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authorDavid Kalnischkies <david@kalnischkies.de>2014-10-15 02:43:44 +0200
committerDavid Kalnischkies <david@kalnischkies.de>2014-10-15 02:43:44 +0200
commit460601d53039b1d1b5688a8cd58bae10fb746f57 (patch)
treea555768f443937b165f82cc7d16a29bb6abf7f65 /apt-private
parentd4f4bcf76bb2035b7df370a82b081384140b3083 (diff)
don't drop privileges if _apt has not enough rights
Privilege dropping breaks download/source/changelog commands as they require the _apt user to have write permissions in the current directory, which is e.g. the case in /tmp, but not in /root, so we disable the privilege dropping if we deal with such a directory based on idea and code by Michael Vogt. The alternative would be to download always to a temp directory and move it then done, but this breaks partial file support. To resolve this, we could move to one of our partial/ directories, but this would require a lock which would block root from using two of these commands in parallel. As both seems unacceptable we instead let the user choose what to do: Either a directory is setupped for _apt, downloading as root is accepted or – which is potentially even better – an unprivileged user is used for the commands.
Diffstat (limited to 'apt-private')
-rw-r--r--apt-private/private-download.cc50
-rw-r--r--apt-private/private-download.h6
2 files changed, 54 insertions, 2 deletions
diff --git a/apt-private/private-download.cc b/apt-private/private-download.cc
index be7d23c31..3ded9e0b9 100644
--- a/apt-private/private-download.cc
+++ b/apt-private/private-download.cc
@@ -5,6 +5,7 @@
#include <apt-pkg/acquire-item.h>
#include <apt-pkg/configuration.h>
#include <apt-pkg/error.h>
+#include <apt-pkg/fileutl.h>
#include <apt-pkg/strutl.h>
#include <apt-private/private-output.h>
@@ -14,9 +15,56 @@
#include <string>
#include <vector>
+#include <unistd.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <fcntl.h>
+
#include <apti18n.h>
/*}}}*/
+bool CheckDropPrivsMustBeDisabled(pkgAcquire &Fetcher) /*{{{*/
+{
+ // no need/possibility to drop privs
+ if(getuid() != 0)
+ return true;
+
+ // the user does not want to drop privs
+ std::string SandboxUser = _config->Find("APT::Sandbox::User");
+ if (SandboxUser.empty())
+ return true;
+
+ struct passwd const * const pw = getpwnam(SandboxUser.c_str());
+ if (pw == NULL)
+ return true;
+
+ if (seteuid(pw->pw_uid) != 0)
+ return _error->Errno("seteuid", "seteuid %u failed", pw->pw_uid);
+
+ bool res = true;
+ // check if we can write to destfile
+ for (pkgAcquire::ItemIterator I = Fetcher.ItemsBegin();
+ I != Fetcher.ItemsEnd() && res == true; ++I)
+ {
+ int fd = open((*I)->DestFile.c_str(), O_CREAT | O_RDWR, 0600);
+ if (fd < 0)
+ {
+ res = false;
+ std::string msg;
+ strprintf(msg, _("Can't drop privileges for downloading as file '%s' couldn't be accessed by user '%s'."),
+ (*I)->DestFile.c_str(), SandboxUser.c_str());
+ c0out << msg << std::endl;
+ _config->Set("APT::Sandbox::User", "");
+ }
+ close(fd);
+ }
+
+ if (seteuid(0) != 0)
+ return _error->Errno("seteuid", "seteuid %u failed", 0);
+
+ return res;
+}
+ /*}}}*/
// CheckAuth - check if each download comes form a trusted source /*{{{*/
bool CheckAuth(pkgAcquire& Fetcher, bool const PromptUser)
{
@@ -31,7 +79,7 @@ bool CheckAuth(pkgAcquire& Fetcher, bool const PromptUser)
return AuthPrompt(UntrustedList, PromptUser);
}
-bool AuthPrompt(std::string UntrustedList, bool const PromptUser)
+bool AuthPrompt(std::string const &UntrustedList, bool const PromptUser)
{
ShowList(c2out,_("WARNING: The following packages cannot be authenticated!"),UntrustedList,"");
diff --git a/apt-private/private-download.h b/apt-private/private-download.h
index a90ac7eaa..809650a97 100644
--- a/apt-private/private-download.h
+++ b/apt-private/private-download.h
@@ -3,14 +3,18 @@
#include <apt-pkg/macros.h>
+#include <string>
+
class pkgAcquire;
+APT_PUBLIC bool CheckDropPrivsMustBeDisabled(pkgAcquire &Fetcher);
+
// Check if all files in the fetcher are authenticated
APT_PUBLIC bool CheckAuth(pkgAcquire& Fetcher, bool const PromptUser);
// show a authentication warning prompt and return true if the system
// should continue
-APT_PUBLIC bool AuthPrompt(std::string UntrustedList, bool const PromptUser);
+APT_PUBLIC bool AuthPrompt(std::string const &UntrustedList, bool const PromptUser);
APT_PUBLIC bool AcquireRun(pkgAcquire &Fetcher, int const PulseInterval, bool * const Failure, bool * const TransientNetworkFailure);