Changeset - r27473:11a007082779
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Rubidium - 15 months ago 2023-06-02 16:13:51
rubidium@openttd.org
Codechange: use C++ strings/paths to resolve links in tars
1 file changed with 41 insertions and 63 deletions:
src/fileio.cpp
41
63
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src/fileio.cpp
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@@ -26,6 +26,7 @@
 
#endif
 
#include <sys/stat.h>
 
#include <sstream>
 
#include <filesystem>
 

			




	
	
	
		
 
#include "safeguards.h"

			




	
	
	
		
 

			




	
	
		
 
@@ -392,15 +393,16 @@ static void TarAddLink(const std::string

			




	
	
	
		
 
 * Replace '/' by #PATHSEPCHAR, and force 'name' to lowercase.

			




	
	
	
		
 
 * @param name Filename to process.

			




	
	
	
		
 
 */

			




	
	
	
		
 
static void SimplifyFileName(char *name)

			




	
	
	
		
 
static void SimplifyFileName(std::string &name)

			




	
	
	
		
 
{

			




	
	
	
		
 
	/* Force lowercase */

			




	
	
	
		
 
	strtolower(name);

			




	
	
	
		
 

			




	
	
	
		
 
	/* Tar-files always have '/' path-separator, but we want our PATHSEPCHAR */

			




	
	
	
		
 
	for (char &c : name) {

			




	
	
	
		
 
		/* Force lowercase */

			




	
	
	
		
 
		c = std::tolower(c);

			




	
	
	
		
 
#if (PATHSEPCHAR != '/')

			




	
	
	
		
 
	for (char *n = name; *n != '\0'; n++) if (*n == '/') *n = PATHSEPCHAR;

			




	
	
	
		
 
		/* Tar-files always have '/' path-separator, but we want our PATHSEPCHAR */

			




	
	
	
		
 
		if (c == '/') c = PATHSEPCHAR;

			




	
	
	
		
 
#endif

			




	
	
	
		
 
	}

			




	
	
	
		
 
}

			




	
	
	
		
 

			




	
	
	
		
 
/**

			




	
	
		
 
@@ -456,6 +458,24 @@ bool TarScanner::AddFile(Subdirectory sd

			




	
	
	
		
 
	return this->AddFile(filename, 0);

			




	
	
	
		
 
}

			




	
	
	
		
 

			




	
	
	
		
 
/**

			




	
	
	
		
 
 * Helper to extract a string for the tar header. We must assume that the tar

			




	
	
	
		
 
 * header contains garbage and is malicious. So, we cannot rely on the string

			




	
	
	
		
 
 * being properly terminated.

			




	
	
	
		
 
 * As such, do not use strlen to determine the actual length (explicitly or

			




	
	
	
		
 
 * implictly via the std::string constructor), but also do not create a string

			




	
	
	
		
 
 * of the buffer length as that makes the string contain essentially garbage.

			




	
	
	
		
 
 * @param buffer The buffer to read from.

			




	
	
	
		
 
 * @param buffer_length The length of the buffer to read from.

			




	
	
	
		
 
 * @return The string data.

			




	
	
	
		
 
 */

			




	
	
	
		
 
static std::string ExtractString(char *buffer, size_t buffer_length)

			




	
	
	
		
 
{

			




	
	
	
		
 
	size_t length = 0;

			




	
	
	
		
 
	for (; length < buffer_length && buffer[length] != '\0'; length++) {}

			




	
	
	
		
 
	return StrMakeValid(std::string(buffer, length));

			




	
	
	
		
 
}

			




	
	
	
		
 

			




	
	
	
		
 
bool TarScanner::AddFile(const std::string &filename, size_t basepath_length, const std::string &tar_filename)

			




	
	
	
		
 
{

			




	
	
	
		
 
	/* No tar within tar. */

			




	
	
		
 
@@ -467,7 +487,7 @@ bool TarScanner::AddFile(const std::stri

			




	
	
	
		
 
		char mode[8];

			




	
	
	
		
 
		char uid[8];

			




	
	
	
		
 
		char gid[8];

			




	
	
	
		
 
		char size[12];       ///< Size of the file, in ASCII

			




	
	
	
		
 
		char size[12];       ///< Size of the file, in ASCII octals

			




	
	
	
		
 
		char mtime[12];

			




	
	
	
		
 
		char chksum[8];

			




	
	
	
		
 
		char typeflag;

			




	
	
		
 
@@ -499,10 +519,6 @@ bool TarScanner::AddFile(const std::stri

			




	
	
	
		
 
	TarLinkList links; ///< Temporary list to collect links

			




	
	
	
		
 

			




	
	
	
		
 
	TarHeader th;

			




	
	
	
		
 
	char buf[sizeof(th.name) + 1], *end;

			




	
	
	
		
 
	char name[sizeof(th.prefix) + 1 + sizeof(th.name) + 1];

			




	
	
	
		
 
	char link[sizeof(th.linkname) + 1];

			




	
	
	
		
 
	char dest[sizeof(th.prefix) + 1 + sizeof(th.name) + 1 + 1 + sizeof(th.linkname) + 1];

			




	
	
	
		
 
	size_t num = 0, pos = 0;

			




	
	
	
		
 

			




	
	
	
		
 
	/* Make a char of 512 empty bytes */

			




	
	
		
 
@@ -524,25 +540,25 @@ bool TarScanner::AddFile(const std::stri

			




	
	
	
		
 
			return false;

			




	
	
	
		
 
		}

			




	
	
	
		
 

			




	
	
	
		
 
		name[0] = '\0';

			




	
	
	
		
 
		std::string name;

			




	
	
	
		
 

			




	
	
	
		
 
		/* The prefix contains the directory-name */

			




	
	
	
		
 
		if (th.prefix[0] != '\0') {

			




	
	
	
		
 
			strecpy(name, th.prefix, lastof(name));

			




	
	
	
		
 
			strecat(name, PATHSEP, lastof(name));

			




	
	
	
		
 
			name = ExtractString(th.prefix, lengthof(th.prefix));

			




	
	
	
		
 
			name += PATHSEP;

			




	
	
	
		
 
		}

			




	
	
	
		
 

			




	
	
	
		
 
		/* Copy the name of the file in a safe way at the end of 'name' */

			




	
	
	
		
 
		strecat(name, th.name, lastof(name));

			




	
	
	
		
 
		name += ExtractString(th.name, lengthof(th.name));

			




	
	
	
		
 

			




	
	
	
		
 
		/* Calculate the size of the file.. for some strange reason this is stored as a string */

			




	
	
	
		
 
		strecpy(buf, th.size, lastof(buf));

			




	
	
	
		
 
		size_t skip = std::strtoul(buf, &end, 8);

			




	
	
	
		
 
		/* The size of the file, for some strange reason, this is stored as a string in octals. */

			




	
	
	
		
 
		std::string size = ExtractString(th.size, lengthof(th.size));

			




	
	
	
		
 
		size_t skip = size.empty() ? 0 : std::stoul(size, nullptr, 8);

			




	
	
	
		
 

			




	
	
	
		
 
		switch (th.typeflag) {

			




	
	
	
		
 
			case '\0':

			




	
	
	
		
 
			case '0': { // regular file

			




	
	
	
		
 
				if (strlen(name) == 0) break;

			




	
	
	
		
 
				if (name.empty()) break;

			




	
	
	
		
 

			




	
	
	
		
 
				/* Store this entry in the list */

			




	
	
	
		
 
				TarFileListEntry entry;

			




	
	
		
 
@@ -562,9 +578,9 @@ bool TarScanner::AddFile(const std::stri

			




	
	
	
		
 
			case '1': // hard links

			




	
	
	
		
 
			case '2': { // symbolic links

			




	
	
	
		
 
				/* Copy the destination of the link in a safe way at the end of 'linkname' */

			




	
	
	
		
 
				strecpy(link, th.linkname, lastof(link));

			




	
	
	
		
 
				std::string link = ExtractString(th.linkname, lengthof(th.linkname));

			




	
	
	
		
 

			




	
	
	
		
 
				if (strlen(name) == 0 || strlen(link) == 0) break;

			




	
	
	
		
 
				if (name.empty() || link.empty()) break;

			




	
	
	
		
 

			




	
	
	
		
 
				/* Convert to lowercase and our PATHSEPCHAR */

			




	
	
	
		
 
				SimplifyFileName(name);

			




	
	
		
 
@@ -578,48 +594,10 @@ bool TarScanner::AddFile(const std::stri

			




	
	
	
		
 

			




	
	
	
		
 
				/* Process relative path.

			




	
	
	
		
 
				 * Note: The destination of links must not contain any directory-links. */

			




	
	
	
		
 
				strecpy(dest, name, lastof(dest));

			




	
	
	
		
 
				char *destpos = strrchr(dest, PATHSEPCHAR);

			




	
	
	
		
 
				if (destpos == nullptr) destpos = dest;

			




	
	
	
		
 
				*destpos = '\0';

			




	
	
	
		
 

			




	
	
	
		
 
				char *pos = link;

			




	
	
	
		
 
				while (*pos != '\0') {

			




	
	
	
		
 
					char *next = strchr(pos, PATHSEPCHAR);

			




	
	
	
		
 
					if (next == nullptr) {

			




	
	
	
		
 
						next = pos + strlen(pos);

			




	
	
	
		
 
					} else {

			




	
	
	
		
 
						/* Terminate the substring up to the path separator character. */

			




	
	
	
		
 
						*next++= '\0';

			




	
	
	
		
 
					}

			




	
	
	
		
 

			




	
	
	
		
 
					if (strcmp(pos, ".") == 0) {

			




	
	
	
		
 
						/* Skip '.' (current dir) */

			




	
	
	
		
 
					} else if (strcmp(pos, "..") == 0) {

			




	
	
	
		
 
						/* level up */

			




	
	
	
		
 
						if (dest[0] == '\0') {

			




	
	
	
		
 
							Debug(misc, 5, "Ignoring link pointing outside of data directory: {} -> {}", name, link);

			




	
	
	
		
 
							break;

			




	
	
	
		
 
						}

			




	
	
	
		
 

			




	
	
	
		
 
						/* Truncate 'dest' after last PATHSEPCHAR.

			




	
	
	
		
 
						 * This assumes that the truncated part is a real directory and not a link. */

			




	
	
	
		
 
						destpos = strrchr(dest, PATHSEPCHAR);

			




	
	
	
		
 
						if (destpos == nullptr) destpos = dest;

			




	
	
	
		
 
						*destpos = '\0';

			




	
	
	
		
 
					} else {

			




	
	
	
		
 
						/* Append at end of 'dest' */

			




	
	
	
		
 
						if (destpos != dest) destpos = strecpy(destpos, PATHSEP, lastof(dest));

			




	
	
	
		
 
						destpos = strecpy(destpos, pos, lastof(dest));

			




	
	
	
		
 
					}

			




	
	
	
		
 

			




	
	
	
		
 
					if (destpos >= lastof(dest)) {

			




	
	
	
		
 
						Debug(misc, 0, "The length of a link in tar-file '{}' is too large (malformed?)", filename);

			




	
	
	
		
 
						fclose(f);

			




	
	
	
		
 
						return false;

			




	
	
	
		
 
					}

			




	
	
	
		
 

			




	
	
	
		
 
					pos = next;

			




	
	
	
		
 
				std::string dest = (std::filesystem::path(name).remove_filename() /= link).lexically_normal().string();

			




	
	
	
		
 
				if (dest[0] == PATHSEPCHAR || StrStartsWith(dest, "..")) {

			




	
	
	
		
 
					Debug(misc, 5, "Ignoring link pointing outside of data directory: {} -> {}", name, link);

			




	
	
	
		
 
					break;

			




	
	
	
		
 
				}

			




	
	
	
		
 

			




	
	
	
		
 
				/* Store links in temporary list */

			




        

    



    


    



    



      

      





    
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