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Kernel+Tests: Allow deleting someone else's file in my sticky directory

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This should be allowed according to Dr. POSIX. :^)
This commit is contained in:
Andreas Kling 2022-12-19 19:32:31 +01:00
parent 47b9e8e651
commit 16f934474f
2 changed files with 50 additions and 1 deletions
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7
Kernel/FileSystem/VirtualFileSystem.cpp
View file

@ -868,8 +868,13 @@ ErrorOr<void> VirtualFileSystem::rmdir(Credentials const& credentials, StringVie
return EACCES;
if (parent_metadata.is_sticky()) {
if (!credentials.is_superuser() && inode.metadata().uid != credentials.euid())
// [EACCES] The S_ISVTX flag is set on the directory containing the file referred to by the path argument
// and the process does not satisfy the criteria specified in XBD Directory Protection.
if (!credentials.is_superuser()
&& inode.metadata().uid != credentials.euid()
&& parent_metadata.uid != credentials.euid()) {
return EACCES;
}
}
size_t child_count = 0;

44
Tests/LibC/TestIo.cpp
View file

@ -15,6 +15,7 @@
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <unistd.h>
#define EXPECT_ERROR_2(err, syscall, arg1, arg2) \
@ -356,6 +357,49 @@ TEST_CASE(rmdir_dot_dot)
EXPECT_EQ(rc, 0);
}
TEST_CASE(rmdir_someone_elses_directory_in_my_sticky_directory)
{
// NOTE: This test only works when run as root, since it has to chown a directory to someone else.
if (getuid() != 0)
return;
// Create /tmp/sticky-dir a sticky directory owned by 12345:12345
// Then, create /tmp/sticky-dir/notmine, a normal directory owned by 23456:23456
// Then, fork and seteuid to 12345, and try to rmdir the "notmine" directory. This should succeed.
// In the parent, waitpid on the child, and finally rmdir /tmp/sticky-dir
int rc = mkdir("/tmp/sticky-dir", 01777);
EXPECT_EQ(rc, 0);
rc = chown("/tmp/sticky-dir", 12345, 12345);
EXPECT_EQ(rc, 0);
rc = mkdir("/tmp/sticky-dir/notmine", 0700);
EXPECT_EQ(rc, 0);
rc = chown("/tmp/sticky-dir/notmine", 23456, 23456);
EXPECT_EQ(rc, 0);
int pid = fork();
EXPECT(pid >= 0);
if (pid == 0) {
// We are in the child.
rc = seteuid(12345);
EXPECT_EQ(rc, 0);
rc = rmdir("/tmp/sticky-dir/notmine");
EXPECT_EQ(rc, 0);
_exit(0);
}
int status = 0;
waitpid(pid, &status, 0);
rc = rmdir("/tmp/sticky-dir");
EXPECT_EQ(rc, 0);
}
TEST_CASE(rmdir_while_inside_dir)
{
int rc = mkdir("/home/anon/testdir", 0700);