canoeboot
/
cbmk
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

util/nvmutil: Prevent unveil allowing dir access 

We were checking directories *after* calling unveil, which
means that the sandboxing was incomplete; we only want files
to be accessed, not directories.

Signed-off-by: Leah Rowe <leah@libreboot.org>
master
Leah Rowe 2025-01-24 12:18:45 +00:00
parent d68d0a8d75
commit fef744d68e
1 changed files with 23 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
util/nvmutil/nvmutil.c
View File

@ -16,7 +16,8 @@
void cmd_setchecksum(void), cmd_brick(void), swap(int partnum), writeGbe(void),
cmd_dump(void), cmd_setmac(void), readGbe(void), cmd_copy(void),
macf(int partnum), hexdump(int partnum), openFiles(const char *path);
macf(int partnum), hexdump(int partnum), openFiles(const char *path),
checkdir(const char *path);
int macAddress(const char *strMac, uint16_t *mac), goodChecksum(int partnum);
uint8_t hextonum(char chs), rhex(void);
@ -55,8 +56,7 @@ void (*cmd)(void) = NULL;
#define err_if(x) if (x) err(ERR(), "%s", filename)
/* Macro for opening a file with errors properly handled */
#define xopen(f,l,p) if (opendir(l) != NULL) err(errno = EISDIR, "%s", l); \
if ((f = open(l, p)) == -1) err(ERR(), "%s", l); \
#define xopen(f,l,p) if ((f = open(l, p)) == -1) err(ERR(), "%s", l); \
if (fstat(f, &st) == -1) err(ERR(), "%s", l)
/* Macros for reading/writing the GbE file in memory */
@ -83,6 +83,11 @@ main(int argc, char *argv[])
else
flags = O_RDWR;
filename = argv[1];
/* Err if files are actually directories; this also
prevents unveil allowing directory accesses, which
is critical because we only want *file* accesses. */
checkdir("/dev/urandom");
checkdir(filename); /* Must be a file, not a directory */
#ifdef __OpenBSD__
/* OpenBSD sandboxing: https://man.openbsd.org/pledge.2 */
/* Also: https://man.openbsd.org/unveil.2 */
@ -125,6 +130,21 @@ main(int argc, char *argv[])
return errno; /* errno can be set by the dump command */
}
/*
* check whether urandom/file is a directory, and err if so,
* to prevent later unveil calls from permitting directory access
* on OpenBSD
*/
void
checkdir(const char *path)
{
if (opendir(path) != NULL)
err(errno = EISDIR, "%s", path);
if (errno = ENOTDIR)
errno = 0;
err_if(errno);
}
/* open gbe file and /dev/urandom, setting permissions */
void
openFiles(const char *path)
@ -134,8 +154,6 @@ openFiles(const char *path)
if ((st.st_size != (SIZE_4KB << 1)))
err(errno = ECANCELED, "File `%s` not 8KiB", path);
xopen(rfd, "/dev/urandom", O_RDONLY);
if (errno == ENOTDIR)
errno = 0;
}
/* read gbe file into memory buffer */