busybox
size busybox_fixed
text data bss dec hex filename
239616 2300 36816 278732 440cc busybox
7) The behaviour of whoami changed:
actually it prints out an username cut down to the size of the buffer.
This could be fixed by increasing the size of the buffer as in id.c or
avoid the use of my_getpwuid and use getpwuid directly instead.
Maybe this colud be also remain unchanged......
Please apply if you think it is ok to do so.
The diff applies on today's cvs tarball (2004-08-25).
Thanks in advance,
Ciao,
Tito
Hi, Erik.
my_getpw(uid/gid) and applets used it have problem:
if username for uid not found, applets can`t detect it
(but code pessent). Also "%8ld " format is bad:
spaces not required (applets have self format
or spec format (tar applet) and overflow for "id" applet...)
This problem also pressent in stable version.
Patch for unstable in attach.
--w
vodz
