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When a mount fails, mount.cifs often prints an error message. In most
cases, this error goes to stdout instead of stderr like it should. Fix
it to print errors to stderr instead.
Reported-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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Guenther
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A few weeks ago, I added some code to cifs.upcall to take the pid sent
by the kernel and use that to get the value of the $KRB5CCNAME
environment var for the process. That works fine on the initial mount,
but could be problematic on reconnect.
There's no guarantee on a reconnect that the process that initiates the
upcall will have $KRB5CCNAME pointed at the correct credcache. Because
of this, the current scheme isn't going to be reliable enough and we
need to use something different.
This patch replaces that scheme with one very similar to the one used by
rpc.gssd in nfs-utils. It searches the credcache dir (currently
hardcoded to /tmp) for a valid credcache for the given uid. If it finds
one then it uses that as the credentials cache. If it finds more than
one, it uses the one with the latest TGT expiration.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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Igor Mammedov pointed out that reverse resolving an IP address to get
the hostname portion of a principal could open a possible attack
vector. If an attacker were to gain control of DNS, then he could
redirect the mount to a server of his choosing, and fix the reverse
resolution to point to a hostname of his choosing (one where he has
the key for the corresponding cifs/ or host/ principal).
That said, we often trust DNS for other reasons and it can be useful
to do so. Make the code that allows trusting DNS to be enabled by
adding --trust-dns to the cifs.upcall invocation.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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...to allow long option names.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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Current kernels don't send IPv6 addresses with the colon delimiters, add
a routine to add them when they're not present.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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Instead of using the hostname given by the upcall to get the server's
principal, take the IP address given in the upcall and reverse resolve
it to a hostname.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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Add a new stack var to hold the flags returned by the decoder routine
so that we don't need to worry so much about preserving "rc".
With this, we can drop privs before trying to find the location of
the credcache.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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cifs.upcall takes a "-c" flag that tells the upcall to get a principal
in the form of "cifs/hostname.example.com@REALM" instead of
"host/hostname.example.com@REALM". This has turned out to be a source of
great confusion for users.
Instead of requiring this flag, have the upcall try to get a "cifs/"
principal first. If that fails, fall back to getting a "host/"
principal.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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The argument list for the decoder is becoming rather long. Declare an
args structure and use that for holding the args. This also simplifies
pointer handling a bit.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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Clean up some unneeded curly braces, and fix some indentation.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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Change the log levels to be more appropriate to the messages being
logged. Error messages should be LOG_ERR and not LOG_WARNING, for
instance.
Add some LOG_DEBUG messages that we can use to diagnose problems with
krb5 upcalls. With these, someone can set up syslog to log daemon.debug
and should be able to get more info when things aren't working.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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If /etc/mtab is a symbolic link to e.g. /proc/mounts, do not update it.
This is a fix for a bug reported in 4675 on samba bugzilla
Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
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If the kernel sends the upcall a pid of the requesting process, we can
open that process' /proc/<pid>/environ file and scrape the KRB5CCNAME
value out of it.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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/bin/mount strips off the ro/rw options after setting the MS_RDONLY
flag appropriately. Make mount.cifs do the same thing.
Signed-off-by: Jeff Layton <jlayton@samba.org>
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When getaddrinfo returns an IPv6 address with a non-zero scope_id, send
that to the kernel appended to the address with a '%' delimiter. This
allows people to mount servers via their link-local IPv6 addresses
(given a kernel that understands this address format, of course).
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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If we get a non-AF_INET(6) address, then just skip it and try the next
one in the list.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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(try#3)
This is the third attempt to clean up the checks when a setuid
mount.cifs is run by an unprivileged user. The main difference in this
patch from the last one is that it fixes a bug where the mount might
have failed if unnecessarily if CIFS_LEGACY_SETUID_CHECK was set.
When mount.cifs is installed setuid root and run as an unprivileged
user, it does some checks to limit how the mount is used. It checks that
the mountpoint is owned by the user doing the mount.
These checks however do not match those that /bin/mount does when it is
called by an unprivileged user. When /bin/mount is called by an
unprivileged user to do a mount, it checks that the mount in question is
in /etc/fstab, that it has the "user" option set, etc.
This means that it's currently not possible to set up user mounts the
standard way (by the admin, in /etc/fstab) and simultaneously protect
from an unprivileged user calling mount.cifs directly to mount a share
on any directory that that user owns.
Fix this by making the checks in mount.cifs match those of /bin/mount
itself. This is a necessary step to make mount.cifs safe to be installed
as a setuid binary, but not sufficient. For that, we'd need to give
mount.cifs a proper security audit.
Since some users may be depending on the legacy behavior, this patch
also adds the ability to build mount.cifs with the older behavior.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
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in Samba 4.
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