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Revert "Merge pull request #52138 from azat/decompressor-inode"

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This reverts commit 6524031348, reversing
changes made to 9bf114f9a3.

This was not a good idea, since the underlying problem was that
`/proc/self/exe` was pointing to `qemu-$ARCH-static` (because the code
uses realpath() over normal interface readlink(), which is not caught by
the qemu linux-user).

And this means that later, it will try to overwrite incorrect binary and
then execute some garbage.

Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
This commit is contained in:
Azat Khuzhin 2023-07-17 12:01:47 +02:00
parent 44929b7d28
commit c374653c7b
1 changed files with 46 additions and 47 deletions
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93
utils/self-extracting-executable/decompressor.cpp
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@ -430,58 +430,55 @@ int main(int/* argc*/, char* argv[])
return 1;
}
int lock = -1;
/// Protection from double decompression
#if !defined(OS_DARWIN) && !defined(OS_FREEBSD)
/// get inode of this executable
uint64_t inode = getInode(self);
/// In some cases /proc/self/maps may not contain the inode for the
/// /proc/self/exe, one of such examples are using qemu-*-static, in this
/// case maps will be proxied through the qemu, and it will remove
/// information about itself from it.
if (inode != 0)
if (inode == 0)
{
std::stringstream lock_path; // STYLE_CHECK_ALLOW_STD_STRING_STREAM
lock_path << "/tmp/" << name << ".decompression." << inode << ".lock";
lock = open(lock_path.str().c_str(), O_CREAT | O_RDWR, 0666);
if (lock < 0)
std::cerr << "Unable to obtain inode." << std::endl;
return 1;
}
std::stringstream lock_path; // STYLE_CHECK_ALLOW_STD_STRING_STREAM
lock_path << "/tmp/" << name << ".decompression." << inode << ".lock";
int lock = open(lock_path.str().c_str(), O_CREAT | O_RDWR, 0666);
if (lock < 0)
{
perror("lock open");
return 1;
}
/// lock file should be closed on exec call
fcntl(lock, F_SETFD, FD_CLOEXEC);
if (lockf(lock, F_LOCK, 0))
{
perror("lockf");
return 1;
}
/// inconsistency in WSL1 Ubuntu - inode reported in /proc/self/maps is a 64bit to
/// 32bit conversion of input_info.st_ino
if (input_info.st_ino & 0xFFFFFFFF00000000 && !(inode & 0xFFFFFFFF00000000))
input_info.st_ino &= 0x00000000FFFFFFFF;
/// if decompression was performed by another process since this copy was started
/// then file referred by path "self" is already pointing to different inode
if (input_info.st_ino != inode)
{
struct stat lock_info;
if (0 != fstat(lock, &lock_info))
{
perror("lock open");
perror("fstat lock");
return 1;
}
/// lock file should be closed on exec call
fcntl(lock, F_SETFD, FD_CLOEXEC);
/// size 1 of lock file indicates that another decompressor has found active executable
if (lock_info.st_size == 1)
execv(self, argv);
if (lockf(lock, F_LOCK, 0))
{
perror("lockf");
return 1;
}
/// inconsistency in WSL1 Ubuntu - inode reported in /proc/self/maps is a 64bit to
/// 32bit conversion of input_info.st_ino
if (input_info.st_ino & 0xFFFFFFFF00000000 && !(inode & 0xFFFFFFFF00000000))
input_info.st_ino &= 0x00000000FFFFFFFF;
/// if decompression was performed by another process since this copy was started
/// then file referred by path "self" is already pointing to different inode
if (input_info.st_ino != inode)
{
struct stat lock_info;
if (0 != fstat(lock, &lock_info))
{
perror("fstat lock");
return 1;
}
/// size 1 of lock file indicates that another decompressor has found active executable
if (lock_info.st_size == 1)
execv(self, argv);
printf("No target executable - decompression only was performed.\n");
return 0;
}
printf("No target executable - decompression only was performed.\n");
return 0;
}
#endif
@ -549,19 +546,21 @@ int main(int/* argc*/, char* argv[])
if (has_exec)
{
#if !defined(OS_DARWIN) && !defined(OS_FREEBSD)
/// write one byte to the lock in case other copies of compressed are running to indicate that
/// execution should be performed
if (lock >= 0)
write(lock, "1", 1);
write(lock, "1", 1);
#endif
execv(self, argv);
/// This part of code will be reached only if error happened
perror("execv");
return 1;
}
#if !defined(OS_DARWIN) && !defined(OS_FREEBSD)
/// since inodes can be reused - it's a precaution if lock file already exists and have size of 1
if (lock >= 0)
ftruncate(lock, 0);
ftruncate(lock, 0);
#endif
printf("No target executable - decompression only was performed.\n");
}