Messages in this thread Patches in this message | ![/](/images/icornerl.gif) | | From | Stephan Maciej <> | Date | Sun, 30 Mar 2003 22:05:06 +0200 | Subject | [PATCH 2.5.66 & 2.4.20] Fix sys_sethostname() and sys_setdomainname() |
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Hi,
a long time ago someone mentioned that sethostname() and setdomainname() properly return -EFAULT when passing an invalid pointer to the new name, but instead of leaving the fields in system_utsname unchanged the nodename and domainname are set to an empty string.
The behaviour of sys_sethostname() can be verified using the attached program (sethostname.c); sys_setdomainname() is almost the same so I guess that it has the same defect :-)
The attached patches fix this.
Stephan --- kernel/sys.c~unmodified 2003-03-30 21:33:17.000000000 +0200 +++ kernel/sys.c 2003-03-30 21:43:20.000000000 +0200 @@ -1154,14 +1154,18 @@ asmlinkage long sys_sethostname(char *name, int len) { int errno; + char tmp[__NEW_UTS_LEN]; if (!capable(CAP_SYS_ADMIN)) return -EPERM; if (len < 0 || len > __NEW_UTS_LEN) return -EINVAL; + down_write(&uts_sem); errno = -EFAULT; - if (!copy_from_user(system_utsname.nodename, name, len)) { + + if (!copy_from_user(tmp, name, len)) { + memcpy(system_utsname.nodename, tmp, len); system_utsname.nodename[len] = 0; errno = 0; } @@ -1193,6 +1197,7 @@ asmlinkage long sys_setdomainname(char *name, int len) { int errno; + char tmp[__NEW_UTS_LEN]; if (!capable(CAP_SYS_ADMIN)) return -EPERM; @@ -1201,10 +1206,13 @@ down_write(&uts_sem); errno = -EFAULT; - if (!copy_from_user(system_utsname.domainname, name, len)) { - errno = 0; + + if (!copy_from_user(tmp, name, len)) { + memcpy(system_utsname.domainname, tmp, len); system_utsname.domainname[len] = 0; + errno = 0; } + up_write(&uts_sem); return errno; } #include <linux/utsname.h> #include <errno.h> #include <stdio.h> #include <string.h> #include <unistd.h>
int main() { int retval; char hostname[__NEW_UTS_LEN];
// Print out current hostname if ((retval = gethostname(hostname, __NEW_UTS_LEN)) == -1) { printf("call to gethostname() failed, retval=%d: %s\n", retval, strerror(errno)); return 1; }; printf("gethostname()=\"%s\"\n", hostname);
// Set "new" hostname if ((retval = sethostname((char *)-1, 10)) != -1) { // We really EXPECT this to fail! printf("The Penguin is in trouble!\n"); return 2; } else printf("sethostname(INVALID, 10)=%d (error \"%s\")\n", retval, strerror(errno));
// And now once again: if ((retval = gethostname(hostname, __NEW_UTS_LEN)) == -1) { printf("call to gethostname() failed, retval=%d: %s\n", retval, strerror(errno)); return 1; }; printf("gethostname()=\"%s\"\n", hostname);
return 0; }; --- kernel/sys.c~unmodified 2003-03-30 21:51:07.000000000 +0200 +++ kernel/sys.c 2003-03-30 21:53:01.000000000 +0200 @@ -1026,6 +1026,7 @@ asmlinkage long sys_sethostname(char *name, int len) { int errno; + char tmp[__NEW_UTS_LEN]; if (!capable(CAP_SYS_ADMIN)) return -EPERM; @@ -1033,7 +1034,8 @@ return -EINVAL; down_write(&uts_sem); errno = -EFAULT; - if (!copy_from_user(system_utsname.nodename, name, len)) { + if (!copy_from_user(tmp, name, len)) { + memcpy(system_utsname.nodename, tmp, len); system_utsname.nodename[len] = 0; errno = 0; } @@ -1065,6 +1067,7 @@ asmlinkage long sys_setdomainname(char *name, int len) { int errno; + char tmp[__NEW_UTS_LEN]; if (!capable(CAP_SYS_ADMIN)) return -EPERM; @@ -1073,9 +1076,10 @@ down_write(&uts_sem); errno = -EFAULT; - if (!copy_from_user(system_utsname.domainname, name, len)) { - errno = 0; + if (!copy_from_user(tmp, name, len)) { + memcpy(system_utsname.domainname, tmp, len); system_utsname.domainname[len] = 0; + errno = 0; } up_write(&uts_sem); return errno; | ![\](/images/icornerr.gif) |