0e29548e09
- fix #449738 - Wakeup on RTC alarm does not work anymore [rebase to rtcwake(8) from util-linux-ng 2.14.1] - fix #454354 - FAT filesystem mount option utf8=0 is not documented
78 lines
2.1 KiB
Diff
78 lines
2.1 KiB
Diff
From ced94242e11e2ac121c9dae5c707bac5b47e501a Mon Sep 17 00:00:00 2001
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From: Karel Zak <kzak@redhat.com>
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Date: Mon, 7 Jul 2008 15:22:22 +0200
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Subject: [PATCH] write: doesn't check for tty group
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write(1) selects a wrong tty, because there is not a proper
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check of tty group ownership:
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$ write kzak
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write: kzak is logged in more than once; writing to tty7
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write: /dev/tty7: Permission denied
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$ ls -la /dev/tty7
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crw--w---- 1 root root 4, 7 2008-07-04 00:32 /dev/tty7
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^^^^
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$ ls -la /usr/bin/write
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-rwxr-sr-x 1 root tty 11864 2008-04-02 16:24 /usr/bin/write
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^ ^^^
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We have to check for tty group owner, because we don't have
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permissions to write to arbitrary tty.
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Fixed version:
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$ write kzak
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write: kzak is logged in more than once; writing to pts/6
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^^^^
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Message from test@nb on pts/7 at 15:22 ...
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^C
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$ ls -la /dev/pts/6
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crw--w---- 1 kzak tty 136, 6 2008-07-07 15:35 /dev/pts/6
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^^^
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Addresses-Red-Hat-Bugzilla: #454252
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Signed-off-by: Karel Zak <kzak@redhat.com>
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---
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misc-utils/write.c | 8 +++++++-
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1 files changed, 7 insertions(+), 1 deletions(-)
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diff --git a/misc-utils/write.c b/misc-utils/write.c
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index 46b8f0a..276fe96 100644
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--- a/misc-utils/write.c
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+++ b/misc-utils/write.c
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@@ -72,6 +72,8 @@ static void done(int);
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int term_chk(char *, int *, time_t *, int);
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int utmp_chk(char *, char *);
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+static gid_t myegid;
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+
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int
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main(int argc, char **argv) {
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time_t atime;
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@@ -83,6 +85,8 @@ main(int argc, char **argv) {
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bindtextdomain(PACKAGE, LOCALEDIR);
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textdomain(PACKAGE);
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+ myegid = getegid();
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+
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/* check that sender has write enabled */
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if (isatty(fileno(stdin)))
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myttyfd = fileno(stdin);
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@@ -267,7 +271,9 @@ int term_chk(char *tty, int *msgsokP, time_t *atimeP, int showerror)
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"write: %s: %s\n", path, strerror(errno));
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return(1);
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}
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- *msgsokP = (s.st_mode & (S_IWRITE >> 3)) != 0; /* group write bit */
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+
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+ /* group write bit and group ownership */
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+ *msgsokP = (s.st_mode & (S_IWRITE >> 3)) && myegid == s.st_gid;
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*atimeP = s.st_atime;
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return(0);
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}
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--
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1.5.5.1
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