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SubjectLinux 2.5 and Zsh bug
From
Date
When running zsh on a Linux 2.5 kernel, the prompt always has a hash
sign '#' rather than the normal user '$'. This probably happens because
the shell function privasserted() is returning true for all users. I
know nothing about Posix capabilities but the zsh code for this looks
suspicious.

Code in question:
------------------------------------------------------------
/* isolate zsh bug */
#include <stdio.h>
#include <sys/capability.h>

int
privasserted(void)
{
if(!geteuid()) {
printf("geteuid() is root\n");
return 1;
}
else {
cap_t caps = cap_get_proc();
if(caps) {
printf("caps = %p\n", caps);
/* POSIX doesn't define a way to test whether a capability
set *
* is empty or not. Typical. I hope this is
conforming... */
cap_flag_value_t val;
cap_value_t n;

for(n = 0; !cap_get_flag(caps, n, CAP_EFFECTIVE, &val); n++)
{
if(val) {
printf("capability %#x is %d\n", n, val);
cap_free(caps); /* missing in original zsh code
memory leak */
return 1;
}
}
printf("last capability %#x\n", n);

cap_free(caps);
}
}
return 0;
}

int main(int argc, const char **argv) {
printf("%s privledged\n", privasserted() ? "Is" : "Not");
}

------------------------------------------------
On 2.4.18
caps = 0x8049844
last capability 0x1d
Not privledged

On 2.5.43
caps = 0x804a00c
capability 0 is 1
Is privledged



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